Effect of cycloplegia on keratometric and biometric parameters in keratoconus and controls

Purpose. This study aimed to evaluate and compare the effect of cycloplegia on keratometric and biometric parameters in keratoconus patients and controls. Materials and methods. A preand post-interventional study was performed on 48 keratoconus (KC) patients diagnosed per Collaborative Longitudinal Evaluation of Keratoconus (CLEK’s) Classification and 41 age-matched controls. Full ophthalmological evaluations included refractive, keratometric, and biometric measurements with an auto kerato-refractometer (Topcon KR-800) and IOL MASTER 700, using 1% cyclopentolate hydrochloride for cycloplegia. Results. The study compared ocular measurements in KC patients and a control group before and after cycloplegia. KC patients exhibited significant changes in flat keratometry K1 (47.52 to 47.34), steep keratometry K2 (52.67 to 52.13), spherical equivalent (SE) (-6.35 to -5.5), lens thickness (LT) (3.49 to 3.44), anterior chamber depth (ACD) (3.75 to 3.84), and central corneal thickness (CCT) (446.78 to 450.72), all significant (p< 0.01), while axial length (AL) remained unchanged (23.5). The control group showed no significant differences in K1, K2, or AL, but SE, LT, ACD, and CCT exhibited significant changes. Conclusion. KC patients have a greater susceptibility to changes in corneal parameters post-cycloplegia compared to controls. These findings highlight the importance of careful evaluation in KC patients due to their distinct ocular responses to cycloplegia.