Comparative Analysis of Cycloplegia’s Effect on Intraocular Parameters in Keratoconus and Controls

Abstract

Background: Cycloplegia, the paralysis of the ciliary muscle, can significantly alter ocular biometrics. However, its effect on the intraocular parameters in individuals with keratoconus (KC), a corneal condition causing visual impairment, remains inadequately understood. This study aimed to elucidate and compare the impact of cycloplegia on ocular parameters in KC patients and controls. Objective: To determine the effects of cycloplegia on anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) in individuals with keratoconus compared to age-matched controls. Methods: This pre- and post-interventional study was conducted at Al-Shifa Trust Eye Hospital's Cornea Department in Rawalpindi. Subjects with KC, diagnosed using the Rabinowitz criteria, and age-matched controls were enrolled. Comprehensive anterior segment examinations, including slit lamp biomicroscopy, were performed. Cycloplegia was induced using 1% cyclopentolate. Measurements of ACD, LT, and AL were taken using the IOL Master 700, both before and after cycloplegia. Data analysis was carried out using DataTab. Results: The study encompassed 72 participants in each of the KC and control groups. The mean ages were 20.46 ± 6.47 (KC) and 22.14 ± 5.8 (controls), with a gender distribution of 58.33% male and 41.67% female in the KC group, and 54.17% male and 45.83% female in the control group. Significant differences were observed in ACD and LT pre- and post-cycloplegia in both groups, but no significant changes were noted in AL. The KC group showed changes in ACD (3.75 ± 0.28 to 3.84 ± 0.28, p < 0.001) and LT (3.49 ± 0.24 to 3.45 ± 0.24, p < 0.001), while AL remained stable (23.5 ± 0.88). Controls showed similar trends in ACD and LT with no significant change in AL. Notably, post-cycloplegia, differences in ACD and LT were significant between the KC and control groups. Conclusion: Cycloplegia significantly influences anterior chamber depth and lens thickness in both keratoconus patients and controls, while axial length remains unaffected. These findings underscore the importance of considering cycloplegic effects in ocular biometric assessments in keratoconus and normal eyes.