Lens Fitting Research Articles

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.

Scleral topography and its usefulness in scleral lens fitting

Background: Scleral lenses are one of the best options to manage corneal irregularities and severe ocular surface diseases. As scleral lenses rest on the sclera, scleral topographical data are necessary when fitting these lenses. Aim: The aim of this article was to present a review of the literature on scleral topography and its usefulness in scleral lens fitting. Method: A search was performed by the author with the PubMed database for the literature related to the topic by using a combination of keywords as search criteria. The most specific combination was represented by the junction of keywords (scleral topography and scleral lens fitting). Forty-four articles were related to scleral topography and scleral lens fitting. Results: Fifteen articles were found to be more relevant to the topic and were selected for review. These articles originated from 11 different countries and five continents. Many (60%) of the articles were from European countries. Conclusion: The shape of the anterior surface of the eye beyond the limbus is not rotationally symmetrical, and the asymmetry increases as we move away from the limbus. Scleral topography is important in the fitting of scleral lenses, especially that keratometry measurements cannot be used to predict the base curve of the best fitting scleral lens.

Midday Fogging of Scleral Contact Lenses: Current Perspectives.

Midday fogging is a common problem in scleral lens wear, as particles accumulate in the tear reservoir between the posterior surface of the lens and the front of the ocular surface during wear. As particulate waste collects, symptoms of blurred vision and discomfort arise, typically leading patients to remove their lenses for cleaning, refilling with fresh solution, and reinsertion into the eye. The appearance of the particulate can vary, likely due to different causes for midday fogging. Studies which attempted to identify the particulate have given some insight into some of the causes, but larger studies are needed to identify this debris. Research on lens solutions used for filling the lens reservoir and of various aspects of scleral lens fits have also begun to culminate in the concept that midday fogging may ultimately be related to inflammation. Since scleral lens wearers can have varied and multiple sources of inflammation, strategies in minimizing midday fogging can differ between patients.

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.

Clinical Importance of Sagittal Height in Orthokeratology Lens Fitting

Clinical Importance of Sagittal Height in Orthokeratology Lens Fitting

Fast versus gradual adaptation of soft monthly contact lenses in neophyte wearers

AimTo determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. MethodAcross four sites, 74 neophytes (18–28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0–100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4–6 days and 12–14 days after lens fitting. Subjective scores were also repeated after 7 days. ResultsThere was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4–6 days, but was similar by 12–14 days. Subjective scores were also similar across the visits and lens types with the exception of ‘lens awareness’ (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12–14 days. ConclusionThere seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients.

Miniscleral Contact Lens in Pediatric Age Group: Indications, Safety, and Efficacy.

To report indications, fitting feasibility, and safety of miniscleral design (MSD) lenses in children. Medical records of patients aged <18 years at the time of referral to Contact Lens Clinic of Farabi Eye Hospital, because of inadequate spectacle-corrected visual acuity, rigid gas-permeable or soft contact lens intolerance, and ocular surface disease were reviewed. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), best-corrected vision with the lens (CCVA), lens parameters, and comfortable daily wearing time (CDWT) were documented. Seventy-two eyes of 52 pediatric patients were fitted with MSD lens over a 9-year period. The indications for MSD lens fitting were keratoconus (29 eyes), corneal scarring from ocular trauma (16 eyes), ocular surface diseases (25 eyes), and postkeratitis corneal scar (2 eyes). The average UCVA and the mean difference between CCVA and BSCVA were 1.20 and 0.55 logarithm of the minimal angle of resolution, respectively, which shows statistically significant improvement. This significant increase in vision was even seen in those who were referred for the management of ocular surface diseases. The mean CDWT for most patients was 10 hr/day. Miniscleral design lens can be used as a safe and helpful modality to provide good vision and comfort in children experiencing ectatic disorders, traumatic corneal scars, and ocular surface diseases.

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.

Clinical performance of presbyopia correction with a multifocal corneoscleral lens.

To assess the clinical performance of a multifocal corneoscleral lens for the presbyopia correction. A prospective clinical trial of the Onefit™ A multifocal corneoscleral lens was conducted with 40 participants with presbyopia. At 4wk of continuous wear of the corneoscleral lens, changes in the distance, intermediate, and near visual acuity (VA) were evaluated. The safety of the corneoscleral lens, central corneal thickness (CCT), corneal endothelial cell count, binocular stereopsis, tear film break-up time (BUT), corneal staining, corneal edema, corneal neovascularization (NV), and conjunctival hyperemia were examined. In addition, a subjective questionnaire addressing satisfaction (rated from 1 to 5 points) and discomfort (rated from 1 to 5 points) was administered. Forty participants were enrolled in this study. Six participants were excluded because of poor compliance with lens fitting (n=2) and loss to follow-up (n=4). The mean age of the participants was 53.0±4.9y. At 4wk of continuous wear of the corneoscleral lens, the best corrected far, intermediate, and near VA was 0.08±0.11, 0.10±0.12, and 0.10±0.12 logMAR, respectively. These results were significant improvements over the baseline uncorrected VA (far: P=0.004; intermediate: P=0.004; near: P=0.002). CCT, corneal endothelial cell count, binocular stereopsis, BUT, corneal staining, corneal edema, corneal NV, and conjunctival hyperemia were not significantly different between baseline and after corneoscleral lens use. The average satisfaction scores for fit sensation; corrected far, intermediate, and near VA; and ease of handling were 4.1, 3.4, 3.6, 3.5, and 3.4, respectively. The average discomfort scores for dryness, irritation, foreign body sensation, redness, fogging, and halo were 1.7, 1.8, 1.5, 1.7, 1.7, and 1.3, respectively. Far, intermediate, and near VA are improved in presbyopic patients with the multifocal corneoscleral lens compared to uncorrected baseline VA, without adverse ocular effects. This evidence supports the safety and effectiveness of presbyopia correction with multifocal corneoscleral lenses.

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.

Application of piggy-back lens in the correction of severe keratoconus: A case study.

This is a case study on the application of a piggy-back lens in the correction of severe keratoconus. From the results of general eye examination, refractive state examination, and corneal morphology examination on the patient, it was determined that corneal protrusion and deformation of the right eye were obvious. The right eye was corrected using a piggy-back lens and the left eye with a rigid gas-permeable contact lens (RGPCL) alone. The right-eye lens fit well and the lens coverage was good. Both the static and dynamic fit results for the left-eye lens were good. After wearing the glasses for one month, the patient attended a review and stated that the lenses were comfortable to wear. The patient's vision was good after wearing the lenses. No obvious congestion was found in the conjunctiva under a slit lamp. The effects on both eyes of wearing RGPCLs were favorable. The corneal curvature reduced and the corneal thickness only changed to a small degree. For keratoconus patients, application of a piggy-back lens can improve corrected visual acuity, comfort levels, and safety, prolong the wearing time, and enhance the effect of orthokeratology.

BCLA CLEAR - Scleral lenses

Scleral lenses were the first type of contact lens, developed in the late nineteenth century to restore vision and protect the ocular surface. With the advent of rigid corneal lenses in the middle of the twentieth century and soft lenses in the 1970’s, the use of scleral lenses diminished; in recent times there has been a resurgence in their use driven by advances in manufacturing and ocular imaging technology. Scleral lenses are often the only viable form of contact lens wear across a range of clinical indications and can potentially delay the need for corneal surgery. This report provides a brief historical review of scleral lenses and a detailed account of contemporary scleral lens practice including common indications and recommended terminology. Recent research on ocular surface shape is presented, in addition to a comprehensive account of modern scleral lens fitting and on-eye evaluation. A range of optical and physiological challenges associated with scleral lenses are presented, including options for the clinical management of a range of ocular conditions. Future applications which take advantage of the stability of scleral lenses are also discussed. In summary, this report presents evidence-based recommendations to optimise patient outcomes in modern scleral lens practice.

BCLA CLEAR - Evidence-based contact lens practice

Evidence-based contact lens practice involves finding, appraising and applying research findings as the basis for patient management decisions. These decisions should be informed by the strength of the research study designs that address the question, as well as by the experience of the practitioner and the preferences and environment of the patient. This reports reviews and summarises the published research evidence that is available to inform soft and rigid contact lens history and symptoms taking, anterior eye health examination (including the optimised use of ophthalmic dyes, grading scales, imaging techniques and lid eversion), considerations for contact lens selection (including the ocular surface measurements required to select the most appropriate lens parameter, lens modality and material selection), evaluation of lens fit, prescribing (teaching self-application and removal, adaptation, care regimen and cleaning instructions, as well as minimising risks of lens wear through encouraging compliance) and an aftercare routine.

“OKVision® SMARTFIT™” Customizable Mini-Scleral Lenses Fitting Guide

As of today, scleral lenses are the only optical rehabilitation method that provides high visual quality of vision for patients with irregular cornea. This fitting guide is aimed at helping ophthalmologists acquire professional knowledge in the field of fitting scleral lenses and suggest tactics for managing patients with irregular corneas.The workshop outlines indications for prescribing scleral lenses, describes the basic principles of lens parameters calculation and fitting, taking into account the patientspecific parameters of the eyes. In addition, guidelines for acquiring skills in assessing and changing the position of scleral lenses on the patient’s eye, using customization options, daily care, manipulations for inserting on and removing lenses, and further dispensary observation are given.Mastering the basic skills of calculation and fitting customized scleral lenses helps practitioners expand their areas of practice, enhance professional competitiveness and provide patients with high quality vision, even in the most difficult clinical cases.

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.

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™.