Intraocular Pressure Changes Following Corneal Cross-Linking in Patients With Keratoconus

This retrospective study found significantly elevated IOP measurements in eyes with keratoconus after CXL at postoperative months 1 and 3, but not after 4.5 months, compared with both baseline and untreated fellow eyes.

To evaluate intraocular pressure changes after corneal collagen cross-linking in patients with keratoconus and compare intraocular pressure measurements across tonometry methods.

A retrospective chart review was performed of 405 patients (405 index eyes and 218 untreated fellow eyes) who underwent cross-linking between January 1, 2012, and January 1, 2024, at Duke Eye Center. Preoperative and postoperative intraocular pressure measurements were collected at ~1 month, 3 months, and ≥4.5 months postoperatively. Generalized estimating equation models included time point, tonometry method (iCare, Tonopen, Goldmann applanation tonometry), corticosteroid use, age, sex, and race. Wilcoxon rank-sum and sign-rank tests were used for tonometry method sub-analyses.

In treated eyes, intraocular pressure significantly increased at 1 month (2.2 mmHg increase, P =0.001) and remained elevated at 3 months (1.1 mmHg increase, P <0.001), returning to baseline by ≥4.5 months ( P =0.168). No significant intraocular pressure change was observed in untreated fellow eyes at any postoperative time point. Tonopen measurements were consistently higher than iCare (all P <0.001). iCare measurements showed significant elevation at 1 month postoperatively ( P =0.005), and Tonopen measurements at 1 month and 3 months (both P <0.001). No elevation was observed beyond 3 months with any tonometry method.

Corneal collagen cross-linking was associated with transient intraocular pressure elevations postoperatively that normalized by ≥4.5 months. Tonometry method significantly influences intraocular pressure measurements, with iCare having lower measurements compared with Tonopen. Awareness of this pattern is important when managing patients with risk factors for glaucoma after cross-linking.