Laser Refractive Surgery Research Articles

Reasons for Re-treatment Following Monovision Laser Refractive Surgery.

To assess the incidence and causes for re-treatment following monovision laser refractive surgery in a large data study spanning a decade. The setting for this retrospective comparative study was Care Vision Laser Center, Tel Aviv, Israel. This study included patients aged 36 to 60 years who underwent monovision laser vision correction at the Care Vision Laser Centers, Israel, from January 2012 to December 2022. Demographic, preoperative, and postoperative data were retrieved for analysis. Overall, 3,674 eyes of 1,847 patients were included. Re-treatment was performed in 1.28% (n = 47) of eyes, 0.84% (n = 31) distance-targeted and 0.44% (n = 16) near-targeted. Monovision reversal in near-targeted eyes occurred due to overcorrection (37.5%, n = 6 of 16), despite being on target (25%, n = 4 of 16), insufficient myopia (18.8%, n = 3 of 16), and de novo astigmatism (12.5%, n = 2 of 16). One eye was targeted for near vision due to de novo astigmatism. Re-treatment in distance-targeted eyes was due to myopic undercorrection (45.2%, n = 14 of 31), myopic regression (19.4%, n = 6 of 31), myopic overcorrection (12.9%, n = 4 of 31), hyperopic regression (6.5%, n = 2 of 31), astigmatism undercorrection (6.5%, n = 2 of 31), de novo astigmatism (6.5%, n = 2 of 31), and astigmatism regression (3.2%, n = 1 of 31). Re-treatment was more likely in distance targeted eyes of patients with monovision compared to near-targeted eyes (P = .025) and patients without monovision (P < .001). In monovision laser vision correction, retreatment in the near-targeted eye is rare when the ideal near target (-1.50 to -1.25 diopters) is achieved. However, the distance-targeted eye is more likely to require re-treatment. Surgeons can plan monovision surgery and advise patients accordingly. [J Refract Surg. 2024;40(11):e892-e897.].

Femtosecond laser assisted cataract surgery in a cataract patient with low vaulted ICL following LASIK: a case report

BackgroundApart from the conventional utilization of ICL implantation for the correction of refractive errors, its recent applications extend to correcting refractive errors post laser refractive surgery. Notably, the development of cataracts stands out as a prevalent postoperative complication, often associated with low vault. Previous cases have demonstrated successful management of cataracts with ICL through the combination of FLACS and ICL removal coupled with IOL implantation, resulting in favorable postoperative visual outcomes. Herein, we present a case of cataract with low vault ICL following LASIK and its subsequent management.Case presentationA 46-year-old male presented with vision loss in the right eye for 9 months, and he had undergone LASIK 22 years prior and had ICL implantation in both eyes 2 years ago to correct refractive error. One day after ICL implantation, both eyes exhibited the UDVA of 1.2 and 1.0, well-positioned ICLs, and approximate vault of 150 μm and 200 μm. Six months ago, the patient became aware of blurred vision in the right eye for a duration of 3 months. Examination revealed cloudy lens cortex in the right eye. During the current review, the UDVA of the right eye was 0.6, where nasal wedge-shaped clouding was evident and worsened, while the left eye lens remained transparent. AS-OCT demonstrated the vault of 54 μm in the right eye and 83 μm in the left eye. Considering the patient’s history of LASIK and the presence of right eye cataract, a monovision approach was adopted. The patient underwent FLACS combined with ICL extraction and monofocal IOL lens implantation in the right eye. At 10 days postoperatively, the patient exhibited the UDVA of 1.0.ConclusionsOur report confirms the feasibility of FLACS in managing cataracts in patients with low vault ICL following LASIK. This procedure does not pose significantly greater challenges than in typical cataract cases, although meticulous care remains essential throughout every step of the surgery, particularly during laser scanning and positioning. With adequate preoperative preparation and precise calculation of the IOL power, surgical outcomes can meet expectations fully.

Evaluation of corneal biomechanical changes in moderate myopia after different techniques of corneal refractive surgeries

Background The most prevalent refractive error, which accounts for between 15 and 49% of cases worldwide, is myopia. Refractive surgery can fix refractive problems and lessen reliance on glasses or contact lenses. Aim This study aims to assess corneal biomechanical alterations following photorefractive keratectomy (PRK) and femtosecond laser small incision lenticule extraction (F-SMILE) in moderate myopic patients using CORVIS-ST (CST). Patients and methods This prospective, comparative, nonrandomized study was conducted on 40 patients’ eyes. with moderate myopia in a private center from January 2020 to December 2020, these eyes were subdivided into two groups: (a) The first group included 20 eyes that will receive PRK (b) The second group included 20 eyes that will receive F-SMILE. All participants will undergo operative (History taking, and examinations), preoperative (PRK, and F-SMILE), and postoperative (medications and Follow-up examinations) evaluations. Results Significant differences existed among the two groups in postoperative follow-up after 1 month and 6 months regarding deformation amplitude, radius, corvis biomechanical index, and intraocular pressure corrected biomechanically but There were insignificant differences among the two groups in terms of SPA in the same periods postoperatively. Conclusion Laser refractive surgery has a major impact on corneal biomechanical properties, as evidenced by significant changes in Corvis ST ocular biomechanical measures following PRK and F-SMILE procedures in myopic patients. The alterations resulting from F-SMILE are more substantial compared with PRK.

Comparison of intraocular lens power prediction by American Society of Cataract and Refractive Surgery formulas and Barrett True-K TK in eyes with prior laser refractive surgery.

To evaluate the prediction accuracy of various intraocular lens (IOL) power calculation formulas on American Society of Cataract and Refractive Surgery (ASCRS) calculator and Barrett True-K total keratometry (TK) in eyes with previous laser refractive surgery for myopia. This retrospective study included eyes with history of myopic laser refractive surgery, which have undergone clear or cataractous lens extraction by phacoemulsification followed by IOL implantation. Those who underwent uneventful crystalline lens extraction were included. Eyes with any complication of refractive surgery or those with eventful lens extraction procedure and those who were lost to follow-up were excluded. Formulas compared were Wang-Koch-Maloney, Shammas, Haigis-L, Barrett True-K no-history formula, ASCRS average power, ASCRS maximum power on the ASCRS post-refractive calculator and the IOLMaster 700 Barrett True-K TK. Prediction error was calculated as the difference between the implanted IOL power and the predicted power by various formulae available on ASCRS online calculator. Forty post-myopic laser-refractive surgery eyes of 26 patients were included. Friedman's test revealed that Shammas formula, Barrett True-K, and ASCRS maximum power were significantly different from all other formulas (P < 0.00001 for each). Median absolute error (MedAE) was the least for Shammas and Barrett True-K TK formulas (0.28 [0.14, 0.36] and 0.28 [0.21, 0.39], respectively) and the highest for Wang-Koch-Maloney (1.29 [0.97, 1.61]). Shammas formula had the least variance (0.14), while Wang-Koch-Maloney formula had the maximum variance (2.66). In post-myopic laser refractive surgery eyes, Shammas formula and Barrett True-K TK no-history formula on ASCRS calculator are more accurate in predicting IOL powers.

Клинический случай поэтапного лечения ребенка с анизометропической амблиопией и гиперметропией, сочетающейся с расходящимся косоглазием

Case study A clinical case of staged treatment in a child with anisometropic amblyopia and hyperopia combined with divergent strabismus I.L. Kulikova, K.A. Aleksandrova, S.M. Pikusova, A.V. Kuzmina S. Fyodorov Eye Microsurgery Federal State Institution, Cheboksary Branch, Cheboksary, Russian Federation Postgraduate Doctors’ Training Institute, Cheboksary, Russian Federation A clinical case of a child with anisometropic amblyopia, hypermetropia and divergent strabismus is considered. Clinical and functional results of staged treatment, including refractive laser surgery and surgical correction of strabismus, are presented. This treatment makes it possible to create optimal conditions for the more effective treatment of amblyopia and preservation of orthotropia in children with anisometropic amblyopia, hypermetropia and divergent strabismus. Key words: amblyopia, hyperopia, exotropia, FS-LASIK

Small-incision lenticule extraction in a patient with congenital motor nystagmus: case report

Introduction: In patients with congenital motor nystagmus, vision correction might be challenging, and laser refractive surgery is thought to be not advisable because of the patient's inability to fixate and uncontrollable eye movements. Patient and Clinical Findings: A 25-year-old man presented with congenital motor nystagmus and reported that he could not wear contact lenses and that spectacles gave him headaches. Diagnosis, Intervention, and Outcomes: Diagnosis of motor nystagmus was established clinically, with exclusion of other abnormalities, intact vision, and a history dating back decades. Small-incision lenticule extraction (SMILE) surgery using a 2000-kHz VisuMax 800 (VM800) femtosecond laser was performed successfully on both eyes. Preoperative uncorrected distance visual acuity (UDVA) was 6/24-1 in the right eye and 6/60-1 in the left eye, improving to 6/7.5+1 and 6/9-1, respectively, on postoperative day 1. At day 7, UDVA further improved to 6/6+2 and 6/7.5-1, and after 1 month, it reached 6/6 for the right eye and 6/7.5-1 for the left eye. The patient had a vision gain of 1 line compared with preoperative best spectacle-corrected visual acuity. Refraction at 1 month was right +0.25 diopter sphere and left +0.25 diopter sphere. No intraoperative complications were observed. Conclusions: SMILE surgery using VM800 proved effective for a patient with congenital motor nystagmus, resulting in a vision gain of 1 line compared with preoperative best spectacle-corrected visual acuity, with no intraoperative complications. Centration was within 0.2 mm of the target. These objective outcomes demonstrate the feasibility and effectiveness of SMILE surgery using a newer generation laser in this population.

Basics of Diagnosis and Treatment of Dry Eye Syndrome During Refractive Surgery

Given the prevalence of refractive surgery in modern ophthalmological practice, when preparing a patient for this type of surgery, it is important to understand the multifactorial mechanism of the development of dry eye syndrome in this group of patients. Analysis of the literature data made it possible to identify key factors in the disruption of the tear formation process after refractive surgery, which include the intersection of the nerve endings of the cornea, which in turn reduces the frequency of blinking and the distribution of the tear film over the ocular surface, and also causes a violation regarding neurotrophic factors secreted by the nerve endings of the cornea . The presence of a postoperative inflammatory reaction, which has a specific course, manifested in a change in the biochemical properties of the tear, damage to the goblet cells of the conjunctiva during the creation of a vacuum during LASIK and SMILE, leading to a subsequent deficiency of mucin in the tear, changes in the curvature of the cornea caused by laser refractive surgery are factors influencing the development of dry eye syndrome after refractive surgery. When preparing a patient for refractive surgery, to reduce the risk of developing severe forms of dry eye syndrome, including corneal ulceration, it is necessary to take into account a history of systemic diseases and allergic reactions, especially in patients with high myopia. The influence of cosmetic procedures, such as eyelash extensions, eyelid tattooing, blepharoplasty, and the use of botulinum toxin in the periorbital area on the course of the postoperative period during refractive surgery, has been poorly studied. Research in this area opens up a new range of opportunities to reduce the incidence of dry eye syndrome in patients after refractive surgery and improve the quality of life of patients and patient satisfaction with the surgical intervention.

Enhancing ectasia screening using advanced AS-OCT: a case series of challenging refractive candidates.

Ectasia screening in candidates for laser refractive surgery is mandatory during preoperative evaluation. Despite the availability of modern imaging techniques, refractive surgeons often face borderline decisions when patients present with suspicious tomographic findings. This case series presents refractive candidates with suspicious tomographic findings and demonstrates how to interpret them using Scheimpflug imaging and additional anterior segment optical coherence tomography (AS-OCT). Department of Ophthalmology, University Hospital, LMU Munich. This case series examines six potential candidates for refractive surgery with a mean age of 29.2 ± 3.9 years, whose corneal assessments using Scheimpflug imaging raised suspicion for ectasia. Each candidate was additionally examined with AS-OCT and reevaluated. The mean manifest subjective spherical equivalent was -3.67 ± 1.8 diopters. The total corneal thickness measured 537 µm ± 30 µm at its thinnest point. None of the candidates had any reported underlying corneal or ophthalmic diseases, and slit lamp examinations revealed no abnormal morphological findings. Both Scheimpflug imaging and AS-OCT are appropriate tools for screening refractive candidates for ectasia. While topographic and elevation analyses yielded comparable results regarding corneal structure, the epithelial mapping provided by AS-OCT played a critical role in decision-making for cases with borderline tomographic findings. Establishing a global consensus on the use of epithelial mapping in ectasia screening is necessary.

Retrospective Study Comparing Topography-Guided and Wavefront-Optimized LASIK Procedures in a Single Center.

To compare visual outcomes of eyes that had laser refractive surgery with the Contoura Phorcides treatment plan and eyes that had laser refractive surgery with the wavefront-optimized treatment plan using the same laser. Retrospective chart review of clinical outcomes of eyes that had either Contoura with Phorcides (CP) or wavefront-optimized (WFO) corneal refractive procedures using the Wavelight EX500 (Alcon Vision, LLC). Data were collected and compared for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, change in postoperative UDVA compared to preoperative CDVA, and change in postoperative CDVA compared to preoperative CDVA. Total eyes included were 348, with 227 in the CP Group and 121 in the WFO Group. Post-operatively, there was a significantly higher percentage of eyes in the CP Group that were 20/16 or better compared to the WFO Group (57%, 129 eyes, and 17%, 21 eyes, respectively; p < 0.001). The percentage of eyes that gained 1 or more Snellen lines of UDVA compared to preoperative CDVA was higher in the CP Group (47%; 107 eyes) compared to the WFO Group (12%; 14 eyes), which was statistically significant (p < 0.001). Differences in refraction were statistically significant. Topography-guided and wavefront-optimized treatment profiles both provided excellent refractive results. A higher percentage of eyes that were treated using Contoura with Phorcides achieved 20/16 or better unaided distance vision compared to eyes receiving a wavefront-optimized treatment plan.

Pediatric refractive surgery: current opinion in ophthalmology.

Pediatric refractive surgery has been growing at a steady pace since its introduction in the early 1980 s. This article will review common laser refractive surgeries performed on pediatric patients along with controversies regarding the practice. Pediatric refractive surgery is reserved for a small population of children who fail amblyopic treatment due to high anisometropic refractive errors. Publications over the years have treated these children with various types of laser refractive surgery. Laser pediatric refractive surgery appears to be well tolerated and effective for the population of children that need it. It provides an alternative for anisometropic amblyopia treatment for children who would have otherwise not been able to improve their vision.

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

Changes in accommodation disorders in children with anisometropic amblyopia and hypermetropia

Background. Accommodation disorders in children with hypermetropia is one of the main factors in emmetropization disorders and maintenance of image defocusing. The most severe changes in accommodation are observed in children with anisometropia and hyperopia.The aim of the work. To evaluate the changes in the accommodative function of the eye in children with hyperopia, amblyopia, who underwent refractive laser surgery (RLS), as well as in children with spectacle and contact lens correction in combination with pleoptic treatment.Methods and materials. Group 1 consisted of 30 children after RLS; group 2 consisted of 29 children who had spectacle correction; group 3 consisted of 26 children who had soft contact lens correction; all children received pleoptic treatment. Clinical examination included the analysis of objective reserves of relative accommodation (RRA) and objective accommodative response (OAR) with an open field autorefractometer, and the results of accommodation measurement.Results. In 1.5 years, statistically significant changes were observed in the coefficient of accommodation response (CAR) of the amblyopic eye between the groups 1 and 2 – 0.12 ± 0.02 and 0.00 ± 0.1 relative units, respectively (p = 0.01). Similar statistically significant changes were obtained in OAR and objective RRA of the amblyopic eye. OAR in the group 1 was –2.1 ± 0.67 dpt, in the group 2 – –1.38 ± 0.19 dpt (p = 0.01). At the end of the observation, the OAR in the group 1 was –2.1 ± 0.67 dpt, the objective RRA – –2.1 ± 0.67 dpt; in the group 2 the OAR was –1.38 ± 0.19 dpt (p = 0.01), the objective RRA – –1.38 ± 0.19 dpt (p = 0.01). There were no statistically significant changes in these parameters of the amblyopic eye between the groups 1 and 3.Conclusion. There was an improvement of accommodation disorders in children with anisometropia, hyperopia and amblyopia after refractive laser surgery and in children with contact lens correction. Due to a decrease in the refractive indices of the amblyopic eye, the values of CAR, OAR and objective RRA after refractive laser surgery tended to be closer to the normal values.

Clinical Evaluation of Corneal Endothelial Parameters following Laser Refractive Surgery in Myopic Eyes: A Review.

Background: The aim of this review was to investigate the influence of various laser refractive surgery methods on the corneal endothelium in myopic patients. The role of the corneal endothelium in laser refractive surgery (LRS) is currently being addressed in the assessment of postoperative corneal edema risk. Methods: Changes in corneal endothelial cell density and morphology after LRS were evaluated based on a systematic review of current studies. The results of a literature search in the PubMed, Science Direct, Google Scholar, and the Web of Science databases, as well as a manual search, were selected for the final review according to the PRISMA 2020 flow diagram. Results: We included 24 prospective clinical trials in the review: surface ablation (twelve), LASIK and FemtoLASIK (two), femtosecond lenticule extraction (two), and comparable studies (eight). Endothelial cell density was determined by specular or in vivo confocal microscopy. In most studies, no statistically significant differences were found between preoperative and postoperative endothelial parameters. In nine studies, the changes were statistically significant, but no vision-threatening complications occurred, and no serious corneal complications developed in any eyes during the follow-up period. Conclusions: Based on collected data, laser keratorefractive surgery appears not to exert a significant effect on the corneal endothelium.

Cornea and Anterior Segment Parameters and Their Importance in Eye Disease

Corneal and anterior segment parameters (ASP) are valuable in diagnosis and risk assessment of diseases such as glaucoma and keratoconus and it is also an invaluable tool in patient selection and surgical planning of excimer laser refractive surgery. Devices where cornea and anterior segment parameters are measured include Sirius system, Pentacam, Orbscan, Galilei, Anterior Segment Optical Coherence Tomography (ASOCT).

Corneal Collagen Crosslinking for Ectasia After Refractive Surgery: A Systematic Review and Meta-Analysis.

Corneal ectasia leads to progressive irregular corneal curvature and reduced visual acuity. To assess the safety and effectiveness of corneal collagen cross-linking (CXL) for managing corneal ectasia resulting from refractive laser surgery (RSL). A systematic review and meta-analysis were realized according to PRISMA guidelines. We searched PubMed, EMBASE, Cochrane, and Web of Science databases for studies on CXL in patients with ectasia after RLS. The outcomes of interest included visual acuity, refractive outcomes, topographic parameters (Kmax, index surface variance (ISV), index of Vertical Asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD) and Rmin (minimum sagittal curvature)), central corneal thickness, endothelial cell count, and possible adverse events. Statistical analysis was performed using the R software (version 4.2.3, R Foundation for Statistical Computing, Vienna, Austria). 15 studies encompassing 421 patients (512 eyes) were included. The mean age was 32.03 ± 4.4 years. The pooled results showed a stable uncorrected visual acuity post-CXL, with a significant improvement in corrected distance visual acuity (SMD = 0.09; 95% CI: -0.07 to 0.26). The spherical equivalent decreased significantly (SMD = -0.09; 95% CI: -0.35, -0.02). The topographic parameter Kmax decreased significantly (SMD = 0.15; 95% CI:0.01 to 0.28); however, the other parameters, ISV, IVA, KI, CKI, IHA, IHD, and Rmin, did not change significantly. Central corneal thickness decreased significantly (SMD = 0.24; 95% CI:0.07 to 0.41), and the endothelial cell count remained stable The complications were rare. CXL is a safe and effective technique for managing corneal ectasia after RLS.

Limitations of and Solutions to Using 6 mm Corneal Spherical Aberration and Q Value after Laser Refractive Surgery.

This study aimed to evaluate the spherical aberration (SA) in different corneal areas before and after femtosecond laser-assisted in situ keratomileusis (fLASIK) and transepithelial photorefractive keratectomy (tPRK), with the goal of identifying the limitations of and potential improvements in using SA within a 6 mm area. The study included 62 patients who underwent fLASIK and tPRK. Complete eye examinations including keratometry, corneal epithelial thickness, central corneal thickness, and topography were performed preoperatively and postoperatively. Anterior, posterior, and total corneal aberrations were measured preoperatively and three months postoperatively, with pupil diameters ranging from 2 to 8 mm. In the fLASIK group, compared to the preoperative SA, the anterior and total SA increased postoperatively in the 6 and 7 mm areas. In the tPRK group, meanwhile, the anterior and total SA of the 5 mm or larger areas increased postoperatively. An area of 6 mm or larger showed an increase in correlation with the changes in Q value and refractive correction. As the corneal SA and asphericity in the 6 mm zone cannot specifically demonstrate the status of areas smaller than 6 mm or changes in the optical zone after laser refractive surgery, comparison with normal values in various areas of the cornea is necessary.

Laser Refractive Surgery (LRS) with Laser Asymmetric Keratectomy (Crescentic LRS) to Avoid LRS Adverse Effects

Laser Refractive Surgery (LRS) with Laser Asymmetric Keratectomy (Crescentic LRS) to Avoid LRS Adverse Effects

Regional analysis of posterior corneal elevation after laser refractive surgeries for correction of myopia of different degrees.

To evaluate regional changes in the posterior corneal elevation after three laser refractive surgeries for correction of myopia of different degrees. Retrospective, comparative, and non-randomized study. Two hundred patients (200 eyes) who underwent laser epithelial keratoplasty (LASEK), femtosecond-assisted laser in-situ keratomileusis (FS-LASIK), and small-incision lenticule extraction (SMILE) were included in this study. According to preoperative spherical equivalent (SE), each surgical group was divided into two refractive subgroups: low-to-moderate myopia (LM group) and high myopia (H group). The posterior corneal elevation from Pentacam Scheimpflug tomography was analyzed preoperatively and at 1 month, 3 months, 6 months, and 12 months postoperatively. Three subregions of the posterior cornea were divided in this study as the central, paracentral, and peripheral regions. Generalized Estimating Equations (GEE). For all three surgical groups, similar changing trends were seen in the two refractive subgroups. H group presented a larger changing magnitude than the LM group in FS-LASIK over time ( P < 0.05), whereas no significant difference was noted in the two refractive subgroups of LASEK or SMILE ( P > 0.05). At 12 months postoperatively, the central posterior corneal elevation returned to the preoperative level in LASEK ( P > 0.05) but shifted forward significantly in FS-LASIK and SMILE ( P < 0.05). Different posterior corneal regions respond differently to corneal refractive surgeries. LASEK, FS-LASIK, and SMILE demonstrate different trends in the regional changes in posterior corneal elevation. The corneal shape seems more stable in LASEK than in FS-LASIK and SMILE.

Factors Predicting the Need for Re-treatment After Laser Refractive Surgery in Patients With Mixed Astigmatism.

To identify risk factors that increase the likelihood of re-treatment following refractive surgery in patients with mixed astigmatism. This was a retrospective study including patients who underwent either laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between 2000 and 2019 and had mixed astigmatism (spherical error of +0.50 D or greater and spherical equivalent of less than 0.00 diopters [D]). Patients were divided into two groups according to whether they underwent re-treatments during the study period. Overall, 785 eyes (785 patients) were included. In total, 5.2% of the eyes (n = 41) underwent re-treatment. The re-treatment group was more likely to have preoperative high astigmatism (80.5% vs 48.3%, P < .001), moderate to high hyperopia (36.6% vs 22.3%, P = .035), and to have undergone surgery earlier during the study period (P < .001). They were also more likely to have undergone surgery using the Wave-Light EX200 rather than the EX500 laser platform (Alcon Laboratories, Inc) (P < .001), have a treated optical zone of 6 mm rather than 6.5 mm (P < .001 for both), and their maximum ablation depth was greater (P < .001). There was no difference between the re-treatment and control groups regarding procedure type (PRK vs LASIK). Binary logistic regression found preoperative high astigmatism (odds ratio = 3.97, P < .001) and the type of laser platform used (EX200, odds ratio = 7.78, P < .001) as the only independent factors associated with re-treatment. Re-treatment rates following correction of mixed astigmatism were 5.2% over 20 years. Use of a sixth-generation laser platform significantly reduced the risk of re-treatment. Presence of high astigmatism is a significant risk factor for re-treatment. There was no difference in retreatment risk between PRK and LASIK. [J Refract Surg. 2024;40(2):e73-e78.].

Refractive Errors Among Members of the Armed Forces of the Czech Republic.

Objective: To evaluate the prevalence of refractive errors among members of the Armed Forces of the Czech Republic, to recommend a safe way of correcting refractive errors with regard to the specific needs of military personnel (especially members of combat units and flying personnel), and to propose a system for solving these errors in order to increase combat effectivity. Methodology: Questionnaire to determine previous refractive surgery and spectacle correction wear. Measurement of refraction with a hand-held autorefractometer and evaluation of current visual acuity on ETDRS optotypes (Landolt rings). Results: 259 servicemen (518 eyes) were investigated. The return rate of the questionnaires was 100%. The incidence of myopia greater than -0.75D was 22% (113 eyes), myopia greater than -0.5D 32% (166 eyes). The mean value of myopia was -0.78 D (SD ±0.6). Hypermetropia values ranged from +0.25 to +5.0 D. The mean value of hypermetropia was 0.63 D (SD ±0.7). Astigmatism values ranged from -0.25 to -3.75. The mean value of astigmatism was -0.55 Dcyl (SD ±0.49). The average visual acuity was 84.1 letters ETDRS SD (±6.1), visual acuity worse than 80 letters was manifested by 23% of the members of the monitored group. 25 people (10%) had undergone laser refractive surgery. Visual acuity after laser refractive surgery was measured in 19 people (38 eyes). Mean uncorrected post-laser visual acuity was 83.87 (SD ±6.1) ETDRS letters. The mean follow-up period after laser refractive surgery was 6.78 (SD ±4.8) years. Conclusion: Despite the initial selection of military personnel and entry limitations, the prevalence of refractive errors is comparable to the general population. However, in contrast with the general population, refractive errors larger than -3.0 D were not represented in the group. Due to the finding of insufficient correction of refractive errors, increased emphasis should be placed on identifying and regularly observing military personnel with refractive errors