Factors affecting epithelial hyperplasia after photorefractive keratectomy

Area of Science:

• Ophthalmology
• Corneal Surgery
• Excimer Laser Surgery

Background:

• Photorefractive keratectomy (PRK) is a common refractive surgery.
• Understanding changes in corneal epithelial thickness post-PRK is crucial for visual outcomes.
• Factors influencing epithelial remodeling after PRK require further investigation.

Purpose of the Study:

• To investigate the impact of patient age, postoperative time, ablation zone dimensions, attempted correction, and corneal topography on corneal epithelial thickness following PRK.
• To compare epithelial thickness changes between different excimer laser platforms (Summit and VISX).

Main Methods:

• Retrospective analysis of 136 myopic patients undergoing unilateral PRK.
• Epithelial thickness measured using a modified optical pachymeter.
• Corneal topography assessed with computerized videokeratoscopy.
• Comparison between treated eyes and untreated fellow eyes (controls).

Main Results:

• Summit laser PRK resulted in a significant 21% increase in epithelial thickness compared to controls, correlated with ablation depth and attempted correction.
• VISX laser PRK showed a 7% decrease in epithelial thickness, not correlated with ablation depth or correction.
• Epithelial hyperplasia was more pronounced with smaller ablation zones and steeper peripheral ablation profiles, irrespective of patient age or follow-up time.

Conclusions:

• Smaller ablation zones, greater attempted corrections, and deeper ablations are associated with increased corneal epithelial thickness post-PRK.
• Larger and smoother ablation profiles may lead to reduced epithelial hyperplasia.
• Laser platform and ablation characteristics significantly influence post-PRK epithelial remodeling.