The effect of large differences between cycloplegic and dry refraction on myopic Laser surgery outcomes

Purpose To compare laser refractive retreatment rates between patients with a clinically significant change in refraction (cycloplegic different) following cycloplegia versus those without (cycloplegic similar). Settings This retrospective study included consecutive patients who underwent laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between January 2005 and December 2019 at the Care-Vision Laser Centers, Tel-Aviv, Israel. Design Myopic patients were divided into two groups according to whether or not they demonstrated preoperative cycloplegic difference (a hyperopic shift of 0.50D or more following cycloplegia). Methods Binary logistic regression analysis, was performed to account for potential confounders of retreatment. Results Overall, 14,679 eyes were included in the final analyses. The age of the participants was 27.4 ± 7.8 years and 53.2% were male. Of these, 1,458 (9.9%) were cycloplegic different. Overall, 0.62% ( n = 91) of eyes underwent retreatment. The cycloplegic different group had a significantly greater retreatment rate (1.10% versus 0.57%, p = 0.01) and eyes which demonstrated cycloplegic difference were 1.94 times more likely (95% CI 1.13 to 3.35) to undergo retreatment. In stepwise binary logistic regression analysis, after accounting for potential confounders (gender, age, central corneal thickness, keratometry, best corrected visual acuity, cylinder, optic zone treatment, treatment type, laser model and ablation depth), cycloplegic difference remained a significant predictor of retreatment (OR = 1.80, 95% CI 1.01–3.18, p = 0.04). Conclusion A hyperopic shift of 0.50D or more in refraction following cycloplegia in myopic patients undergoing laser refractive surgery is associated with an increased risk for subsequent retreatment.