Epipolis Laser In Situ Keratomileusis Research Articles

Clinical outcomes of single-step transepithelial photorefractive keratectomy and off-flap epipolis-laser in situ keratomileusis in moderate to high myopia: 12-month follow-up

BackgroundTo compare the quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy (TPRK) and off-flap epipolis-laser in situ keratomileusis (Epi-LASIK) in moderate to high myopia.MethodsIn this prospective self-control study, we included patients with moderate to high myopia who were randomized to undergo TPRK in one eye and Epi-LASIK in the other eye. Twelve-month follow-up results for visual acuity, refraction, ocular high-order aberrations, contrast sensitivity, postoperative pain, epithelial healing, and haze grade were assessed.ResultsA total of 64 eyes (32 patients) were enrolled in the study. More eyes completed re-epithelialization in the TPRK group than in the Off-flap Epi-LASIK group 3–4 days postoperatively, while all eyes completed re-epithelialization by 7 days. More eyes achieved a visual acuity (both UDVA and CDVA) of better than 20/20 in the TPRK group than in the Off-flap Epi-LASIK group. The ±0.50 D predictability for correction of the spherical equivalent (SE) was higher in the eyes of the TPRK group (91%) than in those of the off-flap Epi-LASIK group (80%) 12 months after surgery. No significant differences in ocular aberrations, including coma, spherical, and trefoil, were found between the two groups at 12 months. There were also no significant differences in visual acuity, contrast sensitivity, pain, and haze grading between the two groups.ConclusionsBoth TPRK and off-flap Epi-LASIK are safe, effective, and predictable treatments for moderate to high myopia with comparable surgical outcomes.Trial registrationThis study was retrospectively registered on ClinicalTrial.gov (NCT05060094, 17/09/2021).

Preoperative refraction, age and optical zone as predictors of optical and visual quality after advanced surface ablation in patients with high myopia: a cross-sectional study

ObjectiveTo investigate the factors associated with optical and visual quality of advanced surface ablation in high myopia.DesignA cross-sectional study of high myopic eyes treated with laser epithelial keratomileusis (LASEK)/epipolis laser...

The influence of corneal epithelial cell apoptosis due to two different excimer laser corneal refractive surgeries

Objective To compare the influence on corneal epithelial cell apoptosis after Epi-LASIK and LASEK. Methods The abandoned corneal epithelium of 100 eyes of 50 cases with Epi-LASIK and LASEK were collected. The corneal epithelial cell apoptosis were observed with Flow cytometry and analyze. Results The difference was statistically in the early apoptotic cell number both of two surgical methods are significant (t=7.860, P=0.000). The early apoptotic cell number of LASEK was higher. The difference in dead cell necrotic number was not statistically significant between Epi-LASIK and LASEK (t=0.274, P=0.953). Conclusion Early apoptotic number of corneal epithelial cells of LASEK was higher than that of Epi-LASIK. Refractive regression of LASEK has expected that was more significantly than that of Epi-LASIK. The difference in number of corneal epithelial cells between LASEK and Epi-LASIK are not statistically significant. Key words: Epipolis laser in situkeratomileusis(Epi-LASIK); Laser epithelial keratomileusis(LASEK); Apoptosis, corneal epithelial cell; Flow cytometry

Epipolis-laser in situ keratomileusis versus photorefractive keratectomy for the correction of myopia: a meta-analysis.

It is unclear whether epipolis-laser in situ keratomileusis (Epi-LASIK) has any significant advantage over photorefractive keratectomy (PRK) for correcting myopia. We undertook this meta-analysis of randomized controlled trials and cohort studies to examine possible differences in efficacy, predictability, and side effects between Epi-LASIK and PRK for correcting myopia. A system literature review was conducted in the PubMed, Cochrane Library EMBASE. The statistical analysis was performed by RevMan 5.0 software. The results included efficacy outcomes (percentage of eyes with 20/20 uncorrected visual acuity post-treatment), predictability (proportion of eyes within ±0.5 D of the target refraction), epithelial healing time, and the incidence of significant haze and pain scores after surgery. There are seven articles with total 987 eyes suitable for the meta-analysis. There is no statistical significance in the predictability between Epi-LASIK and PRK, the risk ratio (RR) is 1.03, 95% confidence interval (CI) [0.92, 1.16], p = 0.18; with respect to efficacy, the odds ratio is 1.43, 95% CI = [0.85, 2.40], p = 0.56 between Epi-LASIK and PRK, there is no statistical significance either. The epithelial cell layer healing time and the pain scores and the incidence of significant haze showed no significance between these two techniques although more pains can be found in Epi-LASIK than PRK at the early-stage post-operation. According to the above analysis, Epi-LASIK has good efficacy and predictability as PRK. In addition, both techniques have low pain scores and low incidence of significant haze.

Effect of wearing of soft corneal contact lens for long term on apoptosis of corneal epithelial cell

Background Wearing of soft contact lens,as one of the important methods to correct ametropia,has been widely applied at present.The clinically deleterious effects of soft contact lens have been reported,but researches about influence of apoptosis of corneal epithelial cells are scant.Objective This study was to detect and compare the ratio of apoptosis of corneal epithelial cells between the patients with contact lens wearing and without contact lens wearing,and explore the influence of soft contact lens wearing for long term on growth of corneal epithelial cells after injury.Methods A retrospective nest case-controlled study was designed.Forty eyes of 20 myopic patients with wearing of soft contact lens for ≥5 years and 40 eyes of 20 myopic patients without wearing of soft contact lens were included in Affiliated Hospital of Guiyang Medical College.All the patients received the off-flap epipolis laser in situ keratomileusis (Epi-LASIK) from 2010 October to 2011 June.The corneal flaps were collected during the surgery.The apoptosis of corneal epithelial cells was detected by flow cytometry(FCM),and the difference of apoptotic proportion between the two groups was compared using independent sample t test.Results The FCM scatter plot showed that compared to the without contact lens wearing group,the early stage of apoptotic cells with high staining annexin V and low staining proaium iodide (PI) were much more,and survival cells with low staining annexin V and PI were less,and necrotic and late stage of apoptotic cells with high staining of annexin V/PI were more in the with contact lens wearing group.The early stage of apoptosis proportion of corneal epithelial cells was (11.23 ± 5.31)％ in the with contact lens wearing group,and that in the without contact lens wearing group was (7.31± 5.43)％,showing a significant difference between them (t=2.754,P=0.008).Conclusions A long term wearing of contact lens induce more apoptosis of corneal epithelial cells,which can result in a disorder of structure and function of ocular surface during the wound healing stage. Key words: Soft contact lens; Epipolis laser in situ keratomileusis; Corneal epithelial cell; Apoptosis; Flow cytometry

Standardized vector analysis of correction of astigmatism after Epi-LASIK

Objective To evaluate the correction of astigmatism after Epi-LASIK (epipolis laser in situ keratomileusis) by standardized vector analysis,and to investigate the factors that affect the outcome of correction.Methods Sixty-eight myopic astigmatism eyes treated with Epi-LASIK were divided into two groups,low-midrange astigmatism (0.00D ～-2.00D) group and high astigmatism (-2.25D ～-4.00D) group.The following-up period was for 6 months.The astigmatism status wasevaluated based on the standardized vector analysis which was recommended by the American National Standards Institute.Results The CR (correction ratio) was positively correlated with IRC (absolute intended refractive correction) (r =0.82,P ＜0.05).The ER (error ratio) was negatively correlated with IRC (r =-0.61,P ＜0.05).The EA (absolute error of angle) was negatively correlated with IRC (r =-0.74,P ＜0.05).The EV (absolute error vector) of low-midrange astigmatism group was significant lower than that of high astigmatism group (P ＜0.05).The EM (error of magnitude) of low-midrange astigmatism group was-0.12±0.15 and EM of high astigmatism group was-0.14±0.42.Conclusions The effectiveness of the correction of astigmatism after Epi-LASIK is closely correlated with that of axis alignment of astigmatism,and the diopter of astigmatism which is set as surgery parameter shall be transferred from spectacle to corneal plane according to the vertex distance of manifest refraction. Key words: Vector analysis; Astigmatism; Epi-LASIK

Expression of occludin in corneal epithelium after flap-free epipolis laser in-situ keratomileusis and laser-assisted subepithelial keratectomy

Background Tight junctions are thought to play a significant role in the maintenance of the corneal epithelial defense for the eye,and the restoration of the tight junctions is critical during epithelial wound healing after refractive surgery.However,there are few reports about this study. Objective The aim of this study was to investigate and compare the expression of occludin in corneal epithelium following flap-free epipolis laser insitu keratomileusis (Epi-LASIK) and laser-assisted subepithelial keratectomy ( LASEK ). Methods Forty-eight clean New Zealand white rabbits were randomized into 2 groups,and 24 rabbits for each group.Flap-free Epi-LASIK and LASEK were performed in the right eyes of the rabbits in two groups,and other 2 age matched normal rabbits were as normal controls.The animals were sacrificed and the corneal samples were obtained at 1,2,3,5 days after surgery.Immunofluorescence staining was used to detect the expression of occludin in the corneal epithelium,and RT-PCR was used to identify the level of occludin mRNA in the central cornea. Results Occludin protein was expressed innormal corneal epithelium and showed the green fluorescence with the regular arrangement.The fluorescence intensity was lower in 1 -2 days in LASEK group with the irregular arrangement;while the fluorescence signal in corneal epithelium was stronger in flap-free Epi-LASIK group.3-5 days after surgery,the fluorescence intensities were bothenhanced in two groups.RT-PCR showed that the relative expression of occludin mRNA in corneal epithelium was 0.11 ±0.02,0.25 ± 0.03,0.43 ± 0.04 in LASEK group 1,2,3 days after surgery,respectively,and was lower than those of flap-free Epi-LASIK group ( 0.20± 0.04,0.44 ± 0.04,0.76 ± 0.04 ),showing significant differences between these two groups ( t =6.476,12.898,17.315,P＜ 0.05 ).No significant difference was seen in the expression of occludin mRNA in 5 days after surgery between two groups( t=-0.733,P＞0.05).The relative values of occludin mRNA expression in corneal epithelium were gradually increased with time prolongation,presenting a significant difference among various time points ( Ftime =768.903,P =0.000). Conclusions The reformation of occludin in flap-free Epi-LASIK group is faster than that in LASEK group.Therefore,flap-free Epi-LASIK is prominant in reducing the stimulated symptoms and complication after the surgery. Key words: Flap-free epipolis laser in-situ keratomileusis; Laser-assisted subepithelial keratectomy; Tight junction ; Occludin

Short-term clinical efficacy of flap-free Epi-LASIK and Epi-LASIK for high myopia

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. Key words: Epipolis laser in-situ keratomileusis; Flap-free epipolis laser in-situ keratomileusis; High myopia

Experimental study on keratocyte apoptosis following Epi-LASIK and off-flap Epi-LASIK in rabbits

目的 观察机械法准分子激光上皮瓣下角膜磨镶术(Epi-LASIK)与去瓣Epi-LASIK术后不同时间点角膜基质细胞的凋亡,探讨2种手术方式对角膜创伤修复过程的影响.方法 42只新西兰大白兔随机编号,其中40只兔各取一侧眼行Epi-LASIK,对侧眼行去瓣Epi-LASIK,剩余2只兔4只眼作为正常对照组.分别于术后4h,1、3、7d共4个时间点取出角膜组织,透射电镜下观察各组兔角膜组织的超微结构改变,采用TUNEL法检测2组兔手术后不同时间点角膜基质细胞的凋亡情况,应用免疫组织化学法检测2组兔手术后不同时间点白细胞介素-1β(IL-1β)在角膜基质细胞中的表达.结果 Epi-LASIK组术后1d及3d角膜基质细胞凋亡细胞数明显高于去瓣Epi-LASIK组,差异均有统计学意义(t=2.42,P＜0.05;t=4.04,P＜0.05);Epi-LASI组术后1、3、7d角膜基质中IL-1β表达的阳性细胞数明显高于去瓣Epi-LASIK组,差异均有统计学意义(t=2.13,P＜0.05;t=3.71,P＜0.05;t=3.06,P＜0.05).Epi-LASIK组术后透射电镜下可见兔角膜基质细胞核固缩,染色质边集并可见凋亡小体.免疫组织化学染色显示Epi-LASIK组术后角膜基质中IL-1β的表达强于去瓣Epi-LASIK组.结论 去瓣Epi-LASIK对角膜基质细胞的损害较Epi-LASIK轻,提示去瓣Epi-LASIK术后早期角膜创伤愈合反应的程度较轻,有利于角膜组织的快速修复。

Experimental study of cornea reparation after epipolis laser in situ keratomileusis

目的 探讨微型角膜刀法准分子激光上皮下角膜磨镶术(Epi-LASIK)术后角膜的愈合规律,并与准分子激光屈光性角膜切削术(PRK)比较.方法 建立兔近视性Epi-LASIK及近视性改良PRK动物模型,用锥虫蓝-茜素红活性染色法观察Epi-LASIK术后角膜上皮细胞活性,裂隙灯显微镜下观察角膜瓣变化、上皮修复过程和上皮下雾状混浊(haze)形成情况,通过角膜组织病理学观察角膜上皮及基质的愈合反应.结果 Epi-LASIK术后角膜上皮愈合时间为(4.67±0.41)d,而PRK术后为(2.75±0.27)d,差异有统计学意义(t=9.550,P=0.000).PRK术后即刻和3d、5d角膜上皮瓣细胞活性率分别为(85.83±2.07)%、(48.67±3.41)%、(91.33±3.10)%,差异有统计学意义 (F=215.060,P=0.000).Epi-LASIK术后角膜瓣逐渐融解并被新生上皮取代,上皮愈合过程较改良PRK缓慢.PRK术后haze分级高于Epi-LASIK,差异有统计学意义(Z=2.27,P=0.02).角膜组织病理学检查显示,术后1个月时2组上皮均明显增厚,3个月时上皮细胞排列仍不规则,6个月时上皮细胞形态基本恢复正常,术后3～6个月时Epi-LASIK组角膜上皮厚度已基本接近正常,与PRK组比较差异有统计学意义(P＜0.05).术后3～6个月时Epi-LASIK组角膜前基质细胞数明显低于PRK组(P＜0.05).结论 Epi-LASIK术后上皮瓣活性随时间的推移而降低,上皮修复较慢.与改良PRK比较,Epi-LASIK术后上皮细胞形态变化和上皮增厚程度较轻,角膜基质细胞恢复快,haze程度明显减轻。

Comparison of central corneal thickness measurements by Orbscan II and Pentacam after corneal refractive surgery

To compare the accuracy of postoperative pachymetry between Orbscan II (Bausch & Lomb) scanning-slit corneal topography/pachymetry and the Pentacam (Oculus) rotating Scheimpflug camera. Central corneal thickness (CCT) was determined in 24 patients (48 eyes) before and after laser in situ keratomileusis (LASIK) or Epipolis LASIK (Epi-LASIK) procedures. All eyes were examined by Orbscan II and Pentacam prior to refractive surgery and at the first, fourth, and twelfth week postoperatively. The residual CCT (RCCT) measured by each instrument was compared to the theoretical RCCT. On the first, fourth, and twelfth week after the refractive surgery, the mean RCCT measurements by Orbscan II were 413 +/- 72, 435 +/- 65, and 440 +/- 69 microm, respectively. Those of Pentacam were 434 +/- 51, 436 +/- 53, and 438 +/- 50 microm, respectively. Orbscan II measurements at the postoperative first and fourth week were significantly smaller than the theoretical RCCT (P < 0.01, P < 0.01, paired t test). There was no statistical difference between the theoretical RCCT and the Pentacam measurements at any stage. The Orbscan II measurement values of postoperative corneas tended to be thinner than the theoretical values, but not those of the Pentacam.

Epipolis-laser in situ keratomileusis (Epi-LASIK)

A review of the literature is presented regarding a new advanced surface ablation procedure, epipolis-laser in situ keratomileusis (Epi-LASIK). Histological findings suggest that the repositioning of the separated epithelial sheet might modulate corneal wound healing after photoablation. Recent clinical studies provide evidence that Epi-LASIK is an effective, safe and predictable method for the treatment of low-to-moderate myopia. However, like other surface treatments, slow visual recovery and postoperative discomfort remain drawbacks of Epi-LASIK in the early postoperative period. Large comparative studies between Epi-LASIK, photorefractive keratectomy and laser epithelial keratomileusis will draw conclusions about the possible advantages of Epi-LASIK over other photorefractive procedures.

Alterations in Endothelial Cell Density After Photorefractive Keratectomy With Adjuvant Mitomycin

To elucidate the distinct role of the intraoperative use of mitomycin C (MMC) on endothelial cell density after photorefractive keratectomy (PRK) in human eyes. Prospective, double-masked, randomized clinical trial. One eye of 15 patients was treated with PRK with intraoperative use of topical 0.02% MMC (15 seconds), whereas the fellow eye was treated with Epipolis laser in situ keratomileusis (Epi-LASIK) in random order. Corneal confocal microscopy was performed in all eyes preoperatively and at one, three, six, and 12 months after the surgery. Moreover, three endothelial images were acquired in each of 15 preoperative-normal eyes to evaluate the repeatability of measuring endothelial cell density. Repeated measures analysis of variance was used to compare the temporal variations of endothelial cell density between the two techniques and the changes of endothelial cell density over time. The coefficient of repeatability of endothelial cell count was 148 cells/mm(2). Preoperative endothelial cell density was not significantly different between the two groups (P = .82). Moreover, the effect of the treatment on the temporal variation of endothelial cell density was insignificant (P = .83), whereas the differences between the preoperative and the postoperative endothelial cell densities reached statistical significance (P <or= .05). Nonetheless, inclusion of the repeatability of the instrument on the analysis diminished these significant differences (P > .05). The prophylactic intraoperative application of MMC (up to 15 seconds) after PRK does not seem to affect the endothelial cell density.

Comparison of Laser Epithelial Keratomileusis Versus Epipolis-Laser in Situ Keratomileusis for Moderate to High Myopia

Purpose: To compare the clinical visual results and complications of laser-assisted subepithelial keratectomy (LASEK) and epipolis laser in situ keratomileusis (Epi-LASIK). Methods: A retrospective analysis of a case series of eyes treated with LASEK or Epi-LASIK with a follow-up of six months was performed. Twenty-two eyes were treated with LASEK, and 20 eyes were treated using Epi-LASIK. The main outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and manifest refraction at one week, one month, three months, and six months after refractive surgery, and the presence of any complications. Results: There was no significant difference of UCVA and mean postoperative spherical equivalent (SE) between the eyes treated with LASEK or Epi-LASIK at one week, three months, and six months. However at one month there was significant difference of UCVA. Additionally, in a comparison between moderate and serve myopia, there was no significant difference of UCVA and mean postoperative spherical equivalent (SE) between groups treated with LASEK or Epi-LASIK at one week, one month, three months, and six months. Seven eyes treated with LASEK and two eyes treated with Epi-LASIK showed persistent epithelial erosion less than one week. Two eyes treated with LASEK exhibited newly-developed corneal opacity, which persisted-through the last visit. Conclusions: Epi-LASIK showed clinical visual results and complications comparable to LASEK and showed better epithelial healing.

Stromal cells change after epipolis laser in situ keratomileusis and laser-assisted subepithelial keratectomy in rabbits

To compare the effects of epipolis laser in situ keratomileusis (Epi-LASIK) and laser-assisted subepithelial keratectomy (LASEK) on the corneal stromal cells, and to evaluate their effects on corneal haze histopathologically. Forty-eight New Zealand white rabbits (96 eyes) were randomly treated with Epi-LASIK in one eye and LASEK in the other, and 2 rabbits (4 eyes) without any treatment were used as control. Cornea stromal cell apoptosis was evaluated by terminal deoxyribonucleotidyl transferase-mediated deoxynuridine triphosphate nick end labeling (TUNEL) assay. Stromal cells proliferation and myofibroblasts generation were evaluated by immunocytochemical analyses the expression of Ki-67 and alpha-smooth muscle actin (alpha-SMA) respectively. Myofibroblast generation was further testified by Western blot analysis of alpha-SMA. Both number of TUNEL, Ki-67 and alpha-SMA positive cells and expression of alpha-SMA were semi quantitatively analyzed to explore their effects on corneal haze. Many TUNEL-positive cells appeared in the central anterior stromal in early stages after both LASEK and Epi-LASIK, and the number of TUNEL-positive cells reached a peak 24 hours after either LASEK or Epi-LASIK. There were more TUNEL positive cells found in LASEK group than that in Epi-LASIK group in 1 week postoperatively (t = 3.63, 7.80, 4.34, 2.95, all P < 0.01). There were a lot of Ki-67-positive cells in anterior corneal stroma after both LASEK and Epi-LASIK, but the peak appeared at 72 hours after the treatments. The significant difference was also found in the number of Ki-67-positive cell between the two treatments in 1 week postoperatively (t = 3.81, 5.85, 5.09, 5.59, all P < 0.01). alpha-SMA-positive cells started to appear apparently at 1 week after both LASEK and Epi-LASIK, and both the peaks appeared at 1 month after the treatments, and there were still a lot of alpha-SMA-positive cells in corneal stroma at 3 months after LASEK. There were more alpha-SMA-positive cells found after 1 week in LASEK group than that in Epi-LASIK group (t = 2.97, 7.19, 6.73, all P < 0.01). There are less stromal cell apoptosis, proliferation and myofibroblast generation in Epi-LASIK than that in LASEK. Therefore, comparing with LASEK, Epi-LASIK induces less corneal haze response in correcting myopia.