The role of anterior chamber depth on post-operative refractive error after phacovitrectomy

Purpose: To investigate the effect of phacovitrectomy on the post-operative anterior chamber depth (ACD) and refractive outcomes, and to analyze the potential differences between vitreous filling with BSS, air and gas. Methods: Patients who underwent phacovitrectomy were included in this study and invited for repeated post-operative examination including refraction and biometry at least 3 months after the surgery. Data retrieved included demographic information, indication for phacov-itrectomy, surgical details, type of vitreous filling (BSS, air or gas), pre-operative and post-operative biometric data including K-readings, axial length (AL), and ACD, as well as spherical equivalent (SE) values of the target and final refraction. Results: Forty-three eyes of 43 patients were included in this study, including 10 eyes filled with BSS, 18 with air and 15 with gas. The mean difference between the final measured spherical equivalent (SE) and the SE of the intended target refraction was 0.61±0.68 D (p = 0.019). Only 58.1% of eyes had a final SE within ±0.5D of the target refraction. Following surgery, AL remained unchanged, while mean pre-operative ACD increased significantly from 3.11±0.34 mm to 4.77±0.47 mm (p < 0.001). There was no difference in refractive error between the vitreous fillings and no correlation with AL or ACD. Conclusions: Phacovitrectomy is associated with lower accuracy of post-operative refraction compared to cataract surgery. This may be attributed to a significant change in ACD, influencing the effective lens position of the IOL, and may require adjustment of the pre-operative calculations.