Objective measurement of corneal light scattering after excimer laser keratectomy

Purpose: To obtain objective measurements of corneal light scattering after excimer laser keratectomy, and to evaluate the relation of light scattering to clinical haze grading and visual acuity. Methods: The authors measured best-corrected visual acuity, subjective clinical haze grade, and corneal light-scattering index in patients undergoing photorefractive keratectomy (PRK) (n = 26) and phototherapeutic keratectomy (n = 8), preoperatively and postoperatively at 1, 3, 6, 9, and 12 months or later. Corneal light scattering was correlated with visual acuity and clinical haze grade. Results: Corneal light scattering increased after PRK and was reduced after phototherapeutic keratectomy. Corneal light-scattering index showed a stronger positive correlation with logMAR visual acuity (r = 0.57) than clinical haze grading (r = 0.34). Corneal light-scattering index (P < 0.05 at I and 3 months) and clinical haze grading (P < 0.05 at 6, 9, and 12 months) were significantly higher in eyes undergoing PRK with ablation depths of more than 80 mu m. Conclusions: Excimer laser surgery affects corneal light scattering. Ablations with depths greater than 80 mu m produce significantly higher levels of haze than those less than 80 mu m. Objective measurement of corneal light scattering may be useful in monitoring the outcome of excimer keratectomy.