Effect of corneal cross linkage (CXL) on intraocular pressure (IOP) measurements in keratoconus patients

This study aims to determine the effect of corneal cross-linkage (CXL) on intraocular pressure (IOP) in keratoconus patients. Methods: A quasi-experimental study was carried out at the Cornea Clinic of Al Ibrahim Eye Hospital Malir, Karachi. A total of 60 eyes of 36 subjects with progressive keratoconus with the age range of 15 to 31 years were fulfilling the criteria of the study. Subjects were selected with convenient sampling and subjects with a previous history of CXL were excluded from the study. A complete history of the patient, clinical examination with slit-lamp biomicroscopy, and visual acuity (VA) with Snellen chart were recorded. Intraocular pressure (IOP) measurements of each subject were recorded with Goldman Applanation Tonometer (GAT) before and immediately after 15 minutes of CXL and on the 2nd day of CXL, 1month, and 3 months after CXL. SPSS version 22 was used to analyze the data. Results: The average preoperative measured intraocular pressure (IOP) was 20.22 +/- 3.97 mmHg. There was a statistically significant decrease in IOP measurements 18.96 +/- 3.73 mmHg on the same day after the corneal cross linkage procedure with (P 0.001) while there was no statistically significant change in intraocular pressure (IOP) measurements was observed on the 2nd day, 1 month and 3 months after CXL. The postoperative mean of IOP measurements was 19.61 +/- 3.47 mmHg on the 2nd day, 19.67 +/- 3.14 mmHg on 1 month, and 19.33 +/- 3.64 mmHg at 3 months respectively. Conclusion: This study shows that reductions in intraocular pressure (IOP) measurements were observed on the immediate response of corneal cross-linkage (CXL) on the same day. This change might be due to immediate alteration in the biomechanics of the cornea during corneal cross-linkage. These changes return to the normal position later because no change was seen on different follow-ups of patients after CXL in eyes with keratoconus.