Differences in Axial Length and IOL Power Based on Alternative A-Scan or Fellow-Eye Biometry in Macula-Off Rhegmatogenous Retinal Detachment Eyes

INTRODUCTION: This study was performed to observe the potential refractive prediction error based on alternative A-scan ultrasound and fellow-eye biometry for phacovitrectomy in macula-off rhegmatogenous retinal detachment (RRD) eyes. METHODS: Phakic macula-off RRD eyes without axial length (AL) measurements obtained using IOLMaster were included. Vitrectomy without lens extraction was performed for RRD repair. Preoperative AL was measured using alternative A-scan ultrasound (AL-US). Postoperative AL was obtained in eyes with silicone oil tamponade (AL-SO) and preoperative fellow-eye biometry (AL-FE) using IOLMaster. Other eyes that faced the same preoperative situation but underwent phacovitrectomy based on fellow-eye biometry were recruited as controls. RESULTS: AL-US, AL–FE, and AL-SO were 25.39 ± 2.14 mm, 25.85 ± 2.16 mm and 26.08 ± 2.53 mm, respectively. The Bland–Altman agreement among AL-US, AL-FE and AL-SO was good (95.5%, 21/22 of cases were in the LoA). The mean IOL power calculated using AL-US (Power-US), AL-FE (Power-FE) and AL-SO (Power-SO) was 16.81 ± 7.19 D, 14.74 ± 6.95 D and 13.54 ± 8.32 D, respectively. The difference between AL-US and AL-SO was significant (P < 0.05), while that between AL-FE and AL-SO was not (P > 0.05). The difference between Power-US and Power-SO was significant (P < 0.05), while that between Power-FE and Power-SO was not (P > 0.05). Nine eyes underwent phacovitrectomy based on fellow-eye biometry and had a final postoperative myopic shift of 0.64 ± 0.78 D. CONCLUSIONS: Alternative A-scan ultrasound led to a significant difference in AL and a prediction error in IOL power, while fellow-eye biometry provided similar results to silicone oil-filled eyes after RRD repair.