Tear function and ocular surface changes following corneal collagen cross-linking treatment in keratoconus patients: 18-month results

Evaluation of Corneal Parameters and Meibomian Gland Alterations After Corneal Cross-Linking in Patients With Progressive Keratoconus

OBJECTIVES

The aim of the study was to evaluate the changes in corneal parameters and meibomian gland alterations after corneal cross-linking (CXL) for progressive keratoconus.

METHODS

Thirty nine eyes of 39 keratoconus patients were treated with CXL. Corneal topography, specular microscopy, the Ocular Surface Disease Index© (OSDI), noninvasive tear break-up time (NITBUT), and meibography indices were evaluated preoperatively and at the first, third, and sixth months after CXL.

RESULTS

The flattest keratometry (K1) ( P =0.003), steepest keratometry (K2) ( P <0.001), apex, central, and thinnest corneal thicknesses ( P <0.001) showed significant differences after cross-linking, whereas the changes in the maximum keratometry (Kmax) were not significant ( P =0.140). The endothelial cell density, coefficient of variation, and hexagonality were unchanged. The NITBUT values decreased after cross-linking; however, there was no significant change in OSDI index ( P =0.313), meiboscore ( P =0.392), and meibomian gland loss degrees ( P =0.300). No change was detected in the morphology of the meibomian glands after CXL.

CONCLUSION

In eyes with keratoconus, a flattening in keratometry readings and thinning in corneal thickness were observed after CXL. The corneal endothelium is protected by dextran-free riboflavin. Cross-linking procedure causes dry eye by changing the corneal structure without affecting the morphology of the meibomian glands.

Evaluation of tear parameters and meibomian gland morphology in keratoconus patients after epithelial-on corneal cross-linking

PURPOSE

To evaluate the variations in tear parameters and meibomian gland morphology after epithelial-on (epi-on) corneal collagen cross-linking (CXL) in keratoconus (KC) patients.

METHODS

This prospective observational study included 38 KC eyes that underwent epithelium-on CXL. Thirty-three eyes of 33 stable KC patients with no prior CXL treatment formed the KC group and 35 eyes of 35 healthy volunteers were recruited as the control group. All participants were evaluated by Schirmer I test, first and average noninvasive tear break-up time (NITBUT), ocular surface disease index (OSDI) questionnaire, and meibography scores. The CXL patients were evaluated preoperatively and at the 1st, 3rd, and 6th months, and participants without any intervention (KC and control groups) were evaluated initially, at 1st, 3rd, and 6th months.

RESULTS

The KC patients had significantly lower average NITBUT, higher OSDI scores, and impaired meibomian gland morphology than healthy individuals (NITBUT(seconds): KC, 12.8(2.4-17.6), healthy group (HG), 17.1(6.8-17.6); p = 0.012, OSDI: KC, 27.5(0.0-87.5), HG, 7.5(0.0-55.0); p < 0.001, p < 0.001, respectively). A significant difference was found in Schirmer values of the CXL group at 0-1st months, first NITBUT values at 1-6 months, and average NITBUT values at 1-3 and 1-6 months (p = 0.003, p = 0.001, p = 0.003, p = 0.001, respectively). All meibography parameters remained unchanged after CXL over a 6-month follow-up compared to initial measurements.

CONCLUSIONS

Even though the KC patients had lower NITBUT, higher OSDI scores, and increased meibomian gland disfunction, the CXL treatment did not significantly affect tear quantity, dry eye symptoms, and meibomian gland morphology.

Analysis of Tear Function Outcomes following Collagen Cross-Linking Treatment in Ectatic Corneas

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.

[Changes in precorneal tear film and ocular surface in keratoconic patients after corneal collagen cross-linking]

The article reviews the current available data on the signs and symptoms of dry eye syndrome (DES) in patients with keratoconus (KC), describes the clinical features of DES in KC patients and the morphological features of this type of keratectasia that lead to manifestations of the «dry eye», and highlights the risk factors, consequences of therapeutic measures, concomitant ophthalmological and general somatic diseases that contribute to the development of DES in KC.

Tear film parameters before and after intracorneal ring segment implantation in keratoconic eyes

PURPOSE

To assess signs of dry eye syndrome in keratoconic eyes following intracorneal ring segment (ICRS) implantation.

PATIENT AND METHODS

Twenty eyes of 20 consecutive patients with keratoconus were assessed for tear film changes following ICRS implantation at 6 months postoperatively. Evaluated parameters included tear osmolarity, non-invasive tear breakup time test (NI-BUT test) and Schirmer test I and II before and after treatment.

RESULTS

No significant changes were found with respect to osmolarity, Schirmer I and II (p = 0.9, p < 0.64, and p < 0.91, respectively). The NITUBT was significantly lower after surgery (p = 0.04).

CONCLUSION

Our results suggest that implantation of ICRS does not result in a significant change in tear film osmolarity, or tear film volume nor improves the tear film stability.