Retinal light sensitivity as outcome measure in recessive Stargardt disease

To evaluate the applicability of mesopic light sensitivity measurements obtained by fundus-controlled perimetry (FCP, also termed 'microperimetry') as clinical trial endpoint in Stargardt disease (STGD1).

In this retrospective, monocentre cohort study, 271 eyes of 136 patients (age, 37.1 years) with STGD1 and 87 eyes of 54 healthy controls (age, 41.0 years) underwent mesopic FCP, using a pattern of 50 stimuli (achromatic, 400-800 nm) centred on the fovea. The concurrent validity of mesopic FCP testing using the MAIA device (CenterVue, Italy), the retest variability and its determinants, and the progression of sensitivity loss over time were investigated using mixed-model analyses. The main outcomes were the average pointwise sensitivity loss in dependence of patients' demographic, functional and imaging characteristics, the intrasession 95% coefficient of repeatability, and the pointwise sensitivity loss over time.

Pointwise sensitivity loss was on average (estimate (95% CI)) 13.88 dB (12.55 to 15.21) along the horizontal meridian and was significantly associated with the electrophysiological subgroup, presence/absence of foveal sparing, best-corrected visual acuity and disease duration. The 95% coefficient of repeatability was 12.15 dB (10.78 to 13.38) and varied in dependence of the underlying mean sensitivity and local sensitivity slope. The global progression rate for the sensitivity loss was 0.45 dB/year (0.13 to 0.78) and was higher for the central and inner ETDRS subfields compared with more peripheral regions.

Mesopic light sensitivity measured by FCP is reliable and susceptible for functional changes. It constitutes a potential clinical outcome for both natural history studies as well as future interventional studies in patients with STGD1.