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Analysis of corneal esthesia in patients undergoing photorefractive keratectomy
摘要： Purpose: To quantitatively analyze corneal esthesia in patients undergoing photorefractive keratectomy (PRK) surgery. Methods: Forty-five patients selected for PRK in one eye underwent corneal esthesia using a Cochet-Bonnet esthesiometer preoperatively and 30 and 90 days postoperatively. Patients with a refractive diopter error of 4 or greater received intraoperative 0.02% mitomycin C for 20 s. Results: Twenty-four (53.3%) of the 45 eyes received intraoperative 0.02% mitomycin. Decreased sensitivity was observed on postoperative day 30. By postoperative day 90, corneal esthesia had normalized but remained 14.9% lower than preoperative levels. In the mitomycin group, no recovery of corneal esthesia to normal sensitivity levels was observed. The mean esthesiometer level was 39.2 mm on postoperative day 90 (P<0.001). Conclusions: The results of the present study demonstrate recovery of corneal esthesia to normal levels at 90 days postoperatively in patients who did not receive mitomycin C. In patients administered mitomycin C, a 23.59% reduction in the corneal touch threshold was observed compared with preoperative levels indicating a failure of recovery to normal levels.
关键词： Mitomycin,Photorefractive keratectomy,Cornea,Prospective studies,Myopia
更新于2025-09-23 15:23:52
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Comparison between Transepithelial Photorefractive Keratectomy versus Alcohol-Assisted Photorefractive Keratectomy in Correction of Myopia and Myopic Astigmatism
摘要： Purpose. The aim of the study was to compare visual acuity, refractive results, safety, and efficacy of TPRK with AAPRK as primary outcomes and surgical time, pain scores, haze levels, and healing time as secondary outcomes in TPRK and AAPRK groups. Setting. Security Forces Hospital, Ophthalmology Department, Riyadh, Kingdom of Saudi Arabia. Design. Prospective, non-randomized case-control comparative study. Methods. A total of 200 eyes of 100 consecutive patients were included. One hundred eyes underwent TPRK in the right eye (study group), and 100 eyes underwent AAPRK in the left eye (control group). Ablations were performed with the Schwind Amaris excimer LASER750S. Clinical outcomes during 6 months’ follow-up were compared. Results. The mean age of patients was 28.3 ± 6.3, 77 were females and 23 males. The mean surgical time was 162.17 ± 14.827 s and 243.24 ± 98.69 s, respectively. At day 1, the UDVA mean was 0.7 in 87% of eyes in the TPRK group while it was 0.5 in 45% of eyes in AAPRK; at week 1, it was 0.9 in 88% of eyes in the TPRK group and 0.6 in 60% of eyes in AAPRK. The mean pain scores were less and lower incidence of corneal haze in the TPRK. Complete epithelial healing time was shorter in TPRK, 3.20 ± 0.686 and 4.60 ± 1.969 days, respectively. Conclusions. TPRK and AAPRK produce similar results 6 months postoperatively. However, in the early postoperative period, there were significant differences in UDVA, pain score, level of haze, and complete epithelial healing time. The pain scores were lower, level of haze was less, and healing time was shorter in the TPRK group which provided patient better felling and comfort in this period. Both of procedures are effective and safe for correction of myopia and compound myopic astigmatism. This trial is registered with NCT03569423.
关键词： TPRK,myopia,photorefractive keratectomy,AAPRK,myopic astigmatism
更新于2025-09-23 15:21:21
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Excimer laser treatment combined with riboflavin ultraviolet-A (UVA) collagen crosslinking (CXL) in keratoconus: a literature review
摘要： Purpose To review the clinical outcome of keratoconus patients after excimer laser treatment with combined riboflavin UV-A collagen crosslinking (CXL) treatment was reviewed in light of the UDVA, CDVA and HOA. Methods Following a PubMed-based literature review of studies on excimer laser treatment with combined riboflavin UV-A CXL published between 2009 and 2018, peer-reviewed English-written studies were evaluated using the GRADE approach (www.gradeworkinggroup.org). The current review focused on the change in the (un)corrected distance visual acuity (UDVA; CDVA) and higher-order aberrations (HOA) as well as the prevalence of postoperative complications. Results Five studies with a total of 573 eyes were included, thereby reporting on 479 eyes were treated with the aforementioned combination therapy. The control group consisted of 94 eyes in total. Changes between pre- and postoperative CDVA and/or UDVA were statistically significant in all five studies after at least a 24-month follow-up period for the combined excimer laser-assisted CXL treatment in comparison with the CXL-only treatment option. Three studies described statistically significant reduction in the number of total HOA, in particular, those related to coma and spherical aberration. Corneal haze was reported in four studies, but the condition was successfully treated in all cases. Conclusion Current studies suggest that CDVA, UDVA and HOA in low-to-moderate keratoconic patients improved in a combined treatment without sacrificing biomechanical stability of the cornea. However, long-term results are needed, as the studies in our review have a follow-up period of 68 months or less.
关键词： Refractive surgery,Keratoconus,Collagen-crosslinking,Photorefractive keratectomy
更新于2025-09-23 15:21:01
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Differences in Simulated Refractive Outcomes of Photorefractive Keratectomy (PRK) and Laser In-Situ Keratomileusis (LASIK) for Myopia in Same-Eye Virtual Trials
摘要： The use of computational mechanics for assessing the structural and optical consequences of corneal refractive procedures is increasing. In practice, surgeons who elect to perform PRK rather than LASIK must often reduce the programmed refractive treatment magnitude to avoid overcorrection of myopia. Building on a recent clinical validation study of finite element analysis (FEA)-based predictions of LASIK outcomes, this study compares predicted responses in the validated LASIK cases to theoretical PRK treatments for the same refractive error. Simulations in 20 eyes demonstrated that PRK resulted in a mean overcorrection of 0.17 ± 0.10 D relative to LASIK and that the magnitude of overcorrection increased as a function of attempted correction. This difference in correction closely matched (within 0.06 ± 0.03 D) observed differences in PRK and LASIK from a historical nomogram incorporating thousands of cases. The surgically induced corneal strain was higher in LASIK than PRK and resulted in more forward displacement of the central stroma and, consequently, less relative flattening in LASIK. This FE model provides structural confirmation of a mechanism of action for the difference in refractive outcomes of these two keratorefractive techniques, and the results were in agreement with empirical clinical data.
关键词： laser in situ keratomileusis (LASIK),refractive surgery,cornea,photorefractive keratectomy (PRK),finite element analysis
更新于2025-09-16 10:30:52
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Fine tuning of the default depth and rate of ablation of the epithelium in customized trans-epithelial one-step superficial refractive excimer laser ablation
摘要： Purpose: To fine tune the default depth and rate of ablation of the epithelium in cTen? customized trans-epithelial one-step superficial refractive surgery by the comparison between the attempted post-operative ideal corneal shape and the achieved corneal shape. Methods: 88 consecutive eyes in 64 patients undergoing trans-epithelial superficial excimer ablation using the iVis laser Suite for either myopic/astigmatic or hyperopic/astigmatic refractive error. Each patient had at least 3 months of post-operative follow-up. Topographic examination of all eyes was carried out pre-operatively and at least 3 months post-operatively using the Precisio? surgical topographer. The comparison of these two measurements yielded values for depth, volumes and rates of ablated corneal tissue. By determining the different ablation rates of stroma and epithelium, a refinement of the depth of epithelium to be removed and a refinement of the stromal ablation were calculated. The mathematical model was applied on each one of the 88 clinical cases and the parameters for the fine tuning of the default depth and rate of ablation of the epithelium were determined using the least squares method. Results: The calculated pure stromal ablation rate was less than the average epithelium/stroma ablation rate used in planning the treatments by a factor of 0.96. The epithelial thickness predefined ablation assumption used to plan removal of the epithelium was adjusted considering the measured ablation and a radial adjustment function established for the fine tuning of the laser radial efficiency and allowing for the normal thickening of the epithelium in the peripheral cornea. From a clinical point of view, this methodology produces an improvement of the efficacy and a reduction of the variance of the clinical results. Conclusion: Comparison of accurately measured pre and postoperative topographies yields accurately established ablation rates of stroma and epithelium in trans-epithelial one step superficial ablation.
关键词： Epithelial thickness refinement,Stromal ablation rate refinement,Epithelial ablation,Transepithelial photorefractive keratectomy
更新于2025-09-12 10:27:22
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Intraocular Lens Power Calculation in Eyes After Laser In Situ Keratomileusis or Photorefractive Keratectomy for Myopia
摘要： Intraocular power calculation is challenging for patients who have previously undergone corneal refractive surgery. The sources of prediction errors for these eyes are well known; however, the numerous formulas and methods available for calculating intraocular lens power in these cases are eloquent testimony to the absence of a definitive solution. This review discusses some of the available methods for improving the accuracy for predicting the refractive outcome for these patients. It focuses mainly on the methods available on the American Society of Cataract and Refractive Surgery (ASCRS) online calculator and provides some practical guidelines for cataract surgeons who encounter these challenging cases.
关键词： intraocular power calculation,in situ keratomileusis,photorefractive keratectomy
更新于2025-09-11 14:15:04
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Effect of 0.05% Cyclosporine A on the Ocular Surface after Photorefractive Keratectomy
摘要： Purpose: To evaluate the effect of 0.05% cyclosporine A on the ocular surface after photorefractive keratectomy (PRK). Methods: This retrospective study included 50 patients who underwent PRK. Patients were divided into two groups: 25 patients in group I were treated with topical 0.05% cyclosporine A with conventional medication, and 25 patients in group II were treated with conventional medication. Visual acuity (VA), tear break-up time (BUT), fluorescein staining score (F-stain), Schirmer I test, and ocular surface disease index (OSDI) were evaluated before surgery and 2 weeks, 1 month, 2 months, and 3 months after surgery. Results: F-stain was significantly lower in group I than in group II at 2 weeks and 1 month (p < 0.05). There was no significant difference in uncorrected VA, BUT, Schirmer I test, or OSDI between the groups. However, group I showed a more effective pattern in dry eye. Conclusions: Combination treatment with 0.05% cyclosporine A was helpful for early ocular surface stability in patients with dry eye after PRK.
关键词： Dry eye,Cyclosporine A,Ocular surface stability,Refractive surgery,Photorefractive keratectomy
更新于2025-09-10 09:29:36
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The Result of Photorefractive Keratectomy Treated with 0.1% Fluorometholone and Tranilast Eye Drops
摘要： ??: ????????????(photorefractive keratectomy) ? 0.1% ??????? ???? ?? ??? ??? ??, ??????(0.5% tranilast, Krix?, JW pharmaceutical, Seoul, Korea) ??? ?? ??? ???? ??? ?? ?? ??? ??? ??? ????? ???. ??? ??: 2014? 5??? 2015? 5??? ???? ????????????? ?? 0.1% ??????? ??? ?? ?, ? ? 1??? ?? ???? ?????? ?????? ???? ??? ?? 49?(49?)? 2012? 12??? 2013? 10??? ??? ??? ?? ?????? ???? ???? ?? 71?(71?)? ??? ?????. ??: ? ? 6?? ? ??? ?????? ???? ????? ?? logMAR -0.08 ± 0.05, logMAR -0.08 ± 0.04? ? ? ?? ??? ???. 0.1% ??????? ?? ??? ?????? ????? 17.7 ± 3.3?, ????? 20.5 ± 3.7???(p＜0.01). ?????? ?? ??? ?????? ????? ? ? 18.4 ± 3.2?, ????? 20.9 ± 3.7???(p＜0.01). ??: ???????????? ? 0.1% ???????? ?? ?? ??? ??? ??, ?????? ??? ?? ??? ????? ????? 0.1% ???????? ?? ??? ??? ????? ??? ???? ? ?? ????.
关键词： Fluorometholone,Tranilast,Intraocular pressure,Photorefractive keratectomy,Steroid-induced glaucoma
更新于2025-09-10 09:29:36