Changes in refraction after cataract phacoemulsification surgery

PURPOSE: After cataract phacoemulsification surgery, spherical equivalent refraction (SER) may be affected by factors including corneal curvature, effective lens position and axial length. While refractive outcomes have been assessed in the immediate post-operative period, longer-term changes in refraction have not been reported. The purpose of this study was to investigate the timeline changes in refraction after cataract surgery over a period of 3 years. METHODS: This was a retrospective observational study that included 344 eyes of 204 patients who underwent cataract emulsification surgery between 1 January and 31 December 2018 at two private hospitals. Keratometry, anterior chamber depth (ACD), central corneal thickness (CCT) and axial length were measured at baseline and post-operatively at 1 month, 1 year, 2 years and 3 years. Changes in SER and ocular parameters were assessed at each post-operative timepoint. RESULTS: Between 1 month and 3 years post-operatively, an overall myopic shift (0.32 ± 0.21 D, p < 0.001) occurred in 33.6% of eyes and a hypermetropic shift in 45.2% of eyes (0.35 ± 0.22 D, p < 0.001). In 21.2% of eyes, there was no reported change in SER between 1 month and 3 years. Significant changes in ACD (p = 0.04) and CCT (p < 0.001) occurred during the first year after surgery. CONCLUSION: The 3-year timeline changes in SER after cataract surgery were evaluated. As hypermetropic shift was the most common refractive change observed, it may be beneficial to aim for a more myopic post-operative refraction target. Patients should be advised of the potential for refractive changes after surgery.