Lens Fitting Research Articles

To assess the feasibility of a novel method for simulating a Rigid Gas Permeable Contact Lenses (RGP-CL) fitting using 3-D printed sclero-corneal surfaces (SCSs). The experiment involved the fabrication of two resin SCSs with biconic corneal geometry and the participation of 22 optician-optometrists as observers. Participants compared the fluorescein patterns of three RGP-CL fitted on each SCS with theoretical patterns generated through computer simulation. To standardize visualization, comparisons were conducted through a multiple-choice questionnaire composed of 6 questions. Each question presented one main fluorescein pattern (either theoretical or experimental) and four additional patterns obtained using the other technique. Optometrists were required to select the fluorescein pattern more similar to the main pattern. A statistical analysis was performed to evaluate the accuracy of the comparison between the two methods. The surface quality of the printed SCSs was sufficient to produce consistent and interpretable fluorescein patterns. In all questions, at least 70 % of optometrists selected the correct pattern. In four questions, more than 90 % identified the correct pattern, and in one question accuracy reached 100 %. The correct option was always the most frequently chosen, with a significantly higher rate than the second most selected option (p = 0.05). The ability of most optometrists to correctly identify patterns suggests that, even without polishing, 3-D printed SCSs can simulate fluorescein patterns closely resembling theoretical ones. This approach shows promise as a supportive tool for training in RGP-CL fitting.

Standardized evaluation of orthokeratology lens fitting status assisted by deep learning algorithm.

Pellucid marginal degeneration (PMD) is a bilateral, peripheral corneal ectasia characterized by inferior corneal thinning and subsequent irregular astigmatism, often leading to poor visual outcomes with glasses or traditional contact lenses. This case report presents a 45-year-old female previously misdiagnosed with keratoconus and advised to consider corneal transplantation due to poor visual acuity and intolerance to earlier contact lens fittings. Comprehensive examination revealed PMD, and the patient was successfully fitted with Onefit scleral contact lenses. The lenses provided significant improvement in both vision and comfort, enhancing her quality of life and eliminating the need for surgical intervention. This case highlights the importance of accurate diagnosis and the efficacy of scleral lenses, particularly the Onefit design, in managing moderate to advanced PMD cases.

Compare of the scleral morphology between healthy populations and keratoconus patients using optical coherence tomography.

Abstract: PURPOSE: Spectacles are a popular method for correcting refractive errors and provide optimal visual acuity for most wearers. However, spectacle intolerance remains a significant challenge in vision correction. The aim of this study is to identify the common causes of spectacle intolerance in Saudi wearers. METHODS: This cross-sectional, multi-optical center study was conducted across various regions of Saudi Arabia between August 2023 and April 2024. It included spectacle wearers aged 3–80 years who returned their new spectacles due to intolerance or discomfort. Spectacle prescriptions were compared to the dispensed lenses, and any discrepancies were corrected. Refraction was rechecked when necessary. RESULTS: The prevalence of spectacle intolerance was 3% of 101 participants who did not tolerate or found their new spectacles uncomfortable, with a mean age of 33.4 ± 15.3 years. The most common reasons for spectacle intolerances were incorrect prescription (38.6%), decentered lenses (21%), adaptation difficulties (20.8%), improper fitting of lenses compared to the prescribed ones (9.9%), and nonprescription-related issues: misunderstanding use of spectacle, antireflection coatings, frame fashion, material, tint problem, and hard coating (3%–15.9%). The most predominant refractive prescription was myopic astigmatism (44%), presbyopia (24%), and myopia (16%). CONCLUSION: The prevalence of spectacle intolerance in Saudi Arabia was 3%. The study found that myopic astigmatism, presbyopia, and myopia were the most frequently spectacle intolerances. The main reasons for spectacle intolerances were incorrect prescription, decentered lenses, adaptation difficulties, and improper fitting of lenses. Age and gender had no effect on spectacle intolerance.

This case series reports two cases of scleral lens (SL)-associated suture erosion of polytetrafluoroethylene CV-8 (Gore-Tex, Newark, DE) in scleral-sutured CZ70BD (Alcon, Fort Worth, TX) posterior chamber intraocular lens (SS-PCIOL). Suture erosion after SS-PCIOL has been reported in two of the patients who were fitted with SL for visual acuity improvement. Erosion was corrected in both cases with suture repositioning and corneal patch graft, with one patient requiring the exchange of the intraocular lens. The other patient was able to transition to an SL of a different size parameter. Scleral lens fitting should consider the position of haptic placement in relation to the suture site and be monitored for suture erosion postoperatively. A scleral flap or corneal tissue patch graft may be needed for patients who have scleral thinning from prior surgery.

To analyse the associations between ocular surface shape parameters and soft contact lens fitting. A total of 106 eyes of 53 participants (53 right and 53 left eyes) fitted with standard silicone hydrogel soft lenses were analysed retrospectively. The sagittal height of the lenses was obtained from an independent publication. The lens fit was analysed objectively with proprietary software and corneo-scleral parameters were obtained with the Eye Surface Profiler. The relationship between the sagittal height of the eye (OC-SAG) and the lens (CL-SAG) was defined as the delta-sag (δ-sag) and characterised for this group. The OC-SAG and δ-sag were in the range of 3600 and 400 μm, respectively, with no statistically significant differences between the right and left eyes. There were statistically significant differences between the corneoscleral junction (CSJ) angle of the right and left eyes (p = 0.002). The nasal portion showed the sharpest transition in both eyes and was significantly different between the right and left eyes only in that specific quadrant (p < 0.001). The peripheral cornea (α) was steeper with a mean value around 38°. The proximal sclera (β) showed a flatter slope close to 36° in both eyes. Following the pattern of the CSJ angle, there were statistically significant differences only between the nasal-α of the right and left eyes (p < 0.001). There were no significant correlations between the δ-sag and the lens fitting features in either eye (p > 0.05). Some moderate and strong associations between the lens fit and peripheral ocular parameters were found, although they were not consistent between the right and left eyes. Soft contact lens movement seems to be influenced by the corneo-scleral transition at the superior and inferior quadrants. It would be better to focus on the slopes in these peripheral areas rather than the central corneal parameters or the sagittal height.

To discuss the results of scleral contact lens fit in patients with difficult corneal and ocular surface pathologies. This single-center, retrospective case-series included 49 eyes of 34 patients who underwent scleral lens fitting for visual acuity improvement from February 2018 to 2023. All patients underwent Orbscan/Pentacam corneal topography before a complete ophthalmological exam. The first trial lens was chosen according to manufacturer guidelines and topographic parameters. Best corrected Snellen visual acuity was assessed with spectacles before fit and over-refraction after fit and converted to logarithm of the minimum angle of resolution (logMAR). The vault was evaluated both at the slit-lamp and with anterior segment optic coherence tomography when possible. Twenty-one patients (61.8%) were male and the mean age was 37.4±14.8 years (range: 12-71). Twenty-three eyes (46.9%) had keratoconus, 11 eyes (22.4%) had refractive error after penetrating keratoplasty, 7 eyes (14.3%) had irregular astigmatism due to corneal scar, 4 eyes (8.2%) had advanced stage Steven-Johnson syndrome, 2 eyes (4.1%) had corneal perforation repair, and 2 eyes (4.1%) had severe dry eye. The appropriate lens was determined after 3.7±1.9 trials (range: 1-8 trials.) Although five patients refused scleral contact lenses due to cost, lenses were successfully fitted and used in 39 eyes of 29 patients. The mean daily wear time was 9.3±4.5 hours (range: 2-16) and mean follow-up was 52±49 months (range: 12-180). Mean uncorrected logMAR visual acuity and mean spectacle-corrected logMAR visual acuity was 1.09±0.47 and 0.67±0.50, which improved significantly to 0.13±0.20 after scleral contact lens fitting. Scleral lens fit is a time-consuming practice for the ophthalmologist and an intimidating task for the patient. However, in addition to their good optical results, they provide very good comfort and stability. Although the large diameter may seem like the major disadvantage during scleral lens trial, the cost becomes more of an issue in developing countries.

Comparison of myopia control efficacy and retinal defocus in adolescents with moderate to high myopia when wearing aspheric lenses with different back optic zone diameters.

PurposeTo evaluate the availability and utilization of the advanced equipment for the diagnosis and management of early keratoconus in the public and private healthcare facilities in Nyanza and Western Kenya.MethodsA cross-sectional study design was applied. An online questionnaire was sent to the eyecare practitioners. Data on socio-demographics, equipment availability, and utilization for early keratoconus diagnosis and management were obtained and analyzed using SPSS V 29.ResultsA total of 134 eyecare practitioners (out of 143), with the majority 80 (59.7%) being males, responded to the questionnaire. The study found that advanced equipment were scarcely available, such as Tomographer 14 (10.4%), Topographer 17 (12.7%) and Pachymeter 21 (15.7%) as compared to basic equipment: distance VA chart 134 (100%), trial lens/phoropter 129 (96.3%), retinoscope 128 (95.5%) and slit-lamp 111 (82.8%), with level 6 having the highest availability. Additionally, the available advanced equipment had working conditions far below standards and below standards: topographer 6 (35.2%) and contact lens fitting set 12 (46.1%). The utilization rates of the advanced equipment were low as follows: contact lens fitting set 8 (31.0%), pachymeter 11 (52.4%) and topographer 9 (52.9%). A chi-square test found a significant association between equipment availability and their utilization, VA chart (p=0.03333), trial lens/phoropter (p=0.00292), slit-lamp (p=0.00283) and keratometer (p=0.00001).ConclusionThe study revealed a lack of advanced diagnostic equipment, with some existing tools falling below standard and underutilized. It recommends that healthcare institutions prioritize the acquisition and maintenance of essential equipment. Additionally, the Ministry of Health should collaborate with stakeholders to incorporate early keratoconus detection into national eyecare guidelines.

The purpose of this study was to develop a standardized artificial intelligence (AI) system integrating corneal topography images and numerical parameters for optimizing orthokeratology (OK) lens fitting. Retrospective data from 1153 patients (2341 eyes) with Euclid OK lenses were analyzed. Five hundred nineteen eyes (393 patients) with treatment zone decentration ≤1 mm were included for model training. A device-agnostic corneal topography reconstruction pipeline generated standardized tangential curvature maps. A hybrid model combined deep learning (ResNet for image features) and machine learning (using numerical parameters) to predict alignment curve (AC) and cylinder power (CP), with numerical regression for AC and classification regression for CP. Multitask learning addressed AC-CP biomechanical coupling. Numerical parameter-based models achieved optimal axial AC prediction (mean absolute error [MAE] = 0.290, R2 = 0.917), and CP prediction (accuracy [ACC] = 0.798, area under the curve [AUC] = 0.791). The image-based deep learning model using baseline corneal topography alone attained acceptable AC prediction (MAE = 0.248, R2 = 0.850), yet demonstrated suboptimal CP classification accuracy (ACC = 0.674, AUC = 0.621). Hybrid modeling achieved breakthrough performance in AC prediction (MAE = 0.136, R2 = 0.973) and superior CP classification (ACC = 0.898, AUC = 0.896). This system standardizes corneal topography across devices, addressing a critical barrier to generalizability in existing AI models, significantly enhancing fitting precision and generalizability for myopia control applications. The device-agnostic design in the present study allows seamless integration into diverse clinical settings. The hybrid AI framework achieves near-expert accuracy, offering a scalable solution to access to high-quality OK lens fitting.

With the emergence of various multi-segment myopic defocus design spectacles, evaluating and verifying their myopia control effectiveness and controlling their quality and wearing safety have gradually attracted widespread attention. At present, myopia prevention and control spectacles have not been classified as medical devices directly supervised by relevant national departments in China. Multi-segment myopic defocus design spectacles, as an important intervention for retarding the progression of myopia, especially for children and adolescents, should ensure the myopia control effectiveness, safety, and adherence to standardized fitting protocols. Aiming to provide guidance and reference for healthcare institutions and practitioners, the Society of Contact Lens Safety Monitoring & Vision Health of Chinese Health Association and the Western Optometry Expert Committee of Sichuan Optometry Society, based on the current evidence-based medical research, combined with practical experience and extensive solicitation of opinions, have reached consensus opinions on the quality control, effectiveness evaluation (including long-term effectiveness), and safety evaluation of multi-segment myopic defocus design spectacles, as well as the service norms for the fitting of spectacles.

Background: Keratoconus is a progressive, noninflammatory corneal ectasia that is characterized by corneal thinning and conical deformation, which leads to irregular astigmatism, myopia, and reduced visual quality. As the disease progresses, spectacles often become inadequate, necessitating the use of rigid gas-permeable or specialty contact lenses to restore vision. Traditional evaluations rely on high-contrast visual acuity tests, which alone do not capture functional vision impairments. A more comprehensive assessment includes contrast sensitivity (CS), a key predictor of real-world visual performance. The ROSE K2 XL semi-scleral lens offers tailored optical correction for irregular corneas. We investigated its efficacy in enhancing best-corrected distance visual acuity (BCDVA) and CS in patients with keratoconus. Methods: In this prospective study, we recruited adults with varying keratoconus severities from the Armed Forces Hospital in Oman, between February and December 2024. The patients were fitted with ROSE K2 XL semi-scleral lenses to assess changes in BCDVA and CS. Participants who had undergone prior ocular surgery (except for corneal crosslinking) or who had other corneal pathologies were excluded. Baseline and post-fitting BCDVA were measured using a crowded Keeler logarithm of the minimum angle of resolution (logMAR) chart. CS was assessed using the Pelli–Robson chart under standardized photopic conditions. Keratoconus severity was graded using the Amsler–Krumeich classification system. All examinations were performed by the same experienced optometrist to ensure consistency and to reduce measurement variability. Results: We enrolled 180 eyes from 90 participants with keratoconus (mean [standard deviation, SD] age: 29.2 [5.4] years; 65.6% [n = 59] female). Disease severity was classified as follows: stage I (n = 16, 8.9%), stage II (n = 52, 28.9%), stage III (n = 70, 38.9%), and stage IV (n = 42, 23.3%). After ROSE K2 XL lens fitting, the mean (SD) BCDVA improved significantly, from 0.90 (0.48) logMAR to 0.10 (0.11) logMAR (P &lt; 0.001). The mean (SD) CS also increased significantly, from 0.96 (0.47) log CS to 1.90 (0.16) log CS (P &lt; 0.001). Significant improvements in BCDVA and CS were observed across all disease stages (all P &lt; 0.001), with the most pronounced gains found in cases of advanced keratoconus (stage IV). Conclusions: Fitting ROSE K2 XL semi-scleral contact lenses in patients with keratoconus resulted in significant improvements in both BCDVA and CS across all disease severity levels. These findings show the clinical value of semi-scleral lenses for visual rehabilitation of keratoconus, particularly in the advanced stages, where conventional spectacles or lenses may offer limited benefits. Incorporating CS assessment with visual acuity evaluations provides a more comprehensive investigation of real-world visual function, supporting evidence-based lens selection to optimize patient outcomes. Future studies should explore the long-term effects of these lenses on corneal physiology and patient-reported quality of life.

The term "midday fogging" is used to describe visual blur, which some scleral lens wearers experience during use. The purpose of this study was to determine whether fit characteristics and biomicroscopic findings in habitual scleral lens wearers contribute to symptoms of fogging. This prospective, observational study analyzed 48 habitual scleral lens wearers who wore lenses in one or both eyes from five clinical sites. Participants indicated whether they experienced fogging. Slit Lamp biomicroscopy was performed to evaluate fluid reservoir (FR) depth and presence or absence of limbal clearance, edge lift or impingement, conjunctival prolapse, and front surface nonwetting. Presence or absence of mucous strands, fine particulate debris, and diffuse haze in the FR were also noted. Backward elimination binomial logistic regression using one eye per participant compared the findings of eyes with and without subjective fogging. Fogging was reported by 58% participants (28/48). Statistical analysis found no significant differences in scleral lens fitting characteristics of eyes with and without reported fogging. The presence of front surface nonwetting and diffuse haze were statistically higher in eyes with fogging. In this study, front surface nonwetting and diffuse haze observed with Slit Lamp biomicroscopy were associated with patient-reported scleral lens fogging.

Gabor patches training programme for neuroadaptation in multifocal contact lenses wearers.

Intraocular pressure following long-term scleral lens wear in Chinese eyes.

Corneal collagen cross-linking is a primary treatment to slow or halt the progression of keratoconus. For visual rehabilitation, important treatments include contact lenses fitting, intracorneal ring segment implantation, and corneal transplantation. Additionally, either phakic intraocular lenses or corneal therapeutic keratectomy combined with corneal collagen cross-linking can assist in visual rehabilitation with limited indications. New methods for visual rehabilitation, such as stromal keratophakia, have been introduced. This review evaluates and compares the efficacy and safety of various treatments for keratoconus based on the latest information.

Orthokeratology (Ortho-K) effectively controls myopia progression. Toric Ortho-K lenses are used for moderate-to-high astigmatism, but predictive models with multiple corneal parameters are limited. This study aimed to identify key predictors for toric lens prescription in Ortho-K. A retrospective analysis was conducted on 506 patients undergoing Ortho-K treatment, incorporating 15 parameters such as age, sex, refractive error, corneal astigmatism, and flat eccentricity. Using both univariate and multivariate models, significant predictors were identified using logistic regression and refined with backward stepwise regression, evaluated by receiver operating characteristic curve analysis. The 4-variable model (corneal astigmatism [∆K], steep eccentricity [Steep e], Sagittal Height Difference at 8 mm [SD8], and Corneal Cylindrical to Spherical [C/S] ratio) achieved an area under the curve (AUC) of 0.92 (sensitivity 89.7%, specificity 79.5%). Receiver operating characteristic analysis validated thresholds: ∆K>1.50 D (AUC 0.87), SD8 greater than 34 μm (AUC 0.82), flat eccentricity greater than 0.68 (AUC 0.73), and C/S ratio greater than 0.59 (AUC 0.63). This study developed the 4-variable model for toric Ortho-K lens fitting, identifying corneal astigmatism and SD8 as key predictors for detecting limbus-to-limbus astigmatism. Steep and flat eccentricities offered predictive and clinical insights, respectively.

Artificial intelligence-assisted fitting method using corneal topography outcomes enhances success rate in orthokeratology lens fitting.

Effect of apical clearance rigid corneal contact lens fitting on keratoconus progression: a controlled longitudinal analysis.