When is refraction stable following routine cataract surgery? A systematic review and meta-analysis.

Purpose: We systematically reviewed the literature to investigate when refraction is stable following routine cataract surgery implanting monofocal intraocular lenses. Current advice recommends obtaining new spectacles 4-6 weeks following surgery. Due to advancements in surgical techniques, we hypothesised that refractive stability would be achieved earlier, which could have major short-term improvements in quality of life for patients.

Methods: Medline, CINAHL, AMED, Embase, Web of Science and the Cochrane Library were searched with key words chosen to find articles, which assessed refraction following uncomplicated cataract surgery. Citation chains and the reference lists of all included papers were searched. Unpublished literature was identified using OpenGrey (www.opengrey.eu). The review considered studies that measured refraction at regular intervals following surgery until stability was achieved.

Results: The search identified 6,680 papers. Two reviewers independently screened the abstracts and nine papers were found to fit the criteria, of which five were included in the meta-analysis. The quality of the papers was evaluated using the Methodological Index for Non-Randomised Studies (MINORS) instrument. Meta-analysis of 301 patients' data of spherical, cylindrical and spherical equivalent correction were performed using Review Manager 5 (RevMan 5.3) (https://revman.cochrane.org/). Refraction at 1-week versus the gold standard of 4-weeks showed no significant difference for sphere data (effect size and 95% confidence interval of; ES = 0.00, 95% CI: -0.17, 0.17; p = 1.00), cylindrical data (ES = +0.06; 95% CI: -0.05, 0.17; p = 0.31), and spherical equivalent (ES = -0.01; 95% CI: -0.12, 0.10; p = 0.90). Heterogeneity was non-significant (I  < 25%) for all refractive elements. Data were similar for 2- versus 4-weeks post-surgery. Acquired data from one study highlighted a small number of patients with very unstable cylindrical corrections at 1-week post-operatively.

Conclusions: No statistical difference was found when comparing sphere, cylindrical and spherical equivalent values at 1- and 4-weeks post cataract surgery. This suggests that new glasses could be provided 1-week after surgery. However, from a clinical perspective, a small number of patients (~7%) from an acquired dataset (N = 72) showed very unstable cylindrical corrections at 1-week. Further work is needed to determine why this is the case and how these patients can be detected.