Laser Refractive Surgery Research Articles

Синдром сухого глаза на фоне дисфункции мейбомиевых желез у пациента рефракционного профиля (клинический случай)

Purpose. To describe a clinical case of a patient planning keratorefractive surgery, diagnosed with dry eye syndrome (DES) on the background of meibomian gland dysfunction (MGD). Material and methods. Patient S. applied to the Department of laser refractive surgery of S.N. Fyodorov Eye Microsurgery Federal State Institution. She was 27 years old with a diagnosis of moderate myopia in both eyes for possible keratorefractive surgery. She underwent a standard refractive diagnosis and consultation with an ophthalmic surgeon. Results.During biomicroscopy and standard ophthalmological examinations of the ocular surface, patient S. was found to have DES and MGD. It was decided to conduct a course of conservative treatment to restore the ocular surface. Conclusion. Thus, the proposed utility model for the treatment of MGD and the associated DES makes it possible to normalize the secretory work of these glands and, as a result, stabilize the condition of the tear film, which contributes to the safe planning of keratorefractive surgery. Keywords: dry eye syndrome, dysfunction of the meibomian glands, tear film, keratorefractive surgery

Accuracy of Haigis Formula Using Total Keratometry for IOL Power Calculation in Eyes with Previous Myopic and Hyperopic LASIK and PRK

Background: this retrospective study aimed to analyze the results of the combination of the Haigis formula and total keratometry (TK) in calculating the IOL power in eyes with previous corneal refractive surgery. Methods: the TK value provided by the IOL Master 700 (Carl Zeiss Meditec) was introduced into the Haigis formula; the mean prediction error (PE), mean absolute error (MAE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.25 D, ±0.5 D, ±0.75 D and ±1.00 D were calculated. Results: ninety-three eyes of 93 patients with previous laser refractive surgery were evaluated. Two groups were defined: the Myopic Group included 51 previously myopic eyes and the Hyperopic Group included 42 previously hyperopic eyes. The mean PE in the Myopic Group was +0.09 ± 0.44 D and 76.47% of eyes had a PE within ±0.50 D. In the Hyperopic Group, the mean PE was −0.15 ± 0.46 D and 66.67% of eyes had a PE within ±0.50 D. Discussion: when compared to the results previously published with other formulas or methods, the Haigis formula combined with TK provided very accurate refractive outcomes for IOL power calculation in eyes with prior myopic and hyperopic corneal refractive surgery. In such eyes the results are similar to or better than those reported in previous studies.

Identifying Content for an Item Bank to Measure the Quality-of-Life Impact of Myopia Refractive Interventions.

To report on the content generation and item refinement phases for a myopia refractive intervention-specific quality-of-life (QoL) item bank that will be operationalized using computerized adaptive testing. Myopia refractive intervention-specific QoL domains and items were generated from (1) a literature search of existing refractive-intervention QoL questionnaires; (2) semistructured interviews with myopic patients corrected using spectacles, contact lenses and/or refractive surgery (n = 32); (3) and myopia experts (n = 9) recruited from the Singapore National Eye Centre. After a thematic analysis, items were systematically refined and tested using cognitive interviews with 24 additional patients with corrected myopia. Of the 32 participants with myopia interviewed (mean ± standard deviation age, 35.6 ± 9.0 years; 71.9% female; 78.1% Chinese), 12 (37.5%) wore spectacles, 7 (21.9%) used contact lenses, and 20 (62.5%) had undergone laser refractive surgery. Initially, 912 items within 7 independent QoL domains were identified. After refinement, 204 items were retained, including those relating to mobility challenges and work-related difficulties that are not well-represented in current refractive intervention-specific questionnaires. Through a rigorous item generation and selection process, we have developed a 204-item and 7-domain myopia refractive intervention-specific item bank that will now undergo rigorous psychometric testing to generate item calibrations for the validation of a novel computerized adaptive testing instrument designed for use in research and routine clinical practice. Once psychometrically validated and operationalized using computerized adaptive testing, this myopia refractive intervention-specific instrument will enable researchers and clinicians to quickly and comprehensively assess the impact of myopic refractive interventions across seven QoL domains.

A No-History Multi-Formula Approach to Improve the IOL Power Calculation after Laser Refractive Surgery: Preliminary Results.

This retrospective comparative study proposes a multi-formula approach by comparing no-history IOL power calculation methods after myopic laser-refractive-surgery (LRS). One-hundred-thirty-two eyes of 132 patients who had myopic-LRS and cataract surgery were examined. ALMA, Barrett True-K (TK), Ferrara, Jin, Kim, Latkany and Shammas methods were evaluated in order to back-calculate refractive prediction error (PE). To eliminate any systematic error, constant optimization through zeroing-out the mean error (ME) was performed for each formula. Median absolute error (MedAE) and percentage of eyes within ±0.50 and ±1.00 diopters (D) of PE were analyzed. PEs were plotted with corresponding mean keratometry (K), axial length (AL), and AL/K ratio; then, different ranges were evaluated. With optimized constants through zeroing-out ME (90 eyes), ALMA was better when K ≤ 38.00 D-AL > 28.00 mm and when 38.00 D < K ≤ 40.00 D-26.50 mm < AL ≤ 29.50 mm; Barrett-TK was better when K ≤ 38.00 D-AL ≤ 26.50 mm and when K > 40.00 D-AL ≤ 28.00 mm or AL > 29.50 mm; and both ALMA and Barrett-TK were better in other ranges. (p < 0.05) Without modified constants (132 eyes), ALMA was better when K > 38.00 D-AL ≤ 29.50 mm and when 36.00 < K ≤ 38.00 D-AL ≤ 26.50 mm; Barrett-TK was better when K ≤ 36.00 D and when K ≤ 38.00 D with AL > 29.50 mm; and both ALMA and Barrett-TK were better in other ranges (p < 0.05). A multi-formula approach, according to different ranges of K and AL, could improve refractive outcomes in post-myopic-LRS eyes.

Predictability of the Refractive Effect after Laser Correction. Determining Factors. Review

Currently, refractive surgery using modern laser systems for the correction of various types of ametropia is one of the most widespread and performed operations worldwide. It is important to obtain refractive results comparable to those expected, both for the patient and for the surgeon himself. However, in some cases, there may be a deviation of the refractive result from the planned one, and in the late period after the operation, a regression of the refractive effect is detected, which, ultimately, may cause patient dissatisfaction. In order to avoid these situations, it is necessary to have a clear understanding of the risk factors that can lead to these phenomena, and, accordingly, take them into account during planning a surgical intervention.Currently, risk factors for regression and factors that can affect the deviation of the refractive result are divided into 2 groups and are actively studied by both Russian and foreign researchers.Given the relevance of the problem of accurate planning and achieving stable refractive results, various nomograms have been actively developed and implemented recently. The purpose of nomograms is to compensate the influence of various factors by introducing adjustments that can be applied at the planning of the operation. Nomograms are considered reliable and effective tools to increase the predictability of refractive surgery, but, for the most part, are the result of the work of a refractive surgeon. The purpose of this review is to analyze the world literature to determine the risk factors for regression and factors affecting the deviation of the refractive result from the planned one, as well as to analyze the existing nomograms designed to improve the planning and prediction of the results of laser refractive surgery.

Refractive surgery and dry eye - An update.

Dry eye disease is the most common complication and a frequent cause of patient dissatisfaction after corneal laser refractive surgery, which includes laser-assisted in situ keratomileusis (LASIK), small-incision lenticule extraction (SMILE), and photorefractive keratectomy (PRK). It has a complex, multifactorial etiology and is characterized by a highly variable clinical presentation. A detailed preoperative screening and optimization of the ocular surface prior to refractive surgery are the key to minimizing the incidence and severity of postoperative dry eye. Diagnosis of postrefractive surgery dry eye remains a challenge as no single symptom or clinical parameter is confirmative of the condition, and the symptoms and signs may not correlate well in many cases. A thorough understanding of the pathomechanism of the disease and its manifestations is essential to facilitate a treatment approach that is individualized for each patient. This article reviews various aspects of postrefractive surgery dry eye including its epidemiology, etiopathogenesis, risk factors, diagnosis, and management.

Systemic contraindications for laser vision correction surgery

Introduction: Laser refractive surgery corrects refractive errors by changing the shape of the anterior surface of the cornea and its refractive power by using a laser. Patients with refractive errors and systemic comorbidities pose a challenge for refractive surgeons. According to the guidelines of ophthalmological societies, the coexistence of autoimmune connective tissue diseases or hormonal disorders, some pharmacotherapies, pregnancy and lactation are contraindications for refractive procedures. These recommendations have been formulated on the basis of case reports or recommendations coming from other ophthalmic surgeries. Aim: The aim of the study was to summarise the current literature data on systemic contraindications for laser vision correction. Materials and methods: The literature review included the PubMed database. In the search for relevant articles, the following keywords were used: “refractive surgery”, “contraindications”, “LASIK”, “PRK”, “laser in situ keratomileusis”, “photorefractive keratectomy”. The references of articles that met the criteria were also analysed. Discussion: The main reason for considering some systemic conditions and pharmacotherapy as exclusion criteria for refractive surgery was the concern of an increased risk of postoperative eye inflammation, unpredictable healing and corneal remodelling, as well as a severe dry eye syndrome. In recent decades, a number of articles have been published supporting the safety profile of refractive procedures in patients with inactive autoimmune diseases, well-controlled diabetes or undergoing specific pharmacotherapy. These publications were based on either retrospective studies or case series, with short-term follow-up and their results should be interpreted with caution. Conclusions: Active or uncontrolled autoimmune diseases, pregnancy and lactation are absolute contraindications for laser vision correction. The decision to perform refractive surgery in patients with inactive and well- controlled systemic diseases or risk factors should be made individually and carefully by an experienced surgeon.

Комбинированный подход к лечению анизометропической амблиопии у детей (клинический случай)

A clinical case of patient K., 12 years old, with a diagnosis of anisometropia, anisometropic amblyopia, mixed astigmatism of the right eye, mild myopia, complex myopic astigmatism of the left eye is presented. Due to the intolerance of eyeglass and contact correction, the preservation of residual amblyopia against the background of regularly performed pleoptic treatment, the patient underwent laser refractive surgery of the amblyopic eye by Femto LASIK method in order to eliminate aniseikonia, which made it possible to successfully select glasses for permanent wearing with correction of the myopic eye and carry out further treatment in conditions of free haploscopy on a binarimeter with obtaining a high functional result. When observed in dynamics after 1 month and six months, the stability of anatomical and functional indicators was noted, which makes it possible to consider a highly effective combined approach in the treatment of anisometropic form of amblyopia in children. Keywords: amblyopia, children, anisometropia, FemtoLASIK, binarimetry

Results of corneal collagen cross-linking in patients with corneal ectasia after laser refractive surgery—A prospective study

PurposeTo evaluate the safety and efficacy of epithelium-off (epi‑off) corneal cross-linking (CXL) in patients with post-LASIK corneal ectasia (PLE) SettingPrivate clinical practice DesignProspective clinical trial Methods82 eyes of adult patients post-LASIK, ages 21–67, with a topography pattern consistent with corneal ectasia, corrected distance visual acuity (CDVA) worse than 20/20, and minimum corneal pachymetry > 400 µm underwent epi‑off CXL. Exclusion criteria were patients with corneas that were thinner than 400 μm or demonstrated central corneal scarring, history of herpetic eye disease, pregnancy or nursing. Follow up examinations of spherical equivalent, uncorrected distance visual acuity (UDVA), CDVA, steep keratometry (KSteep) and minimum pachymetry occurred on different but highly overlapping subsets of the operated eyes yearly until 5 years post-CXL. ResultsOver the 5 years of follow up, spherical equivalent did not significantly change while UCVA and CDVA stabilized or improved to a non-significant degree. KSteep and minimum pachymetry continued to be decreased to a statistically significant degree (p < 0.05 at 5 years). ConclusionsCXL in PLE patients is safe and efficacious: it halts progression of PLE and may improve visual function. KSteep and minimum pachymetry decrease post-CXL. Patients with PLE should be encouraged to stop progression of the disease by undergoing epi‑off CXL once progression is established.

Management of post-keratoplasty ametropia.

Even after a successful corneal transplant, patients experience severe refractive errors, impeding their rehabilitation and satisfaction. Refractive errors can be caused by recipient pathology and corneal thickness, as well as intraoperative factors such as donor-host discrepancy, recipient's eccentric trephination, vitreous length, wound apposition, technique of suturing, and suture material. Also, wound healing and the interim between keratoplasty and suture removal contribute to astigmatism. Lamellar keratoplasty outperforms penetrating keratoplasty in terms of endothelial cell loss and endothelial graft rejection, yet the risk of developing refractive errors is comparable. Nonsurgical interventions such as spectacles and lenses fail to provide desirable vision in cases with high astigmatism and corneal irregularity. When these limitations are encountered, surgical interventions including incisional keratotomy, wedge resection, laser refractive surgeries, intracorneal segments, and intraocular lens implantation are employed. However, occasionally, none of these approaches deliver the desired effects, leading to the need for a repeat keratoplasty.

Changes in accommodation in children with hyperopic anisometropia and unilateral amblyopia after laser refractive surgery and pleoptic treatment

This study comparatively analyzes the state of accommodation in children with hyperopic anisometropia and amblyopia after femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) combined with pleoptic treatment, and after conventional pleoptic treatment. The first group consisted of 30 children with medium and high hyperopia, high and medium amblyopia, and anisometropia greater than 3.0 diopters, who underwent Femto-LASIK in the amblyopic eye. The second group consisted of 28 children with similar local status, who were prescribed traditional correction and received conservative treatment. The follow-up period was 1.5 years. After 1.5 years, higher visual acuity (p<0.05) was achieved in the first group. A significant increase in the coefficient of accommodative response (CAR) was observed in the operated amblyopic eyes in group 1 - by 0.1±0.02 c.u. compared to the control group (p<0.05). In both groups there was an upwards trend for the coefficient of microfluctuations (CMF) in the amblyopic eye, but in the first group CMF increased more significantly (p<0.05). The objective accommodative response (OAR) and positive relative accommodation (PRA) of the amblyopic eye showed a double increase - by 1.0±0.23 and 0.9±0.38 diopters, respectively, at the end of treatment in the first group. The increase in similar indicators in the second group was insignificant (p<0.05). In children of the first group the difference in ciliary muscle thickness (CMT) of the amblyopic eye with disabled and enabled accommodation increased by 0.04±0.01 mm (p<0.05) in the anterior part of the ciliary muscle at the levels of CMTmax and CMT1. The data obtained in this study indicate the strong effect of refractive laser surgery in combination with pleoptic treatment on improving the visual acuity and the state of accommodation of the amblyopic and paired dominant eyes in children with hyperopic anisometropia, in contrast to conventional methods of treatment.

Two-Dimensional Peripheral Refraction and Image Quality for Four Types of Refractive Surgeries.

To provide a comprehensive investigation of the optical quality across the visual field for current mainstream types of refractive surgeries. Sixty eyes from 60 adults who received refractive surgery of either femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), Q-value guided customized laser in situ keratomileusis (Q-LASIK), small incision lenticule extraction (SMILE), or Implantable Collamer Lens (ICL) (STAAR Surgical) implantation were included in this study. Refraction and optical aberrations from a visual field of horizontal 60° (from temporal 30° to nasal 30°) and vertical 36° (from superior 20° to inferior 16°) were measured using a custom-made Hartmann-Shack wavefront peripheral sensor. Refractive error, higher order aberrations, point spread function (PSF), and Strehl ratio were compared among these groups prior to and after the surgical procedures, respectively. All types of surgical procedures achieved an almost plano refraction in the central retina. This was also the case in the peripheral retina for the three types of laser refractive surgeries. However, residual peripheral relative hyperopic defocus was observed after ICL implantation. In all groups prior to the surgery, PSFs showed increasing distortion with eccentricity and arrow-like shape pointing toward the central fovea in the periphery in diagonals. Degradation of the PSFs was diminished by all three types of laser refractive surgeries, whereas ICL implantation made the peripheral distortion more prominent. Although ICL implantation produced a similar impact on refractive correction and objective optical quality in the central vision compared with other laser refractive surgeries, its outcome on the peripheral optics is different. The impact of this difference on visual performance deserves notice and warrants further investigation. [J Refract Surg. 2023;39(1):40-47.].

Epithelial cell curette: simple solution to epithelial cell removal from small-incision lenticule extraction pocket or LASIK flap

Epithelial ingrowth is one of the complications associated with refractive laser surgery. Although treatment is relatively simple following laser in situ keratomileusis (LASIK), the inaccessibility of the pocket makes treatment following small-incision lenticule extraction (SMILE) somewhat difficult. An innovative scraping tool that features a biconcave curette tip allows for the manual removal of epithelial cells from the SMILE pocket without flushing or conversion to a flap. The tool can also be used to remove cells from beneath the LASIK flap without performing a complete relift.

Comparison of keratometry using SS-OCT and dual Scheimpflug-Placido imaging in postmyopic corneal refractive surgery eyes.

To compare simulated (SimK) and total (True-K) keratometry and corneal astigmatism values between the IOLMaster 700 (IOLM) and Galilei G4 (G4) devices in postmyopic laser refractive surgery eyes. Methodist Eye Associates, Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas. Retrospective cohort study. A chart review was conducted on patients with prior myopic laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), undergoing phacoemulsification at a single institution from May 2019 through January 2022, who underwent imaging with both the IOLM and G4. Exclusion criteria were prior radial keratotomy, keratoectatic diseases, and inability to obtain a reliable image. Mean, flat, and steep SimK and True-K (TK from the IOLM and TCP IOL from the G4) values and astigmatism magnitude were compared. 50 eyes of 50 patients were included. The mean difference in SimK and True-K between devices (IOLM - G4) was -0.04 (95% CI -0.13 to 0.06; P > .05) diopters (D) and 1.14 (95% CI 1.02 to 1.25; P < .05) D, respectively. The IOLM measured steeper True-K values than the G4. There were no statistically significant differences between devices for all other SimK values, whereas for True-K there were significant differences in flat K and steep K ( P < .05), but not astigmatism magnitude. Despite an overall good correlation in postmyopic laser refractive surgery eyes in keratometry and astigmatism measurements, there is a significant difference in True-K, with the IOLM measuring steeper values by about 1.0 D compared with the G4, similar to prior studies on nonrefractive surgery eyes.

Perception of COVID-19 Pandemic in Refractive Laser Surgery Patients: Cross-Sectional Research

Perception of COVID-19 Pandemic in Refractive Laser Surgery Patients: Cross-Sectional Research

Clinical Evaluation of Corneal Biomechanics following Laser Refractive Surgery in Myopic Eyes: A Review of the Literature.

The role of corneal biomechanics in laser vision correction (LVC) is currently being raised in the assessment of postoperative corneal ectasia risk. The aim of the paper was to evaluate the changes in corneal biomechanics after LVC procedures based on a systematic review of current studies. The results of a search of the literature in the PubMed, Science Direct, Google Scholar, and Web of Science databases were selected for final consideration according to the PRISMA 2020 flow diagram. Included in our review were 17 prospective clinical studies, with at least 6 months of follow-up time. Corneal biomechanical properties were assessed by Ocular Response Analyzer (ORA), or Corvis ST. The results of the study revealed the highest corneal biomechanics reduction after laser in situ keratomileusis (LASIK) followed by small incision lenticule extraction (SMILE) and surface procedures, such as photorefractive keratectomy (PRK) or laser-assisted sub-epithelial keratectomy (LASEK). In SMILE procedure treatment planning, the use of thicker caps preserves the corneal biomechanics. Similarly, reduction of flap thickness in LASIK surgery maintains the corneal biomechanical strength. Future prospective clinical trials with standardization of the study groups and surgical parameters are needed to confirm the results of the current review.

Correlation of internet search enquiries, incidence of ophthalmological diseases and corneal, cataract and refractive surgical procedures

Analysis of internet search queries (ISQ) could be useful to study public interest and medical need for corneal, cataract, and refractive surgery. To date, there are preliminary data on seasonal trends in ophthalmic conditions, but only few studies correlate these data with real data from healthcare systems. The aim of this study is to analyze ISQ and correlate it with real healthcare system data. Data were retrieved from the KBV registry of patients who underwent outpatient ophthalmic surgery in Germany from 2017 to 2019 and from Statista GmbH from 2010 to 2020 for corneal refractive surgery. Time Series analysis of ISQ was analyzed from 2004 to 2020 and correlated with healthcare system data using bivariate correlation analysis. ISQ correlated significantly with the incidence of ophthalmic procedures such as corneal transplantations (r = 0.69, p < 0.05), cataract- (r = 0.59, p < 0.05) and refractive laser surgery (r = 0.83, p < 0.05) in Germany. In addition, specific trends were observed with respect to individual surgical procedures. The correlation between search intensities and surgical procedures varied significantly. Thus, interests in surgical procedures can be tracked by observing changes in ISQ over time. These data correlate with real healthcare data and could be used in the future for now-casting or even forecasting.

The cost of laser refractive surgery and supplementary sulcus lens implantation for pseudophakic ametropiaand astigmatism, the leeds experience.

The cost of laser refractive surgery and supplementary sulcus lens implantation for pseudophakic ametropiaand astigmatism, the leeds experience.

Surface Refractive Surgery Outcomes in Israeli Combat Pilots

Photorefractive keratectomy (PRK) has long been the method of choice for refractive surgery in pilots, and was FDA approved for U.S. Air Force aviators in 2000. We retrospectively reviewed the medical records of 16 male combat pilots (mean age 25.0 ± 5.5 years) who had undergone bilateral laser refractive surgery with surface ablation (alcohol-assisted PRK: 81.25%, transepithelial-PRK: 18.75%), and who had a mean baseline spherical equivalent (SE) of −2.1 ± 0.7 D in the right eye, and −2.0 ± 0.7 D in the left. The mean follow-up was 8.4 ± 6.6 months. On the last visit, the uncorrected visual acuity (UCVA) had improved from 0.75 ± 0.33 logMar to −0.02 ± 0.03 logMar (p &lt; 0.001), and from 0.72 ± 0.36 logMar to −0.02 ± 0.05 logMar (p &lt; 0.001), for the right and left eyes, respectively. The percentages of participants with a right eye UCVA of at least 0.0, −0.08, and −0.18 logMAR (6/6, 6/5, and 6/4 Snellen in meters) were 100%, 37.5%, and 6.2%, respectively, and for the left eye, 93.7%, 43.75%, and 6.2%, respectively. No complications occurred. This is the first study to assess refractive surgery outcomes in a cohort of Israeli combat pilots. Surface refractive surgery effectively improved UCVA and reduced spectacle reliance for the members of this visually demanding profession.

Laser vision correction in glaucoma; myths and reality

AbstractLaser vision correction has been a well‐established, rapidly developing, safe and widely used technique for refractive error correction. Nevertheless, there are several drawbacks for its use in specific groups of patients. A classic contraindication has been patients with glaucoma. These include those with diagnosed glaucoma and even glaucoma suspects. The main concern remains the evaluation of the intraocular pressure (IOP) after refractive surgery. Newer technology has been helpful in achieving accurate IOP measurements bypassing to an extend the biomechanical changes and thinning of the cornea induced by laser correction. Use of conversion factors may well be applied. Perioperative care of these patients has also been an issue as corticosteroids drops are used, sometimes for a prolonged period of time potentially causing a rise in IOP. Choosing between superficial techniques and LASIK, the former inducing high intraocular pressure during flap dissection is also a question to be answered. In addition, following up those patients to assess possible glaucoma progression can be challenging. Thorough preoperative assessment is mandatory with functional and anatomical testing of the optic nerve. This is especially important so new glaucoma disease is not missed especially in high myopes. Last but not least patients on glaucoma treatment usually have a compromised ocular surface due to the long‐term effects of topical drops. This fact has to be taken into consideration when deciding to proceed or not with laser refractive surgery. In conclusion the glaucoma patient and the glaucoma suspect are challenging patients regarding the potential laser vision correction. Several factors need to be considered in order to make the correct decision. So, myths andreality are analysed that either defeat or support the argument that under the laser vision correction can be safely performed in carefully selected glaucoma eyes.