Journal of Neuro-Ophthalmology, September 1989, Volume 9, Issue 3

Bilateral slowly progressive big blind spot syndrome.

A 33-year-old woman was found with bilateral enlargement of the blind spot without optic disc edema. Her bilateral peripapillary retinas appeared slightly decolored and elevated with obscure margins and fluorescein angiography indicating only slight hyperfluorescence in the late venous phase. Four years after her initial visit, both of her blind spots became enlarged further and dark adaptation was remarkably difficult. Peripapillary retinal lesions appearing as retinal pigmentary degeneration were evident with very definitive margins. The lesions showed strong hyperfluorescence in the arteriovenous phase owing to window defects. From these findings, it appears that bilateral big blind spots without optic disc edema may possibly result from peripapillary retinal degeneration, which may become evident at a much later date.

Journal of Cliniml Neuro- ophtlwlmology 9( 3): 141- 143. 1989. Bilateral Slowly Progressive Big Blind Spot Syndrome Masato Wakakura, M. D., DSc., and Kumiko Furuno, M. D., DSc. © 1989 Raven Press, Ltd .. New York A 33- year- old woman was found with bilateral enlarge­ment of the blind spot without optic disc edema. Her bilateral peripapillary retinas appeared slightly decol­ored and elevated with obscure margins and fluorescein angiography indicating only slight hyperfluorescence in the late venous phase. Four years after her initial visit, both of her blind spots became enlarged further and dark adaptation was remarkably difficult. Peripapillary retinal lesions appearing as retinal pigmentary degener­ation were evident with very definitive margins. The lesions showed strong hyperfluorescence in the arterio­venous phase owing to window defects. From these findings, it appears that bilateral big blind spots without optic disc edema may possibly result from peripapillary retinal degeneration, which may become evident at a much later date. Key Words: Big blind spot syndrome- Peripapillary ret­inal degeneration- Peripapillary pigmentary retinal de­generation. From the Department of Ophthalmology, School of Medi­cine, Kitasato University, Kanagawa, Japan. Address correspondence and reprint requests to Dr. M. Wakakura, Department of Ophthalmology, School of Medicine, Kitasato University, 1- 15- 1 Kitasato, Sagamlhara, Kanagawa 228, Japan. 141 Enlargement of the blind spot is most often caused by edema of the optic disc. However, Fletcher et al. ( 1) reported seven cases of the big blind spot syndrome without this condition of the optic disc. The syndrome in these cases was acute, unilateral, and most likely self- limited. Although both ophthalmoscopy and fluorescein angiogra­phy failed to show any abnormality, multifocal electroretinography indicated possible peripapil­lary retinal dysfunction. In the present case, bilat­eral and slowly progressive blind spot enlarge­ment was noted without optic disc edema. The big blind spot was shown to result from peripapillary retinal lesion closely resembling pigmentary reti­nal degeneration. CASE REPORT On May 31, 1984, a 33- year- old woman came for an examination at the outpatient department with bilateral photophobia and temporal field defects of 10 days' duration. Corrected visual acuity was 20/ 20 OU. Neither relative afferent pupillary defect nor Marcus- Gunn's pupil was noted. Goldmann perimetry showed an absolute scotoma on the blind spot, measuring 27° in the largest horizontal diameter of the right eye and 33° in the left eye. The peripheral fields were normal. Dark adapta­tion was adversely affected in both eyes. The light peak- dark trough ratios of electro- oculography were R. E. 186% and L. E. 156% ( normal, 197 :±: 12%). Slight reduction in contrast sensitivity at high frequencies was noted, but color vision and electroretinography were still normal. A mild pis­ciform cataract was present in each eye. Ophthal­moscopy and contact lens biomicroscopy indicated that the bilateral peripapillary retinas were slightly elevated with relatively obscure margins. Ophthal­moscopical examination showed normal posterior and peripheral retinas and optic discs. Using fluo- 142 M. WAKAKURA AND K. FURUNO FIG. 1. Fluorescein angiograms taken on May 31,1984, of the right eye ( A) and left eye ( B), demonstrating slight hyperfluorescence in the peripapillary area. rescein angiography, slight hyperfluoresence was evident in the peripapillary areas in the late ve­nous phase ( Fig. 1). A CT scan and ultrasonogra­phy failed to indicate any abnormalities. No oph­thalmoscopical or perimetric changes in the 3 months that followed could be detected. Follow­up studies were conducted at the ophthalmology clinic nearest to the patient's home. On March 18, 1988,4 years after the initial visit, she was examined again at the outpatient depart­ment. She had sensed no progress in the severity of visual symptoms during this intermission. However, her husband had noticed recent com­plaints of poor ability in to adjust to the darkness in tunnels while driving. Corrected visual acuity had not changed. Both blind spots had enlarged, measuring 32° in the largest horizontal diameter of the right eye and 38° in the left eye ( Fig. 2). Dark adaptation was remarkably affected in both eyes and further reduction in light peak- dark trough ra­tios of electro- oculography was evident ( R. E. 177%, L. E. 147%). Electroretinographic results were normal. Ophthalmoscopy indicated the bilat­eral peripapillary retinas to have metallic greyish reflexes. The peripapillary lesions were flattened but enlarged with very definitive margins. Two pigmented dots were evident in the upper portion of the lesion of the right eye. The findings closely resemble those of pigmentary retinal degenera­tion. Fluorescein angiography showed the peri­papillary lesions to be strongly hyperfluorescent at the arteriovenous phase, owing to window defects ( Fig. 3). DISCUSSION '~' m, ' 11 ,'; j<;' , , Jiff" r<; notably from the big 1 pr'c'viously. Miller I Clin Neuro- ophthalmol, Vol. 9, No. 3, 1989 ( 2) was the first to use the term " big blind spot syndrome" to describe a condition of unilateral op­tic disc edema without visual loss or increase in intracranial pressure. Fletcher et a1. ( 1) encoun­tered cases resembling the " big blind syndrome" without optic disc edema. These cases showed unilateral conditions with benign prognosis, whereas the present case is characterized by slowly progressive bilateral conditions. Fletcher et al. ( 1) considered that peripapillary retinal dys­function might give rise to the big blind spot syn­drome, since multifocal electroretinography failed to show any waveforms in a large region sur­rounding the optic disc in two patients. In addi­tion, that one case exhibited juxtapapillary retinal pigmentary changes in fluorescein angiography is a significant finding. In the present case, peripap­illary retinal changes resembling pigmentary reti­nal degeneration eventually became evident by ophthalmoscopy. The findings of fluorescein an­giography also indicated involvement of the peri­papillary area. As best as we can determine, there has been two reports of peripapillary pigmentary retinal degen- '<, I) !~( (~, -' / "'"', "-.. FIG. 2. Goldmann perimetry conducted on March 18, 1988, indicating enlargement of the blind spots. BILATERAL BIG BLIND SPOT SYNDROME 143 FIG. 3. Fluorescein angiograms taken on March 18, 1988, demonstrating marked hyperfluorescence with sharp margins of the peripapillary area. Note the lesion of the left eye ( B) to be larger than that of the right eye ( A). Pigmented lesions are indicated by arrowheads. eration ( 3,4), but these cases were not associated with enlargement of the blind spots. Whether this peripapillary retinal degeneration is primary is a point remaining to be clarified. Peripapillary changes in the present case occurred gradually but became remarkably evident over a 4- year period. The results of both dark adaptation tests and elec­tro- oculography also indicated that the patients' condition worsened during this time, indicating that the disease is possibly chronic and progres­sive. Although the etiology remains to be explicitly determined, it should be recognized that bilateral, slowly progressive peripapillary retinal degenera-tion is a new aspect of the " big blind spot syn­drome." REFERENCES 1. Fletcher WA, Imes RK Goodman D, Hoyt WF. Acute id­iopathic blind spot enlargement. A big blind spot syn­drome without optic disc edema. Arch Ophthalmol 1988; 106: 44- 9. 2. Miller NR. The big blind spot syndrome: unilateral optic disc edema without visual loss or increased intracranial pressure. In: Smith ] L, ed. Neuro- ophthalmology Update. New York: Masson Publishers USA, Inc., 1977; 163- 9. 3. Noble KG, Carr RE. Peripapillary pigmentary retinal de­generation. Am J Ophthalmol 1978; 86: 65-- 75. 4. Sabates R, Kolder HE. Peripapillary retinochoroidal degen­eration. Ann OphthalmoI1982; 14: 68-- 3. JClin Neuro- ophthalmol, Vol. 9, No. 3, 1989