Post on 06-Jan-2016
description
Eye Department
The authors have no financial interest in the subject matter of this poster
CHANGES IN CORNEAL VOLUME AFTER MYOPIC PHOTOREFRACTIVE KERATECTOMY
Michele Lanza, Maria Borrelli, Maddalena De Bernardo, Marco De Luca, Antimo Flagiello, Nicola Rosa.
Purpose of our study was to evaluate the changes in central corneal
thickness (CCT) and corneal volume (CV) in eyes that underwent
myopic PRK.
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.
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)
The changes were compared with the amount of refractive
treatment.
The mean preoperative refraction was -5.04 ± 2.23 D
(range: -1 D to -14.5 D)
CV has been measured at 10 mm, as default setting of the device
METHODS
RESULTS
Corneal parameters before and after surgery
BEFORE1 MONTH POST OP
3 MONTHS POST OP
6 MONTHS POST OP
CCT500 – 645 µ
(560.17 ± 30.45 µ)340 – 581µ
(477.14 ± 46.43 µ)324 – 582 µ
(478.01 ± 44.14 µ) 385 – 591 µ
(485.28 ± 39.07 µ)
CV53.2 - 69.8 mm3
(61.88 ± 3.40 mm3)47.3- 66.8 mm3
(59.3 ± 3.53 mm3)47.5 – 67.2 mm3
(59.57 ± 3.49 mm3)53.2 – 69.1 mm3
(60.38 ± 3.59 mm3)
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
RESULTS
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
CONCLUSIONS
2) After myopic PRK when a series of corneal lamellae are severed centrally the remaining peripheral segments relax.
CONCLUSIONSWith 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.