Delayed corneal haze after combined photorefractive keratectomy and corneal cross-linking in non-keratoconus patients.

Purpose: To assess the incidence rate of corneal haze after combined simultaneous photorefractive keratectomy (PRK) and accelerated (10-min, 9 mW/cm²) corneal cross-linking (CXL) for non-keratoconus.

Methods: This is a retrospective cohort study on patients without keratoconus underwent simultaneous CXL-PRK. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, corneal keratometry, and corneal haze were evaluated.

Results: Included were 92 eyes of 55 subjects with mean age of 31.42 ± 4.62 years and mean follow-up time of 13.83 ± 11.24 months (range: 6 to 46 months). Mean UCVA improved significantly from 1.06 ± 0.36 to 0.14 ± 0.17 logMAR after procedure (P = 0.01), but the mean BCVA worsened significantly from 0.02 ± 0.05 to 0.08 ± 0.11 logMAR (P = 0.01). Significant corneal haze occurred in 18 eyes (19.6%). Among them 11 eyes (61.1%) developed corneal haze in first postoperative year. The BCVA deteriorated in 83.3% (15/18) of hazy eyes while 63.5% (47.74) of eyes without haze formation did not have any change of BCVA (P < 0.001). The UCVA improved in majority of eyes with (88.9%, 16/18) or without (97.3%, 72/74) haze formation (P = 0.18). Densitometry analysis showed that the densest layer of cornea in eyes with haze was anterior layer at 10-12 periphery zone followed by anterior layer at 2 mm central zone.

Conclusion: Nearly one-fifth of eyes develops significant corneal haze after CXL-PRK procedure. Despite of UCVA improvement, the loss of BCVA in eyes with corneal haze, suggests that CXL-PRK procedure should be approached with caution.