Corneal Structural Changes Following Crosslinking May Lead To Dry Eye

Patients with keratoconus who undergo corneal crosslinking (CXL) may experience keratometric flattening and corneal thinning, according to a study published in Eye & Contact Lens. A lack of meibomian gland morphology changes and a decrease in noninvasive tear breakup time (NITBUT) values following the procedure suggest that CXL may cause dry eye by altering the corneal structure without affecting meibomian gland morphology, according to the report.

Researchers enrolled 39 patients (48.7% women, mean age, 24.72 years) with keratoconus who underwent CXL at a single center in the nonrandomized, observational study. Participants underwent corneal topography, specular microscopy, NITBUT, and meibography assessment and completed the Ocular Surface Disease Index (OSDI) prior to surgical treatment and during 1-, 3-, and 6-month follow-up visits. 

The flattest keratometry (K1; P =.003) and steepest keratometry (K2) values flattened following the procedure (P <.001), the report shows. The apex, central, and thinnest corneal thicknesses thinned significantly from baseline to the 3-month follow-up (465.62 vs 427.27 µm; 461.77 vs 425.76 µm; 445.44 vs 407.58 µm, respectively, P <.001 for all) and remained significantly thinner at the 6-month visit compared with baseline (P =.032; P =.009; and P =.011, respectively). The changes in maximum keratometry (Kmax; P=.140), endothelial cell density, coefficient of variation, and hexagonality did not attain statistical significance. 

While the NITBUT values decreased after cross-linking, no significant changes were noted for OSDI index (P=.313), meiboscore (P=.392), or meibomian gland loss degrees (P =.300), suggesting that CXL surgery did not affect meibomian gland morphology.

“[T]here may be a deterioration in the quality of meibum without an architectural change in meibography after CXL,” according to the researchers. “CXL surgery mainly worsens meibum expression, and the structural changes may be attributable to chronic [meibomian gland dysfunction] rather than the short-term effect of surgery.”

Study limitations include a small sample size, single center design, and short study duration.