By Shreeya Nanda, Senior medwireNews Reporter
Researchers have used spectral-domain optical coherence tomography (SD-OCT) to identify specific pathological changes that precede the development of drusen-associated atrophy in patients with age-related macular degeneration (AMD).
Robyn Guymer, from the University of Melbourne in Victoria, Australia, and co-authors say that “sensitive, specific, and evolving†functional and structural biomarkers of the early stages of AMD are lacking, which prompted them to conduct this retrospective study in 221 eyes from 181 participants with intermediate AMD who did not have SD-OCT–detected atrophy at the first consultation.
SD-OCT was performed in all participants in the initial cohort every 3 months for up to 30 months. And the prevalence of the relevant structural changes was further evaluated in a second cohort comprising 230 individuals (and 460 eyes), of which 40 were from the first cohort.
After a mean follow-up of 20 months, 20 areas of drusen-associated atrophy were detected in 16 eyes from as many participants. Using serial SD-OCT scans of these areas prior to the development of atrophy, the team identified two morphological features that they believe presage the development of drusen-associated atrophy.
Dubbed nascent geographical atrophy by the authors, these features were the subsidence of the outer plexiform layer (OPL) and inner nuclear layer (INL), and the development of a hyporeflective wedge-shaped band within the OPL. They note that these features are not detectable either with traditional clinical examination or colour fundus photography.
In the second cohort, nascent geographical atrophy was detected in 49 regions of 43 eyes from 37 patients. Despite the low incidence of these features in this group, the authors say their preliminary findings warrant further studies in larger cohorts.
Multivariate analysis showed that pigmentary changes in the examined eye and the presence of nascent geographical atrophy in its fellow were significantly associated with the risk of having nascent geographical atrophy in a given eye.
Guymer et al conclude in Ophthalmology: “The ability to assess early morphological changes that portend the development of drusen-associated atrophy and vision loss provides an opportunity to identify earlier, more frequent endpoints of advanced disease, potentially facilitating the design and implementation of clinical trials for early intervention in AMD.â€
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