Unilateral retinal bipolar cell dysfunction with photophobia

To report a patient with unilateral photophobia but unremarkable multimodal imaging, in whom a negative electroretinogram (ERG) indicated retinal bipolar cell dysfunction, and both the photophobia and the ERG later improved in part.

Single case report. Examinations included best-corrected visual acuity (BCVA), slit-lamp biomicroscopy, color fundus photography, optical coherence tomography (OCT), fundus autofluorescence (FAF), color vision testing, Goldmann and Humphrey perimetry, full-field ERG, multifocal ERG (mfERG), and photopic On-Off ERG, with 3-year follow-up.

A 67-year-old man had a 3-year history of subacute photophobia and central blurring in the left eye that had remained undiagnosed at several institutions. At the initial visit to our hospital, BCVA was 1.2 in decimal in both eyes. Color fundus photography, OCT, FAF, color vision, and perimetry showed no relevant abnormality. Full-field ERG was normal in the right eye; the left eye showed a reduced dark-adapted (DA) 0.01 ERG, a negative DA 3 ERG with a preserved a-wave (b:a ratio = 0.53), mildly reduced oscillatory potentials, and severely reduced light-adapted (LA) 3 and LA 30 Hz ERGs. The mfERG was preserved centrally and reduced peripherally. At 4 years from onset, the photophobia improved, and the b:a ratio of the DA 3 ERG increased to 0.90, with slight recovery of the LA 30 Hz ERG. At 5 and 6 years from onset, the DA 0.01, LA 3, and LA 30 Hz ERGs showed slight further improvement, and the b:a ratio of the DA 3 ERG increased to 1.07 and 1.62, respectively, whereas the photophobia was unchanged.

Unilateral On- and Off-bipolar cell dysfunction presenting as photophobia can show partial improvement. The ERG is essential for diagnosis and objective monitoring.