Corneal morphological changes after myopic excimer laser refractive surgery.
OBJECTIVE
To evaluate the changes in central corneal thickness (CCT) and corneal volume (CV) in eyes that have undergone myopic photorefractive keratectomy (PRK).


METHODS
CCT and CV obtained with an Oculus Pentacam before 1, 3, and 6 months after PRK were analyzed in 84 eyes with a mean preoperative refraction of -4.93 ± 2.23 diopter. The changes were compared with the amount of refractive treatment. The differences were evaluated with the Student t test and the correlations with the Pearson index.


RESULTS
One month after PRK, CCT and CV mean differences were 73.2 ± 31.5 μm (P < 0.001) and 2.2 ± 1.7 mm (P < 0.001), respectively. Three months after PRK, CCT and CV mean differences were 66.6 ± 26.7 μm (P < 0.001) and 1.4 ± 1.3 mm (P < 0.001), respectively. Six months after PRK, CCT and CV mean differences were 65.3 ± 25.7 μm (P < 0.001) and 1.4 ± 1.3 mm (P < 0.001), respectively. The effective treatment at each follow-up point was correlated with CCT changes (R = 0.62, 0.71, and 0.73, respectively), but not with CV changes (R = 0.04, 0.04, and 0.01, respectively).


CONCLUSIONS
Our findings support the hypothesis that after myopic PRK, when a series of corneal lamellae are severed centrally, the remaining peripheral segments relax. The squeezing force on the matrix is reduced, and the distance between the lamellae expands.
Centro Grandi Apparecchiature, 2nd University of Naples, Naples, Italy. nicola.rosa@unina2.it
Nicola
N
Rosa
Maria
M
Borrelli
Maddalena
M
De Bernardo
Michele
M
Lanza
D000328:Adult; D003315:Cornea / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000473:pathology* / Q000601:surgery*; D010781:Photography / Q000379:methods; D011184:Postoperative Period; D011446:Prospective Studies; D054140:Refractive Surgical Procedures / Q000379:methods*; D013997:Time Factors; D055815:Young Adult