Localised loss of sheen in Optos pseudocolour images in Oguchi disease following prior short wavelength autofluorescence imaging

Abstract

Aims/Purpose: Oguchi disease is characterized by night blindness and a striking golden retinal sheen in the light‐adapted state which disappears following prolonged dark adaptation (Mizuo‐Nakamura phenomenon). The sheen is observable clinically and on colour and pseudocolour (Optos plc) imaging. We observed a localized loss of sheen in a patient on colour/pseudocolour imaging in an area corresponding to the 30 degree square illuminated by short wavelength (488 nm) autofluorescence (AF) imaging (Heidelberg Spectralis). We explored whether other cases showed this phenomenon.Methods: Patients in our service with Oguchi disease (diagnosed phenotypically and/or with genetic confirmation) who had undergone colour or pseudocolour imaging were identified. In these patients, note was made of whether prior 30 degree short wavelength autofluorescence images had been undertaken and whether a localized square‐shaped loss of sheen was observed.Results: We identified 13 patients who had undergone colour or pseudocolour imaging. Of these, 4 patients (2 males, 2 females) had undergone prior 30 degree (and not 55 degree) short wavelength AF imaging at the same visit (ages ranging from 12 to 67). In 2 patients (a 12 year old, with variants in GRK1, and a 67 year old, not yet genotyped), a clear central square in which the sheen was absent was observed in the colour or pseudocolour images.Conclusions: The phenomenon of disappearance of the sheen in Oguchi disease following prolonged darkness is well‐described. Paradoxically, we observed loss of the sheen in 2 patients in a defined area corresponding to the field of illumination by bright blue light in 30 degree AF imaging. The blue light is preferentially absorbed by rhodopsin, which becomes bleached. It is possible that the sheen (at least in some patients) is dependent on there being a large proportion of unbleached rhodopsin as well as deficient shut‐off of activated rhodopsin.