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Eye Department. CHANGES IN CORNEAL VOLUME AFTER MYOPIC PHOTOREFRACTIVE KERATECTOMY. Michele Lanza, Maria Borrelli, Maddalena De Bernardo, Marco De Luca, Antimo Flagiello, Nicola Rosa. The authors have no financial interest in the subject matter of this poster. PURPOSE.
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Eye Department CHANGES IN CORNEAL VOLUME AFTER MYOPIC PHOTOREFRACTIVE KERATECTOMY Michele Lanza, Maria Borrelli, Maddalena De Bernardo, Marco De Luca, Antimo Flagiello, Nicola Rosa. The authors have no financial interest in the subject matter of this poster
PURPOSE Myopic photorefractive keratectomy (PRK) is a reliable method to correct refractive errors. With this method a slice of corneal tissue is ablated, thus giving a flattening and a thinning of the central cornea. Purpose of our study was to evaluate the changes in central corneal thickness (CCT) and corneal volume (CV) in eyes that underwent myopic PRK.
METHODS CCT and CV obtained with an Oculus Pentacam Before, 1, 3 and 6 months after PRK were analyzed in 118 eyes of 64 patients (38 male, 26 female) CV has been measured at 10 mm, as default setting of the device The mean preoperative refraction was -5.04 ± 2.23 D (range: -1 D to -14.5 D) The changes were compared with the amount of refractive treatment.
RESULTS Corneal parameters before and after surgery
RESULTS 1 month after PRK CCT and CV mean differences were 82.39 ± 34.56 microns (p<0.001) and 2.47 ± 1.76 mm3 (p< 0.001) respectively. 3 months after PRK CCT and CV mean differences were 79.2 ± 33.48 microns (p<0.001) and 1.98 ± 1.59 mm3 (p<0.001) respectively. 6 months after PRK CCT and CV mean differences were 74.48 ± 28.96 microns (p<0.001) and 1.65 ± 1.37 mm3 (p<0.001) respectively.
RESULTS Our results showed a decrease in both CCT and CV after treatment with a good correlation between CCT changes and treatment (one month after PRK R2=0.48; three months after PRK R2=0.52; six months after PRK R2=0.61) No correlation could be found between CV changes and treatment (one month after PRK R2= 0.05; three months after PRK R2=0.09; six months after PRK R2=0.06).
CONCLUSIONS • It is possible to rise three different hypothesis to explain our findings • Epithelial hyperplasia • Mid peripheral corneal thickening • Both
CONCLUSIONS 2) After myopic PRK when a series of corneal lamellae are severed centrally the remaining peripheral segments relax.
CONCLUSIONS With the reduction of tension in the lamellae the squeezing force on the matrix is reduced and the distance between lamellae expands. This allows the periphery of the cornea to thicken and the peripheral increase in corneal thickness will compensate for the ablated corneal tissue leading to a change in CV.