The natural history of full-field stimulus threshold decline in choroideremia

Purpose: To evaluate full-field sensitivity thresholds (FSTs) across a wide range of choroideremia (CHM) disease stages and to determine their applicability as functional endpoints for CHM clinical trials. Methods: Thirty CHM subjects (60 eyes) and 50 healthy controls (50 eyes) underwent FST testing under dark-adapted conditions to determine rod- and cone-mediated FSTs. Central retinal structure and function were assessed using fundus autofluorescence and microperimetry. Correlation and regression analyses were performed to compare FST responses with the residual area of retinal pigment epithelium in the peri- and parafoveal regions, as well as the mean and highest macular microperimetry sensitivity. Results: All patients with CHM had a baseline of 18 dB elevation in dark-adapted rod FSTs, including the least affected individuals. Further FST sensitivity loss was exponentially associated with decrease in the area of residual peri- and parafoveal retinal pigment epithelium, with precipitous loss of sensitivity noted for fundus autofluorescence areas less than 5 mm2. Cone FSTs were comparable with controls, except for advanced stages of CHM. Full-field sensitivity threshold responses showed high correlation with both mean and highest macular microperimetry thresholds (P
Source: RETINA - Category: Opthalmology Tags: Original Study Source Type: research