Clinical outcomes of corneal refractive surgery comparing centration on the corneal vertex with the pupil center: a meta-analysis

Purpose To compare the visual and refractive outcomes between centration on the corneal vertex and the pupil center in corneal refractive surgery. Methods A comprehensive literature search was conducted using PubMed, MEDLINE, EMBASE, and the Cochrane Library to identify relevant studies. The primary outcomes were the postoperative spherical equivalent (SE), effectiveness [uncorrected distance visual acuity (UDVA) >= 20/20, eyes within +/- 0.50 diopter (D) of target refraction], and safety [loss >= 2 lines of corrected distance visual acuity (CDVA)]. Higher-order aberrations were considered secondary outcomes. Results Seven studies describing a total of 1964 eyes were included in this meta-analysis. A statistical significance in postoperative SE was found between the two centration methods for the correction of myopia that favor the CV-centered method (p < 0.001). No significant differences were observed in the proportion of eyes with UDVA >= 20/20 or loss >= 2 lines of CDVA postoperatively. However, the proportion of eyes within +/- 0.50 D was slightly higher (p = 0.02) and the coma aberration was much lower in the corneal vertex-centered method (p < 0.001). Conclusion Preferable visual and refractive outcomes could be achieved with either centering on the corneal vertex or pupil center in corneal refractive surgery; however, the corneal vertex-centered method has shown partial benefits in some clinical indices. In order to obtain higher quality of clinical evidences, more randomized controlled trials (RCTs) are required in further investigations.