A Comparative Study Of Visual Function And Electrophysiological Characteristics After Unilateral Versus Bilateral Cataract Surgery

This study aims to investigate postoperative visual function and electrophysiological characteristics in unilateral cataract surgery comparing with bilateral cataract surgery. Hoping to find strategies for optimizing visual rehabilitation and surgical decision-making in asymmetric cataract cases.

This prospective observational study enrolled 24 cataract patients (48 eyes) at one eye hospital from March 2024 to August 2024. Patients were divided into two groups: 12 with significant interocular visual disparity (unilateral surgery group) and 12 with bilateral cataracts developed evenly (bilateral surgery group). All procedures adhered to the Declaration of Helsinki and were approved by the institutional ethics committee.

Preoperative assessments included logMAR UDVA and BCVA, contrast sensitivity (measured using the CSV-1000E under photopic and mesopic conditions, with and without glare), optical quality (assessed by the MTF area ratio and Strehl ratio using the OPD-Scan III), visual evoked potential (VEP) parameters (amplitude and latency), and patient-reported outcomes (using the Catquest-9SF and MMSE). After unilateral or bilateral cataract surgeries, postoperative evaluations at 1 week assessed visual outcomes, contrast sensitivity, optical metrics, VEP parameters, and the scores of the two scales. Data were tested for normality and analyzed using paired or independent t-tests, or their non-parametric equivalents, as appropriate (SPSS v25; p < 0.05).

The unilateral surgery group exhibited significant reductions in interocular UDVA (0.82±0.52 vs 0.08±0.08; p=0.001) and BCVA differences (0.45±0.34 vs 0.05±0.05; p=0.002), while the bilateral surgery group showed no significant changes (UDVA:0.30±0.23 vs 0.15±0.08, p=0.076; BCVA: 0.18±0.15 vs 0.10±0.11, p=0.141). Contrast sensitivity improved postoperatively in the unilateral group across spatial frequencies (3-18 c/d) under mesopic/photopic conditions (p<0.05), versus limited improvement in the bilateral group (3 c/d photopic glare, p<0.05). The N135-P100 amplitude was increased (28.73 vs 25.23 μV, p=0.010) and the interocular disparity was reduced (3.20 vs 8.12 μV, p=0.005) in the unilateral group. 

This study demonstrates that unilateral cataract surgery can significantly improve the interocular visual acuity disparities and contrast sensitivity comparing with bilateral cataract surgery. The N135-P100 amplitude is increased and the interocular disparity is reduced in the unilateral surgery group.