ABSTRACT
AIM: To evaluate the effect of 0.02% mitomycin-C(MMC)on the corneal density after transepithelial photorefractive keratectomy(Trans-PRK). METHODS: Retrospective case analysis. Selected 28 patients with 56 eyes in moderate myopia who underwent Trans-PRK surgery from January 2021 to June 2021 in our hospital. They were divided into MMC group in 28 eyes with a combination of 0.02% MMC 20s during the surgery and the control group in 28 eyes was not use MMC during the surgery. The Pentacam anterior segment analyzer was used to measured the corneal density in different diameter ranges and different thickness layers before and after surgery at 14d, and after surgery at 1 and 3mo.RESULTS: The total corneal density value of MMC group was 16.60(15.70,17.10 )before the surgery, after the surgery at 14d was 16.63(15.90,17.50 ), at 1mo was 16.57(15.10,16.70 ), at 3mo was 16.04(14.60,16.60 ). The total corneal density value of control group was 16.30(15.50,17.30 )before the surgery, after the surgery at 14d was 16.20(15.20,17.10 ), at 1mo was 16.08(14.90,16.40 )and at 3mo was 15.60(14.60,16.40 ). In the zone of 0-2mm diameter was centered on the corneal vertex, the corneal density of the two groups at 14d after the surgery was higher than those before surgery(P<0.001 ). In the zone of 2-6mm diameter, the corneal density of the two groups at 1mo and 3mo after surgery was higher than those before the surgery(P<0.001). In the zone of 6-10mm, the corneal density of the two groups at 14d, 1 and 3mo after surgery was higher than those before the surgery(P<0.001). In the layer of anterior 120 μm, the corneal density of the two groups at 1mo and 3mo after the surgery was decreased than that before surgery(P<0.01). In the middle layer, the corneal density of the two groups at 1mo after the surgery was decreased than those before surgery(P<0.01).CONCLUSION:The use of 0.02% MMC during the operation can reduce the corneal density and increase the corneal light transmittance in the early postoperative period. The occurrence and prognosis of haze can be effectively quantified by observing the changes of corneal optical density in different ranges in different time periods after operation.
ABSTRACT
AIM: To explore the long-term efficacy of Q-factor guided laser epithelial keratomleusis ( LASEK ) for myopia and astigmatism with positive Q-factor. METHODS: There were 158 eyes which were myopia and astigmatism with positive Q- factor taken in two groups randomly: 86 eyes accepted Q - factor guided LASEK as observation group and 72 eyes accepted routine LASEK as control group. The difference between the two groups about all data was similar. The uncorrected visual acuity ( UCVA ) and the best corrected visual acuity ( BCVA ) as well as diopter, ocular tension, corneal topography, Keratometry value K, aspherical factor Q, Higher-order aberrations ( HOA ) , corneal thickness by ultrasound and, contrast sensitivity ( CS ) , Haze were examined and compared before and after surgery. All the cased were followed up for 14d, 1, 3, 6, 12mo. And there were no statistical difference among the data before surgery. RESULTS: After 12mo there were no statistical difference between the two groups about UCVA and BCVA. But the safety index of observation group was 1.10, that of control group was 1. 07. The validity index of observation group was 1. 06, that of control group was 0.99. The HOA of observation group was 0. 45±0. 17μm, and that of control group was 0. 72±0.25μm, there was statistically significant difference (t=-8. 193,P=0. 000). Q factor of observation group was 0. 41±0. 17, that of control group was 0. 77±0. 22, there was significant difference (t=11. 377,P = 0. 028). The contrast sensitivity of 3mo post surgery of patients in the observation group returned to the level of before surgery. But in the control group the contrast sensitivity of the patients did not returned until 6mo. CONCLUSION:Q-factor guided LASEK for myopia and astigmatism with positive Q-factor is stable, safe and effective. The operation allow for reducing the high order aberrations, maintaining the most asphericity of cornea, saving more in corneal tissue, which cause faster recovery of contrast sensitivity, less haze and better visual quality.