Abstract
Purpose::
To compare and observe the epithelial behavior in patients undergoing photo refractive keratectomy (PRK) and laser assisted subepitelial keratectomy (LASEK) using confocal microscopy
Methods::
Prospective, longitudinal, comparative and experimental study. Patients undergoing PRK and LASEK on regular protocol were included. Patients were divided in two groups: group 1 patients in which PRK was performed, group 2 patients in which LASEK was done. Confocal microscopy (Confoscan 3, Nidek, Japan) and panoramic pictures in the slit lamp were taken at 1°, 4°, 5°, 12°, 18 and 25 postoperative days. Findings were compared between groups with clinical panoramic photographs in order to study the characteristics of epithelial growth . Also a corneal epithelial basal cell layer count was performed, in a constant area of 0.0192 mm2 (Software NAVIS 4.3.1 ®). The results were compared between groups and statistical analysis was done.
Results::
A total of 33 eyes were studied (17 patients) 21 eyes in group 1, and 12 eyes in group 2. A total of 58,800 confocal photographs were taken, only 900 pictures were selected for the study. A total of 576 clinical pictures were taken, 504 of group 1 and 72 of group 2, only 210 clinical photographs were used in this study. By day 4, pre-basal cells appeared in both groups, with a bilaminar layer in group 2. We noticed a complete replacement of the epithelial flap by pre-basal cells at day 5. By day 12 a bilaminar layer was seen in both groups, and a trilaminar appered by day 18. At day 25, in neither group, the epithelium had a normal appearance compared to the preoperative control. After day 5, group 2 showed hypertrophy and nucleated cells in basal epithelial layer compared with group 1. Preoperative cell density was 139.3 basal cells/0.0192 mm2 in group 1 and 156 basal cells/0.0192 mm2 in group 2. By day 25 the count was 135.4 basal cells/0.0192 mm2 and 144.3 basal cells/0.0192 mm2 in group 2. Cellular density had a statistical difference between both groups at day 5 (x=88.1 group 1, x=110.9 in group 2, P = 0.0008), 12 (x=113.7 group 1, x=128.3, P = 0.04) and 18 (group 1 x=122.5, x=144.4 group 2, P = 0.0001), and no statistical difference in the preoperative control (x=139.3 group 1, x=156.2 group 2 P = 0.06) and day 25 ( x=135.4 group 1, x=144.3 group 2 P = 0.3).
Conclusions::
Corneal epithelium in PRK and LASEK at day 25 still has not returned to normal characteristics. Epithelial cell density in LASEK group is higher than in PRK group.
Keywords: cornea: epithelium • refractive surgery: PRK • refractive surgery: comparative studies