Surgical Correction Of Refractive Errors Research Articles

Creation of a Corneal Flap for Laser In Situ Keratomileusis Using a Three-Dimensional Femtosecond Laser Cut: Clinical and Optical Coherence Tomography Features

Laser in situ keratomileusis (LASIK) is the most frequently used technique for the surgical correction of refractive errors on the cornea. It entails the creation of a superficial hinged corneal flap using a femtosecond laser, ablation of the underlying stromal bed using an excimer laser, and repositioning of the flap. A corneal flap with an angled side cut reduces the risk of flap dislocation and infiltration of epithelial cells and confers unique biomechanical properties to the cornea. A new laser software creating three-dimensional (3D) flaps using a custom angle side cut was retrospectively evaluated, comparing optical coherence tomography 3D (with intended 90° side cut) and 2D flaps (with tapered side cuts) as well as respective intra- and early postoperative complications. Four hundred consecutive eyes were included, two hundred for each group. In the 3D group, the mean edge angle was 92°, and the procedure was on average 5.2 s slower (p = 0). Non-visually significant flap folds were found in thirteen eyes of the 2D group and in seven eyes of the 3D group (p = 0.17). In conclusion, the creation of a LASIK flap using a 3D femtosecond laser cut, although slightly slower, was safe and effective. The side cut angle was predictable and accurate.

Advances in Transepithelial Photorefractive Keratectomy versus Laser-Assisted In Situ Keratomileusis.

(1) Background: Laser-assisted refractive surgery is a safe and effective surgical correction of refractive error. For most patients, both the newer Trans-PRK and the established LASIK technique can produce the required surgical correction, sparking the question of which technique should be opted for. (2) Methods: The study prospectively evaluated 121 patients (230 eyes) for at least one month postoperatively; 66 patients (126 eyes) and 45 patients (85 eyes) returned for 6 months and 1 year follow-up. (3) Results: No statistical difference was recorded at 1 week or 1 month post-operation. At 6 months, a difference was found for spherical diopters (Trans-PRK -0.0476 ± 0.7012 versus FS-LASIK +0.425 ± 0.874, p = 0.004) and spherical equivalent (Trans-PRK -0.1994 ± 0.0294 versus FS-LASIK +0.225 ± 0.646, p = 0.025) but not for CYL D (Trans-PRK -0.3036 ± 0.5251 versus FS-LASIK -0.4 ± 0.820, p = 0.499). Uncorrected visual acuity was better for Trans-PRK 6 months post-operation (UCVA logMAR 0.02523 versus 0.0768 logMAR; p = 0.015 logMAR). At 1-year, Trans-PRK was favored for spherical diopters (Trans-PRK -0.0294 ± 0.6493 versus FS-LASIK +0.646 ± 0.909, p < 0.001) and spherical equivalent (Trans-PRK -0.218 ± 0.784 versus FS-LASIK 0.372 ± 1.08, p = 0.007). Overall speed in visual recovery, variance of results and surgically induced astigmatism were in favor of Trans-PRK. (4) Conclusions: The study reported improvements for Trans-PRK patients, with both techniques found to be safe and effective.

Knowledge, Attitude and Practices among Undergraduate Medical Students Regarding Surgical Correction of Refractive Errors; a Cross-sectional Study

Aim: This study was aimed to assess the knowledge, attitude and practices regarding refractive error correction surgeries among undergraduate medical students.&#x0D; Study Design: In this study cross-sectional study design was used.&#x0D; Duration and Place of Study: The study was conducted amongst the undergraduate MBBS students studying at Dow Medical College, Karachi. The duration of study was seven months (August, 2019 till February, 2020).&#x0D; Methods: A sample size of 189 was calculated for the study with confidence level 95% and confidence limit 5%. Data was collected through a validated self-administered questionnaire which was divided in five subsections used to gain information regarding participant’s demographics, knowledge, attitude and practices regarding refractive error surgeries. Data was analyzed using IBM SPSS V.22.&#x0D; Results: In our study 189 students with a mean age of 21±1.8 years were included. Among the participants 112 (59.3%) had refractive errors. Glasses were used by majority 76 (67.9%) of participants for visual correction. Use of refractive error correction methods at all times was reported by 72 (66.7%) participants. Majority of respondents 142 (75.5%) had heard about surgery being used for correction of refractive errors. A large number of students 117 (66%) refused for surgery and fear of the outcomes was one of the reason for this refusal.&#x0D; Conclusion: We found that majority of the participants were aware about refractive error correction surgeries yet most of them showed unwillingness for these procedures. This negative attitude must be changed to positive in order to enhance the practice for these procedures.

Screening and prophylaxis of retinal degenerations prior to refractive surgery.

The need and demand for surgical correction of refractive errors, particularly myopia, has been increasing. Degenerations involving the peripheral retina are common in myopes and can result in a rhegmatogenous retinal detachment. There are no clear guidelines for retinal screening and management of asymptomatic retinal degenerations prior to refractive surgery or for follow-up of these patients. This article aims to provide a set of guidelines for the management of retinal degenerations in eyes undergoing refractive surgeries.

New advances in amblyopia therapy II: refractive therapies

The treatment of anisometropic or ametropic amblyopia has traditionally enjoyed a high treatment success rate. Early initiation and consistent use of spectacle correction can completely resolve amblyopia in a majority...

Past and present of corneal refractive surgery: a retrospective study of long-term results after photorefractive keratectomy, and a prospective study of refractive lenticule extraction.

Past and present of corneal refractive surgery: a retrospective study of long-term results after photorefractive keratectomy, and a prospective study of refractive lenticule extraction.

Past and present of corneal refractive surgery

Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become possible. Two new procedures were developed, ReLEx flex (FLEX) and ReLEx smile (SMILE). Until this thesis, only a few long-term studies of PRK with a relatively limited number of patients had been published; therefore, this thesis intended to retrospectively evaluate long-term outcomes after PRK for all degrees of myopia for a large number of patients. Furthermore, a prospective contralateral eye study comparing FLEX and SMILE, when treating high to moderate degrees of myopia, had not been performed prior to this study. This was the second aim of this thesis. In the first study, results from 160 PRK patients (289 eyes) were presented. Preoperative spherical equivalent ranged from -1.25 to -20.25 D, with 78% having low myopia (<-6 D). Average follow-up time was 16 years (range 13-19 years), making this the longest published follow-up study on PRK patients. Outcomes from eyes with low myopia were generally superior to outcomes from eyes with high myopia, at final follow-up. Seventy-two percent were within ± 1.00 D of target refraction, as compared to 47% of eyes with high myopia. However, results from a subgroup of unilateral treated PRK patients indicated that refraction at final follow-up was affected by myopic progression. Fifty percent of eyes with low myopia had uncorrected 20/20 distance visual acuity or better, as compared to 22% of eyes with high myopia. Haze did not occur if attempted corrections were <-4 D, and only eyes with high myopia lost two lines or more of CDVA (corrected distance visual acuity). Eighty-one per cent were satisfied or very satisfied with their surgery. The results support the continued use of the excimer laser for corneal surface ablation as a treatment option for correction of low degrees of myopia, and as the treatment of choice for subgroups of refractive patients (thin corneas, etc.). The results also highlight that treatment of higher degrees of myopia with standard PRK should only be done today under special circumstances, due to low refractive predictability, and high risk of corneal haze. Technological advances since then should be taken into account when comparing these results with contemporary techniques. In the second study, 35 patients were randomized to receive FLEX in one eye and SMILE in the other. Preoperative spherical equivalent refraction ranged from -6 to -10 D with low degrees of astigmatism. A total of 34 patients completed the 6 month follow-up period. Refractive and visual outcomes were very similar for the two methods, as well as tear film measurements and changes in corneal biomechanics. Ninety-seven percent were within ± 1.00 D of target refraction, no eyes lost two lines or more of CDVA, and contrast sensitivity was unaffected after both procedures. The changes in higher-order aberrations were also very similar. There were also no differences in tear film parameters 6 months after surgery, although less postoperative foreign body sensation was reported within the first week after surgery in SMILE eyes. Corneal sublayer pachymetry measurements demonstrated equally increased epithelial thickness 6 months after surgery. Contrary to expectations, it was not possible to measure the theoretical biomechanical advantages of a small corneal incision in SMILE as compared to a corneal flap in FLEX. The main differences between FLEX and SMILE were found when the corneal nerves and intraoperative complications were evaluated. Thus, corneal sensitivity was better preserved and corneal nerve morphology was less affected after SMILE, but intraoperative complications occurred more frequently, although without visual sequela. Finally, 97% were satisfied or very satisfied with both their surgeries. The results support the continued use of both FLEX and SMILE for treatment of up to high degrees of myopia. Overall, refractive and visual results for both procedures were good and similar, but from a biological point of view, the less invasive SMILE technique is more attractive, as demonstrated in this study, despite being slightly more surgically demanding than FLEX.

Do air pressure and wind speed influence the outcome of myopic laser refractive surgery? Results from the Hamburg Weather Study

Laser in situ keratomileusis (LASIK) is one of the dominant procedures for the surgical correction of refractive errors. Meteorotropic reaction has been described regarding the field of ophthalmology. This study was thus initiated to assess the impact of air pressure and wind speed on the refractive and visual outcome of LASIK in myopic eyes. Our study comprised 1,052 eyes of 1,052 consecutive myopic patients (419 males, 633 females; mean age at surgery 35.0 ± 9.0 years) with mean preoperative refractive spherical equivalent (SE) of -3.88 ± 1.85 diopters (D). Two subgroups were defined, which had undergone surgery either during meteorological winter or summer. Manifest refraction, uncorrected and corrected visual acuity were assessed pre- and post-operatively. We applied robust regression analysis with efficiency index (EI), safety index, and postoperative SE (D) as dependent variables. At the 1-month (33.0 ± 5.0 days) follow-up, the mean postoperative SE was -0.18 ± 0.44 D. Bivariate comparisons showed that statistically significant better EI was related to days with low to moderate air-pressure. This was confirmed by robust regression analysis. Moderate to high wind speed was related to more appropriate postoperative SE. No change by more than one line on logMar scale was obtained. Although being statistically significant, there is no clinically relevant difference in outcome of LASIK, which demonstrates its highly standardized quality. Prospective, longitudinal studies are warranted to address meteorotropic reactions through evaluating individual risk profiles.

Helen Bawtree

The treatment of anisometropic or ametropic amblyopia has traditionally enjoyed a high treatment success rate. Early initiation and consistent use of spectacle correction can completely resolve amblyopia in a majority...

Refraktive Chirurgie

The surgical correction of refractive errors has gained widespread acceptance in the past 20 years, mainly through the introduction of the excimer laser. The excimer is used to ablate the cornea, renoving stromal tissue in the center (to correct myopia through flattening of the surface), or in the midperiphery (to steepen the cornea to correct hyperopia). Although excimer procedures dominate the field of refractive surgery, other approaches are also available. In the cornea itself, ring segments can be implanted, heat-induced coagulation effects can produce steepening, and cross-linking of the collagen fibers can stiffen a weakened structure. While all corneal procedures are extraocular, refractive surgery can also be performed within the eye. Special intraocular lenses can be implanted in the anterior chamber angle, fixated onto the iris, or placed in the posterior chamber in front of the crystalline lens. These so-called phakic intraocular lenses are available in different optical magnitudes and act to correct the patient's refractive error. Prebyopic individuals can have the crystalline lens removed in a procedure identical to cataract surgery. In such cases the lens is extracted even though no cataract is present, and an intraocular lens is implanted in the now empty capsular bag of the crystalline lens. The implanted lens serves to correct the preoperative refractive error.

Refractive surgery and ectasia: what are we doing differently this year?

At the time of this writing in 2008, I think we can confidently say that refractive surgery has become a widely accepted standard of practice option for the surgical correction of refractive error. It is certainly no longer experimental, but rather regarded as highly effective and safe. As described

Avaliação do impacto da cirurgia refrativa na qualidade de vida por meio do questionário NEI-RQL (National Eye Institute Refractive Error Quality of Life)

To assess the impact of refractive surgery on quality of life using the National Eye Institute Refractive Error Quality of Life instrument (NEI-RQL) and to evaluate the responsiveness of our Portuguese version of the NEI-RQL instrument to surgical correction of refractive error. In this prospective study, the NEI-RQL, a 42-item questionnaire with 13 scales, was self-administered by 96 patients of the Federal University of São Paulo-UNIFESP, between March 2002 and April 2003, before and after undergoing surgical correction of refractive error. An overall scale score was determined by calculating the mean of the 13 scale scores. Differences between preoperative and postoperative NEI-RQL scores were examined. Responsiveness was assessed by calculating the size of effect for each scale of the instrument. Refractive surgery was associated with statistically significant improvements in scores for all the scales of the NEI-RQL. The NEI-RQL has shown to be responsive to surgical correction of refractive error, and the calculated effect sizes ranged from 0.4 ("glare") to 4.19 ("expectations"). The NEI-RQL is highly responsive to changes in vision-related quality of life resulting from keratorefractive surgery. We observed improvements in all the scales of the NEI-RQL, after surgery.

Corneal edema and penetrating keratoplasty after anterior chamber phakic intraocular lens implantation

Phakic intraocular lens (IOL) implantation is an increasingly popular option in surgical correction of refractive error. To date, reports of long-term morbidity are infrequent in the literature. We encountered 3 patients who experienced corneal decompensation and cataract progression following angle-fixated anterior chamber phakic IOL placement.

Responsiveness of the National Eye Institute Refractive Error Quality of Life instrument to surgical correction of refractive error

Objective Refractive error and the means by which it is corrected may impact substantially on quality of vision and health-related quality of life in ways not captured adequately by standard measures of visual acuity. The goal of this analysis was to evaluate the responsiveness of the National Eye Institute Refractive Error Quality of Life (NEI-RQL) instrument to surgical correction of refractive error. Design Prospective, multicenter cohort study. Participants The NEI-RQL, a 42-item measure with 13 scales, was self-administered by 185 patients before and after undergoing surgical correction of myopic or hyperopic refractive error. Preoperative and postoperative clinical information was collected, including refractive error and corrected visual acuity. Methods Differences between preoperative and postoperative NEI-RQL scores were examined. Responsiveness was assessed using the standardized response mean and the responsiveness statistic. We also compared scales using relative efficiency estimates. Main outcome measures Changes in NEI-RQL scales (clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, glare, symptoms, dependence on correction, worry, suboptimal correction, appearance, and satisfaction with correction). Results For myopes and hyperopes combined, refractive surgical correction was associated with statistically significant ( P<0.05) improvements in scores for 11 of 13 scales. The largest improvements, ranging from 26 to 58 points on the 0 to 100 possible score range, were seen in expectations, activity limitations, dependence on correction, appearance, and satisfaction with correction. Separate analysis of myopes and hyperopes revealed similar effects in the 2 groups. Baseline scores were found to be predictive of change after surgery. Conclusions The NEI-RQL is responsive to changes in vision-targeted health-related quality of life resulting from keratorefractive surgery. This instrument may prove useful for evaluating the beneficial and adverse impacts of surgical and nonsurgical methods of refractive error correction.

Surgical correction of refractive error

Surgical correction of refractive error

Surgical correction of refractive errors.

Surgical correction of refractive errors.

Surgical correction of refractive errors after penetrating keratoplasty.

Surgical correction of refractive errors after penetrating keratoplasty.

Surgical correction of refractive errors after penetrating keratoplasty.

Surgical correction of refractive errors after penetrating keratoplasty.