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Show Journal of Neum- Ophtlwlmology 18( 2): 86- 98, 1998. & 1998 Lippincoll- Raven Publishers, Philadelphia Neuro- Ophthalmology of the Pregeniculate Afferent Visual System May, 1997- November, 1997 ( Part II) Laura J. Balcer, M. D., and Steven L. Galetta, M. D. The second half of 1997 was marked by the publication of many timely reports, reviews, and investigations pertaining to the pregeniculate afferent visual system. This review of the neuro- ophthalmologic literature includes the months of May through November, 1997. NEURO- OPTHALMOLOGY AND THE RETINA Paraneoplastic retinopathy was the topic of two reports by Murphy and colleagues ( 1,2). In the first report ( 1), a 74- year- old man was described who presented with rapidly progressive bilateral visual loss. His examination was remarkable for reduced visual acuity, dyschromatop-sia, optic disc pallor, arteriolar attenuation, and mottling of retinal pigment within the macular areas. Electroret-inography showed a 90% reduction in cone function as well as a 50% decrease in rod function. Studies to detect the presence of occult malignancy were unrcvcaling, including chest radiographs, computed tomography ( CT) scans of the abdomen and pelvis, and prostate- specific antigen levels. Cancer- associated retinopathy antibody titers to the 23- kd retinal protein were negative; however, high titers were demonstrated to a novel 60- kd protein. The autoantibodies were found by Western blot analysis to react not only with retinal tissue, but with that from optic nerve, brain, and spinal cord. No reaction of the patient's autoantibody was demonstrated with pineal gland, pituitary gland, or myelin basic protein. Two months later, a follow- up chest radiograph and CT scan revealed a right hilar mass with paratracheal adenopathy. Mediastinoscopic lymph node biopsy demonstrated small cell carcinoma of the lung. Murphy et al. ( 1) thus demonstrated the presence of a novel, yet unidentified, anti- neuronal antibody in a patient with initially occult Manuscript received January 8, 1998; accepted February 25, 1998. From the Division of Neuro- Ophthalmology, Department of Neurology and Ophthalmology, Hospital of the University of Pennsylvania, Scheie Eye Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, U. S. A. Address correspondence and reprint requests to Dr. Steven L. Galetta, Department of Neurology, 3 East Gates, 3400 Spruce Street, Philadelphia, PA 19104, U. S. A. small cell lung carcinoma. The authors ( 1) emphasized that the absence of cancer- associated retinopathy antibody titers to the 23- kd protein may not exclude all cases of paraneoplastic retinopathy. Another patient with a rare paraneoplastic syndrome, bilateral diffuse melanocytic proliferation ( BDUMP), was also described by Murphy et al. ( 2). Bilateral diffuse melanocytic proliferation causes visual loss in patients with occult systemic malignancies, and is characterized by the proliferation of benign melanocytes in both eyes. The patient was a 77- year- old woman with a history of uterine carcinoma who presented with progressive bilateral visual loss to the level of counting fingers. Her examination demonstrated many of the ocular signs typical for this disorder, including elevated intraocular pressures, cataracts, retinal detachments, and patchy yellow and reddish- orange retinal pigment epithelium changes. Markedly dilated conjunctival and episcleral vessels were also present, prompting consideration of carotid- cavernous fistula. Cerebral arteriography was negative. Subsequent examinations revealed pigment cells in the anterior chambers with 1+ corneal endothelial pigment and characteristic choroidal hyperfluorescence on fluorescein angiography. The authors ( 2) emphasized that some of the characteristic features of BDUMP, particularly dilated episcleral vessels and increased intraocular pressures, may initially suggest the presence of a carotid- cavernous fistula. However, the retinal findings may serve as a distinguishing feature of BDUMP. A dominantly inherited multi- infarct syndrome was reported by Jen et al. ( 3) in 11 members of a Chinese- American family. This syndrome, hereditary endotheli-opathy with retinopathy, nephropathy, and stroke ( HERNS), was found to be distinct from CADASIL ( cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) by genetic linkage analysis. The retinopathy, present in all of the 11 family members reported, was characterized by progressive visual loss beginning in the third or fourth decade with macular edema and capillary telangiectasias. Fluorescein angiography was performed in five patients; these studies demonstrated juxtafovealar capillary obliteration with tortuous telangiectatic microaneurysms. Magnetic reso- 86 PREGENICULATE AFFERENT VISUAL SYSTEM: PART II 87 nance imaging ( MRI) showed multifocal areas of high signal in the deep white matter on T2- weighted images. Gadolinium enhancement occurred in patients who had neurologic symptoms. Pathologic examination revealed multilayered vascular basement membranes in the brain, kidney, and other tissues. The mechanism underlying the retinopathy and other manifestations of HERNS was thus thought to be a generalized vasculopathy, with particular involvement of the endothelial cells and basement membranes of capillaries and arterioles. The prevalence of retinal pigment abnormalities associated with the mitochondrial encephalopathy, lactic acidosis, and stroke- like episodes ( MELAS) mitochondrial DNA 3243 point mutation was investigated by Sue and colleagues ( 4). They examined 14 patients from 4 unrelated families using direct and indirect ophthalmoscopy, retinal photography, pattern shift visual evoked potentials, and electroretinography. Symmetric areas of peri-macular depigmentation were noted in eight patients. Fluorescein angiography showed multiple window defects in the retinal pigment epithelium. The authors ( 4) concluded that there was a high prevalence of retinal pigment abnormalities among this small group of patients, and that such findings in patients with MELAS may be more common than previously suggested. That patients with hypertensive retinopathy may have ophthalmoscopic findings similar to those of neuroretini-tis was emphasized by Leavitt et al. ( 5). A 12- year- old girl underwent a routine ophthalmologic examination and was noted to have bilateral optic disc edema with hard exudates. Visual acuities were 20/ 25 in each eye; a CT scan of the brain and serologic studies were unre-vealing. Neuro- ophthalmologic examination 1 year later demonstrated continued bilateral hyperemic disc swelling with macular exudates and star formation. Arteriolar narrowing, arteriovenous " nicking," and peripapillary flame hemorrhages were also present. The patient's blood pressure was noted to be 240/ 148 mm Hg. A renal arteriogram showed focal segmental hypoplasia in the mid- calyx of the left kidney; bilateral grade 2 vesicoureteral reflux was discovered on a voiding cystouro-gram. These abnormalities were consistent with the diagnosis of Ask- Upmark kidney. Leavitt and colleagues ( 5) discussed the importance of considering malignant hypertension in the differential diagnosis for all patients who present with bilateral disc edema and macular star formation. Relative sparing of visual acuity early in the clinical course may help differentiate hypertensive retinopathy from neuroretinitis. Aneurysmal subarachnoid hemorrhage may be complicated by retinal and vitreous hemorrhages. In a study by Frizzell and colleagues ( 6), 99 patients with a history of subarachnoid hemorrhage and angiographically demonstrated cerebral aneurysms underwent ophthalmologic examination to estimate the prevalence of Terson's syndrome ( vitreous and subhyaloid hemorrhage) and other ocular hemorrhages. Each patient in the study was examined by an ophthalmologist at the bedside using direct funduscopy. Although a dilated examination was performed in each case, indirect ophthalmoscopy was not used. Using these methods, 8% of patients were determined to have Terson's syndrome, whereas other types of ocular hemorrhages were present in 17%. As emphasized by the authors ( 6), these percentages may underestimate the true prevalences of ocular hemorrhages and Terson's syndrome in patients with aneurysmal subarachnoid hemorrhage, because the series was noncon-secutive and many of the most severely ill patients were not included. Further studies using indirect ophthalmoscopy and consecutive patient ascertainment may be an important next step in determining the true prevalence of this condition. A comprehensive discussion of Terson's syndrome and other neuro- ophthalmologic manifestations of ruptured and unruptured cerebral aneurysms was presented in a review by Kasner et al. ( 7). The varying patterns of visual loss resulting from compression at the level of the optic nerve, anterior chiasm, posterior chiasm, and optic tract were discussed with the aid of helpful tables and illustrations. THE OPTIC NERVE Optic nerve compression and contact by the carotid artery in asymptomatic patients was the subject of a retrospective study by Jacobson and colleagues ( 8). These investigators sought to estimate the frequency of optic nerve compression or optic nerve contact by the intracranial carotid artery as determined by MRI. Included in the study were 100 patients who had undergone cranial MRI during a 1 - year period and for whom T1 - weighted coronal images had been obtained. Only those patients who had undergone MRI for reasons other than to evaluate the optic nerve or carotid artery were included. For each patient, the coronal image representing the area behind the anterior clinoid process and in front of the optic chiasm was chosen for analysis. The relationship between each optic nerve and carotid artery was then classified using a grading scheme based on the degree of contact or compression ( score 0- 3). The diameter of the carotid artery was also measured to the nearest 0.5 mm. Medical records were reviewed for demographic data and for the presence of vasculopathic risk factors. In 70% of patients, contact between the optic nerve and carotid artery was present to some degree on at least one side. Unilateral or bilateral compression was found in 30%. The presence versus absence of compression was determined to be significantly associated only with increasing carotid artery diameter; hypertension and other factors may not have been present in sufficient numbers of patients to allow for the detection of other associations. Given the high prevalence of carotid artery- optic nerve contact as demonstrated by MRI of asymptomatic patients, the authors ( 8) cautioned against the overinterpre-tation of such findings, even in patients with optic neuropathy. In a series reported by Mizener et al. ( 9), occlusion or severe stenosis of the internal carotid artery was found to be present in 74% of patients with ocular ischemic syndrome. Thirty- two patients ( 39 eyes) with severe ocular ischemia, as manifested by anterior or posterior segment neovascularization, underwent detailed ophthalmologic J Neiiw- Oplilhalmol. Vol. 18, No. 2, I99H 88 L. J. BALCER AND S. L. GALETTA examination and studies of the carotid artery. At the time of initial evaluation, 64% of affected eyes had visual acuities of 20/ 400 or worse. The prognosis for visual recovery was in general poor, with 77% of eyes manifesting 20/ 400 or worse acuity after a median follow- up period of 1 year. Most patients ( 41 % of eyes) presented with sudden visual loss; amaurosis fugax was the initial symptom in 15%. Ipsilateral internal carotid artery occlusion was present in 59% ( 23 of 39 eyes), and ipsilateral severe ( 80- 99%) stenosis was found in 15%. Although the visual benefits of carotid endarterectomy in patients with ocular ischemic syndrome and severe ipsilateral carotid stenosis were not studied specifically, the authors ( 9) emphasized the importance of early diagnosis of carotid stenosis in this situation. That atherosclerotic disease of the carotid artery may be heralded by symptoms of amaurosis fugax, even in the young patient, was discussed in a case report by Slavin ( 10) with comments by Wall and Weinstein. A knowledge of the orbital anatomy and circulation is essential to our understanding of ischemic processes affecting the eye and optic nerve. Ettl et al. ( 11) performed a study of seven normal volunteers to determine whether high- resolution MR1 techniques could be used to construct detailed images of the orbital vasculature and other anatomic structures. Through comparison of MR images with orbital histologic sections, these investigators found that the ophthalmic artery and most of its branches, including the central retinal and posterior ciliary arteries, were visualized. The ophthalmic venous system as well as branches of the third, sixth, and fifth cranial nerves were also successfully imaged. As suggested by the authors ( 11), high- resolution MR1 may be useful in the future for diagnostic purposes, and may aid in the investigation of orbital vascular disorders and optic nerve and retinal ischemia. Risk factors for systemic vascular disease, such as hypertension, diabetes, and smoking, have been observed with high frequencies in patients with nonarteritic anterior ischemic optic neuropathy ( NATON). Jacobson et al. ( 12) performed a retrospective case- control study to examine such conditions as potential risk factors for NAION in 51 patients. Patients were excluded if they were younger than 45 years of age, had a history of previous NAION, had acquired NAION within 2 weeks after surgery, or had signs or symptoms suggestive of giant cell arteritis. Two control groups were used for comparison; the first was a population- based control group from the Marshfield Epidemiologic Study Area ( MESA controls), and the other was a hospital-/ practice-based group consisting of patients evaluated by a Marsh-field Clinic internist or family physician for routine medical care ( comprehensive controls). Three controls per case were selected from the MESA group, matched for age ± 1 year and sex, whereas one control per case, similarly matched, was chosen for the comprehensive control group. Data regarding several potential risk factors, including diabetes, hypertension, hypercholesterolemia, coronary artery disease, chronic obstructive pulmonary disease, current tobacco use, body mass index, hematocrit, creatinine, and white blood cell count, were obtained through review of medical records. The authors ( 12) found that, in this group of patients, only diabetes was significantly associated with NAION for both the MESA control group ( odds ratio = 2.7, 95% confidence interval 1.2- 6.3, P = 0.02) and the comprehensive control group ( odds ratio = 5.0, 95% confidence interval 1.4- 17.3, P = 0.01) in univariate analyses. Jacobson et al. ( 12) emphasized that the detection of significant associations for other potential risk factors may have been limited by the small sample sizes available for the study. As the authors ( 12) also pointed out, larger prospective studies may allow for more complete ascertainment of the presence or absence of potential risk factors, and may allow for the use of multivariate analyses to examine such factors as well as their interactions. That NAION may occur in the setting of a coagulopathy was discussed in a report by Worrall and colleagues ( 13). They described a 61- year- old woman with no known history of vasculopathic risk factors in whom unilateral anterior ischemic optic neuropathy ( AION) developed. Her erythrocyte sedimentation rate ( ESR) was 60 mm/ hour; she had no history of headache, scalp tenderness, or jaw claudication. A temporal artery biopsy was negative for giant cell arteritis. After an extensive evaluation, the patient was found to have laboratory abnormalities consistent with activated protein C resistance. She was maintained on daily aspirin therapy. The authors ( 13) indicated that further studies are necessary to estimate the prevalence of common prothrombotic abnormalities in patients with AION. The time of onset of visual loss in patients with NAION was investigated by Hayreh et al. ( 14) in a study of 635 patients ( 871 eyes, 925 episodes). Among NAION episodes for which information was available, the time of day of discovery of visual loss was examined, as were seasonal variations in the date of onset. Thus, 544 episodes of NAION were examined for time of day of onset; percentages presenting in summer, fall, winter, and spring were determined for 839 episodes. It was found that most episodes had their onset or discovery of visual loss on awakening from sleep in the morning or after a nap ( 51.8% of 544 episodes), or on the patient's first opportunity to use vision for tasks such as reading or shaving ( 21.5% of 544 episodes). Signs and symptoms of NAION were also reported significantly more often ( P = 0.003) during the summer months ( June through August) than during the winter ( December through February). Seasonal monthly onset rates were 82.7 episodes per month for summer, 58.3 for winter, 66.0 for spring, and 72.7 for fall. Confidence intervals for the fall and spring episode rates overlapped those obtained for the summer and winter rates. Hayreh et al. ( 14) suggested that such patterns in the time of day and season of onset may provide helpful insight into the pathogenesis of NAION. As also emphasized by the authors, however, information on the time of day of onset was not available for a large proportion of episodes, and many patients ./ Neum- Oplulwlinol. Vol. IS, No. 2, I99H PREGENICULATE AFFERENT VISUAL SYSTEM: PART II 89 who reported having first discovered visual loss later in the day could not exclude the possibility that their visual loss had been present earlier. This study ( 14) has thus paved the way for future investigations to determine which factors, physiologic or otherwise, may underlie the more frequent discovery of NAION symptoms and signs during the morning hours and during the summer months. Giant cell arteritis was once again emphasized as an important cause of visual loss and other neurologic symptoms ( 15- 18). Amaurosis fugax may be an important initial sign of giant cell arteritis, particularly when symptoms involve both eyes on an alternating basis. Finelli ( 15) described a 77- year- old man with a 3- week history of severe bifrontal headache who experienced numerous episodes of transient monocular visual loss. The first and third episodes, occurring within hours of each other, involved the left eye; the second episode of amaurosis involved the right eye. During the next 3 days, the patient experienced 10 additional episodes in the right eye only. Carotid Doppler ultrasound studies were negative. The ESR was 43 mm/ hour; a right temporal artery biopsy was consistent with giant cell arteritis. The authors ( 15) pointed out that the alternating nature of the patient's amaurosis made the possibility of systemic disease involving both ophthalmic circulations a likely possibility. That patients with giant cell arteritis may present with unusual flow- related brainstem or ophthalmic signs and symptoms was emphasized by Galetta and colleagues ( 16) in a report of two patients. The first patient was an 87- year- old woman who was hospitalized for symptoms of acute unilateral visual loss, headache, and jaw claudication. Her ESR was 57 mm/ hour, and she was placed on intravenous methylprednisolone. A temporal artery biopsy confirmed the diagnosis of giant cell arteritis. On the second hospital day, lethargy, a left internuclear oph-thalmoparesis, a right pronator drift, and ataxia developed in the patient. Magnetic resonance imaging of the brain demonstrated acute infarctions in the dorsal left pons and cerebellum, with evidence of slow blood flow in the basilar artery system. Interestingly, the patient's signs and symptoms consistently improved on lying flat in bed, but would recur within 1 hour of sitting up. These posture- related symptoms improved gradually after the initiation of intravenous heparin and hydration. The second patient was a 78- year- old woman, also with biopsy-proven giant cell arteritis, who experienced recurrent pain and complete blindness in the right eye on the use of bright light for examination. The patient was consistently unable to see out of the right eye for approximately 3 minutes whenever bright light was introduced for more than 5 seconds. These symptoms persisted for 24 days after the initiation of high- dose intravenous methylprednisolone. The authors ( 16) concluded that patients with giant cell arteritis may present with unusual neurologic signs and symptoms. Such manifestations may be blood flow- related, and may thus respond to intravenous hydration and anticoagulation. Cornblath and Eggenberger ( 17) emphasized that some patients with giant cell arteritis may experience severe visual loss that remains progressive even after 48 hours of high- dose intravenous methylprednisolone therapy. They described five patients who experienced worsening of visual loss during the course of intravenous methylprednisolone treatment. Interestingly, worsening of visual loss in all of the five patients reported occurred within the first 24- 96 hours after the initiation of therapy. In four of the five patients, visual acuity was hand motions or worse in at least one eye on admission, indicating the presence of severe disease at the outset in these patients. As emphasized by the authors ( 17), these patients may have presented within a critical period in which severe visual loss or other complications were beyond the point at which intravenous steroid therapy could exert an immediate effect. They also indicate that further experimental studies are needed to determine whether high- dose intravenous versus oral corticosteroid therapy is effective in the prevention or improvement of visual loss in patients with giant cell arteritis. The potential risks and benefits of high- dose intravenous versus oral steroid therapy in elderly patients should also be objectively scrutinized. Krishna and Kosmorsky ( 18) found increased platelet counts in one patient with giant cell arteritis before the initiation of corticosteroid therapy. They described a 77- year- old woman with a 3- month history of weakness, fatigue, weight loss, left temporal headache, and jaw claudication. She had an episode of amaurosis fugax in the right eye and had experienced blurred vision 2 days before examination. Optic disc swelling was present on the left, consistent with AION. The sedimentation rate was 27 mm/ hour and C- reactive protein was elevated at 2.8 mg/ dl ( normal, 0.0- 2.0 mg/ dl). A platelet count obtained before temporal artery biopsy and the initiation of steroids was 981 x 103/| xl. During the first week after platelet plasmapheresis and a 3- day course of high- dose intravenous methylprednisolone, the platelet count was 400 x 103/ pi. As indicated by the authors ( 18), measurement of platelet counts before treatment in large numbers of patients with suspected giant cell arteritis may provide valuable information regarding the prevalence of elevated counts in this group. An elevated platelet count in this situation may represent an acute- phase reactant. That AION may occur in the setting of systemic vas-culitides other than giant cell arteritis was discussed in a report by Schmidt et al. ( 19). They described a 46- year-old woman with bilateral AION and severe visual loss in the setting of Takayasu's arteritis. Bilateral pallid optic disc swelling was present, with a patch of ischemic retina in the left eye. Aortic angiography revealed complete occlusion of the left common carotid artery, left vertebral artery, and brachiocephalic trunk. The right common carotid artery was reconstituted by collaterals; however, the left ophthalmic artery was not demonstrable. The authors ( 19) emphasized that AION in this setting is rare and is usually accompanied by signs of chronic ocular hypoxia, such as retinopathy and microaneurysm formation. J Ncum- Oplilhalmol, Vol. 18, No. 2, 1998 90 L. ./. BALCER AND S. L. GALETTA To determine whether the ophthalmoscopic features of optic disc swelling may be useful in distinguishing AION from optic neuritis, Warner and colleagues ( 20) performed an analysis of 155 stereophotographs. Of the patients for whom photographs were available for examination, 87 ( 56%) had been assigned the diagnosis of NATON, and 68 ( 44%) had been diagnosed with optic neuritis. Masked examinations of each available optic disc photograph were performed by four neuro-ophthalmologists. Each reviewer examined each photograph to evaluate optic disc color ( normal, hyperemic, pale, both), distribution of edema ( diffuse, altitudinal), presence or absence of hemorrhages, and caliber of the veins and arterioles ( normal, arterial attenuation, venous dilation, both). The majority opinion on each photograph was used to determine a consensus for each optic disc feature. Photographs for which there was complete disagreement were excluded from the analysis. Based on the percentages of patients with NAION versus optic neuritis whose photographs demonstrated various characteristics, the authors ( 20) concluded that some features optic disc appearance, particularly the altitudinal versus diffuse pattern of edema and the presence or absence of hemorrhages, may be helpful in distinguishing NAION from optic neuritis. However, as the authors also pointed out, the percentages of cases for which there was complete agreement regarding the distribution of optic disc edema, disc color, and vessel description were low ( 50% for edema distribution, 20% for color and vessel description), thus emphasizing the often subjective nature of fundus photograph review. In a 5- year follow- up, the Optic Neuritis Study Group ( 21) found the cumulative probability of clinically definite multiple sclerosis ( CDMS) to be 30%. This risk did not change, regardless of initial treatment with oral prednisone, intravenous methylprednisolone, or placebo. However, those patients with a negative baseline MRI had only a 16% 5- year risk of CDMS, compared with 51% in those with three or more MRT lesions. Those patients with one to two white matter lesions had 37% chance for development of CDMS. Of interest, multiple sclerosis did not develop in any patient in this 5- year follow- up period with a negative MRI who had 1) painless visual loss, 2) severe optic edema, 3) disc or peripapillary hemorrhage, or 4) macular exudates. This study ( 21) once again emphasized that the brain MRI obtained at the presentation of optic neuritis is the single most important predictor of multiple sclerosis risk. Compared with adults, the risk for development of multiple sclerosis after childhood optic neuritis is less. Lucchinetti et al. ( 22) found in a life table analysis of 79 patients that clinically or laboratory- suggested definite MS would develop in 13% after 10 years of follow- up. By 20 years, that risk rose to 19%. In adults, it is known that the 5- year risk of clinically definite MS after optic neuritis is 30%. There was increased risk for development of multiple sclerosis in those patients with sequential or recurrent optic neuritis compared with those who had unilateral or bilateral simultaneous involvement. For the purposes of this study, " sequential" was defined as optic nerve involvement that was separated by at least 2 weeks; " recurrent" was defined as an event occurring greater than 3 months after the initial event. Uhthoffs phenomenon is usually seen in the setting of demyelinating optic neuritis, but Haupert and Newman ( 23) reported a patient with sarcoidosis of the optic nerves and chiasm who reportedly experienced exacerbations of visual loss after exposure to heat. Her visual loss was steroid responsive and was prolonged compared with the typical Uhthoff symptom experienced by patients with optic neuritis. However, the authors ( 23) emphasized that patients with visual loss exacerbated by heat may have inflammatory conditions of the anterior visual pathways other than demyelinating optic neuritis. In atypical cases, a search for sarcoidosis and other inflammatory diseases should be undertaken. The patient described by Haupert and Newman ( 23) had a serum angiotensin- converting enzyme ( ACE) level of 53 units/ 1, just slightly above the normal range of 8 to 52 units/ 1 for their laboratory. How useful is the serum ACE level in making a clinical diagnosis of ocular sarcoidosis in patients with intraocular inflammation? Stavrou et al. ( 24) compared the ocular manifestations and clinical course in a group of patients with biopsy-proven sarcoidosis ( 18 patients) versus a group with intraocular inflammation and elevated ACE levels ( 22 patients) for whom histologic diagnosis was not practical or possible. The authors ( 24) found that various ocular manifestations, most commonly retinal vasculitis and panuveitis, were not significantly different between the two groups. They emphasized the importance of careful periodic evaluation in patients with ocular findings and elevated ACE levels. The neuro- ophthalmic manifestations of several unusual cancers and their effect on the orbit and anterior visual pathways were described in a series of reports ( 25- 28). Lee and colleagues ( 25) reported the clinical and neuroradiologic findings of two patients with intracranial adenoid cystic carcinoma. One of these patients had severe visual loss secondary to optic nerve involvement. Ing ( 26) presented a 63- year- old woman with non- Hodgkin's lymphoma who experienced progressive visual loss and an orbital apex syndrome secondary to presumed tumor involvement. A 73- year- old woman with optic nerve compression due to an intracranial plasmacytoma in the setting of multiple myeloma was reported by Maini and Macewen ( 27). In retrospect, this patient's first symptoms referable to her disease had been a several- month history of intermittent blurred vision in the right eye. Finally, a rare presentation of a rare tumor was described by Watkins et al. ( 28). They reported a 71 - year- old woman with a history of acute myelogenous leukemia in remission in whom proptosis and optic neuropathy developed secondary to an orbital granulocytic sarcoma. Such tumors, composed of immature granulocytes and sometimes referred to as chloromas, are not only uncommon, but are most often diagnosed in pediatric patients. ./ Neum- Oplilhalnml, Vol. 18, No. 2, 1998 PREGENICULATE AFFERENT VISUAL SYSTEM: PART II 91 The potential for development of anterior visual pathway gliomas in patients with neurofibromatosis type 1 ( NF- 1) and previously negative neuroimaging studies was emphasized by Massry and colleagues ( 29). They reviewed the records of 360 patients with NF- 1; in this group of patients, 28 had CT or MRI scans with demonstrated optic gliomas. Two of the 28 patients with radiographic evidence of such gliomas had undergone previous imaging studies that had demonstrated normal visual pathways. The scans that had revealed the optic gliomas in these two patients were performed at 39 and 35 months of age, with initial scans having been obtained at 2.5 and 19 months of age, respectively. Combining this experience with that of previous authors, Massry et al. ( 29) emphasized the importance of careful follow- up in children with NF- 1, even in the setting of previously normal neuroimaging studies. Optic neuropathies and other disorders of the anterior visual pathways may occur not only as a result of primary and metastatic tumors, but may be caused by cancer therapies. This is emphasized by three reports ( 30- 32). A case report and discussion highlighting the potential ocular and orbital complications of intra- arterial cisplatin was presented by Wu et al. ( 30). After partial surgical resection of a right frontal glioblastoma, a 26- year- old woman received intra- arterial cisplatin that was infused under angiographic guidance directly into the right supraclinoid carotid artery above the origin of the ophthalmic artery. Thirty- six hours after the second monthly infusion, the patient experienced right facial and periorbital edema with proptosis, chemosis, ophthalmo-paresis, and reduced vision to bare light perception. Pallid optic disc swelling, choroidal folds, an inferonasal serous retinal detachment, and multiple serous pigment epithelial detachments were noted in the right eye. Fluorescein angiography showed extensive retinal nonperfu-sion. No visual recovery occurred over a subsequent 3- month period. Another patient, reported by Csaky and Caruso ( 31), had bilateral visual loss and optic neuropathy after intravenous gallium nitrate therapy. This 77- year- old man received five courses of gallium nitrate as treatment for moderately differentiated adenocarcinoma of the prostate with spinal metastases. After the fifth monthly course of treatment, the patient noted visual loss in both eyes of sudden onset. Bilateral central scotomas were present, with visual acuities of 20/ 50 on the right and 5/ 200- 2 on the left. There was mild optic nerve pallor and arteriolar attenuation in the left eye. An electroretinogram was negative; however, the P2 wave was diminished in amplitude on visual evoked potential testing. Although his vision progressively worsened despite oral prednisone therapy, the patient did experience some recovery during the next 12 months while receiving ferrous sulfate. The reasons behind the apparent reversal of visual loss with ferrous sulfate therapy in this patient include the fact that gallium nitrate may interfere with the function of oligodendrocytes by binding to transferrin receptors ( 31). Optic neuropathy is a known potential complication of conventional external- beam cranial radiation therapy. However, radiation optic neuropathy has been reported much less commonly after stereotactic gamma- knife radiosurgery. Girkin and colleagues ( 32) described the clinical and neuroimaging findings of four patients in whom optic neuropathy developed 7 to 30 months after gamma- knife radiation treatment for perichiasmal tumors. All of the patients experienced visual loss of abrupt onset, and three of four had characteristic MRI findings of enhancement and focal swelling of the optic nerve and anterior chiasm. Only one patient had slight improvement of visual acuity ( from 20/ 50 to 20/ 30) after corticosteroids; one patient received hyperbaric oxygen therapy in addition to steroids but the vision did not improve. Because three of the four patients reported had received radiation doses to the visual pathways above the recommended maximum dose of 8 Gy, the authors suggest that careful planning of radiation therapy using MRI guidance and minimization of dosing may help to reduce the potential for this rare complication of stereotactic radiosurgery. Optic neuropathies occurring secondary to local and systemic infectious processes were the topic of numerous reports and reviews ( 33- 36). The neuro- ophthalmic complications of the ubiquitously feared, potentially fatal entity of rhino- orbital mucormycosis were discussed in two reports ( 33,34). Balch et al. ( 33) presented a 66- year- old diabetic woman in whom a painless orbital apex syndrome with progressive ophthalmoparesis, proptosis, and visual loss developed. MRI showed only mild opacification of the right sphenoid sinus, but this area was located close to the involved orbital apex. A transsphenoidal mucosal biopsy confirmed the suspected diagnosis of mucormycosis. The patient's visual acuity improved from count fingers at 1 foot to 20/ 100 after a 3- month course of intravenous amphotericin B. In the second report, Langford and colleagues ( 34) presented a new method of surgical debridement for rhino- orbital mucormycosis that uses serial frozen sections for intraoperative guidance in determining the necessary extent of resection. The patient was a 43- year- old, previously undiagnosed diabetic woman who experienced right eye and facial pain with swelling, proptosis, and reduced facial sensation. A frozen- section- guided surgical debridement was performed, followed by 6 weeks of intravenous amphotericin. The patient had no recurrence as of 34 months after surgery; her vision was normal with no diplopia. In conjunction with systemic antifungal therapy, this method may reduce the need for complete orbital exenteration. Balch et al. ( 33) and Lang-ford et al. ( 34) both emphasized the crucial importance of early suspicion and diagnosis of rhino- orbital mucormycosis when suggestive signs and symptoms are present, even in patients who lack pain or a known history of diabetes. Bafna and Lee ( 35) presented a rare case of cavernous sinus syndrome as a presenting feature of extrapulmonary tuberculosis. The patient was a 65- year- old woman who described a 1- month history of right periorbital pain ./ Neum- Ophlhalmol, Vol. 18. No. 2, 1998 92 L. J. BALCER AND S. L. GALETTA and ptosis. Visual acuity in the right eye was 20/ 400; however, no afferent pupillary defect or other findings consistent with optic neuropathy were present. The reduced visual acuity was attributed to a corneal ulcer and cataract. The diagnosis of tuberculosis was made through a biopsy of an enlarged cervical lymph node; a chest radiograph was negative. Optic nerve dysfunction and other neuro- ophthalmic manifestations of Lyme disease were reviewed by Balcer et al. ( 36). They emphasized that optic nerve disease in this setting occurs most often in the setting of papilledema in patients with meningitis or menigoencephalitis. At the same time, the authors ( 36) cautioned against the sole use of Lyme serologies in the determination of etiology for patients with optic neuritis and positive titers. Optic nerve dysfunction in patients with cryptococcal meningitis may be a manifestation of papilledema or result from direct inflammatory infiltration of the optic nerve. Ferreira and colleagues ( 37) described a 15- year-old girl who had excellent recovery of vision after treatment. The patient, who had a history of systemic lupus erythematosus, experienced headache and diplopia. Decreased vision also ensued, with visual acuities of count fingers in the right eye and 20/ 25 on the left. The optic discs were swollen with peripapillary hemorrhages. A CT scan was negative and a lumbar puncture showed a markedly elevated opening pressure. Cryptococcal meningitis was diagnosed. She was treated with oral fluconazole, acetazolamide, and dexamethasone. After worsening of her right eye acuity to no light perception, the dose of dexamethasone was increased and she underwent serial lumbar punctures to decrease intracranial pressure. Over a 2- week period, visual acuity improved to 20/ 20 in both eyes. Although the authors ( 37) stated that they could not completely exclude the possibility of coincident optic neuritis secondary to systemic lupus in this case, and spinal fluid cryptococcal antigen results and cell counts were not given in this report, they emphasized the importance of early and aggressive treatment in all patients with cryptococcal meningitis in an effort to preserve vision. Pseudotumor cerebri is a widely studied cause of increased intracranial pressure and papilledema. In patients who have severe visual loss refractory to medical therapies, optic nerve sheath fenestration ( ONSF) is often used as the treatment modality of choice. To examine the efficacy of this procedure in a cohort of patients with pseudotumor cerebri, Goh et al. ( 38) reviewed the outcomes of 19 patients ( 29 eyes) who underwent ONSF. Thirteen women and six men were included in this retrospective case series, ranging in age from 16 to 52 years ( mean, 33 years). All patients satisfied clinical criteria for the diagnosis of pseudotumor cerebri, and all had been initially treated with acetazolamide 1.5 g/ day orally without improvement of vision. Patients were examined before and after surgery with respect to Snellen visual acuity and Humphrey 30- 2 or Goldmann perimetry at 1 and 6 months. Visual improvement was defined as an increase in Snellen acuity by two lines or improvement by three levels on gross acuity testing ( i. e., count fingers to 20/ 400). A 5- decibel increase in Humphrey mean deviation or 20- degree increase in an isopter on Goldmann perimetry were considered improvements in the visual field. Masked readers were asked to evaluate the visual fields. One month after surgery, 27 of 29 eyes demonstrated the same or improved visual acuity; there was deterioration in two patients. At 6 months, visual acuity was unchanged from before surgery or improved in 15 eyes ( one patient was lost to follow- up and one additional patient demonstrated deterioration). Improvement of visual fields also occurred in 16 of 28 eyes by 1 month after surgery, whereas 7 eyes did not change and 4 worsened. Of 17 eyes for which 6- month visual field data were available, 9 had improved, 5 were unchanged, and 2 had worsened. Interestingly, not only was improvement or stabilization of acuity and visual field noted in most of the operated eyes, but the authors found that of the nine nonoperated eyes in this series, three improved and six showed no change. None of the contralateral eyes deteriorated. The authors ( 38) thus concluded that ONSF may indeed result in the stabilization or improvement of vision in the operated and nonoperated eyes of patients with pseudotumor cerebri and visual loss refractory to medical therapy. Although no surgical complications occurred in the patients reported by Goh et al. ( 38), ONSF may, in some cases, result in complete blindness, possibly secondary to optic nerve traction injury, ischemia, or edema ( 39). That such blindness may be reversible or improve was demonstrated in one patient reported by Brodsky and Rettele ( 39). A 22- year- old woman with pseudotumor cerebri underwent ONSF in the right eye through a medial approach. Preoperative visual acuities were 20/ 80 in the right eye and 20/ 70 on the left, with marked visual field constriction to 5 to 10 degrees in each eye by Humphrey 30- 2 testing. Her vision in the operated right eye was no light perception 6 hours after surgery. Ophthalmoscopic findings were unchanged; it is not noted whether the pupil was amaurotic. Intravenous methylprednisolone was begun at a dose of 250 mg four times per day. Acetazolamide was also given. During the first 36 hours, the right eye did not improve, but, interestingly, the left eye acuity improved to 20/ 30, with expansion of the left visual field. However, after the first 36 hours, the patient began to detect hand motions in the right eye; acuity in that eye later improved to 20/ 80 by 3 weeks and 20/ 30 by 3 months after surgery. Visual field testing continued to show constriction to 5 degrees in the right eye, with a normal field on the left. Diffuse optic atrophy was present on the right. The authors ( 39) pointed out that it remains unknown whether high- dose intravenous steroid therapy influenced this patient's recovery because improvement continued well beyond discontinuation of the steroid taper. However, this case did illustrate that visual recovery may occur even in the setting of apparent blindness after ONSF. Several proposed mechanisms of reversible optic nerve dysfunction, including axonal demy-elination secondary to stretch injury, were discussed. ./ Neuro- Ophthalmol, Vol. IS, No. 2, 1998 PREGENICULATE AFFERENT VISUAL SYSTEM: PART II 93 The appropriate role of lumboperitoneal shunting in the surgical management of pseudotumor cerebri was examined in an investigation by Burgett et al. ( 40). They reviewed their experience with 30 patients with pseudotumor cerebri who had undergone lumboperitoneal shunting at any time after or before initial neuro-ophthalmologic consultation. Data were obtained for each patient by retrospective chart review, and included age, sex, race, associated medical conditions ( e. g., obesity), indication for shunting, and effect of the procedure on symptoms and signs. Improvement in Snellen acuity was again defined as a change of at least two lines; an increase of at least 5 degrees in at least one quadrant for 2 isopters defined improvement on Goldmann perimetry. Of the 30 patients who had lumboperitoneal shunting, 19 required at least one revision during a mean follow- up of 34.9 months. Four patients required 10 or more revisions for malfunction; however, shunt infection was not reported in any patient. Seventeen of the 30 patients were examined both before and after surgery by one of the authors ( V. A. P.). Among this group, 13 experienced significant improvement in symptoms ( most frequently headache) after shunting. In terms of visual function, 10 of 14 eyes with preoperative visual acuity of 20/ 30 or worse improved by at least two lines after surgery. Of the 34 eyes for which Goldmann perimetry was performed, abnormal preoperative fields were present in 28. Among these abnormal eyes, 5 were normal after surgery, 13 demonstrated improvement, and 8 remained unchanged. Of 25 eyes judged to have severe papilledema before shunting, 24 had complete or near complete resolution of disc swelling after surgery. Based on their data and those of previous series, Burgett et al. ( 40) concluded that lumboperitoneal shunting is in general a safe and effective alternative surgical treatment for patients with pseudotumor cerebri and medically refractory headache and visual loss. The exact pathophysiologic mechanisms that underlie the increased intracranial pressure in pseudotumor cerebri are unknown. Sugerman and colleagues ( 41) performed a prospective study to determine if patients with central obesity and pseudotumor cerebri have increased intra- abdominal and cardiac filling pressures. The authors hypothesized that such pressures may be elevated in patients with central obesity, thus contributing to increased intracranial pressure through a decrease in venous return from the brain. Six patients with severe obesity ( defined as body mass index 5^ 35 kg of weight per meter squared of height) and pseudotumor cerebri underwent gastric bypass surgery. During the surgical procedure, measurements of intra- abdominal pressure, as estimated by urinary bladder pressure, were obtained. Central venous pressure, pulmonary artery pressure, and pulmonary artery wedge pressure were determined after insertion of a central venous catheter. These pressures served as measures of cardiac filling pressure. Transesophageal pleural pressure was also determined. Compared with values previously observed in a study of morbidly obese patients without pseudotumor cerebri, measures of cardiac filling pressure were significantly higher ( P < 0.001) in the current group of patients. Cardiac filling pressures were also markedly elevated in the six study patients compared with published normal values. The authors ( 41) proposed that increased intraabdominal pressure, with consequent increased intrapleural and cardiac filling pressures, may impede venous return from the brain, thus contributing to increased intracranial pressure. The characteristics and prevalence of associated conditions in children and adolescents with pseudotumor cerebri were examined by Scott et al. ( 42). They reviewed the records of 22 patients aged 18 years or younger who were diagnosed with pseudotumor cerebri during an 8- year period at the Bascom Palmer Eye Institute and the Arkansas Children's Hospital. Data from these 22 patients was combined with those from previously published series, and numbers and proportions of patients with obesity and other conditions were reported. Among the combined series, 374 patients were identified, 199 of whom were female ( 53.2%). In the series of Scott et al. ( 42) alone, 77.3% of the 22 patients were female. In the combined group of 374 patients, data regarding obesity were available for 169 patients; among these, obesity was noted in 50 ( 29.6%). As the authors ( 42) pointed out, criteria used in the current and previously published series for the determination of obesity were not reported. In the series by Scott et al. ( 42), 2 of 22 patients were reported to be obese. The authors ( 42) also emphasized, however, that these data suggest that obesity and female sex may be less commonly associated with pseudotumor cerebri in patients aged 18 years and younger. Because the pediatric age group included both young children and adolescents, further studies are needed to determine how increasing age may affect the likelihood of obesity in children with pseudotumor cerebri. Increased optic nerve subarachnoid fluid may be noted on ultrasound or MRI studies in patients with increased intracranial pressure and papilledema. Lam et al. ( 43) performed a prospective observational study to determine the amount of optic nerve subarachnoid fluid in normal adults using MRI. They also sought to determine if subarachnoid fluid of the optic nerve is displaced by abduction of the eye, as has been reported using 30- degree A- scan echography testing. Twenty- three healthy adult volunteers with no previous history of headache, systemic disease, or neurologic or ophthalmic disease ( other than refractive error), underwent MRI of the optic nerves. T2- weighted coronal images with fat saturation were obtained; two patients were excluded from analysis because of the presence of motion artifacts. Images were obtained with the eyes in primary, extreme right, and extreme left gaze. Horizontal and vertical measurements of optic nerve and sheath diameter were made for each of four imaging planes perpendicular to the optic nerve axis. Mean nerve and sheath diameters were then calculated for each direction of gaze ( primary, right, left) based on data from each of the 21 volunteers ( 42 eyes) J Newo- Ophthalmol, Vol. 18. No. 2, 1998 94 L. J. BALCER AND S. L. GALETTA included in the study. Using the paired Mest to compare mean sheath diameters in abduction and adduction with those in primary gaze, no significant differences were found. Although not statistically significantly different, mean optic nerve sheath diameters in abduction and adduction were actually slightly larger than those obtained in primary gaze. In these normal volunteers, MRI also showed that optic nerve subarachnoid fluid was not displaced or compressed in lateral gaze. The authors ( 43) concluded that T2- weighted MRI may be used effectively to assess the amount of optic nerve subarachnoid fluid, and that the amount of fluid may vary substantially between patients, even among those without signs or symptoms of increased intracranial pressure. Hansen and Helmke ( 44) investigated the response of the optic nerve sheath diameter to changes in spinal fluid pressure in 12 patients undergoing intrathecal infusion tests to evaluate suspected spinal fluid absorption disorders. Serial B- mode ultrasound scans of the anterior optic nerve were performed during the spinal fluid absorption studies, which involved intermittent lumbar intrathecal infusions with monitoring of spinal fluid pressure. Increases in optic nerve sheath diameter were clearly documented in all patients during the intrathecal infusion, exhibiting direct covariance with increasing and decreasing spinal fluid pressures. The mean change in baseline sheath diameter was 1.8 mm, corresponding to an average increase of 45% from baseline. This relationship between increasing spinal fluid pressure and sheath diameter varied between individual patients with respect to the magnitude of diameter change for a given change in pressure. This study documented in vivo that the relationship between optic nerve sheath enlargement and increased intracranial pressure is indeed present and detectable by B- scan ultrasonography, but may vary from patient to patient. Leber's hereditary optic neuropathy ( LHON) was the subject of numerous studies and reports. The 14484 mitochondrial DNA mutation has been associated with a higher incidence of visual recovery compared with other primary mutations ( 1 1778 and 3460) in the white population. Four Japanese patients with LHON were reported by Yamada and colleagues ( 45), three of whom likewise experienced visual recovery in the setting of the 14484 mutation. Visual acuities at worst for all four patients ranged from 20/ 200 to 2/ 200; central and cecocentral scotomas were described in all patients. One patient recovered vision within 2 years to 20/ 20 in both eyes. Two of the others recovered to the 20/ 25 to 20/ 50 range in both eyes. Thus, Japanese patients with LHON and the 14484 mutation may have a similar incidence of visual recovery as is found in white patients ( approximately 50% in many series). This finding suggests that disease occurrence and severity in patients with the 14484 mutation may be more dependent on epigenetic factors than in those with other Leber's mutations. As emphasized by Biousse et al. ( 46), the de novo occurrence of a mitochondrial DNA point mutation in a patient with LHON is rare. However, these authors ( 46) described a pair of monozygotic twin brothers, only one of whom showed clinical evidence of LHON, who demonstrated the occurrence de novo of the 14484 mutation. Extensive testing of mitochondrial DNA from multiple cell types in the twins' mother did not reveal the mutation. Interestingly, the 14484 mutation was heteroplas-mic in both the twin brothers; such heteroplasmy ( coexistence of both mutant and wild- type mitochondrial DNA in the same individual) has been thought to explain some of the variation in clinical expression among patients with mitochondrial DNA mutations. In fact, work by Carelli and colleagues ( 47) on the bioenergetic relevance of mitochondrial DNA mutations in LHON suggested that differential tissue heteroplasmy may also be important in determining disease penetrance. The effects of each of the three primary LHON mitochondrial DNA mutations ( 11778, 14484, 3460) on in vivo skeletal muscle mitochondrial function were investigated by Lodi et al. ( 48) in a study of patients with LHON and carriers. Phosphorus ( 3IP) magnetic resonance spectroscopy was performed in one affected patient and two carriers with each mutation ( three carriers were examined with the 14484 mutation). This study demonstrated that, although skeletal muscle mitochondrial function is clinically spared in patients with LHON, some abnormalities, including below- normal phosphorylation potentials at rest, were found in all cases. Mitochondrial adenosine triphosphate ( ATP) production rates after exercise were reduced to 27% of normal in patients with the 11778 mutation and to 53% of normal in those with the 14484 mutation. Only mild reduction of mitochondrial function was seen in those with the 3460 mutation because rates of ATP production were normal. Overall, the greatest degree of reduction in mitochondrial ATP production rates was demonstrated for the 11778 mutation. The authors ( 48) suggested that compensatory mechanisms present in skeletal muscle but not in the optic nerve or other central nervous system structures may allow for the absence of clinical muscle involvement in patients with LHON. Optic nerve avulsion is a severe form of traumatic optic neuropathy in which the optic nerve is disinserted from the retina, choroid, and vitreous with retraction of the lamina cribrosa from the scleral rim. Foster and colleagues ( 49) retrospectively reviewed the records of six patients with documented partial or complete traumatic optic nerve avulsions. Their objective was to characterize further the clinical features and course in such patients and to examine the diagnostic role of neuroimaging studies. All of the six patients had received blunt traumatic injuries. Initial visual acuities were no light perception or light perception in all but one patient; this individual had an initial acuity of 20/ 100 and was the only patient to exhibit visual recovery. Of the imaging modalities used in these patients ( CT scanning in five patients, MRI in two patients, B- scan ultrasonography in four patients, and color Doppler ultrasound in one patient), only CT scanning demonstrated findings suggestive of optic nerve avulsion in a single patient. In this patient, an area ./ Ncitro- Ophthalmol, Vol. IS, No. 2, 1998 PREGENICULATE AFFERENT VISUAL SYSTEM: PART II 95 of hypolucency at the junction of the affected optic nerve and globe as well as a hyperdensity suggestive of a ret-rodisplaced lamina cribrosa were seen on the CT scan. None of the other imaging techniques revealed abnormalities in this patient or in others. The authors ( 49) concluded that, at present, neuroimaging or ocular imaging may not add significantly to the clinical examination of patients with optic nerve avulsion. Ford et al. ( 50) described another patient with optic nerve avulsion secondary to forceful traumatic globe rotation during a diving accident. This 17- year- old boy jumped feet- first into a river from a height of 50 feet. While holding his nose with his right thumb and index finger, his right thumb was pushed upward toward the medial aspect of his right globe on impact with the water. Immediately after the accident, the patient noted no light perception in the right eye; this was confirmed by a neuro- ophthahnic examination 8 hours later. Ophthalmoscopy revealed temporal separation of the optic nerve head from the sclera. Vitreous hemorrhage was also noted. Enlargement of the optic nerve was seen on a CT scan. The patient's vision did not improve after 48 hours of intravenous spinal cord trauma- dose steroid therapy. The authors ( 50) proposed, with carefully designed illustrations, that the mechanism of avulsion in this case was a sudden, forcible medial rotation of the posterior globe caused by insertion of the thumb into the medial orbit. The safety of the commonly used practice of nose holding while jumping into water was questioned by the authors. THE OPTIC CHIASM AND BEYOND " Why fatheads just don't see" was explored in a Feature Photo by Kosmorsky and Straga ( 51). They presented a 61- year- old woman in whom blurred vision and bitemporal hemianopsia developed. Magnetic resonance imaging disclosed a 2.1- cm suprasellar pituitary mac-roadenoma with compression of the optic chiasm. A transsphenoidal resection was performed with fat packing in the operative bed. One week later, after the patient experienced headache and worsening of visual acuity, the fat packing graft, thought to be causing compression of the chiasm, was removed. Significant improvements in the Humphrey visual fields (> 12 decibels in mean deviation) and visual acuities were noted by the third postoperative day. The authors ( 51) pointed out that although packing with subcutaneous fat is often done to prevent spinal fluid leakage or chiasmal prolapse after pituitary adenoma resection, such packing may likewise lead to chiasmal compression and reversible visual loss. A case of " unusual scotomas" after transsphenoidal surgery for a pituitary macroadenoma was described by Dollfus et al. ( 52). Seven days after surgery, scotomas developed in a 30- year- old woman in a " necklace"- like pattern in the lower temporal fields of the right and left eyes. Magnetic resonance imaging did not demonstrate any evidence of hemorrhage or arachnoiditis. The patient received 3 days of intravenous methylprednisolone ( 50 mg/ day) followed by oral prednisone; the visual defects resolved within 4 days of starting the steroid therapy. Although the exact etiology of the scotomas was unclear, the authors ( 52) raised the possibility of postoperative inflammation affecting the vascular supply to the optic tract as one potential mechanism for the patient's visual disturbance. Penetration of the optic chiasm by a ruptured anterior communicating artery aneurysm was reported in one patient by Date et al. ( 53). This rare complication of aneurysmal rupture occurred in a 40- year- old man who presented with sudden onset of headache, left homonymous hemianopsia, and count fingers vision in the right eye. A 7- mm anterior communicating artery aneurysm was revealed by angiography after CT scanning had disclosed a hyperdense suprasellar mass. During surgery, it was noted that the thrombosed dome of the aneurysm had penetrated the right chiasm and had also caused compression of the adjacent optic tract. The aneurysm was successfully clipped, but the patient's visual deficits did not resolve. According to the authors ( 53), this case represented the first report of a patient with visual loss in the setting of chiasmal penetration by a ruptured anterior communicating artery aneurysm. Visual field defects suggestive of chiasmal disease developed in a patient reported by Groom and colleagues ( 54) with familial dysautonomia ( Riley- Day syndrome). This 45- year- old man of Ashkenazi Jewish descent had a history of progressive visual loss. Examination revealed visual acuities of 20/ 50 in each eye, bilateral dyschro-matopsia, and central scotomas with a suggestion of temporal depression of computerized perimetry. The optic discs were pale. Several other abnormalities characteristic of familial dysautonomia were present, including ovoid pupils, corneal scarring, and absent fungiform papillae of the tongue. Because the patient refused neuroimaging, chiasmal compression secondary to an unrelated process could not be ruled out. However, the authors ( 54) emphasized that optic atrophy may present as a rare manifestation of familial dysautonomia, especially because patients with this disorder are living longer. Pendular see- saw nystagmus is a neuro- ophthal-mologic sign usually associated with bitemporal hemianopsia and chiasmal compression. That such nystagmus may present in patients with visual loss secondary to retinal or other ocular disease alone was demonstrated by a patient described by May and Truxal ( 55). A 23- year-old man noted central visual loss that progressed over several years. Electroretinography and retinal examination demonstrated findings consistent with autosomal recessive cone- rod dystrophy. By 40 years of age, visual acuities were hand motions at 2 feet; pendular see- saw nystagmus was noted. A neurologic examination was otherwise negative. On MRI, no abnormalities of the optic chiasm, midbrain, or thalamus were revealed. The nystagmus was not present in the dark, suggesting, according to the authors ( 55), a complex vision- dependent mechanism for see- saw nystagmus in the setting of ocular disease. A unilateral temporal visual field defect associated J Neuro- Ophlhalmol, Vol. 18, No. 2, 199H 96 L. J. BALCER AND S. L. GALETTA with compression or other disease of the ipsilateral optic nerve at its junction with the anterior chiasm is referred to as the " junctional scotoma of Traquair." A pituitary microadenoma was the cause of such a defect in a 26- year- old woman reported by Mojan et al. ( 56). She presented with blurred vision in the left eye, and was noted to have 20/ 30 visual acuities bilaterally, a left afferent pupillary defect, and mild dyschromatopsia. Both computerized and Goldmann visual field testing demonstrated a paracentral temporal scotoma in the left eye that respected the vertical meridian. A 2.5 x 1.5 x 1.5- cm enhancing suprasellar mass was demonstrated by MRI, and prolactin levels were markedly elevated. Minimal paracentral decreased sensitivity in the left eye on computerized perimetry remained after transsphenoidal resection of the pituitary adenoma. The authors ( 56) emphasized the distinction between junctional scotoma of Traquair, caused by lesions to nasal crossing fibers at the anterior angle of the chiasm, and the more familiar " junctional scotoma" resulting from ipsilateral optic nerve and contralateral crossed nasal fiber involvement. The neuroimaging and visual findings of two patients with junctional field loss were presented in a radiologic-clinical correlation by Lee et al. ( 57). One patient, a 46- year- old woman with a giant internal carotid aneurysm, demonstrated visual loss consistent with a junctional scotoma. She had no light perception in the right eye and a superotemporal defect in the left. A second patient had a suprasellar meningioma and a junctional scotoma of Traquair. These authors ( 57) likewise discussed the localization and differential diagnosis of chiasmal visual field defects. Two reports ( 58,59) serve as reminders to neuro-ophthalmologists that suprasellar masses and tumors of the anterior visual pathways should be considered in children who present with unexplained visual loss. Lee et al. ( 58) described a 6- month- old infant who was initially noted to have " peculiar eye movements" at 3 months of age. Optic nerve hypoplasia was noted on funduscopic examination. A large suprasellar mass was discovered on CT and MRI; the pathologic results after resection were consistent with a benign teratoma. A 13- year- old girl reported by Roh et al. ( 59) had been previously diagnosed with amblyopia in her right eye. She was subsequently found to have a junctional scotoma and bilateral optic nerve pallor. Transsphenoidal biopsy and debulk-ing of a large intrasellar mass revealed glial tissue with prominent Rosenthal fibers, consistent with a juvenile pilocystic astrocytoma. Optic tract compression by the anterior cerebral artery was noted in a patient with craniopharyngioma and visual field defects ( 60). Huang and colleagues ( 60) described an 18- year- old man who experienced decreased vision in the right eye associated with headaches and lethargy. Visual acuity in the right eye was 20/ 400, with 20/ 30 acuity in the left. Goldmann visual field testing disclosed a dense left homonymous hemianopsia with evidence also of a right superior temporal quadrantanop-sia. The patient underwent transsphenoidal decompression and subsequent craniotomy with resection for a large calcified suprasellar mass; a large cyst cavity within the tumor was noted. During surgery, it was discovered that the right anterior cerebral artery had been pressed against the superior surface of the optic tract, forming a groove in this structure. A tabular summary of visual field defects reported in the literature in patients with craniopharyngiomas was also presented with a review by the authors ( 60). Not surprisingly, the most common abnormalities were bitemporal defects, present in 346 of 911 patients. Normal visual fields were reported in 211 patients, whereas 152 had homonymous defects. Less commonly associated with craniopharyngioma were unilateral and bilateral blindness, unilateral temporal defects, generalized constriction, and isolated scotomas. Among those with bitemporal defects, the proportions having predominantly superior versus inferior visual field involvement were not presented. BASEBALL AND THE AFFERENT VISUAL SYSTEM Dutton et al. ( 61) have suggested that traumatic optic neuropathy may be to blame in baseball players who have experienced symptoms consistent with the Pulfrich phenomenon. Among a series of 187 patients with a history of mid- facial injuries, 6 were found to demonstrate signs of the Pulfrich phenomenon secondary to presumed mild traumatic optic neuropathy. Although visual acuities in these patients were 20/ 30 or better, all had decreased perception of bright light in the affected eye. In addition, symptoms of altered depth perception were present in all six patients. Patients reported sudden changes in the direction of a swinging pendulum when viewing it with one eye versus both eyes. 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