Study finds, Visual dysfunction and structural correlates in
A Study was conducted to elucidate morphological determinants of rod-and cone-dysfunction in Sorsby Fundus Dystrophy (SFD) and systematically compare visual function tests for interventional trials.

Patients with SFD(n=16) and controls(n=20) underwent visual function testing (best-corrected and low-luminance visual acuity [BVCA, LLVA], contrast sensitivity, mesopic and dark-adapted fundus-controlled perimetry [FCP], rod-mediated dark adaptation [RMDA]), and multimodal imaging. Vision-related-quality-of-life (VRQoL) was evaluated. FCP and RMDA thresholds were analyzed using mixed-models and structure-function correlation using machine learning (ML).

--While photopic BCVA was normative in SFD, LLVA was impaired and scotopic visual function with a delayed rod-intercept-time and marked DA cyan mean sensitivity loss, paralleled by a reduced VRQoL.

--ML-based structure-function correlation allowed to predict mesopic, DA cyan and red sensitivity with high accuracy, whereas RMDA could be slowed even in absence of fundus alterations on multimodal imaging.

--Following high-dose vitamin A supplementation, RMDA and DA thresholds improved markedly.

Conclusively, even in the absence of funduscopic abnormalities on multimodal imaging, patients with SFD have profoundly reduced scotopic visual function. Scotopic visual function tests, unlike BCVA, can be used to quantify early-stage impairment. Improvement in scotopic dysfunction following (off-label) high-dose vitamin A administration, as seen in one patient, is consistent with a local vitamin A deficit caused by Bruch's membrane changes.