Corneal collagen cross-linking in patients with keratoconus associated with dry eye

Purpose The aim of this study was to assess the safety and efficacy of corneal collagen cross-linking in keratoconus associated with dry eye.Patients and methods This study included 35 eyes of 29 patients diagnosed as having keratoconus associated with moderate dry eye manifestations (as measured by Schirmer 1 test result of 8-4 mm after 5 min). Moreover, 12 keratoconic eyes were also included in this study without any manifestations of dry eye as a control group (as measured by Schirmer 1 test result of ≥15 mm after 5 min). All eyes were subjected to preoperative and postoperative assessments including uncorrected visual acuity, best-corrected visual acuity, pachymetry, simulated keratometry, and corneal topography. The thinnest corneal thickness was at least 400 μm in all eyes. As mentioned before, the degree of preoperative dry eye was assessed using Schirmer 1 test. Epithelium-on cross-linking technique was used. All data were analyzed and recorded.Results The results of ‘epithelium-on’ collagen cross-linking are variable, but its noninvasive nature makes it potentially useful in cases when epithelium debridement is better to be avoided, such as in patients with dry eyes.In our study, there was a remarkable improvement regarding postoperative uncorrected visual acuity and best-corrected visual acuity (one line or more). There was no statistical significant difference between the results among dry eyes and nondry eyes. Average K readings showed a marked reduction reaching more than 2 D. The mean astigmatism showed unremarkable changes. The main central corneal thickness showed marked corneal thinning with reduction in the corneal thickness of ∼50 μm or more in many eyes.Conclusion This study showed no significant difference in efficacy and safety of corneal collagen cross-linking among eyes with keratoconus either associated with dry eye or not