Sushrutha's Reflex: A Novel Clinical Sign for Detecting Focal Macular Surface Elevation

Purpose: To describe a novel clinical sign, eponymously named Sushrutha's reflex, and to evaluate its diagnostic effectiveness for identifying focal retinal surface elevations, such as those found in central serous chorioretinopathy (CSCR) and pigment epithelial detachments in eyes of younger patients (ages 18-56 years). Methods: A prospective, observational study was conducted in a cohort of patients with optical coherence tomography (OCT)-confirmed focal convex retinal surface elevations at National Eye Hospital, Colombo, Sri Lanka, from April 2011 to September 2018. Eyes of included patients were examined by an independent researcher using indirect ophthalmoscopy with a 90-diopter, 78-diopter, or 66-diopter condensing lens. The technique involves moving the lens vertically while observing the position of the light reflex on the retinal surface. A normal retina is considered to have a foveal light reflex that moves in the direction of the lens movement, but as the image of the retina from the condensing lens is inverted, it is seen as moving against the motion of the lens. In a retina with a focal elevation, such as in CSCR, a light reflex is seen around the retinal elevation. This retinal light reflection moves against the direction of lens movement, and this pattern constitutes the clinical sign known as Sushrutha's reflex. Results: Of 76 patients with OCT-confirmed retinal elevations (primarily CSCR), 70 (92.1%) demonstrated a positive Sushrutha's reflex. The mean age of patients was 37 years (range, 18-56 years). The sign was also successfully identified in a case of extramacular CSCR. Six patients with confirmed elevation did not exhibit the sign. Conclusion: Sushrutha's reflex is a highly sensitive (92.1% detection rate) clinical sign for detecting focal retinal surface elevation in younger eyes, whereas in older eyes, the light reflex becomes dull, and its position will be harder to determine. In those with a clear light reflex, the test is a rapid, simple, and noninvasive technique that requires no additional equipment beyond standard indirect ophthalmoscopy. The technique's high utility, particularly in low-resource settings where access to definitive imaging is limited, makes it a significant addition to the clinical examination for diagnosing conditions like CSCR.