Stromal haze, myofibroblasts, and surface irregularity after PRK

Area of Science:

• Ophthalmology
• Corneal Surgery
• Tissue Regeneration

Background:

• Photorefractive keratectomy (PRK) is a common refractive surgery.
• Corneal haze and myofibroblast generation can be complications.
• Stromal surface irregularity is a potential factor influencing these complications.

Purpose of the Study:

• To investigate the relationship between stromal surface irregularity after PRK and myofibroblast generation.
• To assess the impact of irregularity on corneal haze development.
• To evaluate the efficacy of PTK-smoothing in mitigating these outcomes.

Main Methods:

• Variable stromal surface irregularity was induced in rabbit corneas using an excimer laser with a mesh screen.
• Haze grading and slit-lamp analysis were performed.
• Histochemical analysis (TUNEL, alpha-smooth muscle actin, integrin alpha4) assessed apoptosis, myofibroblasts, and basement membrane integrity.

Main Results:

• Increased stromal surface irregularity correlated with higher corneal haze and myofibroblast (alpha-smooth muscle actin positive) density.
• PTK-smoothing significantly reduced stromal irregularity, haze, and myofibroblast levels.
• Basement membrane disruption was observed in corneas with significant haze, with myofibroblasts located near defects.

Conclusions:

• Stromal surface irregularity after PRK is directly related to corneal haze and myofibroblast generation.
• PTK-smoothing is an effective method to reduce stromal irregularity, thereby decreasing haze and myofibroblast density.
• Defective basement membrane regeneration and altered TGF-beta signaling are hypothesized mechanisms linking irregularity to myofibroblast increase.