Impact of Simultaneous TG-PRK on Corneal Haze After Cross-Linking for Keratoconus: A Quantitative Densitometry Analysis.

Purpose: To compare the impact of simultaneous topography-guided photorefractive keratectomy (TG-PRK) on corneal haze in patients undergoing accelerated corneal cross-linking (CXL) for keratoconus, using corneal densitometry.

Methods: Retrospective, case-control study comparing patients undergoing accelerated CXL alone (CXL group) or combined CXL and TG-PRK (TG-PRK group). All patients performed PTK-assisted 50-μm deepithelization, followed by 10-minute ultraviolet-A exposure at 10 mW/cm2 (6 J/cm2 total dose). In the TG-PRK group, patients had simultaneous TG-PRK ablation for topographic regularization. Corneal densitometry was measured preoperatively, at 3 months, and at 1 year postoperatively using a Scheimpflug device. Changes in densitometry values across different corneal regions were analyzed to assess haze evolution.

Results: A total of 106 eyes were included, with 50 eyes in the CXL group and 56 eyes in the TG-PRK group. At 3 months and 1 year postoperatively, patients in the TG-PRK group exhibited significantly higher corneal densitometry values across all areas of the anterior and central middle stroma (P < 0.001). By 1 year, densitometry values in both groups had largely returned to baseline, except for the central 2 mm of the anterior cornea in the TG-PRK group. Patients with greater flattening had significantly more haze after CXL with TG-PRK, but no correlation was found between haze formation and changes in visual acuity in both groups.

Conclusions: Simultaneous TG-PRK and CXL result in more significant and prolonged corneal haze compared with CXL alone. Haze improves over time but persists longer in the combined procedure. Corneal densitometry is valuable for assessing haze and optimizing patient management.