| OCR Text |
Show PHOTO ESSAY Monocular Temporal Hemianopia With Septo- Optic Dysplasia Dain B. Brooks, MD and Prem S. Subramanian, MD, PhD B FIG. 1. A. " Bowtie" optic disc pallor and small- diameter optic disc in the right eye and normal optic disc in the left eye. B. Visual fields show temporal hemianopia in the right eye and a normal result in the left eye. C. Postcontrast T1 coronal MRI shows a thin right optic nerve just anterior to the optic chiasm, absent septum pellucidum, and normal- appearing pituitary gland ( left); midorbital view shows a thin right optic nerve ( right). J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 195 J Neuro- Ophthalmol, Vol. 26, No. 3, 2006 Brooks and Subramanian Abstract: A 26- year- old woman displayed a monocular temporal hemianopic defect together with an ipsilateral afferent pupillary defect and bowtie optic nerve hypoplasia. MRI revealed a thin right optic nerve, an asymmetrically thinned chiasm, and an absent septum pellucidum. Monocular temporal visual field loss from organic lesions is quite rare but has been reported in conjunction with compressive lesions at the optic nerve- optic chiasm junction. This is the first report to demonstrate this visual field defect together with bowtie optic nerve hypoplasia. (/ Neuro- Ophthalmol 2006; 26: 195- 196) A26- year- old black woman was referred to the neuro-ophthalmology service after she described bumping into things on her right side for the last 18 months. She also believed that the vision on the right side was diminished. She had a history of childhood esotropia with amblyopia in the right eye and had been treated with patching of the left eye. During the same time period, she reported the onset of systemic hypertension and low back pain. She denied recent trauma or serious illnesses requiring hospitalization. Visual acuity was 20/ 70 in the right eye and 20/ 20 in the left eye. There was a right afferent pupillary defect ( APD) and a small- diameter optic disc with a " bowtie" pattern of pallor ( Fig. 1A). A right temporal visual field defect respecting the vertical midline was noted by finger confrontation and confirmed on automated perimetry ( Fig. IB). Brain MRI disclosed a small- diameter right optic nerve and absence of the septum pellucidum ( Fig. 1C). Pituitary function was normal. A monocular temporal hemifield deficit may result from optic nerve damage just anterior to the optic chiasm. In this variant of the anterior chiasmal syndrome ( 1), the damage often ( but not always) produces an APD on the side of the lesion and a visual field defect that variably respects the vertical midline ( 2,3). " Wilbrand's knee" need not exist for this type of nerve fiber damage to occur ( 4). In a series of 24 patients, selective compression of the nasal crossing fibers from one optic nerve by suprasellar or juxtasellar tumors was suggested to be the most common cause of monocular temporal field loss ( 2). It is unclear what makes Ophthalmology Service ( DBB, PSS), Walter Reed Army Medical Center, Washington, DC; and the Division of Ophthalmology ( PSS), Uniformed Services University of the Health Sciences, Bethesda, Maryland. Address correspondence to Prem S. Subramanian, MD, PhD, Ophthalmology Service, Walter Reed Army Medical Center, 6900 Georgia Ave. NW, Washington, DC 20307- 5001; E- mail: prem. subramanian@ na. amedd. army. mil the fibers destined to cross more vulnerable to compressive damage. Psychogenic vision loss also must be suspected in cases of monocular temporal field loss, particularly when the defect seems to respect the vertical midline precisely ( 5- 7). Optic disc pallor, an APD, and disappearance of the defect on binocular testing can help to identify an organic source of the field loss. MRI with particular attention to the sella turcica and parasellar regions may reveal compressive lesions. However, in our patient, who had no compressive lesions identified on imaging, why were the nasal nerve fibers selectively damaged? An incomplete midline cleavage defect might be expected to damage only the crossing fibers of one eye, although the marked asymmetry defies easy explanation. Monocular temporal hemianopia with absent septum pellucidum has been reported previously ( 8) but the features notably differ. Specifically, we found optic nerve hypoplasia with " bowtie" nerve fiber loss in lieu of apparent nasal agenesis of the optic nerve; the potential association of such markedly different patterns of optic nerve hypoplasia with apparent midline dysgenesis is unexpected. We further demonstrate that the abnormality of the optic nerve is visible both intraorbitally and intracra-nially Finally, our case demonstrates that this condition may go unrecognized until adulthood with apparent new onset of symptoms. REFERENCES 1. Schiefer U, Isbert M, Mikolaschek E, et al. Distribution of scotoma pattern related to chiasmal lesions with special reference to anterior junction syndrome. Graefes Arch Clin Exp Ophthalmol 2004; 242: 468- 77. 2. Hershenfeld SA, Sharpe JA. Monocular temporal hemianopia. Br J Ophthalmol 1993; 77: 424- 7. 3. Kosmorsky GS, Tomsak RL, Diskin DK. Absence of the relative afferent pupillary defect with monocular temporal visual field loss. J Clin Neuroophthalmol 1992; 12: 181- 91. 4. Horton JC. Wilbrand's knee of the primate optic chiasm is an artefact of monocular enucleation. Trans Am Ophthalmol Soc 1997; 95: 579- 60. 5. Acaroglu G, Guven A, Ileri D, et al. Monocular temporal hemianopia in a young patient. Turk J Pediatr 2004; 46: 98- 100. 6. Neetens A, Smet H. [ Functional monocular hemianopsia.] Klin Monatsbl Augenheilkd 1988; 192: 551^ k 7. Gittinger JW Jr. Functional monocular temporal hemianopsia. Am J Ophthalmol 1986; 101: 226- 31. 8. Smolyar A, Eggenberger ER, Kaufman DI. Monocular temporal hemianopia associated with optic nerve hypoplasia. Arch Ophthalmol 2005; 123: 1155. 196 © 2006 Lippincott Williams & Wilkins |
