Biometric refractive error after cataract and retina surgery: a systematic review and a benchmark proposal

Abstract Purpose: To systematically review studies on refractive error after phacovitrectomy and phacoemulsification and to investigate factors associated with larger error. Materials and methods: A literature search was performed using PUBMED and EMBASE until May 2020. The articles were included in the study if they reported data about refractive error as the difference in spherical equivalent between actual vs. target refraction in patients who underwent phacovitrectomy and phacoemulsification according to the type of biometry (ultrasound or optical). An inverse variance meta-analysis technique was used to pool errors; standard deviations (SDs), which are an expression of random error, were reported descriptively as median and range of the 95% coefficient of reproducibility (95% CR: 1.96 SD). Results: Twenty-one studies (197,353 eyes) were included. The mean error obtained using optical biometry was negligible for phacoemulsification (0.04 D, 95% CI: -0.04 to 0.12; 8 studies, 587 eyes) and was consistent with larger datasets using mixed biometric methods (0.02, 95% CI -0.07 to 0.04; 5 studies, 194,522 eyes). A trend towards hyperopia was found with ultrasound biometry after phacoemulsification (+0.21 D, 0.00-0.42 D; 7 studies, 394 eyes). Mean error after phacovitrectomy was clinically insignificant with optical biometry (-0.10 D, -0.22 to 0.02;, 8 studies, 453 eyes), and) and a mild myopic shift was possible with ultrasound biometry (-0.39 D, 95% CI: -0.68 to -0.09 D; 6 studies, 529 eyes). The 95% CR was greater and more variable with ultrasound biometry in patients who underwent phacovitrectomy (median 1.75 D, range 0.47-2.5) while it was consistent and lower with optical biometry in patients who underwent phacoemulsification (median 0.96 D, range 0.60-1.2]). Conclusions: Phacovitrectomy causes a mild myopic shift compared to phacoemulsification, which is clinically relevant only with ultrasound biometry. Furthermore, our review provides estimates of fixed and random error for postoperative vs. target spherical equivalent as a continuous variable, that is easy to use as benchmark for quality assurance.