Quantification of Metamorphopsia using a Smartphone-based Hyperacuity Test in Patients with Idiopathic Epiretinal Membranes: Prospective Observational Study.

Background: Quality of vision in patients with idiopathic epiretinal membranes (iERM) is closely linked to distorted vision (metamorphopsia), which is often underestimated in clinical settings. Current surgical decision-making relies heavily on visual acuity and OCT findings, which do not adequately reflect the patient's functional vision or the severity of metamorphopsia. There is a clinical need for tools that can reliably quantify this symptom to improve patient outcomes and streamline care pathways.

Objective: This study is the first to assess the utility of a novel smartphone-based hyperacuity test (SHT) in quantifying metamorphopsia before and after surgical intervention for iERM, comparing it to a conventional printed chart.

Methods: This prospective observational study included 27 iERM patients with symptomatic metamorphopsia detected on the Amsler grid scheduled for vitrectomy with membrane peeling. The SHT (Alleye, Oculocare medical Inc., Zurich, Switzerland) and the horizontal (MH) and vertical (MV) M-chart (Inami & Co., Ltd., Tokyo, Japan) tests were performed three times before and three months after surgery. Pre- and postoperative metamorphopsia scores, changes in distance-corrected visual acuity (DCVA), optical coherence tomography (OCT) biomarkers and subjective perception of metamorphopsia were evaluated.

Results: The mean SHT score significantly (r=.686, P<.001) improved from 55.2 ± 18.9 before surgery to 63.5 ± 16.3 after surgery while the improvement of the M-chart scores were insignificant (MH r=.37, P=.06; MV r=.18, P=.36). Pre- and postoperative SHT scores showed very weak and insignificant correlations with the MH, MV, and MH+MV scores. Both metamorphopsia tests showed good reliability (intraclass correlation coefficients >0.75).

Conclusions: The smartphone-based hyperacuity test (SHT) showed a significant improvement in postoperative metamorphopsia scores, indicating that it could be a valuable tool for quantifying visual distortion in iERM patients. While discrepancies with M-chart results were observed, both tests demonstrated good reliability. Clinically, the SHT may offer a practical solution for monitoring metamorphopsia and guiding complex surgical decision-making, particularly in telemedicine settings. Its accessibility could improve patient management, potentially enhancing pre-operative triaging and reducing unnecessary visits.

Clinicaltrial: ClinicalTrials.gov NCT05138315.