scholarly journals Photorefractive Keratectomy for Residual Myopia after Myopic Laser In Situ Keratomileusis

2017 ◽  
Vol 2017 ◽  
pp. 1-5 ◽  
Author(s):  
Kamal A. M. Solaiman ◽  
Sameh M. Fouda ◽  
Ashraf Bor’i ◽  
Haitham Y. Al-Nashar
Keyword(s):  
Corneal Thickness ◽  
Laser In Situ Keratomileusis ◽  
Photorefractive Keratectomy ◽  
Safety Index ◽  
Corneal Resistance Factor ◽  
Corrected Visual Acuity ◽  
High Predictability ◽  
Efficacy Index ◽  
The Mean

Purpose. To evaluate the safety, efficacy, and predictability of photorefractive keratectomy (PRK) on the corneal flap for correction of residual myopia following myopic laser in situ keratomileusis (LASIK).Patients and Methods. A retrospective study on eyes retreated by PRK on the corneal flap for residual myopia after LASIK. All eyes had no enough stroma after LASIK sufficient for LASIK enhancement. Data included spherical equivalent (SE), uncorrected and best corrected visual acuity (UCVA and BCVA), central pachymetry, corneal higher order aberrations (HOAs), corneal hysteresis (CH), corneal resistance factor (CRF), and corneal haze.Results. The study included 64 eyes. Before PRK, the mean central pachymetry was400.21±7.8 μm, the mean SE was −1.74±0.51 D, and the mean UCVA and BCVA were0.35±0.18and0.91±0.07, respectively. 12 months postoperatively, the mean central corneal thickness was382.41±2.61 μm, the mean SE was −0.18±0.32 D (P<0.01), and the mean UCVA and BCVA were0.78±0.14(P=0.01) and0.92±0.13(P>0.5), respectively. The safety index was 1.01 and the efficacy index was 0.86. No significant change was observed in corneal HOAs.Conclusions. Residual myopia less than 3 D after LASIK could be safely and effectively treated by PRK and mitomycin C with a high predictability. This prevents postoperative ectasia and avoids the flap related complications but has no significant effect on HOAs.

scholarly journals Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Alex L. K. Ng ◽  
Tommy C. Y. Chan ◽  
George P. M. Cheng ◽  
Vishal Jhanji ◽  
Cong Ye ◽  
...  
Keyword(s):  
Corneal Thickness ◽  
Early Postoperative Period ◽  
Safety Index ◽  
Corrected Distance Visual Acuity ◽  
Spherical Equivalent Refraction ◽  
Lenticule Extraction ◽  
Efficacy Index ◽  
Bed Thickness ◽  
The Mean ◽  
And Control

Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE.Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively.Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p<0.021). At 6 months, no eyes lost more than 1 line in corrected distance visual acuity. The safety index was0.96±0.06and1.00±0.00in SMILE Xtra and control, respectively (p<0.001). 89% and 94% of eyes were within ±0.50 D of target refraction, respectively, with the mean error in SEQ correction being-0.17±0.26 D for SMILE Xtra and+0.03±0.25 D for control (p=0.021). The efficacy index was0.88±0.13and0.97±0.06, respectively (p=0.005).Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

Changes in Central Corneal Thickness After Laser in situ Keratomileusis and Photorefractive Keratectomy

2003 ◽  
Vol 19 (2) ◽  
pp. 149-153
Author(s):  
Igor Kozak ◽  
Marek Hornak ◽  
Tomas Juhas ◽  
Arvind Shah ◽  
E Franklin Rawlings
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Laser In Situ Keratomileusis ◽  
Photorefractive Keratectomy

scholarly journals Higher-order aberrations following wavefront-guided photorefractive keratectomy and laser in situ keratomileusis

2021 ◽  
Vol 1 (2) ◽  
pp. 100-104
Author(s):  
Esra Vural ◽  
Deniz Kilic ◽  
Ayse Cicek ◽  
M. Rasit Sirem ◽  
Necati Duru ◽  
...  
Keyword(s):  
Higher Order ◽  
Laser In Situ Keratomileusis ◽  
Photorefractive Keratectomy ◽  
City Hospital ◽  
Higher Order Aberrations ◽  
Significant Difference ◽  
Manifest Refraction ◽  
Group A ◽  
The Mean

Background: We aimed to evaluate higher-order aberrations (HOAs) following wavefront-guided photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in patients with myopia and myopic astigmatism. Methods: This retrospective observational case-control study included patients who underwent wavefront-guided PRK (40 eyes of 20 patients) or LASIK (40 eyes of 20 patients) between August 2018 and November 2018 at the refractive surgery unit of Kayseri City Hospital Eye Clinic, Turkey. The corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and HOAs were evaluated preoperatively and 3 months postoperatively in all patients. Results: The mean age ± standard deviation (SD) was 27.13 ± 5.54 years and 29.10 ± 4.38 years in the PRK and LASIK groups, respectively (P = 0.06). Both groups had a mean CDVA of 1.00. The mean ± SD of spherical and spherical equivalent values was -2.09 ± 1.56 diopter (D) and -3.03 ± 1.72 D in the PRK group and -2.23 ± 1.69 D and -3.35 ± 1.71 D in the LASIK group, respectively (P = 0.58). When the preoperative and postoperative HOAs and root mean square (RMS) values (for a 6-mm pupil diameter) were compared in the PRK group, a significant difference was found in vertical coma and total RMS values (P = 0.003 and P ˂ 0.001, respectively); in the LASIK group, there was a significant difference in preoperative and postoperative vertical coma and total RMS values (P = 0.0.001 and P ˂ 0.001, respectively). There was no significant difference in preoperative and postoperative vertical coma values between the two groups (P = 0.735 and P = 0.583, respectively). Conclusions: In terms of HOAs, total RMS values decreased significantly and vertical coma values increased significantly at 3 months postoperatively in both PRK and LASIK groups. However, there were no differences between the two groups.

scholarly journals Evaluating the Ectasia Risk Score System in Cancelled Laser In Situ Keratomileusis Candidates

2020 ◽  
Author(s):  
Mehrdad Mohamadpour ◽  
Masoud Khorrami-Nejad ◽  
Mohammad Yaser Kiarudi ◽  
Keivan Khosravi
Keyword(s):  
Risk Score ◽  
Corneal Thickness ◽  
Laser In Situ Keratomileusis ◽  
Spherical Equivalent ◽  
Score System ◽  
Manifest Refraction ◽  
Bed Thickness ◽  
The Mean ◽  
Risk Score System

Purpose: To evaluate the ectasia risk score system in cancelled laser in situ keratomileusis (LASIK) candidates at an academic hospital. Methods: LASIK candidates who had been cancelled by a surgeon considering the patient age, preoperative central corneal thickness, residual stromal bed thickness, or preoperative manifest refraction spherical equivalent were retrospectively reviewed, and their Randleman ectasia risk score system score was calculated. Results: The mean ectasia score of 194 eyes (97 patients) was 4.5 ± 2.67; 40 (20.6%), 46 (23.7%), and 108 (55.7%) eyes were classified as low-, moderate-, and high-risk eyes, respectively. The topography was abnormal in 69% of the patients. The mean manifest refraction spherical equivalent, central corneal thickness, and estimated residual stromal bed thickness were 4 (+0.50 to –15.50) diopters, 520 (439 to 608) μm, and 312.38 (61.5 to 424.12) μm, respectively. The main cause of cancellation in low- and moderate-risk patients (86 eyes) was the presence of unstable refractive error in the past year. Conclusion: Although promising, some other criteria, such as stable refraction, should be added to this scoring system to achieve greater practicality since a main cause of cancelling LASIK candidates in this study was the presence of unstable refraction.

Femtosecond laser assisted in situ keratomileusis (FS-LASIK) yields better results than transepithelial photorefractive keratectomy (Trans-PRK) for correction of low to moderate grade myopia

2020 ◽  
pp. 112067212098034
Author(s):  
Assaf Gershoni ◽  
Olga Reitblat ◽  
Michael Mimouni ◽  
Eitan Livny ◽  
Yoav Nahum ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Outcome Data ◽  
Photorefractive Keratectomy ◽  
Efficacy And Safety ◽  
Safety Index ◽  
Cohort Study Design ◽  
Safety Parameters ◽  
Efficacy Index ◽  
In Trans

Introduction: The purpose of this study was to compare the outcomes of transepithelial photorefractive keratectomy (Trans-PRK) with femtosecond laser assisted in situ keratomileusis (FS-LASIK) for the correction of low to moderate myopia. Methods: A retrospective cohort study design was used. The study group included patients with myopia less than −6.0 D, with or without concomitant astigmatism under 2.0 D, who were treated with FS-LASIK or Trans-PRK in 2013 through 2014. Background, clinical and outcome data were collected from the patient files. A comparison between eyes treated with FS-LASIK or Trans-PRK was performed. Results: The Trans-PRK group was comprised of 1793 eyes and the FS-LASIK group of 666 eyes. Mean ± SD spherical equivalent (SE) refraction prior to surgery was −3.43 ± 1.27 D in the Trans-PRK group and −3.18 ± 1.34 D in the FS-LASIK group ( p < 0.001). Efficacy index values were 0.95 ± 0.14 in the Trans-PRK group and 0.98 ± 0.12 in the FS-LASIK group ( p < 0.001), and corresponding safety index values were 0.96 ± 0.13 and 0.99 ± 0.12 ( p < 0.001). Distance from target refraction was 0.45 ± 0.42 D in Trans-PRK group and 0.43 ± 0.38 D in the FS-LASIK group ( p = 0.537); 71.6% and 74.2% of eyes were within ±0.5 D of attempted correction, respectively ( p = 0.193) Conclusions: Both Trans-PRK and FS-LASIK demonstrated excellent results, mostly comparable with the current literature. FS-LASIK achieved better results than Trans-PRK surgery in the efficacy and safety parameters.

scholarly journals Long-term evaluation of eyes with central corneal thickness <400 µm following laser in situ keratomileusis

2016 ◽  
pp. 535 ◽  
Author(s):  
Mohammad Reza Djodeyre ◽  
Jaime Beltran ◽  
Julio Ortega-Usobiaga ◽  
Felix Gonzalez-Lopez ◽  
Ana Ruiz-Rizaldos ◽  
...  
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Laser In Situ Keratomileusis ◽  
Term Evaluation

Detecting subclinical keratoconus by biomechanical analysis in tomographically regular keratoconus fellow eyes

2021 ◽  
pp. 112067212110637
Author(s):  
Victor A Augustin ◽  
Hyeck-Soo Son ◽  
Isabella Baur ◽  
Ling Zhao ◽  
Gerd U Auffarth ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Case Series ◽  
Biomechanical Analysis ◽  
Corvis St ◽  
Corrected Visual Acuity ◽  
The Mean ◽  
Best Corrected Visual Acuity ◽  
Fellow Eyes

Purpose To analyze the tomographically non-affected second eyes of keratoconus patients using the Corvis ST to detect any biomechanical abnormalities or subclinical keratoconus. Methods In this retrospective, single-center, consecutive case series 244 eyes of 122 keratoconus patients were analyzed between November 2020 and February 2021. Fourteen fellow eyes fulfilled the inclusion criteria and showed no clinical or tomographic signs of keratoconus. Main outcome measures included best-corrected visual acuity, tomographic and biomechanical analyses using Scheimpflug imaging: Pentacam and Corvis ST (Oculus, Wetzlar, Germany). Tomographic analyses included anterior and posterior simulated keratometry, K-Max, central corneal thickness, thinnest corneal thickness, Belin/Ambrosio Ectasia Display, and the ABCD grading system. For biomechanical analyses, the corneal biomechanical index (CBI) and tomographic biomechanical index were used. Results The mean best-corrected visual acuity was 0.01 ± 0.10 logMAR. Mean K-Max was 43.79 ± 1.12 D, mean central corneal thickness 529 ± 25 µm, mean thinnest corneal thickness 524 ± 23 µm, and mean Belin/Ambrosio Ectasia Display 1.0 ± 0.32. The mean CBI was 0.30 ± 0.21. Regular CBI values were found in six of 14 patients. The mean tomographic biomechanical index was 0.47 ± 0.22 with regular values observed in only two of 14 patients. No signs of tomographic or biomechanical abnormalities were shown in only one of 14 keratoconus fellow eyes, with regular ABCD, Belin/Ambrosio Ectasia Display, CBI and tomographic biomechanical index values. Conclusions Tomographically normal fellow eyes of keratoconus patients are rare. In these cases, a biomechanical analysis of the cornea may help detect a subclinical keratoconus. The tomographic biomechanical index was the most sensitive index to verify a mild ectasia.

scholarly journals Analysis of the factors affecting decentration in photorefractive keratectomy and laser in situ keratomileusis for myopia

1999 ◽  
Vol 40 (3) ◽  
pp. 221 ◽  
Author(s):  
Jae Bum Lee ◽  
Jae In Jung ◽  
Young Kwang Chu ◽  
Jong Hyuck Lee ◽  
Eung Kweon Kim
Keyword(s):  
Laser In Situ Keratomileusis ◽  
Photorefractive Keratectomy ◽  
Factors Affecting
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