Contact Lens Fitting Research Articles

Scleral lens fitting after paediatric limbal dermoid removal

Purpose. This case report describes the management of refractive error and amblyopia using a scleral lens fitted to the eye of a young child with an irregular cornea resulting from limbal dermoid removal and corneal transplant in infancy. Material and Methods. A young infant was initially fitted with spectacles and occlusion therapy following the surgical excision of a limbal dermoid and full thickness corneal transplant. The vision did not improve in spite of patching so the child was referred for contact lens fitting. Various iterations of scleral lens fitting were carried out. Results. Scleral lens fitting was attempted from the age of 2 years but transplant rejections, the COVID-19 pandemic and variable cooperation meant that adequate lens wear could not be achieved in the early stages. In addition, the corneal shape changed during the course of the fitting. During these periods, spectacle wear and occlusion therapy were maintained until a good lens fit could be achieved following several modifications. Treatment is ongoing but at the age of 5 years, the visual acuity is 0.24 logMAR letters. Conclusion. Scleral lenses can be used to habilitate the vision in an eye with an irregular cornea but when scleral lens wear is not possible, it is important to persevere with spectacle correction and patching therapy. Several iterations of scleral lenses may be needed as the eye changes and the child grows.

Referral Pattern and Comanagement of Patients With Keratoconus in West Africa: A Survey-Based Study of Optometrists in Ghana and Nigeria.

To investigate the referral and management patterns of patients with keratoconus among primary eye care practitioners in Ghana and Nigeria. A questionnaire adapted from previous studies was modified and created using Google Forms. The online survey was distributed to prospective participants using e-mails and other social media platforms. Data were analyzed using the Statistical Product and Service Solutions software (version 25.0; IBM Corp, Armonk, NY; Released 2017). One hundred and sixty-nine optometrists responded to the survey (61.54% from Nigeria and 38.46% from Ghana). Most (88.6%) practiced without corneal topographers. Most respondents (77.7%, n=136) reported not fitting rigid gas-permeable (RGP) contact lenses in a year and 68% were willing to refer for contact lens fitting to another practitioner. The major barriers to RGP fitting were lack of experience (44.4%, n=72), cost to practice (15.4%, n=25), and other reasons (12.4%), whereas 27.8% (n=45) preferred not to answer. Seventy-six percent of respondents (n=133) were willing to fit RGPs if the respondents received the training to do so. About half of the respondents (53.8%) reported progression of cornea signs as the reason for referral to an ophthalmologist. Half of the respondents (n=51.4%) did not have a cornea surgeon in the area the respondents practiced, and 76.3% reported not comanaging patients at all with ophthalmologists. This study highlights the current standard of care of patients with keratoconus in West Africa. The findings from this study suggest that clinical guidelines and further training of eye care practitioners in West Africa are needed to better manage patients with keratoconus.

Does the palpebral morphology influence the tear meniscus height between Caucasian and Asian eyes?

The central lower TMH is used as a clinical measure of tear volume in the assessment of contact lens candidates and patients with dry eyes. Ethnic differences in eyelid morphology may influence the measurement of the TMH. Furthermore, with the advent of larger contact lenses, such as scleral lenses, it would be of clinical value to assess the TMH centrally and peripherally. The purpose of this study was to evaluate and compare the TMH at different positions along the palpebral margin between Caucasian and Asian eyes. This prospective study evaluated the lower TMH in five positions (central, temporal and nasal limbus and temporal and nasal periphery) of the right eye using the Keratograph 5M (Oculus) instrument in Caucasian and Asian participants between 10 am and 12 pm. The TMH at each position was taken three times and averaged and analyzed using a 5 × 2 repeated-measures analysis of variance. Central TMH did not differ significantly (F = 0.02, p=0.88) in Caucasians (n = 20, aged 24.45 [2.30] years, TMH 0.320 [0.052] mm) and Asians (n = 20, aged 22.25 [3.43] years, TMH 0.325 [0.048] mm). A difference was noted with respect to TMH positions along the lid margin (F = 64.17, p<0.001), independent of ethnicity (F = 2.15, p=0.15). A post hoc analysis revealed a significantly higher TMH temporally when compared with centrally or nasally (p<0.001). This study demonstrated the similarity of the central TMH and the differences in the peripheral TMH within Caucasian and Asian eyes. This may be clinically relevant when using the Tear Film & Ocular Surface Society Dry Eye Workshop II diagnostic algorithm for dry eyes and when fitting scleral contact lenses. Future studies need to consider that ethnic differences may exist for certain tests in order to personalize the care and management of each patient.

Changing indications for keratoplasty: monocentric analysis of the past two decades

Abstract Purpose Over the past two decades, lamellar keratoplasty procedures, such as Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) and Descemet's Membrane Endothelial Keratoplasty (DMEK) as well as Deep Anterior Lamellar Keratoplasty (DALK), have become an integral part of clinical practice. With advances in contact lens fitting for keratoconus management and the implementation of UVA-Riboflavin Crosslinking (CXL), the landscape of keratoplasty indications is undergoing changes. Procedures and indications in a single tertiary care center over the past two decades are reviewed in this retrospective analysis. Methods: Retrospective analysis utilized anonymized electronic data from the LIONS cornea bank Baden-Württemberg, Eye Center Freiburg, spanning from beginning of 2004 to end of 2023. The primary focus was on surgical procedures and indications for keratoplasty. Results The study encompassed a comprehensive analysis of 7130 corneal transplants. Penetrating keratoplasty (PK) exhibited a significant decline from 95% (n = 206, 2004) to 11% (n = 46, 2023), while DMEK increased from 48% (n = 157, 2012) to 82% (n = 347, 2023). Fuchs endothelial dystrophy (FED) emerged as the dominant indication, witnessing a significant increase from 24% (2004, n = 39) to 72% (2023, n = 288). Conversely, keratoconus (KC) showed a reciprocal change from 25% (2004, n = 40) to 4% (2023, n = 17). PK demonstrated a noteworthy indication shift in descending order from Bullous Keratopathy (BK), FED, and KC in 2004 to KC, graft failure, corneal scars, and ulcers in 2023. Repeat keratoplasty following DMEK remained rare, but a discernible upward trend was observed for PK. Conclusion This retrospective analysis highlights significant changes in both keratoplasty indications and techniques over the past two decades. DMEK has emerged as a successful intervention for treating endothelial diseases, while PK retains its qualitative indispensability for a wide range of indications. Modern corneal banks are urged to maintain a robust supply of grafts for all surgical techniques in anticipation of potential increased demand in the future, particularly for repeat keratoplasties. Key messages What is known • Over the past two decades, lamellar keratoplasty procedures such as DSAEK and DMEK have increasingly replaced penetrating keratoplasty (PK) in clinical practice due to their improved outcomes and reduced complications for certain indications. New Findings • Our study reveals a significant shift in keratoplasty indications, with Fuchs endothelial dystrophy (FED) emerging as the predominant indication, increasing from 24% in 2004 to 72% in 2023, while keratoconus (KC) declined from 25 to 4% during the same period. • Penetrating keratoplasty (PK) has shown a marked decline in use, dropping from 95% of keratoplasties in 2004 to 11% in 2023, whereas DMEK has grown to represent 82% of procedures in 2023. • Despite the rise of DMEK, PK remains vital for a broad spectrum of indications, highlighting the necessity for corneal banks to maintain a versatile supply of grafts to meet diverse clinical needs, particularly in cases of repeat keratoplasties.

International trends in prescribing silicone hydrogel contact lenses for daily wear (2000–2023): An update

PurposeIntroduced around the turn of the 21st century, silicone hydrogel contact lenses alleviated hypoxic anterior eye complications due to their high oxygen transmissibility. The purpose of this work is to update earlier surveys by describing international trends in silicone hydrogel daily wear contact lens fitting between 2000 and 2023. MethodAn annual contact lens prescribing survey was sent to eye care practitioners in up to 71 countries between 2000 and 2023. Data relating to 260,144 daily wear soft contact lens fits undertaken in 20 countries returning reliable longitudinal data were analysed in respect of silicone hydrogel daily wear contact lens fitting. ResultsThere has been a dramatic increase in silicone hydrogel daily wear lens fits (p < 0.0001), increasing from 2.8 % of all daily wear soft lens fits in 2000 to 73.7 % in 2023. Of all daily wear soft contact lenses prescribed to males, 44.6 % were silicone hydrogel lenses, compared with 43.5 % for females (p = 0.0146). The mean age of those wearing silicone hydrogel daily wear lenses was 32.0 ± 14.5 years, compared to 30.4 ± 13.6 years for those wearing daily wear hydrogel lenses (p < 0.0001). Between 2019–2023, the average percentage of fits was – (a) material type: silicone hydrogel – 73 %; mid-water content hydrogels – 13 %; high water content hydrogels – 9 %; and low water content hydrogels – 5 %, and (b) lens design: spherical – 44 %, toric – 32 %, multifocal – 17 %, monovision – 4 %, and ‘other’ – 3 %. ConclusionThe dramatic increase in silicone hydrogel contact lens prescribing for daily wear has been commensurate with the introduction of multiple lens brands and an ongoing expansion of lens designs, parameters and replacement frequency options. The balance between silicone hydrogel and hydrogel lens prescribing is perhaps starting to approach an equilibrium.

Anpassung von Skleral-Kontaktlinsen bei Terrien‘s marginaler Hornhautdegeneration

Purpose. This case report describes the possible visual rehabilitation with scleral lenses of a patient with Terrien’s marginal degeneration with different degrees of progression between the right and left eye. Material and Methods. Scleral contact lenses were fitted with the help of corneal tomography and by observing and assessing the fit of measuring lenses. A slit lamp with a corresponding camera helped to modify the diagnostic lenses. Results. In this case, the fitting of scleral contact lenses resulted in an improvement in distance vision in both the right and left eye. Near vision could not be evaluated at the time of writing. Conclusion. Scleral contact lenses can be a good alternative to glasses for complex corneas to improve visual performance. It is recommended to use a slit lamp with a camera to make it easier to discuss scleral contact lenses modifications with the manufacturer of the lenses. Keywords: TERRIEN’S MARGINAL CORNEAL DEGENERATION, PELLUCIDE MARGINAL CORNEAL DEGENERATION, SCLERAL LENSES

Kontaktlinsenversorgung bei ausgeprägter Sicca bei vermuteter Alakrimie bei einem sechsjährigen Kind

Purpose. The aim of this case report is to describe a case of suspected alacrimia in a six-year-old child that resulted in irregular astigmatism with risk of amblyopia. A specialty contact lens fitting for visual rehabilitation was performed. Material and Methods. Different wearing modes (extended wear and daily wear) as well as contact lens types (soft silicone hydrogel contact lenses of different wearing rhythms, as well as rigid gas permeable (RGP) contact lenses were fitted. Results. In this case, different contact lens types (soft and rigid contact lenses) could not achieve a satisfactory treatment result. However, a piggyback contact lens system with daily wear was a good treatment solution. Conclusion. Irregular astigmatism in children is always a high risk of amblyopia. For this reason, timely optical treatment for visual rehabilitation is a high priority. Sometimes it is necessary to combine different contact lenses and wearing modalities to achieve the best solution for a complex treatment situation. Keywords: ALACRIMIA, HYPOLACRIMIA, SICCA, IRREGULAR ASTIGMATISM, VISUAL REHABILITATION, AMBLYOPIA RISK

Globe Subluxation in the Specialty Contact Lens Practice

Purpose. This report documented the occurrence of globe subluxation (GSL) during the insertion of a scleral contact lens (SL) and described the management of two keratoconus patients, in need of a gas permeable contact lens prescription and experiencing GSL. Furthermore, an anatomical explanation for the occurrence of spontaneous GSL is attempted. Material and Methods. Two separate case reports of GSL were evaluated and described. In case 1, the patient experienced GSL secondary to insertion of a trial SL and in case 2 the patient had experienced multiple GSLs secondary to Grave’s disease. Different management strategies were taken to help to provide functional vision for these patients. In case 1, the patient was fitted with a smaller corneal gas permeable lens to minimize lid manipulation needed to insert a lens and provide effective correction. In case 2, the patient’s existing Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) SL was designed to increase vertical lens steepness to tighten the lens fit and minimize the chance of losing the lens during wear. Results. With the help of the individually fitted contact lenses, it was possible to achieve visual rehabilitation in accordance with the patient’s specific needs. Conclusion. SL are fitted with increasing frequency and tend to require excessive lid manipulation, which may lead to GSL. This small case series demonstrated different lens design and selection maybe utilized to minimize the occurrence of GSL. The superior septum orbitale is perforated several times across the width of the upper lid by the aponeurosis of the levator. This structural arrangement weakens the superior septum orbitale and, postulated here, predisposes the eye to GSL by a herniation primarily of the superior septum orbitale.

Is it possible to calculate the sagittal height for soft contact lens fitting? Validation of a theoretical calculator: Sagitador

Is it possible to calculate the sagittal height for soft contact lens fitting? Validation of a theoretical calculator: Sagitador

Attitudes and behaviours of UK eyecare practitioners towards fitting contact lenses for children and young people

Attitudes and behaviours of UK eyecare practitioners towards fitting contact lenses for children and young people

Optometrists’ perspectives on speciality programme development in South Africa

Background: South Africa (SA) has postgraduate research-based master’s and doctorate qualifications in optometry with no clinical coursework qualifications in special interest fields. As a result, it hinders professional growth and career path for optometrists and further limits patients’ access to various care pathways from would-be upskilled optometrists.Aim: To explore optometrists’ perspectives on postgraduate programme development in special interest fields of optometry for SA.Setting: Study population of practicing optometrists registered with the Health Professions Council of South Africa (HPCSA).Methods: A quantitative cross-sectional descriptive design was employed, utilising an online questionnaire developed with the Evasys survey system v8.2. Non-probability sampling was used to access eligible participants.Results: From 424 survey responses, 83.5% had undergraduate qualifications and 95.5% worked in patient-facing environments. Participants responded positively (88%) to this need for educational expansion. Educational needs in Ocular Disease (75.6%), Paediatric Optometry (66.4%), Binocular Vision (65.1%) and sub-specialties of myopia control (41.2%) and Specialised Contact Lens Fitting (31%) were reported. With combined ‘highly important’ and ‘likely important’ responses, participants indicated that obtaining professional recognition (94.9%) and to improve patient care (98.8%) were the main drivers for pursuing additional education and training.Conclusion: A notable demand was found for coursework postgraduate programmes by the study populations from which professional recognition can be awarded in various special interest fields of optometry. The benefit of improved patient care from upskilled optometrists was expressed.Contribution: The findings would contribute towards the development of a conceptual framework for postgraduate education and training for optometrists in SA.

CONTACT LENSES: Introduction to scleral contact lenses

Contact lens expert, Nick Howard, outlines the fascinating history of scleral contact lens fitting

Bacterial contamination in contact lens training area in private optical clinics

BackgroundContamination in the contact lens training area could be due to bacteria, which can lead to the major consequence of ocular infections. We aimed to investigate the contamination caused by bacteria in the contact lens training area in private optical clinics of the Udupi district, India.MethodsA cross-sectional study evaluated the swabs from the contact lens container, contact lens solution tip, washing area and lens fitting area for bacterial contamination. Twenty swabs collected from different areas of five optical clinics were inoculated in Brain heart infusion broth (BHIB). The broth was streaked in MacConkey and Blood agar and incubated at standard conditions for the growth of bacteria. All isolates were identified using conventional culture methods, and Gram staining was performed.ResultsTwenty samples (contact lens case, n = 5; contact lens solution tip, n = 5; washing area, n = 5; cleaning towel, n = 5) from private optical clinics were recruited for the study. Bacterial growth was indicated in which lactose fermentation was seen at (15%), non-lactose fermentation at (35%), and no bacterial growth at (50%) in MacConkey agar. Partial or alpha-hemolytic (α hemolysis) was seen in (5%), complete or beta-hemolytic (β hemolysis) was seen in (40%), no hemolysis or gamma hemolysis (ϫ haemolysis), was seen in (30%), no growth was seen in (25%) on blood agar. Gram-positive cocci (45%), Gram-negative bacilli (20%), and no increase in (35%) were observed in MacConkey agar and Blood agar. Bacterial species were not identified in this study.ConclusionContamination was found in lenses, solution tips, washing areas, and cleaning towels which might lead to ocular infections. Perception should be given to those responsible for fitting lenses.

Internationale Perspektiven in der Kontaktlinsenanpassung

Purpose. Contact lenses are global health care products (medical devices) and are fitted routinely in many countries. Key indications for contact lenses are the correction of ametropias, myopia progression control, and cosmetic reasons, occasionally also therapeutic applications. The article is based on a lecture that was presented at the VDCO Sichtkontakte Conference in Berlin 2023. The purpose of this article was to provide an insight into international aspects of contact lens fitting to allow comparisons with contact lens fitting practice in predominantly German-speaking countries and to strengthen the evidence base. Material and Methods. Subjective non-representative selection of relevant literature. Results. Assessments of international practitioner fitting preferences are conducted frequently. Contact lens related research is being commonly carried out with the aim to optimise clinical care and to reduce drop-out rates. There are considerable geographical differences in contact lens fitting practice as well as in the assessment of opportunities and risks associated with contact lens practice among practitioners. Conclusion. Practitioners in Europe hold largely positive views of opportunities and risks in relation to contact lens practice. The published literature indicates that the areas of ortho-K and myopia control are being considered to present promising opportunities for contact lens practice. Further strengthening of the scientific evidence base, e.g. in relation to novel contact lens materials, is preferable to support advancements in contact lens care. Keywords International contact lens market, orthokeratology, therapeutic contact lenses, myopia control

Tear film hTERT and corneal nerve characteristics in dry eye disease

ABSTRACT Clinical relevance The behaviour of human telomerase reverse transcriptase (hTERT) in tears reflects its role in maintaining the ocular surface homoeostasis, as it is increased after the initial fitting of contact lenses and post-overnight lid closure. Background hTERT has been shown to respond to cellular stress in neurodegenerative diseases and to enhance axonal regeneration after peripheral axotomy in an animal model. This work investigated whether the behaviour of hTERT in the tear film reflects ocular surface inflammation and neuronal changes in the presence of dry eye disease. Methods Flush tears were collected from 18 participants with dry eye disease (14 females, 4 males, mean age 34.7 ± 5.2 years) and from 18 healthy participants without dry eye disease (8 females, 10 males, mean age 31.9 ± 5.8 years). Dry eye disease status was defined using the TFOS DEWS II diagnostic criteria. hTERT levels in tears were measured using enzyme-linked immunosorbent assays. Confocal images were taken at the level of the subbasal nerve plexus at the central cornea and at the inferior whorl, and the densities of corneal immune cells were evaluated as well as corneal nerve morphology metrics using a fully automated technique (University of Manchester, United Kingdom). Results In participants with dry eye disease, hTERT levels were significantly higher compared to controls (median [interquartile range]: 434 [320–600] ng/ml, and 184 [42–390] ng/ml, respectively, p = 0.01). Increased nerve fibre width at the inferior whorl, was seen in those with dry eyes (0.0219 [0.0214–0.0236] mm/mm compared to controls 0.0217 [0.0207 0.0222] p < 0.001), but no significant differences were found in the density of corneal immune cells. Conclusions hTERT levels were elevated in participants with dry eye disease, and this was accompanied by increased nerve thickness in the inferior cornea. The hTERT response may reflect the stress induced to the ocular surface and corneal nerves due to having dry eye disease.

Long-term evolution of signs and symptoms in contact lens wearers

The purposes of the study were to describe the evolution of contact lens (CL) prescription patterns during a long-term period in the same sample of CL wearers evaluated in a protocolized manner, and to determine the predisposing factors responsible for the changes observed in CL fittings. Data on clinical files (CL type, wearing time, visual acuity, symptoms, and clinical signs) of CL wearers who attended a Spanish eye setting between 2010 and 2020 were collected. The profile of CL wearers was compared between 2010 and 2020. The CL characteristics were compared between CL types, replacements, and designs. Finally, factors predicting a change in CL fitting were assessed. Seventy-four CL wearers (28 men and 46 women) aged 39.0 ± 9.1 years old were included. Silicone hydrogel (p = 0.01) and daily disposable (p &lt; 0.001) CL fittings increased during the follow-up period. The main reasons for CL refitting were the appearance or increase of clinical signs and/or symptoms. CL wearing time and visual acuity differed between CL types and replacements (p ≤ 0.02). Both, rigid and conventional replacement CL wear were associated with a lower probability of CL fitting changes (p ≤ 0.03). In conclusion, this study provides useful clinical information about the profile of successful long-term CL wearers in the last decade. Adequate aftercare examinations of long-term CL wearers can avoid worsening of signs and symptoms. Hydrogel and frequent replacement CL wearers are more likely to undergo CL refitting when compared to rigid corneal and conventional CL wearers.

What Happens 20 to 30 years After Radial Keratotomy? Case Series.

Radial keratotomy (RK) was commonly performed in the 1980s and 1990s. We aimed to clarify the current status of post-RK refractive correction and treatment. We retrospectively reviewed the charts of 70 patients with a history of RK. Of the 70 patients, 44 were identified for clinical outcomes. Refractive or therapeutic intervention (rigid gas-permeable contact lens fit, spectacle prescription, corneal surgery, and use of pilocarpine hydrochloride for photophobia) was possible in 59% of patients with postoperative visual deterioration after RK; in the remaining 41%, therapeutic intervention was not possible. Rigid gas-permeable contact lens fit for corneal irregular astigmatism was the most common refractive intervention and was effective in 36% of cases in the university hospital.

Assessing the Impact of Tropicamide on Anterior Segment Parameters in Diabetic Patients: A Randomized Clinical Trial.

Evaluation of anterior segment parameters is crucial in ophthalmic procedures such as intraocular surgeries and contact lens fitting. However, the use of tropicamide in diabetic patients presents challenges due to its potential impact on biometric measurements. This study aims to investigate and compare the effects of 0.5% and 1% tropicamide on anterior segment parameters in diabetic patients. This double-masked randomized clinical trial enrolled 98 patients with diabetes mellitus. Participants were randomly assigned to receive either 0.5% or 1% tropicamide. Anterior segment parameters were measured using Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) before and 30 minutes after tropicamide administration. Parameters included anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), keratometry, central corneal thickness (CCT), white-to-white distance (WTW), and pupillary diameter (PD). Both concentrations of 0.5% and 1% tropicamide induced significant changes in anterior segment parameters. There was a notable increase in PD (2.99 ± 0.62, 3.11 ± 0.55, respectively, both P-values < 0.001), ACD (both 0.10 ± 0.05, both P-values < 0.001), ACV (16.69 ± 9.56, 17.51 ± 9.26, respectively, both P-values < 0.001), and WTW (0.06 ± 0.14,0.03 ± 0.30, respectively, both P-values < 0.001), along with a decrease in ACA (-3.50 ± 10.65, -3.30 ± 6.87, P-value< 0.001 and P-value=0.001,respectively), and CCT (-6.10 ± 8.06,-6.39 ± 9.97,respectively, both P-values < 0.001) post-dilation. However, no significant changes were observed in keratometry (front Km (-0.03 ± 0.19, -0.04 ± 0.21, respectively), back Km (0.01 ± 0.05, 0.004 ± 0.05, respectively), P-values> 0.05). Both concentrations of tropicamide exhibited comparable effects on anterior segment parameters in diabetic patients. These post-dilation changes should be considered for accurate intraocular lens power calculation and decision-making for cataract, phakic intraocular lens, and refractive surgeries.

The influence of eyelid pressure and eye contour factors on rigid corneal contact lens fitting

PurposeThis study aimed to investigate the impact of eyelid pressure (ELP) and eye contour factors on rigid corneal contact lens fitting. MethodsThis prospective cross-sectional study involved 20 participants (one eye per person). Rigid corneal contact lenses with three different base curves were selected for each participant. The base curves were calculated according to the average keratometry value. The original value and its variations (+0.1 mm and − 0.1 mm) were considered. Eye contour factors, lens decentration under natural eye position (LD I) and full eyelid exposure (LD II), and lens vertical movement were taken by a Canon camera mounted on a digital slit lamp biomicroscope. Upper and lower ELPs were measured by a novel blepharo-tensiometer. ResultsThe mean values of LD I, LD II, and lens vertical movement significantly increased as the base curve increased (P＜0.001, ＜0.001, and = 0.005). Upper ELP was positively correlated with lens vertical movement of the three base curves (P = 0.047, 0.001, and 0.004). Furthermore, upper ELP (odds ratio [OR]: 1.039; 95 % confidence [CI]: 1.009–1.069; P = 0.009) and flat keratometry values (OR: 0.873; 95 % CI: 0.786–0.969; P = 0.011) independently influenced lens vertical movement. ConclusionsELP and base curve independently influenced rigid corneal contact lens fitting. Thus, ELP should be considered during rigid corneal contact lens fitting in clinical practice.

Machine learning-based prediction of tear osmolarity for contact lens practice.

This study addressed the utilisation of machine learning techniques to estimate tear osmolarity, a clinically significant yet challenging parameter to measure accurately. Elevated tear osmolarity has been observed in contact lens wearers and is associated with contact lens-induced dry eye, a common cause of discomfort leading to discontinuation of lens wear. The study explored machine learning, regression and classification techniques to predict tear osmolarity using routine clinical parameters. The data set consisted of 175 participants, primarily healthy subjects eligible for soft contact lens wear. Various clinical assessments were performed, including symptom assessment with the Ocular Surface Disease Index and 5-Item Dry Eye Questionnaire (DEQ-5), tear meniscus height (TMH), tear osmolarity, non-invasive keratometric tear film break-up time (NIKBUT), ocular redness, corneal and conjunctival fluorescein staining and Meibomian glands loss. The results revealed that simple linear regression was insufficient for accurate osmolarity prediction. Instead, more advanced regression models achieved a moderate level of predictive power, explaining approximately 32% of the osmolarity variability. Notably, key predictors for osmolarity included NIKBUT, TMH, ocular redness, Meibomian gland coverage and the DEQ-5 questionnaire. In classification tasks, distinguishing between low (<299 mOsmol/L), medium (300-307 mOsmol/L) and high osmolarity (>308 mOsmol/L) levels yielded an accuracy of approximately 80%. Key parameters for classification were similar to those in regression models, emphasising the importance of NIKBUT, TMH, ocular redness, Meibomian glands coverage and the DEQ-5 questionnaire. This study highlights the potential benefits of integrating machine learning into contact lens research and practice. It suggests the clinical utility of assessing Meibomian glands and NIKBUT in contact lens fitting and follow-up visits. Machine learning models can optimise contact lens prescriptions and aid in early detection of conditions like dry eye, ultimately enhancing ocular health and the contact lens wearing experience.