• SD-OCT Features That Precede New-Onset GA

    By Jean Shaw
    Selected By: Andrew P. Schachat, MD

    Journal Highlights

    Ophthalmology Retina, May 2021

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    Using spectral-domain (SD) OCT, Pasricha et al. sought to identify precursor features of new geographic atrophy (GA) prior to onset. They found that early photoreceptor changes and drusen accumulation herald the evolution to GA, as early as four years before GA is diagnosed, suggesting an early anatomic end point in trials of late-stage atrophic age-related macular degeneration (AMD).

    For this retrospective study, the re­searchers analyzed SD-OCT images and color photographs from 488 patients (488 eyes) with intermediate AMD at baseline. During the study’s seven-year time frame, 62 eyes with sufficient image quality developed new-onset GA during year 2 and thereafter.

    The area of new-onset GA and one size-matched control region in the same eye were separately segmented, and corresponding spatial volumes on SD-OCT images were defined at the GA incident year as well as at two, three, and four years prior to GA onset. Differences in SD-OCT features between paired precursor regions were evaluated through matched-pairs anal­yses. The main outcome measure was localized SD-OCT features two years before GA development.

    Results showed that, at two, three, and four years before onset, the GA precursor regions had greater drusen volume than did the paired control regions (p = .01, p = 003, and p = .003, respectively). At two and three years before GA onset, the precursor regions were associated with the presence of hypertransmission, hyperreflective foci, SD-OCT–refractive drusen substruc­tures, and loss or disruption of the photoreceptor zone, ellipsoid zone, and retinal pigment epithelium. At four years before onset, the precursor regions were associated with photore­ceptor zone thinning and interdigita­tion zone loss.

    These changes may correspond to biologically active sites in atrophy pathogenesis, the authors said, and they called for further studies on SD-OCT features and the molecular pathogene­sis of AMD. (Also see related commen­tary by Robyn Guymer, MD, in the same issue.)

    The original article can be found here.