Letters to the Editor

Structural-Functional Dissociation Observed During Recovery Phase of Optic Neuropathies We read with great interest the article by Masvidal et al (1) titled ‘‘Structural-functional dissociation in presumed ethambutol optic neuropathy'' and commend the authors for their excellent observation. We would like to share our experience with regard to this observation by presenting 2 cases. Case 1 A 65-year-old Chinese man was diagnosed with presumed ethambutol-associated optic neuropathy in January 2008, 4 months after he began taking the medication. Ethambutol was discontinued immediately. At the initial examination, best-corrected visual acuity was counting fingers, right eye, and 6/120, left eye. The patient was not able to see any of the Ishihara color plates with the right eye but could accurately identify 12 of 15 plates with the left eye. There was no relative afferent pupillary defect. The optic discs were pink with cup to disc ratio of 0.3 bilaterally. Results of visual field testing are shown in Figure 1A. Mean deviation (MD) was 222.98 decibels (dB) in the right eye and 212.87 dB in the left eye. Using time-domain optical coherence tomography (OCT) (Stratus OCT; Carl Zeiss Meditec), the average retinal nerve fiber layer (RNFL) thickness was 119.85 mm and 128.80 mm in the right and left eyes, respectively. Five months later, the patient had visual acuity of 6/120, right eye, and counting fingers at 1.5 m, left eye, and he could identify 3 of 15 Ishihara plates with each eye. Automated perimetry also showed progression of visual field loss with MD of 229.03 dB in the right eye and 228.37 dB in the left eye. Thirty-four months after the onset of optic neuropathy, the patient's visual acuity had improved to 6/45, right eye, and 6/30, left eye, and he could now identify 12 of 15 plates with each eye. Visual fields showed improvement (Fig. 1B) with MD of 210.90 dB, in the right eye, and 211.35 dB in the left eye. Repeat time-domainOCT showed further decrease in the average RNFL thickness, measuring 90.21 mm in the right eye and 90.05 mm in the left eye, and both optic discs appeared pale. Case 2 A 66-year-old Chinese man was seen in our neuro-oph-thalmology clinic in February 2010 after MRI of the brain revealed a large solid pituitary mass measuring 3 3 2.6 3 1.6 cm, compressing the optic chiasm and the prechiasmatic portions of both optic nerves. On examination, visual acuity was 6/12, right eye, and 6/9, left eye. Pupillary reactions were normal, and the patient identified 14 of 15 Ishihara color plates with the right eye and 13 of 15 with the left eye. Automated visual field revealed a bitemporal hemianopia (Fig. 2A) with MD of 215.12 dB in the right and 215.24 dB in the left eyes. Both optic discs were pale, and spectral-domain OCT (Carl Zeiss Meditec) showed diffuse RNFL loss, with an average rim thickness of 69 mm, right eye, and 66 mm, left eye. The patient underwent an uneventful transcranial de-bulking of his pituitary macroadenoma, and 1 year later, his visual acuity was 6/9, right eye, and 6/12 left eye. Visual field showed improvement (Fig. 2B) with MD of 210.91 FIG. 1. Case 1. A. Visual fields reveal peripheral constriction with cecocentral scotomas. B. Visual fields improved 34 months after the cessation of ethambutol. 290 Letters to the Editor: J Neuro-Ophthalmol 2011; 31: 290-293 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. dB in the right and 214.11 dB in the left eyes, but spectral-domain OCT showed further RNFL loss (53 mm, right eye; 54 mm, left eye). Both of our cases demonstrate ‘‘disparate correlation between structure and function'' during the recovery phase of optic neuropathy. This appears to hold true for a variety of optic nerve disorders, including those due to a toxic, inflammatory, or compressive cause. Further studies are warranted to understand the basis for these seemingly paradoxical clinical findings. Katherine Wan Xian Lun, MBBCh, BAO (Ireland) Su Ann Lim, MBBS, MMed (Ophth), FRCS (Edin) Department of Ophthalmology, Tan Tock Seng Hospital Singapore [e-mail] REFERENCE 1. Masvidal D, Parrish RK II, Lam BL. Structural-functional dissociation in presumed ethambutol optic neuropathy. J Neuroophthalmol. 2010;30:305-310. Monocular Elevation Deficiency (‘‘Double Elevator'' Palsy): A Cautionary Note Iread with interest the article by Brodsky and Karlsson (1) and the authors' caution that tethering and buckling of the central lower eyelid in down gaze of patients with monocular elevation deficiency can simulate impaired infraduction in the involved eye. However, I wish to express a different opinion on the description of the figure shown by the authors. Indeed, contrary to the description submitted, figure 1C does in fact demonstrate a deficit of infraduction of the abnormal right eye. Two clear landmarks can be used to come to that conclusion: first, the relative alignment of the upper limbus of each eye that clearly shows a lack of ade-quate depression movement of the affected eye. Second, the rounded pupil image of the right eye, as opposed to its oval-shaped counterpart (0.5 mm difference in vertical diameter), is in keeping with the difference in downward gaze position of the 2 eyes. Unfortunately, in this case, the pictures do not show which eye is fixating in down gaze due to the lack of corneal light reflection. Furthermore, there is no photographic documentation of ductions. A review of some of the key publications on double elevator palsy shows a dramatic similarity with the documentation by Brodsky and Karlsson. For example, 4 of 5 cases with adequate pictorial documentation show a hyperdeviation in down gaze of the abnormal eye in textbooks by both Rosenbaum and Santiago (2) and von Noorden and Campos (3). Surprisingly, this deviation in down gaze is poorly discussed throughout the literature, most of the attention being directed at the classical findings of good alignment in primary position, a deficit of elevation in adduction and abduction, and the presence in some patients of a Bell phenomenon. Finally, this deficit in depression of the abnormal eye referred to here and illustrated by the authors could be an indicator of a miswiring of either the superior rectus or the inferior rectus, another example of the ever-growing spec-trum of congenital primary extraocular cranial neuropathies. G. Robert LaRoche, MD, FRCSC Division of Pediatric Ophthalmology and Ocular Motility Department of Ophthalmology and Visual Sciences Dalhousie University, Halifax, Nova Scotia, Canada The author reports no conflicts of interest. FIG. 2. Case 2. A. Bitemporal hemianopia prior to surgery. B. One year later, there is partial resolution of the visual field defects. Letters to the Editor: J Neuro-Ophthalmol 2011; 31: 290-293 291 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. REFERENCES 1. Brodsky MC, Karlsson V. Monocular elevation deficiency (‘‘double elevator'' palsy): a cautionary note. J Neuroophthalmol. 2011;31:56-57. 2. Rosenbaum A, Santiago A. Clinical strabismus management. Philadelphia, PA: Saunders, 1999:273. 3. von Noorden G, Campos E. Binocular vision and ocular motility, 6th edition. St. Louis, MO: Mosby, 2002:442-443. Branch Retinal Vein Occlusion During Fingolimod Treatment in a Patient With Multiple Sclerosis Fingolimod (FTY720; Novartis) is a new oral drug that acts as a superagonist of the sphingosine-1-phosphate-1 receptor on thymocytes and lymphocytes, sequestering these cells in lymph nodes (1). This medication has been shown to be effective in the management of multiple sclerosis (2,3). The most frequent adverse events reported with fingolimod are nasopharyngitis, influenza, and headache, but cases of arterial vasospasm (4) and reversible cystoid macular edema (5) have also been described. A 47-year-old woman with a 9-year history of multiple sclerosis, who had been treated with fingolimod for the past 6 years, complained of sudden visual loss in her left eye. Visual acuity was 20/20 in the right eye and 20/40 in the left eye. Anterior segment evaluation was unremarkable. The right fundus was normal while a superotemporal branch retinal vein occlusion was noted in the left eye (Fig. 1). Spectral-domain optical coherence tomography (SD-OCT) revealed the presence of intraretinal cystic changes and thickening of the superior nasal macula with foveal involvement (Fig. 2A). The central foveal thickness mea-sured 396 mm. Fluorescein angiography showed the blocking effect of the intraretinal hemorrhages and an area of delayed choroidal filling (Fig. 2B). There was no evidence of retinal vasculitis. Fingolimod was discontinued, and an intravitreal injection of ranibizumab (Lucentis; Novartis) FIG. 1. Left fundus showing a superotemporal branch was administered. A thorough evaluation for a coagulation retinal vein occlusion. FIG. 2. A. SD-OCT reveals superotemporal macular thickening (top) with intraretinal cystic spaces (bottom). B. Top, fluorescein angiography is consistent with a superotemporal branch retinal vein occlusion and an area of delayed choroidal filling (arrows); bottom, choroid fills late in the angiogram. 292 Letters to the Editor: J Neuro-Ophthalmol 2011; 31: 290-293 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. disorder was conducted, but no significant abnormality was detected. The presence of cardiovascular risk factors, such as smoking, arterial hypertension, or diabetes, was also excluded. Three weeks later, vision was 20/20 in the left eye and the SD-OCT showed normalization of the foveal contour without cystic spaces and a mild superonasal macular thickening (Fig. 3). We are not aware of any previous reports of retinal vein occlusion in patients treated with fingolimod. Although we cannot prove a causal relationship between fingolimod and retinal vein occlusion, we believe that this drug should be considered in the diagnostic algorithm of patients with this retinal vascular disorder. Roberto Gallego-Pinazo, MD Enrique Espan˜a-Gregori, MD Bonaventura Casanova, MD Diamar Pardo-Lo´pez, MD Manuel Dı´az-Llopis, PhD, MD New University and Polytechnic Hospital La Fe and University of Valencia Valencia, Spain [e-mail] REFERENCES 1. Kappos L, Antel J, Comi G, Montalban X, O'Connor P, Polman CH, Haas T, Korn AA, Karlsson G, Radue EW; FTY720 D2201 Study Group. Oral fingolimod (FTY720) for relapsing multiple sclerosis. N Engl J Med. 2006;355:1124-1140. 2. Comi G, O'Connor P, Montalban X, Antel J, Radue EW, Karlsson G, Pohlmann H, Aradhye S, Kappos L; FTY720D2201 Study Group. Phase II study of oral fingolimod (FTY720) in multiple sclerosis: 3-year results. Mult Scler. 2010;16:197-207. 3. Cohen JA, Barkhof F, Comi G, Hartung HP, Khatri BO, Montalban X, Pelletier J, Capra R, Gallo P, Izquierdo G, Tiel-Wilck K, de Vera A, Jin J, Stites T, Wu S, Aradhye S, Kappos L; TRANSFORMS Study Group. Oral fingolimod or intramuscular interferon for relapsing multiple sclerosis. N Engl J Med. 2010;362:402-415. 4. Schwarz A, Korporal M, Hosch W, Max R, Wildemann B. Critical vasospasm during fingolimod (FTY720) treatment in a patient with multiple sclerosis. Neurology. 2010;74: 2022-2024. 5. Saab G, Almony A, Blinder KJ, Schuessler R, Brennan DC. Reversible cystoid macular edema secondary to fingolimod in a renal transplant recipient. Arch Ophthalmol. 2008;126: 140-141. FIG. 3. Three weeks after an intravitreal injection of ra-nibizumab, there was a near-complete resolution of retinal edema. Letters to the Editor: J Neuro-Ophthalmol 2011; 31: 290-293 293 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.