Identifying SIRE may aid in early detection of exudation
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Patients with OCT images that displayed a shallow, irregular retinal pigment epithelium elevation sign had a higher risk for nonexudative macular neovascularization, according to a cross-sectional study published in Ophthalmology.
This study indicated that shallow, irregular retinal pigment epithelium elevation (SIRE) may serve as a useful screening tool on routine structural OCT imaging to help identify eyes with nonexudative macular neovascularization (NE-MNV) and neovascular age-related macular degeneration.
“SIRE can be detected on the more ubiquitously available structural OCT B-scans and indicate eyes at higher risk of NE-MNV and, thus, subsequently neovascular AMD,” Callum Narita, BMedSc(Hons), from the Center for Eye Research Australia, Royal Victorian Eye and Ear Hospital in East Melbourne, and colleagues wrote. “These eyes could benefit from more frequent follow-up and patients given more targeted advice regarding self-monitoring so that the likelihood of early detection of exudation before irreversible vision loss is increased.”
Investigators assessed a discovery cohort (four eyes) comprising patients previously identified with AMD with definitive NE-MNV as detected on swept-source OCT angiography (SS-OCTA) and the double-layer sign on spectral-domain OCT to describe characteristic features of signs associated with NE-MNV. They next analyzed an evaluation cohort (233 eyes) comprising patients with AMD with large drusen (125 µm or more) in at least one eye.
Review of the discovery cohort showed that characteristics of the double-layer sign common in NE-MNV included a length of 1,000 mm or more, RPE elevation less than 100 mm, an irregular overlying RPE layer and a nonhomogenous reflectivity. Researchers termed all of these features as SIRE.
Features on OCT images from the evaluation cohort significantly associated with NE-MNV when RPE evaluation was more than 1,000 µm included height of RPE elevation, overall flat or variable morphologic features, irregular RPE layer and nonhomogeneous reflectivity (all P =.032).
Researchers identified 24 eyes (10.3%) with SIRE. Six eyes in the evaluation cohort were found to have definite NE-MNV on SS-OCTA imaging, all graded positively for SIRE. Investigators identified the absence of SIRE in 209 of 227 eyes (92.1%) without NE-MNV.
“The findings of our analysis of the diagnostic and predictive performance of the combined graded features that were associated significantly with NE-MNV suggest that together these features will detect almost all cases of NE-MNV,” the researchers wrote. – by Erin T. Welsh
Disclosures: Narita reports no relevant financial disclosures. Please see the full study for other authors’ relevant financial disclosures.
Editor's note: This article was updated to reflect the correct source journal.
Perspective
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Steven Ferrucci, OD, FAAO
This article attempts to determine some features of SD-OCT, described as the “double layer sign” that would indicate subclinical, nonexudative choroidal neovascular membranes in asymptomatic eyes. The concept is important, as anything a clinician can find on OCT that may make a patient more likely to convert from dry to wet or exudative AMD is crucial. That way, we could follow these patients at higher risk more frequently, to refer for treatment at the first sign of conversion to wet AMD. It is also important that these findings can be seen on SD-OCT and not only on swept source or OCT angiography, as many clinicians do not have these more expensive options.
Shortcomings include that these OCT findings described can be subtle at times, so the practitioner must be quite astute to use this information. Further, the OCT used was a Heidelberg, so it is unclear if these findings would relate to other brands of OCTs, although it seems likely that it would, as long at the resolution is sufficient. Also, as the authors point out, the sample size was relatively small, and the patients were not followed longitudinally, neither of which I feel outweigh the significance of this study.
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