Predicting Progression to GA Using Imaging Biomarkers
Several OCT findings can help clinicians better understand a patient’s risk of progression to sight-threatening disease.
Kelly Donovan, MD, PhD, and Eleonora M. Lad, MD, PhD
Retina Today 
KEY TAKEAWAYS In the clinic, the most granular assessment of retinal anatomy is derived from OCT, which has generated most modern imaging biomarker candidates. Promising dry AMD imaging biomarkers include drusenoid lesions, intraretinal hyperreflective foci, loss of outer retinal integrity, choriocapillaris perfusion and thickness, and pigmentary changes. Eventually, the integration of multivariable risk calculators may provide composite progression estimates for patients, clinicians, and researchers. The modern parameters for dry AMD disease staging were first outlined by the Beckman classification in 2013.1 In 2017, the Classification of Atrophy Meeting provided an updated consensus on OCT-based classification of geographic atrophy (GA).2 Dry AMD disease staging relies on a combination of dilated fundus examination, color fundus photography (CFP), fundus autofluorescence (FAF), and OCT. Disease progression is gauged by these same modalities, with OCT being the most reliable for assessing interval anatomic changes. FAF is particularly well-suited for tracking GA lesion topography over time, with active expansion of GA lesion(s) on FAF representing the key indication for considering anticomplement therapy. Other structural and functional testing modalities are also under investigation as adjuncts for assessing the progression of dry AMD. For example, there is burgeoning interest in using OCT angiography to evaluate regional flow features of the choriocapillaris in different stages of dry AMD.3 In addition, functional measurements can be used to quantify sub-anatomic AMD progression in patients, with studies validating functional metrics such as microperimetry, dark adaptation, contrast sensitivity, and low-luminance visual acuity.4,5 In clinic, the most granular assessment of retinal anatomy is derived from OCT, which has generated most modern imaging biomarker candidates. A variety of tomographic disease features have been reported, providing us with broad insight into the diversity of anatomic changes that can occur during the natural history of dry AMD. The ability to leverage these imaging biomarkers into risk stratification algorithms will improve our ability to counsel patients and direct clinical trial design.
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