Purpose
To characterize and quantify disease activity and response to treatment of wet Age-related Macular Degeneration (AMD) with standard intravitreal anti-VEGF agents using 3-D Computer-Automated Threshold Amsler Grid (3D-CTAG) as a functional assessment of macular function over time.
Methods
10 eyes in 10 patients with wet AMD underwent quantification of central field abnormalities with 3D-CTAG (Fink & Sadun, JBO 2004) before and one week after treatment with standard intravitreal anti-VEGF agents including bevacizumab (Avastin, Genentech), ranibizumab (Lucentis, Genentech), and aflibercept (Eyelea, Regeneron). Quantitative analysis of 3D visual field abnormalities included: Lost Area Grade (LAG = scotoma area ratio as a function of contrast sensitivity), Preserved Area Grade (PAG = intact visual field area ratio as a function of contrast sensitivity), and Hill-of-Vision Volume Loss (HVL = ratio of not seen vs. total number of Amsler grid points).
Results
Wet AMD patients exhibited a central defect at low vs. a larger central defect at higher contrast sensitivity levels. We demonstrated the quantification and improvement of macular structure and function using 3D-CTAG before and after standard treatment of wet AMD: LAG, PAG, and HVL indices showed marked improvement following treatment, which correlated with regression of the choroidal neovascular membrane complex after use of standard anti-VEGF agents. Overall, 3D-CTAG provided easy clinical access to measuring and assessing the functional health of the retina in vivo to quantify change over time.
Conclusions
3D-CTAG is a direct, non-invasive, and easy-to-use functional retinal imaging technology. It allows characterization and quantification of longitudinal changes in macular function before and after treatment of patients with wet AMD. 3D-CTAG may prove useful as a screening tool in wet AMD and other central macular diseases like geographic atrophy due to dry AMD. As newer therapeutics are developed, the distinctive and quantitative measurements offered by 3D-CTAG may become an increasingly important marker to characterize AMD, monitor disease severity, and provide quantitative outcome measures of therapy. Objective indices (e.g., LAG, PAG, HVL) delivered by 3D-CTAG may serve as useful adjunctive measures in clinical trials guided by functional outcomes.
Keywords: 550 imaging/image analysis: clinical •
412 age-related macular degeneration •
585 macula/fovea