Exploring the relationship between accommodation and intraocular pressure: a systematic literature review and meta-analysis.

Purpose: To investigate the relationship between accommodation and intraocular pressure (IOP).

Methods: Systematic literature search and meta-analysis following PRISMA guidelines was conducted on studies analyzing the relationship between accommodation and intraocular pressure. After removal of duplicates, title and abstract screening, full-text analysis was performed to select relevant articles and meta-analysis was then conducted as well.

Results: Of the 1357 records identified, 17 met the selection criteria and were included. Overall, all studies showed that accommodation can influence IOP levels and meta-analysis indicated a significant IOP reduction of 1.10 mmHg (95%CI, -1.77; -0.42) following accommodative stimulus in healthy individuals, albeit with high heterogeneity among studies. Differences in IOP changes between emmetropic and progressing myopic individuals were not significant. Controversial results were obtained in patients with glaucoma with significantly lower IOP fluctuations being noted in eyes with previous trabeculectomy; however, the clinical heterogeneity of enrolled patients among studies made it not possible to combine results. Type of accommodative task, extraocular muscle contraction, head and body position all could potentially play a role in the measured IOP changes with, interestingly, near reading on a smartphone suggesting IOP increase.

Conclusion: Accommodation has an impact on IOP measurements and, overall, determines IOP decrease in healthy individuals. While such variations might not hold clinical significance for individuals in good health, their impact in patients with glaucoma should be considered. Further studies focused on specific components of such relationship are required to elucidate their individual impact and to define their potential role as non-pharmacological strategies to reduce IOP levels in selected patient categories.