Longitudinal Study to Assess the Quantitative Use of Fundus Autofluorescence for Monitoring Disease Progression in...

Characterisation of preserved autofluorescence (PAF) area in choroideremia (CHM) and its validity for monitoring disease progression in clinical trials is of importance.

Eighty patients with molecularly confirmed CHM were recruited. PAF area was measured manually by 2 graders and half-life was calculated based on exponential decay model.

Mean age at baseline and follow-up examination was 38.1 (range, 10-69) and 40.7 (range, 11-70) years. Mean follow-up interval was 29 months (range, 6-104). The median LogMAR visual acuity was 0.10 (OD) and 0.18 (OS). Interobserver repeatability for PAF area was -0.99 to 1.03 mm² (-6.46 to 6.49% of area). There was a statistically significant relationship between age and rate of PAF area loss (r² = 0.28, p = 0.012). The half-life for PAF area was 13.7 years (range, 1.7-216.0 years). The correlation between half-life and age was stronger than between half-life and log transformed baseline PAF area, although neither was statistically significant.

The intra- and inter-observer PAF area measurement variability provides a baseline change, which must be overcome in a clinical trial if this metric were to be used. Treatments must slow progression to alter the exponential decay in a timely manner accounting for naturally slow progression patterns.