Abstract
Purpose::
To report long-term follow-up data on a case of ESCS presenting with adult-onset acute macular RS, and its successful treatment with the oral carbonic anhydrase inhibitor (CAI), acetazolamide.
Methods::
ETDRS best-corrected visual acuity (BCVA), Goldmann visual fields (GVFs), dark- (DA) and light-adapted (LA) monochromatic automated perimetry (MAP) to 500nm (DA, rods), 600nm (white LA, L/M-cones), and 440nm stimuli (yellow LA, S-cones), optical coherence tomography (OCT3), and flash electroretinogram (ERG) were performed. The NR2E3 gene was screened for disease causing variations.
Results::
In this unusual case of ESCS, there was no macular RS and BCVA was 20/16 bilaterally until age 48, when acute RS (cystic macular changes to OCT3 without retinal edema) developed in the left eye (OS), leading suddenly to 20/200 BCVA and metamorphopsia. Prompt treatment with acetazolamide (125 mg twice daily) led to disappearance of macular RS in OS. BCVA was restored to 20/20 and the metamorphopsia resolved. At age 48, S-cone sensitivity was supernormal across most of the field, whereas L/M-cone sensitivity varied from mildly (1-5dB) to markedly (>21dB) depressed at most loci across the visual field. ERGs were electronegative to both DA and LA bright flashes but markedly reduced in size. There was minimal decline in GVF visual field expanse over time (-10% to V4e target between age 9 and 48). The main defect was concentrated in the initial area of ring scotoma (12-30 degrees of eccentricity), progressing from relative to absolute. However, peripheral retinal sensitivity declined over time (I4e target area decline from >100% at age 9 to 3.3% at age 48). The patient was homozygous for the previously reported R311Q variation in the NR2E3 gene.
Conclusions::
In this case of ESCS, there was only minimal decline in visual field size over time. The only absolute defect corresponded anatomically to the area, in ESCS, of highest S-cone density (normally, the area of highest rod density). When L/M-cone sensitivity was variably depressed, supernormal S-cone sensitivity persisted across most of the field. Neither the adult-onset acute development of macular RS nor its successful treatment with an oral CAI had been previously reported in ESCS. This finding and the recent report of improved macular RS with topical CAIs in X-linked RS (Apushkin & Fishman, Retina 2006; 26:741-5) indicate that the macular RS may be treated successfully with CAIs also in ESCS.
Keywords: retinal degenerations: hereditary • clinical (human) or epidemiologic studies: natural history • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials