Abstract
Advancements in imaging modalities have led to insights into disease pathology and progression. As anatomic measures have less variability than functional testing, they are attractive outcome measures for clinical trials. Studies correlating anatomic measures to functional testing are the most useful in establishing these anatomic measurements as surrogate outcome measures for function. Understanding and quantifying the anatomic changes over time is critical for understanding the magnitude of change relative to the device’s margin of error. The area of hypoautofluorescence on autofluorescence imaging in geographic atrophy and the area of ellipsoid zone loss in Macular Telangiectasia type 2 are both examples of anatomic measures validated with functional testing using microperimetry and used as primary outcomes in interventional clinical trials. Other measures from optical coherence tomography (OCT) imaging are currently being explored for use in retinitis pigmentosa and hydroxychloroquine toxicity. Imaging modalities, including adaptive optics, would be considered primary outcome measures since they could reveal a reduction of photoreceptor loss with therapy and directly relate to preservation of visual function.