Inter-eye asymmetry in manifest refraction, keratometry and pachymetry in eyes with keratoconus

Aim of the study
To evaluate selected visual system parameters in keratoconus patients and establish criteria which will enable better screening for keratoconus.

Material and methods
146 eyes of 73 patients diagnosed with keratoconus were included in the study. Each patient underwent optometric and ophthalmological examination with corneal tomography.

Results
We found a statistically significant inter-eye difference between the better and worse eye in median values of uncorrected (0.24 vs. 0.62 LogMAR) and best corrected (0.03 vs. 0.24 LogMAR) distance visual acuity. Our study also showed statistically significant differences in median values of keratometry between the better and worse eye (K1 43.1 vs. 45.4 D, K2 45.2 vs. 49.0 D), mean values of thinnest central cornea (TCC) (488 vs. 458 µm) and median grade 1.5 and 2.5 for the better and worse eye, respectively. The most prevalent refractive error was compound myopic astigmatism, followed by hyperopic compound or mixed astigmatism.

Conclusions
Keratoconus should be suspected in patients with inter-eye differences in manifest refraction, especially when astigmatism exists. Any inter-eye asymmetry in keratometry or pachymetry values should be an indication for full keratoconus screening.