Long-Term Changes in Corneal Power in Young Patients With Progressive and Nonprogressive Keratoconus

To investigate the long-term changes in corneal power in young patients with keratoconus (KC) and compare corneal power between eyes with and without progression by Fourier analysis using anterior segment optical coherence tomography (OCT).

Clinical records containing OCT data were retrospectively reviewed in patients with KC younger than 25 years at the first visit with a minimum follow-up duration of 2 years and at least one eye with abnormal KC findings. Eyes were divided into progressive (P) and nonprogressive (NP) groups using the ABCD grading system of Scheimpflug-based tomography. Baseline values and changes in Fourier components (spherical, regular astigmatism, asymmetry, and higher-order [HO] irregularity components) from the anterior and posterior corneal surfaces between the initial and last visits obtained with OCT were compared between both groups. Multivariate logistic regression analysis with stepwise selection was performed for baseline values to determine predictive baseline factors.

Twenty-three and 16 eyes were assigned to the P and NP groups, respectively. Changes in the anterior spherical and HO irregularity and posterior spherical components were significantly greater in the P group than in the NP group ( P <0.05). Baseline HO irregularity, regular astigmatism, and asymmetry components from the posterior cornea were predictive of KC progression, with the highest areas under the receiver operating characteristic curve of 0.796, 0.760, and 0.740, respectively.

Indices of regular and irregular astigmatism (asymmetry and HO irregularity) from the posterior corneal surface component can be potential prognostic indicators of KC progression in young patients.