scholarly journals The assessment of the stability of the corneal structure after LASIK correction of myopia by different optical zone diameters

2016 ◽  
Vol 73 (6) ◽  
pp. 572-576 ◽  
Author(s):  
Milorad Milivojevic ◽  
Vladimir Petrovic ◽  
Miroslav Vukosavljevic ◽  
Ivan Marjanovic ◽  
Mirko Resan
Keyword(s):  
Structural Parameters ◽  
Preoperative Assessment ◽  
Laser In Situ Keratomileusis ◽  
Group I ◽  
Significant Difference ◽  
Optical Zone ◽  
Corneal Structure ◽  
The Stability ◽  
Corneal Thinning

Background/Aim. Enlargement of optical zone (OZ) diameter during laser in situ keratomileusis (LASIK) correction of myopia postoperatively improves the optical outcome, however, it also leads to the increased stroma tissue consumption - progressive corneal thinning. The aim of this investigation was to present the possibility of safe OZ enlargement without impairing the structural stability of the cornea, while obtaining an improved optical outcome with LASIK treatment of shortsightedness. Methods. Preoperative assessment of the cornea structure and prediction of the ablated stroma tissue consumption was conducted in 37 patients (74 eyes) treated for shortsightedness by means of the LASIK method. With the eyes that, according to their cornea structure, had the capacity for OZ diameter enlargement of 0.5 mm, LASIK treatment was performed within the wider OZ diameter of 7.0 mm compared to the standard 6.5 mm. The following two groups were formed, depending on the diameter of the utilized OZ: the group I (the eyes treated with the OZ 6.5 mm, n = 37) and the group II (the eyes treated with the OZ 7.0 mm, n = 37). Results. No significant difference in the observed structural parameters of the cornea was detected between the groups of patients treated with different OZ diameters. The values of all the parameters were significantly bellow the threshold values for the development of postoperative ectasia. Conclusion. Diameter enlargement of the treated OZ, if there is a preoperative cornea capacity for such enlargement, will not impair the postoperative stability of the cornea structure, and will significantly improve the optical outcome.

Stability of corneal topography and aberrometry after hyperopic laser in situ keratomileusis with a 500-Hz excimer laser platform: A 3-year follow-up study

2019 ◽  
Vol 30 (6) ◽  
pp. 1238-1245
Author(s):  
Ana B Plaza-Puche ◽  
Verónica Vargas ◽  
Pilar Yébana ◽  
Samuel Arba ◽  
Jorge L Alio
Keyword(s):  
Excimer Laser ◽  
Spherical Aberration ◽  
Case Series ◽  
Corneal Topography ◽  
Laser In Situ Keratomileusis ◽  
Case Series Study ◽  
Significant Difference ◽  
Optical Zone

Purpose: The aim of this study is to analyze the long-term stability of the corneal topography, the functional optical zone, and the refractive stability throughout 3 years following laser in situ keratomileusis surgery for hyperopia using a 500-Hz excimer laser system. Methods: This retrospective consecutive observational case series study comprised 66 eyes that underwent laser in situ keratomileusis to correct hyperopia with a postoperative follow-up of 3 years. Laser in situ keratomileusis procedures were performed using the SCHWIND Amaris 500-Hz excimer laser. Main outcomes measured were stability of the functional optical zone at corneal topography and corneal aberrometry. Results: Statistically significant differences were found in simulated keratometry (K2 (steep meridian) and Km (mean keratometry)) between 3 and 36 months postoperatively ( p ⩽ 0.01); these differences disappeared at 12 and 36 months ( p ⩾ 0.18). No statistically significant changes were observed in the horizontal and vertical diameter of the functional optical zone throughout the whole follow-up ( p ⩾ 0.07). A statistically significant difference was found in the spherical aberration between 3 and 36 months ( p = 0.02); this difference disappeared when compared between 12 and 36 months ( p = 0.72). Statistically significant correlations were detected between the vertical functional optical zone and coma root mean square ( r = –0.510, p < 0.01) and between the vertical functional optical zone and spherical aberration ( r = 0.441, p = 0.02) 36 months after surgery. Conclusion: Following 3 years of hyperopic laser in situ keratomileusis with a 500-Hz Amaris excimer laser, keratometry, functional optical zone, and corneal aberrations remain stable from 1 year after surgery. Topographical regression is not observed in hyperopic laser in situ keratomileusis with this excimer laser technology from 1 year after surgery.

scholarly journals Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

2021 ◽  
Vol 10 (3) ◽  
pp. 129-137
Author(s):  
Mariam A Elshawarby ◽  
Ali Saad ◽  
Thanaa Helmy ◽  
Mouamen M. Seleet ◽  
Tamer Elraggal
Keyword(s):  
Visual Acuity ◽  
Refractive Error ◽  
Ablation Depth ◽  
Laser In Situ Keratomileusis ◽  
Treatment Modalities ◽  
Significant Difference ◽  
Corneal Asphericity ◽  
Optical Zone ◽  
The Mean

Background: Many studies have used functional optical zone (FOZ) as a measure to compare different refractive laser treatment modalities. However, to our knowledge, no study has compared wavefrontoptimized (WFO) and wavefront-guided (WFG) laser in situ keratomileusis (LASIK) using FOZ. We compared the FOZ after WFO versus WFG LASIK in patients with myopia and myopic astigmatism.Methods: In this prospective comparative study, we included 100 myopic eyes of 50 patients with or without astigmatism. They were divided into two groups according to the platform used: WFO or WFG femtosecond LASIK. Using Holladay’s equivalent keratometry reading (EKR) report of Pentacam HR, FOZ was defined as a zone centered on the pupil center with a standard deviation (SD) of 0.5 D, around the mean EKR. The differences in FOZ between the two platforms were analyzed at 3 months postoperatively. Visual acuity, refractive error, corneal asphericity (Q-value), and root mean square of higher-order aberrations (RMS for HOAs) were evaluated and compared.Results: The mean ± SD of patient age was 26.64 ± 5.67 years. The preoperative characteristics of the two groups were comparable (all P > 0.05). The intended optical zone (IOZ) was 6 mm in both groups. The mean laser ablation depth was significantly greater in the WFG group (18 ?m per D) than in the WFO group (16 ?m per D) (P = 0.035). At 3 months postoperatively, the mean ± SD of FOZ diameter was 4.32 ± 0.94 mm (71.99 ± 15.68% of intended optical zone) in the WFO group and 4.16 ± 1.13 mm (69.33 ± 18.78% of intended optical zone) in the WFG group, with no significant difference between the two groups (P = 0.622). The change in corneal asphericity was greater in the WFG group than in the WFO group (P = 0.034). Postoperative mean corrected and uncorrected distance visual acuity, manifest refraction, and RMS for HOAs showed no significant difference between the two groups (all P > 0.05).Conclusions: We found that WFG LASIK resulted in greater ablation depth and change in corneal asphericity than WFO LASIK at 3 months postoperatively. However, there was no significant difference in FOZ diameter, refractive error, and RMS for HOAs between the two groups. Further research is needed to confirm these findings.

scholarly journals SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Min-jie Ye ◽  
Cai-yuan Liu ◽  
Rong-feng Liao ◽  
Zheng-yu Gu ◽  
Bing-ying Zhao ◽  
...  
Keyword(s):  
Spherical Aberration ◽  
Laser In Situ Keratomileusis ◽  
Small Incision Lenticule Extraction ◽  
Corneal Surface ◽  
Small Incision ◽  
Significant Difference ◽  
Lenticule Extraction ◽  
A Prospective Study ◽  
High Order Aberrations

Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE).Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone.Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P<0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P<0.05).Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK.

A quality of life assessment of military recruits after refractive surgery

2020 ◽  
Vol 1 (1) ◽  
pp. 42-46
Author(s):  
Jian-He Xiao ◽  
◽  
Shi-Yang Li ◽  
Xing Xing ◽  
Ai-Hong Zhao ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Refractive Error ◽  
High Myopia ◽  
Refractive Surgery ◽  
Laser In Situ Keratomileusis ◽  
Significant Difference ◽  
Lenticule Extraction ◽  
Postoperative Interval

AIM: To evaluate the quality of life of recruits after refractive surgery. METHODS: Population-based, cross-sectional study. Using the Quality of Life Impact of Refractive Correction (QIRC) questionnaire, the quality of life in 615 recruits underwent refractive surgery was evaluated. The overall score and each question score of QIRC were compared between subgroups of different strength of preoperative refractive error, postoperative interval, type of surgical procedure and postoperative recovery. RESULTS: The mean overall QIRC score of recruits underwent refractive surgery was 49.15±7.89. Significant difference was found for strength of preoperative refractive error (F=4.16, P<0.05), with the low myopia group (50.67±7.59) had significantly better scores than those with high myopia (47.57±7.52, F=4.16, P<0.05). Recruits after a postoperative interval no more than 6mo (49.18±7.86) scored equally to those of more than 6mo (49.18±8.03). Recruits underwent surface ablation surgery scored lowest (46.68±6.09), but showed no significant difference when compared with all underwent refractive surgery (t=1.99, P>0.05). Scores of recruits underwent mechanical microkeratome laser in situ keratomileusis (MK-LASIK), Sub-Bowman’s keratomileusis (SBK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), femtosecond lenticule extraction (ReLEx flex) or small-incision lenticule extraction (ReLEx SMILE) procedure showed no significant difference too. Recruits had adverse complaints postoperatively (45.85±6.66) scored lower when compared with all underwent refractive surgery (t=5.28, P<0.01). CONCLUSION: The quality of life of recruits after refractive surgery was good except those with postoperative complications. Preoperative low myopia recruits had better quality of life than medium and high myopia ones.

scholarly journals Efficacy and Safety of Topical Timolol Eye Drops in the Treatment of Myopic Regression after Laser In Situ Keratomileusis: A Systematic Review and Meta-Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaochen Wang ◽  
Guiqiu Zhao ◽  
Jing Lin ◽  
Nan Jiang ◽  
Qian Wang ◽  
...  
Keyword(s):  
Meta Analysis ◽  
Treated Group ◽  
Laser In Situ Keratomileusis ◽  
Control Group ◽  
Eye Drops ◽  
Efficacy And Safety ◽  
China National Knowledge Infrastructure ◽  
Knowledge Infrastructure ◽  
Significant Difference

Aims. The aim of this study was to assess the efficacy and safety of timolol in the treatment of myopic regression after laser in situ keratomileusis (LASIK).Methods. We searched MEDLINE, CENTRAL, EMBASE, China National Knowledge Infrastructure (CNKI), and Chinese Biological Medicine (CBM) from the inception to July 2015 for relevant randomized controlled trials that examined timolol therapy for myopic regression. The methodological quality of the studies included was assessed using the Revman 5.3 software.Results. We included six clinical trials involving 483 eyes in this review, including 246 eyes in treated group and 237 eyes in controlled group. We observed statistically significant improvements on the postoperative SE in the 3 months. However, the change of CCT was not statistically different between the control group and the experimental group. There were fewer cases of IOP, UDVA, and CDVA in treated group having significant difference from the controlled group.Conclusions. Topical timolol could be an effective treatment for reduction of myopic regression especially the spherical errors after myopic LASIK. Further RCTs with larger sample sizes for these trials are warranted to determine the efficacy and limitation for myopic regression after LASIK.

Effect of varying the optical zone diameter on the results of hyperopic laser in situ keratomileusis

Ophthalmology ◽  
2001 ◽  
Vol 108 (7) ◽  
pp. 1261-1265 ◽  
Author(s):  
Jonathan M Davidorf ◽  
Farid Eghbali ◽  
Tania Onclinx ◽  
Robert K Maloney
Keyword(s):  
Laser In Situ Keratomileusis ◽  
Zone Diameter ◽  
Optical Zone

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis

2019 ◽  
pp. 112067211989243
Author(s):  
Asaf Friehmann ◽  
Michael Mimouni ◽  
Negme Assad ◽  
Gilad Rabina ◽  
Oriel Spierer ◽  
...  
Keyword(s):  
Operating Room ◽  
Odds Ratio ◽  
Room Temperature ◽  
Multivariable Analysis ◽  
Laser In Situ Keratomileusis ◽  
Database Analysis ◽  
Significant Difference ◽  
Temperature Operating ◽  
The Right

Purpose: To determine factors associated with early flap misalignment following microkeratome-assisted laser in situ keratomileusis. Materials and Methods: This retrospective study included the right eyes of consecutive patients who underwent laser in situ keratomileusis procedure between 2005 and 2016 at Care-Vision Laser Centers, Tel-Aviv, Israel. Patients were divided into two groups according to whether or not they subsequently developed early flap misalignment. Results: A total of 14,582 eyes (mean age of patients: 32.4 ± 10.3 years) were included. Post-laser in situ keratomileusis early flap misalignment developed in 158 eyes (1.1%). Misalignment was more frequent during the spring (32.3% vs 22.8%, p = 0.003) and in a higher operating room temperature (23.34 ± 1.06 vs 22.98 ± 1.26, p < 0.001). In addition, in the misalignment group, there was a higher rate with the of use of the a Moria M2 microkeratome (rather than sub-Bowman’s keratomileusis microkeratome) head (55.2% vs 40.5%, respectively, p < 0.001). In a multivariable analysis adjusted for surgeon and year of surgery, high operating room temperature (odds ratio = 1.22, p = 0.006), treatment zone of 9.0 mm (as opposed to smaller treatment zones, odds ratio = 1.54, p = 0.04), and springtime (odds ratio = 1.58, p = 0.02) were associated with flap misalignment. There was a significant difference in misalignment rates between surgeons (p = 0.02). Conclusion: This study found that larger treatment zones, higher operating room temperature, operating during the spring, and the use of Moria M2 microkeratome were associated with increased flap misalignment rates. The association with operating room temperature and seasonal variation is of interest and merits further research.

Comparison between the change in total corneal astigmatism and actual change in refractive astigmatism in transepithelial photorefractive keratectomy (tPRK), laser in situ keratomileusis (LASIK) and femtosecond laser assisted laser in situ keratomileusis (FsLASIK)

2021 ◽  
pp. 112067212110593
Author(s):  
Maja Bohac ◽  
Alma Biscevic ◽  
Violeta Shijakova ◽  
Ivan Gabric ◽  
Kresimir Gabric ◽  
...  
Keyword(s):  
Corneal Astigmatism ◽  
Laser In Situ Keratomileusis ◽  
Significant Difference ◽  
Actual Change ◽  
The Difference ◽  
Induced Changes ◽  
Surgically Induced ◽  
Refraction Data ◽  
Total Corneal Astigmatism

Purpose To compare changes in astigmatism by refraction and total corneal astigmatism after tPRK, LASIK and FsLASIK. Setting Specialty Eye Hospital Svjetlost, Zagreb, Croatia. Design Partially masked, semi-randomized, prospective, case-by-case, interventional, clinical study. Methods Patients with a stable refraction (-0.75DS to −8.00DS, astigmatism ≤1.00DC) underwent tPRK, LASIK or FsLASIK without complication. Astigmatism was measured at both corneal surfaces over the central 3.2 mm zone (approximately using Pentacam HRTM) preoperatively and 3 months postoperatively. Pentacam and refraction data were subjected to vector analysis to calculate the surgically induced changes in i) total corneal astigmatism (SIATCA) ii) any astigmatism by refraction (SIAR) and the vectorial difference (DV) between SIATCA and SIAR. Results Reporting key findings (p < .01), there was a significant difference between mean SIATCA and SIAR powers after tPRK (75eyes) but not after LASIK (100eyes) or FsLASIK (100eyes). Mean (±sd,95% CIs) values for DV powers were, tPRK −1.13DC(±0.71, −1.29 to −0.97), LASIK −0.39DC(±0.23,-0.44 to −0.34), FsLASIK −0.55DC(±0.38,-0.62 to −0.47). The differences were significant. For the tPRK and FsLASIK cases, linear regression revealed significant associations between I) SIATCA (x) &DV (z) powers (tPRK z = 1.586x-0.179, r  =  0.767, p < .01; FsLASIK z  =  0.442x-0.303, r  =  .484,p < .01), II) sines of SIATCA (x1) &DV (z1) axes (tPRK, z1 = 0.523 × 1 + 0.394, r = .650,p < .01; FsLASIK z1 = 0.460 × 1-0.308, r = .465,p < .01). Conclusions tPRK is more prone to unintended changes in astigmatism. The difference between SIATCA & SIAR after tPRK or FsLASIK is mediated by SIATCA. Photoablating deeper regions of the cornea reduces the gap between SIATCA & SIAR.

Evaluation of corneal functional optical zone after laser in situ keratomileusis

2002 ◽  
Vol 28 (6) ◽  
pp. 948-953 ◽  
Author(s):  
Brian S. Boxer Wachler ◽  
Vu N. Huynh ◽  
Ayman F. El-Shiaty ◽  
Damien Goldberg
Keyword(s):  
Laser In Situ Keratomileusis ◽  
Optical Zone
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