Contact Lens Fitting Research Articles

Driving performance and road sign identification by multifocal contact lens wearers in a driving simulator

PurposeThe purpose of this study was to compare sign identification distances and driving performance metrics in presbyopic participants while wearing multifocal contact lenses (MFCL) and while wearing progressive addition lens (PAL) spectacles. Methods19 presbyopic participants completed PAL spectacle assessments and contact lens fitting and follow up visits before driving assessments began. These assessments occurred in a simulator equipped with a full-sized sedan on a motion platform and a 260 degree screen. Participants completed the driving task with PAL and with MFCL. Participants followed a lead car and identified signs at various distances from the road. For the two wearing conditions, comparisons of the distance along the road at which signs were identified were made using repeated measures ANOVA. Paired t-tests were used to compare driving performance for the two conditions. ResultsThere was no statistical difference in sign identification distance between PAL and MFLC for signs 32.0 m from the road side of the road (182 ± 46 m for MFCL; 205 ± 45 m for PAL; P = 0.07) or 51.4 m from the side of the road (204 ± 43 m for MFCL; 216 ± 36 m for PAL; P = 0.3). Only signs 70.2 m from the roadside showed a significant difference (207 ± 42 m with MFCL; 232 ± 39 m with PAL; P = 0.01), All distances were greater than those required to safely stop a vehicle. There were no significant differences in the driving performance metrics between the refractive corrections. ConclusionDriving performance metrics were similar for MFCL and PAL spectacles. Sign identification distances with both eyewear types were well within the distances required for safe vehicle stopping.

On the art and science of rigid contact lens fitting

ABSTRACT Clinical relevance Examination of the literature can help answer the age-old question of the extent to which rigid contact lenses can be considered an art versus a science. Background This work aims to assemble rigid contact lens-related publication metrics to identify the most impactful papers, authors, institutions, countries and journals. Methods A search was undertaken of the Scopus database to identify rigid contact lens-related articles published since this lens type was first described in 1949. The 25 most highly cited papers were determined from the total list of 1,823 papers found. Rank-order lists by count were assembled for the ‘top 25ʹ in each of four categories: authors, institutions, countries and journals. A subject-specific rigid contact lens h-index (hRL-index) was derived for each author, institution, country and journal to serve as a measure of impact in the field. A short list of the top constituents in each category were ranked by hRL-index and tabulated. Results The most highly cited paper (467 citations) is entitled ‘Risk factors and prognosis for corneal ectasia after LASIK’, by Randleman et al. Karla Zadnik (hRL = 20; 32 papers) and Richard Hill (h = 10; 50 papers) are most impactful and prolific authors, respectively. The Ohio State University (hRL = 24; 96 papers) is the most impactful and prolific institution and the United States (hRL = 51; 680 papers) is the most impactful and prolific country. Optometry and Vision Science (hRL = 30; 233 papers) is the most impactful journal. Conclusions Impactful authors, institutions, countries and journals in the field of rigid lenses are identified. Although there is perhaps an artistic element to rigid contact lens fitting, the solid literature base underpinning the field of rigid contact lenses revealed here belies the notion that rigid lenses fitting is more of an art than a science.

Anpassung von Sklerallinsen unter Berücksichtigung der Torizität des Corneo-Skleralprofils

Purpose. The case report describes the conversion of a cor- neal lens wearing keratoconus patient to scleral lenses. Material and Methods. Based on an analysis of the corneosc- leral profile using the CSP module of the Oculus Pentacam, the patient was fitted with individual scleral lenses with a peripheral toricity. The exact determination of the corneal topography, the corneoscleral profile, the interpretation of the fluorescein images of diagnostic and prescription lenses as well as all other fitting relevant measurements and exami- nations are described. Results. In the present case a successful conversion of the contact lens fitting from a corneal lens to a scleral lens could be performed. Wearing comfort as well as subjective and objective tolerance of the contact lenses could be optimized in connection with a simultaneous increase of visual acuity. Conclusion. Visual rehabilitation of keratoconus patients with scleral lenses can be a good alternative to other contact lens treatments depending on the individual case. Quantification of the corneoscleral profile is of great benefit in determining scleral lens parameters. Keywords keratoconus, keratoconus qualification, scleral lenses, contact lens acceptance, corneoscleral profile

Tear Film Surface Quality in Modern Daily Disposable Contact Lens Wear.

As reported previously, tear film surface quality (TFSQ) should be considered in contact lens (CL) fitting. This study followed noninvasive keratograph tear film break-up time (NIKBUT) in CL wearers for 12 months to validate its clinical utility in predicting CL performance. Fifty-five subjects (M/F=17/38) aged 26±4 years were prescribed silicone hydrogel or hydrogel CLs. The study included baseline measurements without CLs; 2 visits for CL fitting and control; follow-up after 3, 6, and 12 months of CL wear; and postwear visit without CLs. Ocular Surface Disease Index (OSDI), 8-Item Contact Lens Dry Eye Questionnaire (CLDEQ-8), first and mean NIKBUT (F/M-NIKBUT), fluorescein tear film break-up time (FBUT), and ocular surface staining were evaluated. Post hoc analysis of each pair of visits showed differences between baseline and all CL visits for F-NIKBUT, M-NIKBUT, FBUT, and corneal staining. No difference was reported in symptoms. In addition, differences between baseline and postwear visits were noted in OSDI, M-NIKBUT, FBUT, and corneal staining, with three of the latter parameters showing a downward trend. No changes in TFSQ and symptoms were reported over 12 months. Introducing NIKBUT as part of routine CL fitting is advised to improve CL fit and predict success.

Mini-Scleral Contact Lens for Asian Eyes Post-Penetrating Keratoplasty with Smaller Palpebral Aperture: Case Reports

PurposeTo report the use of miniscleral contact lenses (MSCLs) with diameter of 14.7 mm for Asian eyes to improve vision in patients after penetrating keratoplasty (PKP) surgery.MethodsTwo patients with high corneal astigmatism post-PKP were evaluated for a contact lens fitting. Visual acuity, slit lamp, and anterior segment OCT findings before and after fitted the lens of 14.7 mm diameter were recorded.ResultsA Kmax of case 1 and 2 were 52.8 D and 76.9 D, respectively at the first visit. Both patients were successfully fit with MSCLs, showing adequate corneal clearance of over 250 μm with no corneal touch on OCT and sufficient limbal clearance and edge alignment. MSCLs use resulted in improved comfort and visual acuity of 20/30 or better.ConclusionMSCLs with diameter of 14.7 mm can be considered a safe and effective option for patients with highly steep corneas post-PKP surgery in Asian eyes.

Quarter of a century of contact lens prescribing trends in the United Kingdom (1996 – 2020)

PurposeTo document contact lens prescribing trends in the United Kingdom over the past quarter of a century. MethodsAn annual survey of contact lens prescribing was conducted each year from 1996 to 2020, inclusive, by asking a random selection of optometrists and contact lens opticians to provide information relating to 10 consecutive contact lens fits between January and March. ResultsOver the 25 year survey period, 2,671 practitioners returned survey forms, reporting a total of 25,575 contact lens fits. The mean (± standard deviation) age of lens wearers was 35 ± 15 years, of which 64 % were female. Over the survey period, rigid lens new fits decreased from 22 % to 2%. The prescribing of silicone hydrogel lenses has increased steadily since their introduction towards the end of the 1990s, and now represent 80 % of soft lens fits. Soft toric lens prescribing has gradually increased to 47 % – a value at which astigmatism ≥ 0.75DC is theoretically corrected in all contact lens wearers. Daily disposable prescribing increased steadily over the survey period and now represents 63 % of lenses prescribed. Extended wear fits remain at very low levels, except for some prescribing for overnight orthokeratology. Multi-purpose lens care solutions are ubiquitous; peroxide and other systems are now seldom prescribed. Rigid lenses and monthly replacement soft lenses are predominantly worn on a full time basis, whereas daily disposable soft lenses are mainly worn part time. ConclusionsThis report documents the evolution of contact lens fitting in the United Kingdom over the past 25 years. The most likely lens fit is a spherical design silicone hydrogel daily disposable contact lens prescribed for a 35 year old female and worn on a part-time basis.

Ocular surface topographic evaluation in patients of astigmatism in normal and pathologic eyes

Keratometry is the measurement of anterior surface of corneal curvature in its steepest and flattest axis by various methods. There are many advances in measurement of keratometric values. Corneal topography and Modern videokeratoscopes provide an accurate representation of the anterior corneal surface to allow assessment of corneal irregularities in keratoconus, pellucid marginal degeneration, preoperative cataract workup - IOL calculation/TORIC lens implantation, refractive surgery preoperative assessment and post-op evaluation, evaluating pathologies like coneal dystrophies, scars, pterigium, recurrent erosions and contact lens fitting and evaluating the corneal contribution to optical aberrations of the whole eye Astigmatism (more than 0.5 diopters) is a commonly encountered refractive error, accounting for about aprx. 13-40 per cent of the refractive errors of the human eye according to various studies. In our study, 200 eyes of patients were studied over period of 2 year, with autorefractometer which measures total astigmatism (corneal and lenticular) and Bausch and Lomb manual keratometer and oculus topographer which measures anterior corneal astigmatism and results were compared. In our study 92.5% of eyes had regular astigmatism while 7.5% of eyes had irregular astigmatism. Various causes of corneal astigmatism were pterygium, keratoconus, PMCD, corneal degeneration, corneal opacity in that order. No significant clinical cause was found in 74.5% of eyes. Maximum repeatability was found with oculus topographer followed by autorefractometer and Bausch and Lomb manual keratometer.

Is soft toric contact lenses fitting a feasible option to improve optical quality and visual performance in corneal ectasia?

ObjectivesTo assess the feasibility of fitting soft toric contact lenses (STCL) in corneal ectasias and their impact on optical quality and visual performance. MethodsA total of 22 eyes were fitted with a molded STCL: 11 eyes/9 subjects with corneal ectasia and 11 healthy eyes/11 subjects. Wavefront aberrations were analyzed using a Hartmann-Shack aberrometer. Visual performance was measured under photopic (85 cd/m 2) and mesopic (≤3 cd/m 2) conditions. High-(96 %) and low- (10 %) contrast VA (HCVA and LCVA respectively) were assessed using the ETDRS charts and contrast sensitivity (CS) using the Pelli-Robson chart. ResultsAfter STCL fitting in the ectatic corneas, oblique astigmatism increased 0.15±0.17 μm and 0.34 ± 0.36 μm for 3 mm- and mesopic pupil diameters, respectively.Mean defocus decreased 1.41 ± 0.36 μm and 2.17 ± 0.85 μm for the same pupil diameters. More positive values of vertical coma were found with a change of 0.05 ± 0.06 μm and 0.12 ± 0.10 μm for 3 mm and mesopic pupil diameters, respectively. Comparing changes between both groups, with a 3 mm pupil aperture, statistically significant differences (p < 0.05) were detected in oblique astigmatism, defocus, vertical secondary trefoil and horizontal secondary coma. In the group with corneal ectasia, photopic HCVA and LCVA improved 0.09 ± 0.11 logMAR and 0.12 ± 0.15 logMAR respectively. In mesopic conditions, HCVA, LCVA and CS improved 0.11 ± 0.12 logMAR, 0.18 ± 0.15 logMAR and 0.11 ± 0.07 log. units, respectively. ConclusionsThe analyzed molded soft toric contact lens is a feasible option for good vision in corneal ectasia with moderate irregularity and negative vertical coma.

Contact lens education for the practitioners of the future.

The World Health Organization has identified a shortage of trained human resources as one of the greatest challenges to increasing the availability of eye care services and reducing preventable visual impairment around the world. Increased prevalence of myopia and new strategies for myopia management have raised the prospect of various interventions, including contact lenses for therapeutic use as well as for refractive correction. More personnel skilled in contact lens fitting will be needed to address potential worldwide demand for these interventions. This review investigates the current status and future requirements of global contact lens education in light of these developments. The COVD-19 pandemic led educational institutions worldwide to move towards online delivery. An online survey among 546 educators, conducted in May 2020, investigated changes to contact lens education delivery before and after the onset of the pandemic. A total of 214 responses were received from 32 countries. Prior to COVID-19 restrictions, 23% of educators had conducted more than 50% of their total teaching online; however, 69% expected to conduct more than half of their teaching online by the end of 2020 and 12% anticipated 90% or more of their teaching would be online. Some 76% of educators expected to provide more online lectures after the pandemic and 63% anticipated new methods to deliver practical education. Around half were planning to introduce new teaching online platforms (54%) and more online assessment methods (53%). The global need for increasing numbers of skilled personnel points to a crucial role for educators in teaching the contact lens practitioners of the future. Contact lens education delivery was already evolving prior to COVID-19, and changes that are currently occurring may lead to permanent differences in the way contact lenses are taught in future. The International Association of Contact Lens Educators (IACLE) provides educators with a standardised global curriculum, online resources and teaching technology that could also serve as a model for wider ophthalmic education in future.

Basics of Practical Contact Lens Fitting (Part 1: Materials, Indications and Differences in Optics Compared to Glasses)

The great potential of contact lenses for improving vision in all forms of corneal irregularities, e. g. keratoconus, after keratoplasty, after keratitis, is in danger of being forgotten. Especially by the younger generation of ophthalmologists and opticians there is a risk that the skill of fitting contact lenses professionally will be lost. There are many situations in which the practicing ophthalmologist should recognize that the contact lens can be a useful option for the visual rehabilitation of his patient. In this article, we provide a summary of "The basics of practical contact lens fitting". The first part is about materials, fields of application and differences in optics compared to glasses.

Scleral contact lenses: Visual outcomes and tolerance. A prospective study about 98 eyes

To assess the improvement in visual acuity (VA), tolerance and quality of life of patients after scleral contact lens (SCL) fitting. We carried out a prospective observational study conducted from April 2016 to August 2017. Patients fitted with SCL were included. For the purpose of this study, we analyzed VA and quality of life score (NEI-VFQ25) after 6 months of use. We identified 98 eyes of 56 patients; the major indication for SCL fitting was keratoconus in 64.3%; the other indications were post-penetrating keratoplasty, other irregular astigmatism, severe ametropia and ocular surface disease. The mean follow-up was 10.71 months. The mean daily wearing time was 9.89±1.63 hours. Best corrected Visual acuity "BCVA" (baseline 1.11±0.37 in the right eye and 1.13±0.42 LogMar in the left eye) improved to 0.19±0.20 and 0.23±0.38 LogMar respectively in the right and left eyes after SCL wear (P=0.000). The scores on the various subscales of the NEI-VFQ 25 questionnaire were significantly higher 6 months after SCL fitting, with a mean score of 87.28±9.87 with SCL versus 39.94±11.33 without these lenses (P=0.000). In our group, no complications related to the SCL wear occurred, except for the occurrence of "loose conjunctival tissue" at the inferior limbus in one patient. Our results complement those of several large series published on this subject. The best visual acuities were reported after correction of irregular astigmatism, in particular keratoconus. Therefore, SCL fitting has become an alternative or a precursor to penetrating keratoplasty in patients with advanced keratoconus. In the case of ocular surface disease, in addition to the improvement in VA, the comfort and recovery of the homeostasis of the ocular surface is greater, with fewer wearing complications. Hence, their inclusion in the therapeutic arsenal for severe ocular surface disease alongside the conventional treatment options. SCL have proven their efficacy and safety in the optical correction of irregular corneas and in the management of ocular surface problems. Additional studies are needed to compare the many lenses currently available and assess optimal fitting strategies for each type of scleral lens for easier fitting procedures and better wearing comfort.

The use of a modern web-application to assist reusable toric lens fitting success

Purpose: Increasing numbers of online tools are available to assist ECPs in fitting contact lenses. In this study, the contact lens prescription of a reusable toric silicone hydrogel lens was determined using a traditional fitting guide and the results were compared to the prescription recommended by the lens fitting app OptiExpert™.

Toric lens fitting success supported by an online fitting App

Purpose: Increasing numbers of online tools are available to assist ECPs in fitting contact lenses. In this study, the contact lens prescription of a reusable toric silicone hydrogel lens was determined using a traditional fitting guide and the results were compared to the prescription recommended by the lens fitting app OptiExpert™.

Seven Ways: Steps to improve toric contact lens fittings

Ian Cameron identifies how toric contact lenses can best be used in practice.

Validation of the online fitting app OptiExpert for a reusable multifocal soft contact lens

Purpose: The multifocal soft lens calculator within the OptiExpert™ app was developed by CooperVision, Inc. to make multifocal contact lens fitting simpler and more efficient. Comparisons between clinician-dispensed lens prescription and app-recommendation were conducted to validate the software.

Clinical lens fit characteristics of a new silicone hydrogel daily disposable and two commercially available daily disposable contact lenses

Purpose: A new silicone hydrogel (SiHy) contact lens (verofilcon A; 51% water content) with “SmartSurface” has been developed. The intent of these studies was to assess contact lens fit characteristics of a new SiHy daily disposable (verofilcon A) and commercially available HEMA-based (etafilcon A) and SiHy (somofilcon A) daily disposable contact lenses.

Multifocal acceptance score to evaluate vision: MAS-2EV

We present a new metric (Multifocal Acceptance Score, MAS-2EV) to evaluate vision with presbyopic corrections. The MAS-2EV is based on a set of images representing natural visual scenes at day and night conditions projected in far and near displays, and a near stereo target. Subjects view and score the images through different binocular corrections (monofocal corrections at far; bifocal corrections; monovision and modified monovision) administered with soft contact lenses (in cyclopleged young subjects) or with a binocular simultaneous vision simulator (in presbyopic and cyclopleged young subjects). MAS-2EV scores are visually represented in the form of polygons, and quantified using different metrics: overall visual quality, visual degradation at far, visual benefit at near, near stereo benefit, visual imbalance near-far, overall visual imbalance and a combined overall performance metric. We have found that the MAS-2EV has sufficient repeatability and sensitivity to allow differentiation across corrections with only two repetitions, and the duration of the psychophysical task (3 min for subject/condition/correction) makes it useable in the clinic. We found that in most subjects binocular bifocal corrections produce the lowest visual imbalance, and the highest near stereo benefit. 46.67% of the subjects ranked binocular bifocal corrections first, and 46.67% of the subjects ranked monovision first. MAS-2EV, particularly in combination with visual simulators, can be applied to select prospective presbyopic corrections in patients prior to contact lens fitting or intraocular lens implantation.

Efficacy and safety of a soft contact lens to control myopia progression

ABSTRACT Clinical relevance The control of myopia progression is currently considered an evidence‐based therapeutic need. Background To determine the efficacy and safety of the Esencia lens, a new soft contact lens (SCL) designed to slow down myopia progression in paediatric patients. Methods This study was a randomised, parallel, double‐masked clinical trial. Seventy myopic (−0.50 to −8.75 D) boys and girls, 7–15-years of age, were randomised and allocated to one of two groups: (i) study (n = 36) or (ii) control (n = 34). Study group patients were given the Esencia lens, a progressive multifocal and reverse geometry SCL. Control group patients were given conventional SCLs. Efficacy measurements (change in cycloplegic autorefraction and axial length) were measured at baseline and at the six‐month intervals over a 12‐ month period. Visual performance measurements were corneal power, comfort, quality of vision and contact lens fitting. Safety measures included detection of adverse events. Results Mean changes in cycloplegic autorefraction after 12-months were −0.28 ± 0.35 D for study and −0.57 ± 0.52 D for control group patients (p = 0.02). A significantly lower increase in axial length was found in the study group (0.13 ± 0.12-mm) compared to control (0.22 ± 0.14-mm) patients (p = 0.03). Compared to control group patients, there was less myopia progression in the study group: 51 and 41 per cent in terms of cycloplegic autorefraction and axial length, respectively. No significant differences between groups for change in corneal power, comfort, vision quality and contact lens fitting were found (p > 0.05). Regarding safety, there were no serious and/or unexpected adverse events during the study. Conclusions The Esencia lens seems to be efficacious in slowing down progression of myopia in children compared to traditional SCLs in the short term, with comparable safety features and visual outcomes.

Contact lens fitting in nonamblyopigenic anisometropia secondary to monocular aphakia caused by ocular trauma

Anisometropia is characterized by difference between the refractive errors of the eyes and can be classified into refractive and axial. Aniseikonia is one of the possible consequences of anisometropias. As a general rule, aniseikonia tends to be less significant when we correct axial anisometropias with spectacles and refractive anisometropias with contact lens. One of the possible causes of refractive anisometropias is aphakia, which can be a result of ocular trauma. Amblyopia is a visual neurological disorder characterized by inadequate consolidation of visual acuity, due to insufficient visual stimulation. We present a case of contact lens fitting in a patient with significant difference in axial length between the eyes, but without the corresponding anisometropia, since the patient became aphakic after blunt trauma during childhood affecting the eye with the longest axial length, and probably as a consequence of the aphakia, she did not become amblyopic.

Effects of Scleral Contact Lenses for Keratoconus Management on Visual Quality and Intraocular Pressure.

PurposeTo evaluate the visual acuity level achieved by scleral contact lens (CL) fitting in patients affected by keratoconus and to evaluate possible intraocular pressure (IOP) changes during the scleral CL wear using a transpalpebral tonometer.MethodsIn a prospective case series a comparison was made between visual acuity obtained with glasses, RGP and 16.8mm diameter scleral CL in 30 consecutive patients affected by keratoconus. IOP was tested during scleral CL wear by transpalpebral Diaton Tonometer (DT) and also by Goldmann Applanation Tonometer (GAT) before and after scleral CL wear.ResultsThe mean logMAR visual acuity improved from 0.2±0.25SD with glasses and 0.1±0.02SD with RGP, to −0.002±0.041SD when using the scleral CL (p<0.05). The mean IOP value before scleral CL wear was 12.93mmHg±2.20SD when measured with GAT and 7.85mmHg±2.27SD when measured with DT. During scleral CL wear, IOP was assessed through DT, with a mean value of 8.86mmHg±2.36SD; values were stable after 8 hours of scleral CL use. Immediately after scleral CL removal, the mean IOP measured with GAT was 12.85mmHg ±2.40SD and the mean IOP measured with DT was 7.66mmHg±1.88SD. Therefore, during scleral CL wear, it was evidenced a small but statistically significant increase of the mean IOP value (1.01mmHg; p<0.01), with a reversion to values prior to application when scleral CL was removed.ConclusionScleral CLs remarkably improved visual acuity in keratoconus patients when compared to glasses or RGP contact lenses. Even if it was evidenced a small increase of the mean IOP value during their wear, it may not be significant in otherwise healthy eyes. Statistical analysis demonstrated good agreement between GAT and DT but their numerical values presented a constant gap, that should be taken into account when there is a need to relate the DT values to the reference ones.