To analyze the errors associated to corneal power calculation using the keratometric approach in keratoconus eyes after accelerated corneal collagen crosslinking (CXL) surgery and to obtain a model for the estimation of an adjusted corneal refractive index ( n k adj ) minimizing such errors.
Potential differences (Δ P c) among keratometric ( P k ) and Gaussian corneal power ( P c Gauss) were simulated. Three algorithms based on the use of n k adj for the estimation of an adjusted keratometric corneal power ( P k adj ) were developed. The agreement between P k(1.3375) (keratometric power using the keratometric index of 1.3375), P c Gauss, and P kadj was evaluated. The validity of the algorithm developed was investigated in 21 keratoconus eyes undergoing accelerated CXL.
P k(1.3375) overestimated corneal power between 0.3 and 3.2 D in theoretical simulations and between 0.8 and 2.9 D in the clinical study (Δ P c). Three linear equations were defined for n k adj to be used for different ranges of r 1c. In the clinical study, differences between P k adj and P c Gauss did not exceed ±0.8 D n k = 1.3375. No statistically significant differences were found between P k adj and P c Gauss ( p > 0.05) and P k(1.3375) and P k adj ( p < 0.001).