ABSTRACT
Background Compare with the lamellar laser refractive surgery,the laser slip on the surface operation is a better method in the correct of refractive error without the flap-related complications.However,whether to remain corneal epithelial flap and its influence for epithelial healing and visual restoration are still under investigation.Objective The aim of this study was to compare the short-term clinical efficacy of epipolis laser insitu keratomileusis (Epi-LASIK) and flap-free Epi-LASIK for correction of refractive error in high myopia.Methods The paired control design was adopted.Sixty eyes of consecutive 30 patients with high myopia were collected in this study.The written consent form was obtained from each patients prior to operation.Regular EpiLASIK was performed in the right eyes and the flap-free Epi-LASIK was carried out in the left eyes.Patients were followed-up for one month.The postoperative ocular irritation symptoms were scored,and the healing period of corneal epithelium and uncorrected visual acuity were examined at 1,3 and 5 days after operation.The naked visual acuity,diopter,best corrected visual acuity and the grading of haze were recorded and compared between the two groups at one month after operation.Results After surgery,the scores of corneal irritation were 3.13 ±0.43 and 3.30±0.47on the first day,showing insignificant differences between these two groups (t =- 1.54,P＞0.05 ).However,there existed statistically significant difference in the scores of corneal irritation on the third day after operation between the two groups (t =- 17.95,P＜0.01 ).The average time of corneal epithelial healing were (2.58 ±0.49 ) days in the flapfree Epi-LASIK group and ( 3.98 ±0.74) days in Epi-LASIK group with the significant difference between them (t=-11.36,P＜0.01 ).There was no statistical difference in uncorrected visual acuity in the first day (0.59±0.12 vs 0.58±0.11,t=0.39,P＞0.05),the fifth day (0.69±0.08 vs 0.67±0.09,t=0.84,P＞0.05) and 1 month (t =-1.90,P＞0.05 ).No significant difference was seen in the diopter between the two groups in 1 month after surgery (-1.03±0.45 vs -1.07 ±0.38,t =-0.31,P＞0.05 ).The eye numbers of corneal haze for 0 grade were 27 ( 90.00％ ) and over the 0.5 grade were 3 ( 10.00％ ) in flap-free Epi-LASIK group respectively,and those of corneal haze for 0 grade were 26(86.66％ ) and above the 0.5 grade were 4 (13.33％) in Epi-LASIK group respectively,showing a considerably difference between the two groups (x2 =0.0031,P＞0.05).Conclusions Both the flapfree or reserved epithelial Epi-LASIK allow the safe and effective correction of refractive error in high myopia,showing good predictability and stability in short term.Flap-free Epi-LASIK can relieve the corneal irritation symptom and accelerate the healing of corneal epithelium and recovery of visual acuity.
ABSTRACT
Background Free-flap Epi-LASIK surgery show a fast epithelial healing and mild trauma responses.Its mechanism is notable. Objective The aim of this study was to compare the corneal epithelial healing response following photorefractive keratectomy(PRK)and flap-free Epi-LASIK surgery. Methods Twelve experimental rabbits were randomly assigned to high cutting group(-10.00 D)and low cutting group(-3.00 D),and 2 normal matched rabbits were used as controls.PRK was performed in lateral eyes and flap-free epipolis laser in situkeratomileusis(Epi-LASIK)surgery was curried out in the fellow eyes.The corneal wound healing response in early stage of post-operation was examined under the slim lamp,and the inflammatory cells infiltration in cornea,basic fibroblast growth factor(bFGF)and nuclear transcription factor(NF-KB)expressions in corneal stroma were detected by hematine-eosin staining and immunohistochemstry in the seventh day after operation. Results The inflammatory reaction was milder in the eyes with Epi-LASIK than ones of PRK under the slim lamp.No significant difierences were found in numbers of inflammatory cells in cornea.expressions of bFGF and NF-κB in corneal stroma between two types of surgeries in low cutting group(P＞0.05).In high cutting group,the numbers of inflammatory cells were(12.25±1.22)/400 field in PRK eyes,and those of free-flap Epi-LASIK eyes were(6.67±0.31)/400 field,showing obvious difference between them(t=-8.87,P＜0.01).Expressions of NF-κB(A value)in cornea were 6.11±1.36 and 41.82±8.7 1 in PRK eyes of low cutting group and high cutting group.and those in free-flap Epi-LASIK were 3.01±0.81 and 11.59±4.55.indicating a drastically increase in PRK eyes(P＜0.05).The expressions of bFGF(A value)in corneal stroma were 33.59±6.98 and 123.68±18.81 in PRK eyes and those in free-flap Epi-LASIK eyes were 69.20±8.85 and 123.68±1 8.81 in low cutting group and high cutting group,presenting a considerably decrease in PRK eyes (P＜0.05).The corneal epithelial healing was faster in free-flap Epi-LASIK eyes than that in PRK eyes.and deeper cutting slowed the healing procedure. Conclusion In low cutting group,healing time of corneal epithelium is close between PRK and flap-free Epi-LASIK.But in high cutting group,epithelial healing is faster and inflammatory reaction is lighter in flap-free Epi-LASIK compared with PRK.