Purpose: To establish with negative electroretinogram (ERG) the clinical entity of eight patients with unilateral severe photophobia, essentially normal fundus, good visual acuity, and severe cone and rod dysfunction.
Study design: Multicenter retrospective observation case series.
Methods: Comprehensive ophthalmologic examinations were performed, including best-corrected visual acuity (BCVA), full-field ERGs and multifocal ERGs (mfERGs), fundus photographs, and OCT. Systemic and genetic examinations were performed.
Results: The mean (± SD) age at the onset was 60.0 ± 8.4 years, and the six patients noticed severe photophobia in the affected eye in spite of almost normal fundus appearance and good BCVA. The dark-adapted bright flash ERGs in the affected eye had relatively well-preserved a-waves and depressed b-waves, i.e., a negative ERG. Cone ERGs and both b- and d-waves of the photopic long-duration ERGs were almost undetectable. Rod ERGs were severely reduced; however, only two patients complained of night blindness. In five patients, the mfERGs were extinguished in the periphery but preserved in the central retina, resulting in good BCVA. Electrophysiological findings indicated a severe diffuse dysfunction of the inner retina affecting bipolar cells of both ON- and OFF-pathways, and in five patients there was a reduction in the thickness of the inner nuclear layer. In seven patients the retinal arteries were attenuated. Anti-retinal antibodies were detected in the serum of two patients. No genetic causes were found.
Conclusions: The common features in the eight patients with unilateral negative ERGs suggest a new disease entity of unilateral acute inner retinal layer dysfunction. In most patients, the only subjective complain was photophobia.
Keywords: Negative ERG; Normal fundus; Normal visual acuity; Photophobia; Unilateral bipolar cell dysfunction.