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Objective measurement of corneal light scattering after excimer laser keratectomy
R E Braunstein1, S Jain, R L McCally
1Wilmer Institute, Johns Hopkins University, Baltimore, MD, 21287-9233, USA.
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 1 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 microns.
Conclusions:
Excimer laser surgery affects corneal light scattering. Ablations with depths greater than 80 microns produce significantly higher levels of haze than those less than 80 microns. Objective measurement of corneal light scattering may be useful in monitoring the outcome of excimer keratectomy.