Tear Function and Ocular Surface Alterations After Accelerated Corneal Collagen Cross-Linking in Progressive Keratoconus

To investigate the alterations in the ocular surface and tear film parameters 3 months after accelerated corneal collagen cross-linking (A-CXL) in progressive keratoconus (KC) patients. Twenty-six patients (33 eyes total) with progressive KC were enrolled in this study. All patients were subjected to ophthalmic surface examination, such as OSDI (ocular surface disease index) scoring, the osmolarity tear test, Schirmer test, tear film breakup time (TBUT) analysis, rose bengal (RB) and fluorescein (Fl) ocular surface staining, and conjunctival impression cytology (IC) analysis, respectively. These tests were performed at baseline and 3 months after A-CXL. Nelson's grading system was used to evaluate the cell morphology and goblet cell density. No statistically significant differences in the levels of tear osmolarity, TBUT, Schirmer test, OSDI scoring, and Fl and RB staining between pretreatment and 3 months postoperatively were observed (all P values >0.05). A statistically significant increase in superior (P=0.005) and temporal (P=0.006) IC grading was seen at the postoperative third month compared to pretreatment. Only metaplastic changes and a reduction in the density of the goblet cells were seen in conjunctival IC, which is probably because of the toxicity of ultraviolet-A 3 months after A-CXL. However, these results do not lead to deterioration in TBUT. In this study, A-CXL has no adverse effect on ocular surface and tear function, which are important for visual quality.