Proposal of a simple optical coherence tomography-based scoring system for progression of age-related macular degeneration

To develop a simple, clinically practical, optical coherence tomography (OCT)-based scoring system for early age-related macular degeneration (AMD) to prognosticate risk for progression to late AMD.

We retrospectively reviewed OCT images (512 × 128 macular cube, Cirrus) from 138 patients diagnosed of early AMD in at least one eye and follow-up of at least 12 months. For patients with early AMD in both eyes, only the right eye was chosen as the study eye for longitudinal assessment. Scans were graded on four SD-OCT criteria associated with disease progression in previous studies: drusen volume within a central 3-mm circle ≥0.03 mm³, intraretinal hyperreflective foci (HRF), hyporeflective foci (hRF) within a drusenoid lesion (DL), and subretinal drusenoid deposits (SDD). Each criterion was assigned one point. For risk assessment of the study eye, the baseline status of the fellow eye was also considered, and thus these four features were also assessed in the fellow eye. The number of risk factors were summed for both eyes, yielding a total score (TS) of 0 to 8 for each patient. A fellow eye with evident choroidal neovascularization (CNV) or atrophy automatically received 4 points. Scores were then grouped into four categories to facilitate comparative analysis: I. (TS of 0, 1, 2), II. (TS of 3, 4), III. (TS of 5, 6) and IV. (TS of 7, 8). Correlation of baseline category assignment with progression to late AMD (defined as the presence of atrophy or CNV on OCT) by the last follow-up visit was evaluated with logistic regression analysis.

The rate of progression to late AMD was 39.9% (55/138). Progression rates by category (I to IV) were 0, 14.3, 47.5, and 73.3%, respectively. Logistic regression analysis showed risk of progression to late AMD was 3.0 times (95% CI: 1.2–7.9) higher for an eye assigned to category IV than for an eye in category III and 16.4 (95% CI: 4.7–58.8) times higher than for an eye in category II.

A simple scoring system relevant to prognosis for early AMD, and practical for use in a busy clinic, can be developed using SD-OCT criteria alone.