Assessment of Corneal Endothelial Layer in Contact Lens Wearers with the Aid of an Endothelial Microscope

Aims: The main aim of our study was to demonstrate the difference in endothelial cell density between a group of keratoconus contact lens users and non-contact lens users (without keratoconus).
Material and methods: In our study we had data from 96 subjects with an average age of 40.5 ±14.05 years. For the purposes of our study, we worked with each eye separately for each subject (n = 192). Keratoconus (research group) was diagnosed in 97 eyes. The mean age of the patients in the research group was 41.9 ±10.6 years. Keratoconus was not diagnosed in the remaining 95 eyes (control group). The mean age of the patients in the control group was 39.5 ±16.6 years. In the keratoconus group, the patients wore hard contact lenses (HCL) in a total of 43 eyes, hybrid contact lenses (HbCL) in 48 eyes and soft contact lenses (SCL) in 6 eyes. The average total period of contact lens use in the research group was 10.6 ±2.36 years.
Results: The average number of endothelial cells in the research group was 2607.11 ±298.45 cells per mm2. The average number of endothelial cells in the control group was 2831.94 ±523.51 cells per mm2. We tested these two variables using a T-test, which showed a statistically significant difference (p < 0.001). A statistically significant difference in the mean endothelial cell count related to patient age and use / non-use of contact lenses of two types was demonstrated only in the under-40 group in a comparison of the non-contact and keratoconus group with the keratoconus group using HCL 
(p = 0.02). A statistically significant difference in the length of contact lens wear was demonstrated between the keratoconus-free group with or without SCL and the keratoconus group when wearing HCL or HbCL for more than 20 years (p = 0.01 and p = 0.02). For HbCL users, this difference was demonstrated also after 15 years of wearing (p = 0.001).
Conclusion: From our results we can conclude that there is a difference in endothelial cell density between patients with and without keratoconus.