Applications of confocal microscopy in refractive surgery

PURPOSE: To evaluate applications of the Confoscan 2.0, a computerized confocal optical microscopy system by Nidek, in refractive surgery. METHODS: We used the Confoscan 2.0 to evaluate the tissue reparative response after PRK, LASEK, and LASIK in 60 eyes of 40 patients. Confoscan 2.0 provided highly detailed images of the corneal layers, up to the cellular level. Furthermore, it measured corneal thickness as well as precise positioning of each single recorded corneal layer. The Confoscan was also used to analyse the LASIK flap. RESULTS: Findings in the transition zone between epithelium and anterior stroma in PRK and LASEK eyes were divided into two groups: Group 1, with marked hyper-reflectivity, and Group 2, with less hyper-reflectivity, similar to normal eyes. Group 2 eyes belonged to patients that underwent smoothing with a masking solution after ablation. Group 1 eyes received no smoothing. In LASIK eyes, we evaluated the quality of the flap interface. Hyper-reflecting specks could be observed in the interface, showing a tendency to decrease over time. Depth of the LASIK flap was measured, and showed variable thickness with all microkeratomes tested. CONCLUSION: We hypothesize that a more regular corneal surface, obtained with smoothing in PRK and LASEK, allows a better reparative response after refractive surgery. In LASIK eyes, the Confoscan provided precise measurement of the residual stromal bed, information particularly valuable for the prevention of ectasia in retreatments.