A recent study developed a statistical model to assess the visual significance of subretinal fluid (SRF) and other OCT features in wet AMD and found that SRF levels below 150µm thickness have a minimal visual impact.

The researchers used labelled data from 1,211 OCTs of wet AMD patients in England to build their model. They created a four-dimensional plot to represent SRF’s visual impact in the context of atrophy and subretinal hyperreflective material on OCT.

Their model showed that SRF levels below 150µm had a low visual impact while levels 200µm or greater had an increasing impact on vision, so long as the presence of atrophy or subretinal hyperreflective material was minimal.

“It may be postulated that subretinal fluid, when associated with these characteristics, is more likely to be caused by RPE pump failure and therefore less directly responsible for vision loss,” the researchers wrote in their paper. “Alternatively, the presence of significant atrophy and subretinal hyperreflective material are themselves highly detrimental to visual function, and perhaps any additional negative impact from subretinal fluid is relatively minimal and thus doesn’t impact substantially on vision.”

The researchers concluded that their study “represents a novel approach providing detail and depth to the debate within the retinal scientific community around the importance of treating subretinal fluid with anti-VEGF injections.”