Abstract
Purpose To analyze tear function outcomes following collagen cross-linking (CXL) treatment in ectatic corneas. Methods Fifty-seven eyes of 34 patients were included, and patients with keratoconus who underwent epithelium-on (epi-on) or epithelium-off (epi-off) CXL were evaluated. The following tests were performed preoperatively and at 1, 3, 6, and 12 months postoperatively: best-corrected visual acuity (BCVA), maximum keratometry value (Kmax), ocular surface disease index (OSDI) questionnaire, slit-lamp examination, tear meniscus height, first noninvasive Keratograph breakup time (1st NIKBUT), average NIKBUT, and bulbar redness. Results BCVA improved in both epi-on and epi-off groups at most follow-up points, but was not significantly different between groups. At 12-month follow-up, Kmax in the epi-on and epi-off groups improved after CXL, but there was no significant difference between the groups. The OSDI in both groups decreased after operation compared with before surgery, and there was no significant difference between the two groups. Comparing the two groups, only the change in the tear meniscus height at 6 months postoperatively was statistically significant, and the pre- and postoperative values of the two groups were within the normal range (>0.20 mm). The change was small and had no clinical significance. There was no change in the 1st NIKBUT and average NIKBUT between the epi-on and epi-off groups. A change in bulbar redness was significantly better in the epi-off group than in the epi-on group at 3 months postoperatively. Comparing the effects at 1 year postoperatively, both groups had positive results in OSDI, NIKBUT, tear meniscus height, and bulbar redness. Conclusion Both epi-on and epi-off CXL can control the progression of keratoconus, although epi-off CXL is more effective. Both methods have a positive effect on dry eye, which can improve the condition of the tear film and reduce dry eye symptoms in patients with keratoconus.
Highlights
Keratoconus is a progressive primary ectatic disease, which involves irregular astigmatism and corneal thinning due to structural and biomechanical changes in the stroma, leading to vision loss [1, 2]
All visits were conducted in the morning, between 10 and 12 AM. e patient stopped wearing rigid gas permeable (RGP) contact lenses for 1 week before each visit to avoid the influence of RGP on the ocular surface. e incidence of complications was recorded at the 12-month follow-up
Few studies have compared epi-on and epi-off surgery in terms of visual and tear film functional changes, or even in terms of the progression of keratoconus [18, 19]. erefore, we studied the effects of two surgical methods on best-corrected visual acuity (BCVA), which are described as decimal visual acuity style and tear film function of patients with keratoconus. e Tear Film and Ocular Surface Society Dry Eye Workshop suggested that a noninvasive measure of tear stability was preferred in the diagnosis of dry eye [20, 21]
Summary
Keratoconus is a progressive primary ectatic disease, which involves irregular astigmatism and corneal thinning due to structural and biomechanical changes in the stroma, leading to vision loss [1, 2]. Treatment is selected based on the severity of the disease and is aimed at improving vision and preventing ectasia progression [2]. Various CXL protocols have been extensively investigated and applied [5], including epithelium-on (epi-on) and epithelium-off (epi-off) protocols with transepithelial riboflavin application. Both of these surgical methods are popular and well researched [6, 7]. We analyzed the influence of epi-on and epi-off CXL on the tear function of Chinese patients with keratoconus
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