Macular Dysfunction in Oguchi Disease with the Frequent Mutation 1147delA in the SAG Gene.

AIM/

BACKGROUND

A 1-bp deletion (1147delA) in the SAG (also known as arrestin or S-antigen) gene is the most frequently seen mutation in Japanese patients suffering from Oguchi disease, a recessively inherited stationary night blindness. We investigated macular function in a patient with Oguchi disease with the 1147delA mutation.

METHODS

A 43-year-old Japanese male patient was diagnosed with Oguchi disease. The patient underwent complete ophthalmic examinations, including spectral-domain optical coherence tomography and Humphrey visual field testing. Full-field electroretinograms (ff-ERG) and multifocal ERG (mf-ERG) were recorded. Mutational analysis of the SAG gene was performed.

RESULTS

Corrected visual acuity was good in both eyes. Funduscopy showed retinal pigment epithelium atrophy along the vascular arcade bilaterally. The inner segment-outer segment (ISOS) boundary lines were preserved in the foveal and parafoveal areas, whereas ISOS boundary defects and thinning of the outer nuclear layer (ONL) were seen outside the preserved ISOS boundary. Humphrey testing showed significant paracentral field defects in both eyes. In addition to an absence of rod responses, cone and 30-Hz flicker responses were markedly reduced in ff-ERG. The central (ring 1) and paracentral (ring 2) responses with normal latencies were relatively preserved, but the outer waveforms (rings 3-5) were attenuated and prolonged in mf-ERG. The deletion mutation (1147delA) was identified homozygously.

CONCLUSIONS

The reduced/delayed mf-ERG responses and visual field defects in paracentral macula areas are most likely to be correlated with ISOS boundary defects and thinning of the ONL. Macular dysfunction can occur in Oguchi disease with the 1147delA mutation in the SAG gene.