Assessment of Corneal Epithelial Thickness in Chronic Contact Lens Users Using Anterior Segment Optical Coherence Tomography

Abstract Introduction The corneal epithelium is stratified epithelium that is continuously renewed and provides the frontline of defence against invading ocular pathogens and a smooth refractive surface essential for vision. In the absence of a contact lens, pre-existing ocular trauma or disease, the epithelium maintains an inaccessible defence against attacks from pathogenic microorganisms, affording a high level of resistance against microbial invasion. Aim The aim of this study is to determine the effect of chronic use of contact lens on corneal epithelium thickness using anterior segment optical coherence topography as a non- invasive diagnostic accurate measure. Patients and Methods 30 eyes of control subjects who don’t wear contact lens along their life aged between 15-45 years ,where compared with similar age group of 30 eyes of chronic contact lens users; who wear contact lens every day not less than 8 hours per day for along time interval between 6 months up to 5 years. Results The average corneal epithelial thickness in the central, paracentral and midperipheral zones was 47.767 ± 5.550 µm, 46.267 ± 5.644 µm, 44.300 ± 4.858 µm, respectively, in chronic soft contact lens users; and 49.800 ± 3.316 µm, 49.200 ± 3.367 µm, 45.733 ± 2.333 µm ,in control group who had never worn contact lens. There were insignificant thinning of corneal epithelium of soft contact group compared to control group regarding the average corneal epithelial thickness in those 3 zones. In all the 8 sectors of corneal epithelium of paracentral zone and midperipheral zones there is insignificant thinning between the two groups except for the inferior temporal sector in the paracentral zone and mid peripheral zone, which shows significant thinning in soft contact lens group compared to control group. The corneal epithelial thickness in the inferior temporal sector of paracentral and mid peripheral zones was 46.333 ± 5.677 µm, 44.933 ± 4.813 µm, respectively, in chronic soft contact lens users compared to 48.767 ± 3.266 µm, 46.900 ± 2.510 µm in control group (p = 0.046, p = 0.052, respectively). Conclusion AS-OCT helps us to evaluate the corneal epithelium of contact lens users, which could be very useful in corneal refractive surgeries in patients depending on contact lens in their lives as a comfortable refractive aid, It is necessary to do AS-OCT hand on hand with pentacam in patients underwhelming refractive surgery to give a proper assessment to their corneal epithelium before determining which type of refractive surgery suits them.