Clinical Perspectives and Trends: Microperimetry as a Trial Endpoint in Retinal Disease.

Endpoint development trials are underway across the spectrum of retinal disease. New validated endpoints are urgently required for the assessment of emerging gene therapies and in preparation for the arrival of novel therapeutics targeting the early stages of common sight-threatening conditions such as age-related macular degeneration and diabetic macular oedema. Visual function measures are likely to be key candidates in this search. Over the last 2 decades, microperimetry has been used extensively to characterise functional vision in a wide range of retinal conditions, often detecting subtle defects in retinal sensitivity that precede visual acuity loss and tracking disease progression over relatively short periods of time. Given these appealing features, microperimetry has already been adopted as an endpoint in interventional studies, including multicentre trials, on a modest scale. A review of its use to date shows a concurrent lack of consensus in test strategy and a wealth of innovative disease and treatment-specific metrics which may show promise as clinical trial endpoints. There are practical considerations to consider for its use, but these have not held back its popularity and it remains a widely used psychophysical test in research. Endpoint development trials will undoubtedly be key in understanding the validity of microperimetry as a clinical trial endpoint, but existing signs are promising.