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.

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

Introduction: Corneal ectasia leads to progressive irregular corneal curvature and reduced visual acuity. Objective: To assess the safety and effectiveness of corneal collagen cross-linking (CXL) for managing corneal ectasia resulting from refractive laser surgery (RSL). Methods: 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). Results: 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. Conclusion: CXL is a safe and effective technique for managing corneal ectasia after RLS.

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

Comparing high and low energy outcomes on day one for SmartSight myopic-astigmatism treatments with the SCHWIND ATOS: a retrospective case series.

BACKGROUND: Impact of low energy asymmetric spacings vs. high energy symmetric spacings on the immediate/early (postoperative day 1 (POD1)) outcomes of SmartSight lenticule extraction for myopic astigmatism with a new femtosecond laser system. METHODS: The first 112 eyes of 56 patients consecutively treated using low energy asymmetric spacings (Group A; Study group) were compared at POD1 to the last 112 eyes of 56 patients consecutively treated using high energy symmetric spacings (Group S; Controls). Mean age of the patients was 28 ± 5 years with a mean spherical equivalent of -4.41 ± 1.76 diopters (D) and a mean magnitude of refractive astigmatism of 0.89 ± 0.82 D. RESULTS: Laser Energy was -25 ± 1nJ lower for asymmetric treatments (p < .0001); Spot and Track distances were + 0.7 ± 0.1 µm larger and -0.8 ± 0.1 µm tighter for asymmetric treatments, respectively (p < .0001 for both). At POD1, astigmatism was -0.08 ± 0.02D lower for asymmetric treatments (p < .0003); uncorrected and corrected visual acuities (UDVA and CDVA, respectively) were -0.03 ± 0.01logMAR better for asymmetric treatments (p < .0007); differences between postop UDVA and preop CDVA along with change in CDVA were + 0.3 ± 0.1lines better for asymmetric treatments (p < .0003). CONCLUSIONS: Lenticule extraction treatment using SmartSight is safe and efficacious already at POD1. Findings suggest that low energy asymmetric spacings may further improve the immediate and short-term outcomes of SmartSight lenticule extraction in the treatment of myopic astigmatism compared to conventional settings (high energy symmetric spacings).

Refractive errors among medical students in Jordan: prevalence, types and possible risk factors.

Aim: This study aims to determine the prevalence of refractive errors among medical students in Jordan. Materials & methods: Cross-sectional model through an online questionnaire was conducted. The questionnaire was distributed randomly to 700 medical students. Results: Females participated more than males. It was revealed that 525 (75%) of the total students were found to have a refractive error. Myopia was the most common type. About 79.0% of students have a positive family history of refractive errors which was more significant in students with refractive errors. Spectacles were the most common used method of treatment. Conclusion: The prevalence of refractive errors was high among medical students in Jordan. A positive family history was associated with students having refractive errors.

Many reports have studied refractive errors and their risk factors in different groups and ethnicities. Also, types of refractive errors were found to have a different prevalence in different age groups. Whilst refractive errors in medical students have been studied in many countries, the prevalence of refractive errors has never been studied in Jordanian medical students before. In this study, we found that myopia (with or without astigmatism) was the most common type of refractive error in medical students.

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

PURPOSE: To evaluate the safety and efficacy of epithelium-off (epi­off) corneal cross-linking (CXL) in patients with post-LASIK corneal ectasia (PLE) SETTING: Private clinical practice DESIGN: Prospective clinical trial METHODS: 82 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 epi­off 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. RESULTS: Over 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). CONCLUSIONS: CXL 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 epi­off CXL once progression is established.

Comparison between the CASIA SS-1000 and Pentacam in measuring corneal curvatures and corneal thickness maps.

PURPOSE: To compare the intra-device repeatability and inter-device reproducibility between two anterior segment imaging instruments, the CASIA SS-1000 (Tomey Corp., Nagoya, Japan) and Pentacam (OCULUS, Arlington, WA) in measuring anterior segment parameters. METHODS: Single-center, prospective clinical trial. Participants ≥20 years of age were included. One eye was randomly selected, each imaged by three CASIA SS-1000 devices and three Pentacam devices by three different examiners. Each photographer operated a pair of devices, one CASIA SS-1000 and one Pentacam. The image order for each participant was determined by a random permutation table. Three images were taken from each device. A total of 18 images were taken for each eye. Ratios of the standard deviations, referenced as (CASIA/Pentacam), were calculated to compare the repeatability and reproducibility of the two imaging instruments. RESULTS: In all, 66 participants with a mean age of 46.4 years (±21.7) were enrolled in the study. All repeatability ratios and intra-device variability were less than 1 (anterior corneal curvature: flat = 0.86, steep = 0.85; posterior corneal curvature: flat = 0.43, steep = 0.61; and map: thinnest = 0.22; central = 0.24, 2 mm = 0.26, 4 mm = 0.27, and 6 mm = 0.30). All reproducibility ratios, which measure the inter-device variability, were less than 1 (anterior corneal curvature: flat = 0.58, steep = 0.73; posterior corneal curvature: flat = 0.25, steep = 0.31; and pachymetry map: thinnest = 0.20; central = 0.20; 2 mm = 0.20; 4 mm = 0.19; and 6 mm = 0.22). A ratio of less than 1 indicates that the CASIA SS-1000 has more consistent measurements. CONCLUSIONS: The CASIA SS-1000 was found to have better repeatability and reproducibility compared to the Pentacam for both corneal curvature and pachymetry maps. This greater consistency may require further study to determine whether the decreased variability can be translated into improved clinical results.

Clinical Ocular Biomechanics: Where Are We after 20 Years of Progress?

Purpose: Ocular biomechanics is an assessment of the response of the structures of the eye to forces that may lead to disease development and progression, or influence the response to surgical intervention. The goals of this review are (1) to introduce basic biomechanical principles and terminology, (2) to provide perspective on the progress made in the clinical study and assessment of ocular biomechanics, and (3) to highlight critical studies conducted in keratoconus, laser refractive surgery, and glaucoma in order to aid interpretation of biomechanical parameters in the laboratory and in the clinic.Methods: A literature review was first conducted of basic biomechanical studies related to ocular tissue. The subsequent review of ocular biomechanical studies was limited to those focusing on keratoconus, laser refractive surgery, or glaucoma using the only two commercially available devices that allow rapid assessment of biomechanical response in the clinic.Results: Foundational studies on ocular biomechanics used a combination of computer modeling and destructive forces on ex-vivo tissues. The knowledge gained from these studies could not be directly translated to clinical research and practice until the introduction of non-contact tonometers that quantified the deformation response of the cornea to an air puff, which represents a non-destructive, clinically appropriate load. The corneal response includes a contribution from the sclera which may limit corneal deformation. Two commercial devices are available, the Ocular Response Analyzer which produces viscoelastic parameters with a customized load for each eye, and the Corvis ST which produces elastic parameters with a consistent load for every eye. Neither device produces the classic biomechanical properties reported in basic studies, but rather biomechanical deformation response parameters which require careful interpretation.Conclusions: Research using clinical tools has enriched our understanding of how ocular disease alters ocular biomechanics, as well as how ocular biomechanics may influence the pathophysiology of ocular disease and response to surgical intervention.

Advanced Optical Wavefront Technologies to Improve Patient Quality of Vision and Meet Clinical Requests.

Adaptive optics (AO) is employed for the continuous measurement and correction of ocular aberrations. Human eye refractive errors (lower-order aberrations such as myopia and astigmatism) are corrected with contact lenses and excimer laser surgery. Under twilight vision conditions, when the pupil of the human eye dilates to 5-7 mm in diameter, higher-order aberrations affect the visual acuity. The combined use of wavefront (WF) technology and AO systems allows the pre-operative evaluation of refractive surgical procedures to compensate for the higher-order optical aberrations of the human eye, guiding the surgeon in choosing the procedure parameters. Here, we report a brief history of AO, starting from the description of the Shack-Hartmann method, which allowed the first in vivo measurement of the eye's wave aberration, the wavefront sensing technologies (WSTs), and their principles. Then, the limitations of the ocular wavefront ascribed to the IOL polymeric materials and design, as well as future perspectives on improving patient vision quality and meeting clinical requests, are described.

Outcomes and eye care knowledge in rhegmatogenous retinal detachment patients with a history of laser refractive surgery for myopia.

Purpose: To investigate the surgical outcomes and eye care knowledge of patients with rhegmatogenous retinal detachment (RRD) who had previously undergone laser refractive surgery (LRS) for myopia in a myopia epidemic area. Methods: This retrospective study included patients with primary RRD who underwent surgery and had a history of LRS for myopia at a tertiary medical center. Data were reviewed from medical charts to analyse the surgical outcomes. Questions about eye care knowledge and attitude toward myopia and LRS were obtained. Results: A total of 774 patients underwent RRD surgery, among whom 341 (44%) had myopia > -3 dioptres, 66% of whom had high myopia. Thirty eyes of 26 patients had a history of LRS for myopia. The mean age of patients with a history of LRS was significantly lower than that of those without a history of LRS (45.7 ± 2.9 years vs. 53.8 ± 1.0, p < 0.001). The mean pre-LRS spherical equivalent was -8.66 ± 0.92 (range: -3.00--12.00) dioptres. In more than half the patients (n = 15, 57.7%), the interval between LRS and RRD was more than 10 years. The primary retinal reattachment rate was only 60%, whereas the final retinal reattachment rate was 93%. The mean final visual acuity (VA) improved from a 20/286 to 20/105 (p = 0.006). Linear mixed model analysis showed factors of male sex and macular detachment were significant with poor visual outcome (p = 0.046 and 0.008) Eye care knowledge obtained from the 19 RRD patients with history of LRS, 47% of patients (9/19) mistakenly thought that LRS could cure myopia and its complications, and 63% of patients were less willing to visit an ophthalmologist because uncorrected VA improvement after LRS. Eighty-four percent thought that proper knowledge and more education about LRS and myopia for the public are important. Conclusion: In the RRD patients with a history of LRS for myopia, their age was relative younger. Male sex and macular detachment were associated with poor visual outcome. More education with proper knowledge of LRS, myopia and RRD is recommended for the patients to prevent or early detect the occurrence of RRD.

Effectiveness of Laser Refractive Surgery to Address Anisometropic Amblyogenic Refractive Error in Children: A Report by the American Academy of Ophthalmology.

PURPOSE: To review the published literature assessing the safety and effectiveness of laser refractive surgery to treat anisometropic amblyogenic refractive error in children aged ≤ 18 years. METHODS: A literature search of the PubMed database was conducted in October 2021 with no date limitations and restricted to publications in English. The search yielded 137 articles, 69 of which were reviewed in full text. Eleven articles met the criteria for inclusion and were assigned a level of evidence rating. RESULTS: The 11 included articles were all level III evidence and consisted of 1 case-control study and 10 case series. Six studies used laser-assisted in situ keratomileusis (LASIK), 1 used photorefractive keratectomy (PRK), 1 used refractive lenticule extraction/small incision lenticule extraction, and the rest used a combination of LASIK, PRK, laser epithelial keratomileusis (LASEK), or refractive lenticule extraction/small incision lenticule extraction. Five studies enrolled patients with anisometropic myopia, 2 studies enrolled patients with anisometropic hyperopia, and the remainder were mixed. Although all studies demonstrated an improvement in best-corrected visual acuity (BCVA), the magnitude of improvement varied widely. As study parameters varied, a successful outcome was defined as residual refractive error of 1 diopter (D) or less of the target refraction because this was the most commonly used metric. Successful outcomes ranged between 38% and 87%, with a mean follow-up ranging from 4 months to 7 years. Despite this wide range, all studies demonstrated an improvement in the magnitude of anisometropia. Regression in refractive error occurred more frequently and to a greater degree in myopic eyes and eyes with longer follow-up, and in younger patients. Although one study reported 2 free flaps, most studies reported no serious adverse events. The most common complications were corneal haze and striae. CONCLUSIONS: Findings from included studies suggest that laser refractive surgery may address amblyogenic refractive error in children and that it appears to decrease anisometropia. However, the evidence for improvement in amblyopia is unclear and long-term safety data are lacking. Long-term data and well-designed clinical studies that use newer refractive technologies in standardized patient populations would help address the role of refractive surgery in children and its potential impact on amblyopia.

Computational study for temperature distribution in ArF excimer laser corneal refractive surgeries using different beam delivery techniques.

Refractive errors are the most common causes of vision impairment worldwide and laser refractive surgery is one of the most frequently performed ocular surgeries. Clinical studies have reported that approximately 10.5% of patients need an additional procedure after the surgery. The major complications of laser surgery are over/under correction and dry eye. An increase in temperature may be a cause for these complications. The purpose of this study was to estimate the increase in temperature during laser refractive surgery and its relationship with the complications observed for different surgical techniques. In this paper, a finite element model was applied to investigate the temperature distribution of the cornea when subjected to ArF excimer laser at a single spot using various beam delivery systems (broad beam, scanning slit, and flying spot). The Pennes bio-heat equation was used to predict the temperature values at different laser pulse energies and frequencies. The maximum temperature increase by ArF laser ([Formula: see text] frequency and [Formula: see text] pulse energy) at a single spot was [Formula: see text] for [Formula: see text] diopter correction ([Formula: see text] of ablation of corneal stroma) using broad beam, scanning slit, and flying spot beam delivery approaches respectively. The peak temperature due to a single pulse was estimated to be [Formula: see text]. Although the peak temperature (sufficient energy to break intermolecular bonds) exists for a very short time ([Formula: see text]) compared to the thermal relaxation time ([Formula: see text]), there is some thermal energy exchange between corneal tissues during a laser refractive surgery. Heating may cause collagen denaturation, collagen shrinkage, and more evaporation and hence proposed to be a risk factor for over/under correction and dry eye.

Resultados refractivos y visuales en pacientes operados de miopía con técnicas de superficies / Refractive and visual results in patients operated on for myopia with surface techniques

Objetivo: Comparar los resultados visuales y refractivos pre- y posoperatorios en pacientes miopes operados con técnicas de superficie y perfil de ablación asférico. Métodos: Se realizó un estudio experimental controlado aleatorizado abierto, tipo de equivalencia y no inferioridad, en 160 pacientes (320 ojos). En el estudio se formaron dos grupos: el primero quedó constituido por 80 pacientes (160 ojos), a quienes se les realizó queratectomía fotorrefractiva más mitomicina C, y el segundo fue conformado por 80 pacientes (160 ojos), a quienes se les realizó LASEK más mitomicina C. Resultados: Predominaron en ambos grupos las mujeres con miopía leve y edades entre 21 y 29 años. A los tres meses el grupo queratectomía fotorrefractiva más mitomicina C tenía agudeza visual sin corrección de 0,97 ± 0,09; esfera 0,003 ± 0,21; cilindro -0,09 ± 0,30 y equivalente esférico -0,04 ± 0,23. En el grupo LASEK más mitomicina C, la agudeza visual sin corrección fue de 0,96 ± 0,11; la esfera -0,007 ± 0,24; el cilindro -0,08 ± 0,25 y el equivalente esférico -0,06 ± 0,26. Conclusión: Ambas técnicas quirúrgicas mejoraron significativamente los resultados refractivos y visuales, pero no hubo diferencia entre ellas(AU)

Objective: Compare the pre- and postoperative visual and refractive results in myopic patients operated with surface techniques and aspheric ablation profile. Methods: An open randomized controlled experimental study, equivalence and non-inferiority type was carried out in 160 patients (320 eyes). In the study, two groups were formed: the first group was made up of 80 patients (160 eyes), who underwent Photorefractive keratectomy - mitomycin C, and the second group made up of 80 patients (160 eyes), underwent LASEK - mitomycin C. Results: Women with mild myopia and ages between 21 and 29 years old predominated in both groups. At three months, the Photorefractive keratectomy - mitomycin C group had AVSC 0.97 ± 0.09; sphere 0.003 ± 0.21; cylinder -0.09 ± 0.30 and spherical equivalent -0.04 ± 0, 2. 3. In the Photorefractive keratectomy - mitomycin C group, AVSC 0.96 ± 0.11; sphere -0.007 ± 0.24; cylinder -0.08 ± 0.25 and spherical equivalent -0.06 ± 0.26. Conclusion: Both surgical techniques improved significantly refractive and visual results, but there was no difference between them(AU)

Aberrometric, Keratometric, and Visual Outcomes After Trans-Epithelial Topography-Guided Phototherapeutic Keratectomy for the Treatment of Irregular Corneas.

PURPOSE: To assess the safety, aberrometric and keratometric changes, and stability of trans-epithelial topography-guided phototherapeutic keratectomy (TE-TG-PTK) with mitomycin C (MMC) using the ALLEGRO Topolyzer platform for the treatment of irregular astigmatism. METHODS: This is a retrospective case series including 57 eyes that underwent TE-TG-PTK + MMC using the ALLEGRO Topolyzer platform for the treatment of irregular astigmatism. CDVA, manifest refraction (MR), keratometry readings, and aberrometry readings were analyzed at 1, 3, 6, and 12 months. RESULTS: Causes of corneal irregularity included non-infectious leucoma (n=23), infectious leucoma (n=7), adenoviral keratitis (n=20), corneal haze (n=2), post-penetrant keratoplasty (PKP) (n=1), and others (n=4). Overall, 76% of the eyes (n=40) gained lines of vision; patients gained 1, and 2 or more lines of vision in 76%, and 38% of cases, respectively. Only 1 patient (2%) lost 5 lines of vision. Mean preoperative CDVA (LogMAR) was 0.37 ±0.31 and improved to 0.14 ±0.18 (p<0.001) at final follow-up (12 months). CDVA remained unchanged in 10 eyes (21%). No significant changes were observed in mean keratometry (Kmean) and keratometric astigmatism readings. Regarding aberrometry, only changes in coma proved to be significant 6 months after surgery (P<0.01). No intraoperative/postoperative complications were reported. CONCLUSION: At final follow-up, significant improvements were observed in CDVA and coma. TE-TG-PTK + MMC proved to be an effective and safe procedure for the treatment of corneal irregular astigmatism due to several causes.

Risk Factors for the Structural Progression of Myopic Glaucomatous Eyes with a History of Laser Refractive Surgery.

As laser refractive surgeries (LRS) have been widely performed to correct myopia, ophthalmologists easily encounter patients with glaucoma who have a history of LRS. It is well known that intraocular pressure (IOP) in eyes with glaucoma is not accurate when measured using Goldmann applanation tonometry. However, risk factors for glaucoma progression, particularly those associated with measured IOP, have rarely been studied. We analysed data for 40 patients with a history of LRS and 50 age-matched patients without a history of LRS. Structural progression was defined as significant changes in thickness in the peripapillary retinal nerve fibre layer as identified using optical coherence tomography event-based guided progression analysis. Risk factors were determined via Cox regression analysis. Disc haemorrhage (DH) was associated with glaucoma progression in both the non-LRS group and LRS group (hazard ratio (HR): 4.650, p = 0.012 and HR: 8.666, p = 0.019, respectively). However, IOP fluctuation was associated with glaucoma progression only in the LRS group (HR: 1.452, p = 0.023). Our results show that DH was a significant sign of progression in myopic glaucoma eyes. When treating patients with myopia and glaucoma, IOP fluctuation should be monitored more carefully, even if IOP seems to be well controlled.

Item banks for measurement of refractive error-specific quality of life.

PURPOSE: To evaluate the psychometric properties of refractive error-specific quality of life (QoL) item banks and assess their performance using computerised adaptive testing (CAT) simulations. METHODS: In this cross-sectional study a 392-item questionnaire, grouped under 11 QoL domains, was interviewer-administered to 305 people with refractive error [mean age ± S.D., 30.5 ± 14.1 (range (18 to 83) years; male, 50.5%; mean ± S.D. spherical equivalent refractive error -2.4 ± 2.9 (range: -15.0 to +11.0) Dioptres; spectacles (n = 257), contact lens (n = 37), refractive surgery (n = 25), uncorrected refractive error (n = 57)]. Rasch analysis was conducted on each QoL domain using the Andrich rating scale model to investigate parameters including response category functioning, person- and item-reliability, infit and outfit statistics, unidimensionality, targeting, differential item functioning and local item dependency. The resulting item banks underwent CAT simulations in 1,000 cases with 'high' and 'moderate' precision stopping rules. RESULTS: Rasch analysis iterations resulted in 13 refractive error-specific item banks (Convenience, Health concerns, Economic, Activity limitation, Mobility, Emotional, Social, Visual symptoms frequency, Visual symptoms severity, Visual symptoms bothersome, Comfort symptoms frequency, Comfort symptoms severity and Comfort symptoms bothersome), containing a total of 366 items. The item banks had good psychometric properties including satisfactory measurement precision, infit and outfit statistics and unidimensionality. In CAT simulations, the mean number of items required to achieve high and moderate measurement precision was 9.4 and 4.7, respectively. CONCLUSION: Overall, refractive error-specific QoL item banks show promise in their ability to comprehensively and precisely evaluate a range of quality of life parameters. These items banks when administered using a CAT system offer unique outcome tools for implementation in clinical trials, healthcare and research.

The Impact of Image Registration for Ablation Orientation on Clinical Outcomes After Wavefront-Optimized Refractive Surgery in Eyes with Myopia and Astigmatism.

PURPOSE: To compare the clinical outcomes from laser refractive surgery performed with the same laser with and without incorporating iris registration technology to compensate for ocular cyclotorsion. DESIGN: Single-site, two-arm, retrospective chart review. METHODS: Clinical outcomes at a single site after wavefront-optimized LASIK using the Wavelight excimer laser with and without the Vario imaging system for iris registration (IR) were evaluated. Eligible subjects were those that received on-label wavefront-optimized treatment of myopia with astigmatism >1.5 D. Measures of interest were the amount of residual refractive cylinder after surgery, the refractive error, and the best-corrected (BCVA) and uncorrected (UCVA) visual acuities, with a target follow-up of around 90 days. RESULTS: A total of 112 eligible eyes that were treated with IR and 126 similar eyes treated without IR (NO IR) were included. The refractive sphere and spherical equivalent refractions were statistically significantly different between groups (p < 0.05), but the mean differences were <0.1 D in both cases. Refractive cylinder averaged around 0.12 D and was not statistically significantly different between groups. The number of eyes with residual cylinder >0.50 D was higher in the NO IR group vs the IR group (6% vs 1%, respectively, p = 0.04). The mean logMAR UCVA and BCVA were statistically significantly better in the IR group, with a difference of 1.5 letters for UCVA and 1.0 letters for BCVA (p < 0.001 for both). Significantly more eyes in the IR group had a UCVA (p = 0.01) and a BCVA of 20/15 or better (p = 0.003). Overall, 96% of eyes in the IR group and 91% of eyes in the NO IR group had uncorrected visual acuity of 20/20 or better. CONCLUSION: Iris registration with the VARIO imaging device demonstrably reduced the overall variability in clinical outcomes.

Clinical Outcomes After Topography-Guided Refractive Surgery in Eyes with Myopia and Astigmatism - Comparing Results with New Planning Software to Those Obtained Using the Manifest Refraction.

PURPOSE: To compare clinical outcomes from topography-guided laser refractive surgery based on new planning software to outcomes based on using the manifest refraction. DESIGN: Single site, two-arm, retrospective chart review. METHODS: Clinical outcomes at a single site after topography-guided LASIK using the Wavelight excimer laser were evaluated, with a target postoperative follow-up time of 90 days. Eligible eyes were those that received on-label topography-guided treatment of myopia or myopic astigmatism with correction based on either the manifest refraction or results from the Phorcides Analytical Engine (PAE). Measures analyzed included the uncorrected (UDVA) and best-corrected (CDVA) distance visual acuity, the magnitude of refractive cylinder after surgery, the refractive error and changes from preoperative CDVA. RESULTS: The study included 115 eyes in the PAE group and 133 eyes in the Manifest group. Significantly more eyes in the PAE group had a CDVA of 20/15 or better (p = 0.05) and a UDVA of 20/15 or better (p = 0.05). Significantly more eyes in the Manifest group had a UDVA of 20/25 or worse (13/133 vs 1/115 in the PAE group, p = 0.002). There were significantly more eyes in the PAE group with no postoperative refractive cylinder (90% vs 77% in the Manifest group, p = 0.004). No eye in either group had a postoperative CDVA a line or worse than their preoperative CDVA. Three eyes in the Manifest group and no PAE eyes have had subsequent enhancement surgery. CONCLUSION: Mean results for postoperative refractive astigmatism, CDVA and UDVA were similar between the groups, but the clinical outcomes for the PAE group appeared less variable, with more eyes having no refractive astigmatism and a higher percentage of eyes having 20/15 or better CDVA and UCVA. The objective nature of the PAE is an advantage.

Refractive surgery with simultaneous collagen cross-linking for borderline corneas - A review of different techniques, their protocols and clinical outcomes.

Simultaneous corneal cross-linking (CXL) has been proposed as an adjunct therapy to corneal refractive procedures to prevent future ectasia, especially when performed in borderline corneas. This review analyses the currently available literature (minimum follow-up 6 months) on corneal refractive surgery and simultaneous CXL (PRK Xtra, LASIK Xtra, and SMILE Xtra) to evaluate the overall results including the safety, efficacy, and potential complications associated with these procedures. A comprehensive literature search of various electronic databases (PubMed, PubMed Central, Cochrane database, and MEDLINE) was performed up to 20th May 2020. Four relevant studies were found for PRK Xtra, 12 for LASIK Xtra, and 3 for SMILE Xtra. The total number of eyes included in this review was 1,512: 294 for PRK Xtra, 221 for PRK-only, 446 eyes for LASIK Xtra, 398 eyes for LASIK-only, 91 for SMILE Xtra and 62 for SMILE-only. Current literature suggests that refractive surgery and simultaneous CXL is generally safe and delivers comparable results in terms of visual and refractive outcomes than refractive surgery alone. However, there is no consensus on a standard cross-linking protocol, and complications such as diffuse lamellar keratitis, central toxic keratopathy, and corneal ectasia following Xtra procedures have been reported. It is therefore suggested that surgeons exercise caution in case-selection and counsel their patients regarding the potential risks and benefits with Xtra procedures. Also, further studies are required to standardize the UV-A irradiation protocols and to evaluate the long-term effect on safety, refractive predictability, and stability of these procedures.