CORNEAL LIGHT-SCATTERING WITH STROMAL REFORMATION AFTER LASER IN-SITUKERATOMILEUSIS AND PHOTOREFRACTIVE KERATECTOMY

Objective: To correlate corneal light scattering with keratocyte and e xtracellular matrix reformation after laser in situ keratomileusis (LA SIK) and photorefractive keratectomy (PRK). Setting: Wilmer Ophthalmol ogical Institute, Johns Hopkins University, Baltimore, Maryland, USA. Methods: Sixteen pigmented rabbit eyes were randomly divided into 2 gr oups. Group 1 (n=8) hand a 5.0 mm, -10.0 diopter (D) LASIK treatment a nd Group 2 (n=8), a 5.0 mm, -10.0 D surface PRK treatment after mechan ical epithelial debridement. The stromal surface exposed at surgery wa s stained with dichlorotriazinylaminofluorescein (DTAF) solution. Slit lamp biomicroscopic and objective measurement of corneal light scatter ing using a scatterometer were performed 1 and 2 days and 1, 2, 3, 4, 8, and 12 weeks after surgery. In each group, 2 corneas were harvested at 1 week and 1 month and 4 corneas were harvested at 12 weeks. Tissu e sections were examined by light and fluorescence microscopy. The per centage of newly formed stromal tissue was calculated and correlated w ith the scatterometry index. Results: In Group 1, corneas remained cle ar and healed without significant scarring throughout the study. In Gr oup 2, subepithelial scarring was noted. Extracellular matrix reformat ion peaked at 1 month and showed a slight regression thereafter. The p ercentage of extracellular matrix reformation was strongly correlated with the scatterometry index (r = .86, P < .001). Conclusions: In this study, significant subepithelial stromal tissue reformation followed PRK. The percentage of extracellular matrix reformation correlated wel l with the objective corneal light scattering measurements.