Effect of High Myopia on Cataract Surgery: An Age-Matched Case-Control Study

Introduction This study aimed to investigate the demographic factors and outcomes of cataract surgery in patients with high myopia. Methods This was an age-matched case-control study conducted at Hospital Pulau Pinang, Malaysia, involving patients who underwent phacoemulsification with intraocular lens implantation between September 2022 and August 2023. Seventy patients with axial length (AXL) ≥ 26.00 mm were included in the high myopia group, while 70 age-matched patients with AXL 22.00-25.99 mm served as the control group. Results The mean age of both groups was 67.3 years (SD = 7.86). Significant differences were observed between the control and high myopia groups in sex (p = 0.009), ethnicity (p < 0.001), AXL (p < 0.001), keratometric reading (K1) (p = 0.033), biometry (p = 0.049), and preoperative targeted spherical equivalent (SE) (p < 0.001). In the high myopia group, laser interferometry achieved a significantly higher proportion of postoperative SE within ±1.00 D compared with immersion ultrasound (p = 0.043), while no significant difference was found between biometry methods in the control group (p = 1.000). No significant differences were observed between the groups in preoperative or postoperative best corrected visual acuity (BCVA), BCVA improvement thresholds (≥ 0.2, ≥ 0.4, and ≥ 0.6 logMAR), K2, achieved SE, or SE differences. Simple and multiple logistic regression performed as a secondary analysis did not identify any significant predictors of postoperative SE > ±1.0 D. Conclusion Male sex and Chinese ethnicity were associated with high myopia in this cohort. In highly myopic eyes, the use of laser interferometry was associated with better refractive outcomes compared to immersion biometry. Surgeons intentionally targeted a more myopic preoperative SE in highly myopic eyes as a deliberate refractive strategy to reduce the risk of hyperopic surprise and to achieve postoperative refractive outcomes comparable to the control group.