Retinitis punctata albescens is the only congenital cause of nyctalopia in this chapter that is progressive. It is essentially a rod–cone dystrophy. Retinitis punctate albescens can be distinguished from fundus albipunctatus by incomplete recovery on dark adaptation.
Mutation: RLBP1 → retinaldehyde-binding protein
Clinical examination:
- Finer white dots than those seen in fundus albipunctatus
- Vascular attenuation
ERG: Severely subnormal
Dark Adaptation: Slight recovery with prolonged adaptation, but without normalization
Which of the following findings helps distinguish fundus albipunctatus from retinitis punctata albescens?
(A) Retinitis punctata albescens is the only disease in this chapter associated with progressive changes. (B) The yellow iridescent reflex following light exposure is the Mizuo–Nakamura phenomenon, which is seen in Oguchi disease. (C) The yellow–white dots in retinitis punctata albescens are finer. (D) With prolonged dark adaptation, fundus albipunctatus can show normalization of the ERG, whereas retinitis punctata albescens may improve only partially and never becomes completely normal.