A 15-year-old boy with mild blurring of vision has a normal-appearing fundus except for subtle foveal changes. Electroretinogram is normal. Which electrophysiological test will establish the diagnosis of Best vitelliform macular dystrophy?

• A Pattern electroretinogram
• B Electrooculogram showing reduced light rise ✓
• C Multifocal electroretinogram
• D Dark adaptation testing

Explanation

Best disease is caused by mutations in the BEST1 gene affecting the RPE bestrophin channel. Its hallmark is a selectively abnormal electrooculogram with a reduced or absent light rise and a decreased Arden ratio, even when the fundus appears nearly normal in early stages. The full-field ERG remains normal because photoreceptor function is preserved, which distinguishes it from retinitis pigmentosa. This dissociation between a normal ERG and an abnormal EOG is the classic examination point.

Reference: AAO Basic and Clinical Science Course, Section 12: Retina and Vitreous, 2023-2024 ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.