ACCURACY OF OIL CALCULATIONS USING ULTRASONIC BIOMETRY BASED ON THE FELLOW EYE FOR PHACOVITRECTOMY IN PATIENTS WITH MACULA-OFF RHEGMATOGENOUS RETINAL DETACHMENT

Abstract

Background: Macula-off rhegmatogenous retinal detachment (RRD) can distort axial-length measurement and reduce the accuracy of intraocular lens (IOL) power calculation before phacovitrectomy. Objective: To determine the refractive accuracy of fellow-eye ultrasonic biometry compared with affected-eye biometry for IOL calculation in patients undergoing phacovitrectomy for macula-off RRD. Methods: This prospective diagnostic accuracy study included 71 patients treated at LRBT Eye Hospital, Township, Lahore, from 18 February to 17 June 2026. Axial length and keratometry were recorded in both eyes, and IOL power was calculated with the SRK/T formula. Postoperative prediction error and mean absolute prediction error (MAE) were compared between fellow-eye and same-eye calculations. Results: Mean age was 52.8±10.7 years and 62.0% were male. Affected-eye axial length was shorter than fellow eye axial length (23.31±0.91 vs 23.66±0.88 mm; p<0.001). Fellow-eye calculations produced a lower MAE than same-eye calculations (0.67±0.53 vs 1.09±0.77 D; p<0.001). Absolute prediction error was within ±0.50 D in 54.9% versus 31.0% (p=0.004) and within ±1.00 D in 83.1% versus 60.6% (p=0.003), respectively. Conclusion: Fellow-eye ultrasonic biometry provided better refractive prediction than affected-eye biometry in selected patients with macula-off RRD and may be a practical alternative when affected-eye axial-length measurements are unreliable.