Gaze and behavioural metrics in the refractive correction of presbyopia

PURPOSE

To investigate gaze and behavioural metrics at different viewing distances with multifocal contact lenses (MFCLs), single vision contact lenses (SVCLs) and progressive addition lenses (PALs).

METHODS

Fifteen presbyopic contact lens wearers participated over five separate study visits. At each visit, participants were randomly assigned to wear one of five refractive corrections: habitual PAL spectacles, delefilcon A (Alcon Inc.) MFCLs and three separate pairs of delefilcon A single vision lenses worn as distance, intermediate and near corrections. Participants wore a Pupil Core headset to record eye and head movements while performing three visual tasks: reading, visual search and scene observation. Data were investigated using linear regression and post-hoc testing. Parameters of interest included gaze (fixation duration, head movement) and behavioural (reading speed, reading accuracy, visual search time) metrics.

RESULTS

Reading speed in SVCLs was significantly faster than in MFCLs and PAL spectacles (F = 16.3, p < 0.0001). Refractive correction worn did not influence visual search times (F = 0.16, p = 0.85). Fixation duration was significantly affected by the type of visual task (F = 60.2, p < 0.001), and an interaction effect was observed between viewing distance and refractive correction (F = 4.3, p = 0.002). There was significantly more horizontal and vertical head movement (F = 3.2, p = 0.01 and F = 3.3, p = 0.01, respectively) during visual search tasks when wearing PAL spectacles compared to SVCLs or MFCLs.

CONCLUSION

This work showed that the type of refractive correction affects behavioural metrics such as reading speed and gaze behaviour by affecting horizontal and vertical head movements. The findings of this study suggest that under certain conditions, wearers of MFCLs make fewer head movements compared to PAL spectacles. Gaze behaviour metrics offer a new approach to compare and understand contact lens and spectacle performance, with potential applications including peripheral optical designs for myopia management.

End-of-day assessment of asymptomatic versus highly symptomatic soft contact lens wearers

PURPOSE

To investigate differences in key clinical parameters between asymptomatic and highly symptomatic soft contact lens (CL) wearers after 14 h of wear.

METHODS

In this pilot investigation, Phase 1 identified asymptomatic (CLDEQ-8 score ≤ 7) and highly symptomatic (CLDEQ-8 score ≥ 20) subjects after fitting with nelfilcon A CLs. Phase 2 investigated the following over a single nelfilcon A CL-wearing day (14 ± 2 h): blinking characteristics, tear meniscus height (TMH), non-invasive tear break-up time (NIBUT), tear film osmolarity and eyelid margin staining. Parameters for the two groups were compared using linear mixed models and post-hoc testing. The relationship between comfort scores and the clinical parameters was also investigated.

RESULTS

Overall, 161 and 42 subjects were enrolled into Phase 1 and 2, respectively. Twenty-five asymptomatic and 17 symptomatic subjects completed Phase 2. Lower eyelid TMH was decreased after 14 h in symptomatic compared with asymptomatic subjects (least square mean [LSM] difference -0.04 mm, 95% CI: -0.07, -0.01). Osmolarity was lower in symptomatic than in asymptomatic subjects at fitting (LSM difference -9.89, 95% CI: -18.91, -0.86). Upper eyelid margin staining was greater after 14 h in symptomatic than in asymptomatic subjects (LSM difference 0.53, 95% CI: 0.01, 1.05) and greater after 14 h than baseline in the symptomatic group (LSM difference 0.61, 95% CI: 0.16, 1.07). There was a significant relationship between comfort and upper eyelid margin staining (r = -0.40, 95% CI: -0.63, -0.11) and blink rate (r = -0.31, 95% CI: -0.57, -0.003).

CONCLUSION

The potential parameters most effective in differentiating asymptomatic from symptomatic wearers were upper eyelid margin staining and lower TMH. The parameter with the strongest relationship to comfort was upper eyelid margin staining, where higher comfort scores were associated with lower levels of staining.

Temporal variations in meibomian gland structure-A pilot study

PURPOSE

To investigate whether there is a measurable change in meibomian gland morphological characteristics over the course of a day (12 h) and over a month.

METHODS

The study enrolled 15 participants who attended a total of 11 study visits spanning a 5-week period. To assess diurnal changes in meibomian glands, seven visits were conducted on a single day, each 2 h apart. For monthly assessment, participants attended an additional visit at the same time of the day every week for three consecutive weeks. Meibography using the LipiView® II system was performed at each visit, and meibomian gland morphological parameters were calculated using custom semi-automated software. Specifically, six central glands were analysed for gland length ratio, gland width, gland area, gland intensity and gland tortuosity.

RESULTS

The average meibomian gland morphological metrics did not exhibit significant changes during the course of a day or over a month. Nonetheless, certain individual gland metrics demonstrated notable variation over time, both diurnally and monthly. Specifically, meibomian gland length ratio, area, width and tortuosity exhibited significant changes both diurnally and monthly when assessed on a gland-by-gland basis.

CONCLUSIONS

Meibomian glands demonstrated measurable structural change over short periods of time (hours and days). These results have implications for innovation in gland imaging and for developing precision monitoring of gland structure to assess meibomian gland health more accurately.

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

BCLA CLEAR Presbyopia: Management with contact lenses and spectacles

This paper seeks to outline the history, market situation, clinical management and product performance related to the correction of presbyopia with both contact lenses and spectacles. The history of the development of various optical forms of presbyopic correction are reviewed, and an overview is presented of the current market status of contact lenses and spectacles. Clinical considerations in the fitting and aftercare of presbyopic contact lens and spectacle lens wearers are presented, with general recommendations for best practice. Current options for contact lens correction of presbyopia include soft simultaneous, rigid translating and rigid simultaneous designs, in addition to monovision. Spectacle options include single vision lenses, bifocal lenses and a range of progressive addition lenses. The comparative performance of both contact lens and spectacle lens options is presented. With a significant proportion of the global population now being presbyopic, this overview is particularly timely and is designed to act as a guide for researchers, industry and eyecare practitioners alike.

BCLA CLEAR Presbyopia: Definitions

Presbyopia is often the first sign of ageing experienced by humans. Standardising terminology and adopting it across the BCLA CLEAR Presbyopia reports, improves consistency in the communication of the evidence-based understanding of this universal physiological process. Presbyopia can be functionally and psychologically debilitating, especially for those with poor access to eyecare. Presbyopia was defined as occurring when the physiologically normal age-related reduction in the eye's focusing range reaches a point that, when optimally corrected for far vision, the clarity of vision at near is insufficient to satisfy an individual's requirements. Accommodation is the change in optical power of the eye due to a change in crystalline lens shape and position, whereas pseudo-accommodation is the attainment of functional near vision in an emmetropic or far-corrected eye without changing the refractive power of the eye. Other definitions specific to vision and lenses for presbyopia were also defined. It is recommended that these definitions be consistently adopted in order to standardise future research, clinical evaluations and education.

A Deep Learning Approach for Meibomian Gland Appearance Evaluation

Purpose

To develop and evaluate a deep learning algorithm for Meibomian gland characteristics calculation.

Design

Evaluation of diagnostic technology.

Subjects

A total of 1616 meibography images of both the upper (697) and lower (919) eyelids from a total of 282 individuals.

Methods

Images were collected using the LipiView II device. All the provided data were split into 3 sets: the training, validation, and test sets. Data partitions used proportions of 70/10/20% and included data from 2 optometry settings. Each set was separately partitioned with these proportions, resulting in a balanced distribution of data from both settings. The images were divided based on patient identifiers, such that all images collected for one participant could end up only in one set. The labeled images were used to train a deep learning model, which was subsequently used for Meibomian gland segmentation. The model was then applied to calculate individual Meibomian gland metrics. Interreader agreement and agreement between manual and automated methods for Meibomian gland segmentation were also carried out to assess the accuracy of the automated approach.

Main Outcome Measures

Meibomian gland metrics, including length ratio, area, tortuosity, intensity, and width, were measured. Additionally, the performance of the automated algorithms was evaluated using the aggregated Jaccard index.

Results

The proposed semantic segmentation-based approach achieved average aggregated Jaccard index of mean 0.4718 (95% confidence interval [CI], 0.4680-0.4771) for the 'gland' class and a mean of 0.8470 (95% CI, 0.8432-0.8508) for the 'eyelid' class. The result for object detection-based approach was a mean of 0.4476 (95% CI, 0.4426-0.4533). Both artificial intelligence-based algorithms underestimated area, length ratio, tortuosity, widthmean, widthmedian, width10th, and width90th. Meibomian gland intensity was overestimated by both algorithms compared with the manual approach. The object detection-based algorithm seems to be as reliable as the manual approach only for Meibomian gland width10th calculation.

Conclusions

The proposed approach can successfully segment Meibomian glands; however, to overcome problems with gland overlap and lack of image sharpness, the proposed method requires further development. The study presents another approach to utilizing automated, artificial intelligence-based methods in Meibomian gland health assessment that may assist clinicians in the diagnosis, treatment, and management of Meibomian gland dysfunction.

Financial Disclosures

The authors have no proprietary or commercial interest in any materials discussed in this article.

Evaluation of Meibomian gland structure and appearance after therapeutic Meibomian gland expression

CLINICAL RELEVANCE

Evaluating how Meibomian glands can change in appearance has the potential to advance the understanding of Meibomian gland health and may lead to enhanced diagnosis and therapy.

BACKGROUND

This work aimed to investigate Meibomian gland appearance after therapeutic Meibomian gland expression.

METHODS

Fifteen subjects attended three study visits over a two-week period. Meibography was performed before and after therapeutic Meibomian gland expression, the following day, and 2 weeks after expression. Six central glands were used to calculate Meibomian gland morphological parameters such as gland length ratio, gland width, gland area, gland tortuosity, and gland contrast. A custom semi-automated image analysis software was used to calculate Meibomian gland metrics. Furthermore, a high-resolution imaging system was developed to capture clear images of the Meibomian glands, free of any artefacts, which were used for precise calculations of Meibomian gland contrast.

RESULTS

The expression procedure had a significant impact on Meibomian gland contrast and length ratio immediately afterwards. The least square mean difference (95% CI) from baseline for Michelson contrast was -0.006 (-0.010, -0.001) and -1.048 (-2.063, -0.033) for simple contrast. The least square mean ratio of the gland length ratio immediately after the expression to baseline was 0.758 (0.618, 0.931).

CONCLUSIONS

Following therapeutic expression, Meibomian glands exhibit reduced brightness and length. However, within 24 h, they appear to recover and return to their baseline state, indicating a relatively short recovery time. This sheds light on whether meibography is solely focused on capturing gland structure or if it also captures acinar activity. The hyperreflective properties of lipids suggest that the decrease in contrast observed after expression could be attributed to a reduction in the visualisation of acini activity. A decrease in Meibomian gland length ratio implies that the loss of gland structure following treatment may be indicative of a temporary structural alteration.

Clinical performance and Willingness To Pay for soft toric contact lenses in low and moderate astigmats

PURPOSE

To determine clinical performance and the 'Willingness To Pay' for toric vs. spherical soft contact lenses in an astigmatic population.

METHODS

In the clinical study, subjects with binocular low to moderate astigmatism (-0.75DC to -1.50DC) wore pairs of soft toric (Biofinity toric) and spherical (Biofinity) contact lenses in random sequence. Visual acuity (high and low contrast, monocular and binocular), subjective comfort and subjective vision were recorded. In the economics study, first subjects who had participated in the clinical study were presented with a series of randomised economic scenarios in order to determine their Willingness To Pay a premium (i.e. an increase) for toric lenses. Then, a similar set of scenarios were presented to a much larger group of online respondents and again, Willingness To Pay was established.

RESULTS

For the four measures of visual acuity, the Biofinity toric lens out-performed the Biofinity spherical lens by 0.6 to 1.1 lines.. Subjective vision performance was statistically significantly better with the toric lens for the distance task only. Comfort scores were not significantly different. Similar findings for Willingness To Pay were established for the clinical subjects and for the online respondents. The Willingness To Pay premium (additional fee) for a monthly supply of toric lenses (over spherical lenses) was between £13 and £16, if a toric lens provides better vision and similar comfort, as shown in the clinical study.

CONCLUSION

Consumers are willing to pay a monthly premium of around 50% to benefit from the typical experience of better vision and similar comfort for toric vs. spherical lenses. The level of additional cost for toric lenses compared to their spherical equivalents is less than this in the market, so eye care professionals should consider that toric lenses are delivering a greater clinical return than anticipated by wearers for the relatively small increase in price.

Who cites optometry journals?

PURPOSE

This work seeks to identify the most impactful journals, papers, authors, institutions, and countries that cite optometry journal articles.

METHODS

The Scopus database was searched for papers citing at least one article published in any of the 18 optometry journals included in that database (i.e. 'optometry articles'). The 10 most highly cited papers that cite optometry journal articles were determined from 82,830 papers found. A h-index for "optometry journal citations" (the hOJC-index) was derived for each entity in the categories of journals, papers, authors, institutions and countries to serve as a measure of impact.

RESULTS

The hOJC-index of the body of papers citing optometry journal articles is 370. Papers citing optometry journal articles have themselves been cited 2,054,816 times. Investigative Ophthalmology & Visual Science (hOJC = 154) is the most impactful journal citing optometry articles and Optometry and Vision Science the most prolific (5310 papers). The most impactful paper citing optometry journal articles (5725 citations) was published in Journal of Clinical Epidemiology. Ophthalmologist Seang Mei Saw (hOJC = 69) is the most impactful author and optometrist Nathan Efron is the most prolific (288 papers). Harvard University (hOJC = 127) is the most impactful and UNSW Sydney is the most prolific institution (1761 papers). The United States is the most impactful and prolific nation (hOJC = 313; 28,485 papers).

CONCLUSIONS

Optometry journal articles are cited extensively by optometrists, ophthalmologists, and vision scientists world-wide, as well as authors from a broad spectrum of non-ophthalmic research domains. This work confirms the utility and influence of optometry journals.

Bibliometric Analysis of Ophthalmic Journals

Importance

The primary vehicle for reporting and testing advances in eye care is refereed ophthalmic journals, which can be characterized using targeted bibliometric analyses.

Objective

To identify all ophthalmic journals and evaluate citation metrics relating to articles, journals, authors, institutions, and countries published therein.

Design and Setting

A bibliometric analysis was undertaken of all ophthalmic journals included in the Scopus database (Elsevier). The search was restricted to all article types published in ophthalmic journals in English from inception through November 18, 2022. After excluding general medical journals, journals published in a language other than English, and spurious titles unrelated to the ophthalmic field, the Scopus database was found to list 335 ophthalmic journal titles that have published 471 184 articles, constituting the data set for this analysis. The 20 most highly cited articles were identified. Rank-order lists by article count were assembled for journals, authors, institutions, and countries.

Main Outcomes and Measures

An h-index for ophthalmic journal articles was derived from citations and article counts for each constituent of each category.

Results

The h-index for ophthalmic journal articles was determined to be 494. The journal with the highest h-index was Ophthalmology (h-index, 297). The journal with the greatest number of articles was American Journal of Ophthalmology (38 441 articles). The most highly cited article was by Quigley and Broman, 2006 (5147 citations), concerning the epidemiology of glaucoma. The author with the highest h-index for ophthalmic journal articles was Ronald Klein, MD (h-index, 126), and the most prolific was Carol L. Shields, MD (1400 articles). Johns Hopkins University (h-index, 215) was the institution with the highest h-index for ophthalmic journal articles, and Harvard University was the most prolific (10 071 articles). The United States was the nation with the highest h-index for ophthalmic journal articles (h-index, 444) and was the most prolific (180 017 articles).

Conclusions and Relevance

In this study, the most highly cited articles published in ophthalmic journals were revealed, as well as the leading journals, authors, institutions, and countries. While excluding ophthalmology articles in general medical journals, this investigation affords a means of identifying highly cited authors, institutions, and countries which individuals or institutions can use as a guide regarding contributions to the field.

Challenges to the new soft contact lens wearer and strategies for clinical management

Soft contact lens discontinuations have a dramatic impact on the overall success of this form of vision correction, and evidence suggests that the reasons for contact lens cessation are different for new wearers than for established lens users. In descending order, these relate to vision, discomfort, handling, inconvenience/loss of interest, ocular health and cost. This paper considers the background and underlying evidence for these causes of soft lens discontinuation in new wearers, and presents clinical management strategies to minimise this phenomenon. Such measures can reasonably be expected to significantly reduce the number of contact lens discontinuations leading to happier patients, increased satisfaction for eye care professionals (ECPs), and greater success for both individual practices and the contact lens industry more broadly.

Development of Artefact-Free Imaging System for Accurate Meibomian Gland Reflectivity Assessment

Purpose

To develop and evaluate a custom imaging system to provide high-resolution, wide depth-of-field, reflection-free, multispectral infrared (IR) imaging of the Meibomian glands.

Methods

Lower eyelids of 15 volunteers were everted to obtain multispectral images of the Meibomian glands with custom imaging setup. Photographs were captured at 10 different ISO settings (from underexposure to overexposure) and using nine IR imaging filters (ranging from 600 nm to 1000 nm in 50-nm steps). Meibomian gland contrast (simple and Michelson) was calculated for the images to choose an optimal wavelength for Meibomian gland imaging and to determine differences in contrast across individuals.

Results

The overall linear regression model showed a significant effect of wavelength on Meibomian gland contrast (Simple contrast: F = 7.24, P < 0.0001; Michelson contrast: F = 7.19, P < 0.0001). There was a significant negative correlation between Meibomian gland contrast and Meibomian gland depth for 750-nm IR filter (ρs= -0.579; P = 0.026).

Conclusions

Meibomian gland contrast varies across individuals and depends on Meibomian gland depth. IR filter of 750 nm is the optimal choice for Meibomian gland imaging because it provides images of greatest contrast.

Translational Relevance

This study adds to our understanding of Meibomian gland imaging. It has successfully demonstrated that Meibomian glands that are deeper in the tarsal plate require longer wavelengths for imaging.

Affluence and Contact Lens Prescribing

OBJECTIVES

To assess the impact of national affluence on the extent of prescribing of various types of soft contact lenses.

METHODS

Using information derived from a large bank of contact lens prescribing data, the relationship between the percentage prescribing of daily disposable, toric, silicone hydrogel, and multifocal contact lenses versus the gross domestic product at purchasing parity per capita (GDP [PPP]) was determined for all countries in which contact lens prescribers returned survey forms relating to greater than 100 contact lens fits between 2017 and 2021, inclusive.

RESULTS

Data from 39 countries were analyzed, comprising 94,181 contact lens fits. The relationship between percentage contact lens prescribing versus GDP (PPP) was highly statistically significant for daily disposable lenses (r 2 =0.35, P <0.0001), marginally significant for toric lenses (r 2 =0.08, P =0.06), and not significant for silicone hydrogel lenses (r 2 =0.01, P =0.42) or multifocal lenses (r 2 =0.02, P =0.35).

CONCLUSIONS

The rate of prescribing daily disposable contact lenses, and to a lesser extent toric lenses, is related to national affluence. The contact lens industry, practitioners, and governments/regulatory bodies should remain cognizant of this association and, where possible, reduce cost barriers to the purchase of such contact lens products so that they can be prescribed based on important clinical, refraction, and lifestyle considerations.

Global contact lens prescribing 2000-2020

CLINICAL RELEVANCE

Contact lens prescribing data serve as a benchmark for eye care clinicians in assessing their own prescribing patterns and provide useful contextual information for researchers and the contact lens industry.

PURPOSE

To document global trends in contact lens prescribing during the first two decades of this century.

METHODS

A longitudinal survey of contact lens prescribing was conducted by asking contact lens practitioners to provide 11 items of information from 10 consecutive contact lens fits between January and March each year from 1996 to 2020, inclusive.

RESULTS

Data relating to 406,859 contact lens fits were collected from 71 countries between 1996 and 2020, generating 4.5 million data points. Demographic analysis for 61 nations returning ≥100 fits demonstrated that a majority of lenses (65-70%) were fitted to females. The average age of lens wearers was 30.8 ± 13.9 years for males and 32.5 ± 14.3 years for females. Trend analysis of 20 countries returning prescribing data for ≥13 years between 2000 and 2020 revealed the following: increase in the age of lens wearers; dramatic rise in the extent of fitting silicone hydrogel and daily disposable lenses; increased fitting of soft toric and multifocal lenses; increasing proportion of rigid lens fits in specialist (non-spherical) designs; incomplete provision of near contact lens corrections for contact lens wearing presbyopes; ongoing low levels of extended wear fits; and almost exclusive use of multi-purpose care systems. Daily disposable lenses were used for both full-time and part-time wear, whereas rigid and soft reusable lenses were primarily worn full time.

CONCLUSIONS

The evolution of international contact lens fitting over the first two decades of this century is documented. The data presented here may assist all stakeholders in advancing contact lens clinical practice, informing contact lens research, and guiding contact lens manufacturers.

The impact of COVID-19 on global contact lens education

PURPOSE

To investigate the effects of the global COVID-19 pandemic on contact lens education around the world.

METHODS

An online survey among contact lens educators (educator members of the International Association of Contact Lens Educators), conducted in May 2020.

RESULTS

A total of 214 responses were received from 32 countries (representing a 39% response rate). Overall, 71% of respondents' institutions were closed to students to attend at that time. A majority (58%) were delivering more online education than they would normally provide. Live online lectures and discussion was the most commonly used method (68%). Zoom was the most common videoconferencing technology (56%) and the most popular social media platform for communicating with students was WhatsApp (48%). About half (54%) were running online exams or assessments, 24% holding these for students to attend in person, and 27% were conducting practical sessions. Two in three (68%) said they would conduct more than 50% of their total teaching online by the end of 2020, and 12% anticipated 90% or more of their teaching would be online. Of all respondents, 74% expressed interest in an online platform delivering educational resources.

CONCLUSION

The COVID-19 pandemic has had a major impact on the teaching of contact lenses, as educational institutions worldwide move to online delivery. Major challenges remain with online contact lens education, with respect to teaching practical skills, student assessment and interaction. More support will be needed for educators to meet these challenges as the recovery from the pandemic continues.

Global optometrist research ranking derived from a science-wide author database of standardised citation indicators

CLINICAL RELEVANCE

Publications in refereed scientific journals provide a rigorous research base that underpins clinical optometric practice. Leading optometrists who generate this literature can be identified and ranked using standardised citation indicators.

BACKGROUND

This work seeks to identify and rank all optometrists included in a Science-Wide author database of standardised citation indicators (S-W) and to compare this ranking with the Global Optometrist Top 200 Research Ranking (T200).

METHODS

A search was conducted for the names of all optometrists in the T200 who were included in the S-W, which is a world-wide listing of the top 2% of scientists in each of 174 subfield disciplines, ranked according to a composite citation indicator (c_ns) that excludes self-citations and corrects for multiple authorships and author order.

RESULTS

The names of 66 optometrists are found in the S-W. Of these, 58 are designated as working in the primary sub-field 'Ophthalmology & Optometry'; this listing, in rank-order of c_ns, is referred to as the 'S-W-derived Optometrist Research Ranking' (S-WORR). Australian optometrist Nathan Efron is ranked #1 in the S-WORR. The number (%) of optometrists in the S-WORR from each country is: the United States - 26 (45%), Australia - 12 (21%), the United Kingdom - 11 (19%), Canada - 5 (9%), Spain - 2 (3%), Hong Kong - 1 (2%) and South Africa - 1 (2%). The universities housing the equal highest number of optometrists in the S-WORR (five each) are the University of California, Berkeley, USA; the University of New South Wales, Australia; and Queensland University of Technology, Australia. There is a moderately strong correlation between T200 and S-WORR rankings (ρ = 0.6017, N = 58, p < 0.0001).

CONCLUSIONS

The S-WORR represents an elite cohort of optometrists who ought to be celebrated for their outstanding, leading and impactful contributions to optometric research.

Bibliometric analysis of the keratoconus literature

CLINICAL RELEVANCE

Clinicians, researchers funding agencies and indeed the general public can benefit from knowledge of the most highly cited papers and most impactful authors, institutions, countries and journals in the field of keratoconus.

BACKGROUND

Bibliometrics relating to the keratoconus literature were derived to enable identification of the most impactful papers published, as well as the leading authors, institutions, countries and journals.

METHODS

A search was undertaken of the titles of papers on the Scopus database to identify keratoconus-related articles. The 20 most highly cited papers were determined from the total list of 4,419 papers found. Rank-order lists by count were assembled for the 'top 20' in each of four categories: authors, institutions, countries and journals. A subject-specific keratoconus-related h-index (h_KC-index) was derived for each constituent of each category to serve as a measure of impact in the field. The top 10 constituents of each category were ranked by h_KC-index and tabulated for consideration.

RESULTS

The h_KC-index of the keratoconus field is 125. The 4,419 papers have been cited a total of 98,010 times, and 18.5% of these papers have never been cited. The most highly cited paper is a general review of keratoconus by Yaron Rabinowitz, who is also the most impactful author in the field (h_KC = 31). The Cedars Sinai Medical Center in the United States produces the most impactful keratoconus-related papers (h_KC = 36), and the United States is the most impactful country (h_KC = 91). The Journal of Cataract and Refractive Surgery is the most impactful journal (h_KC = 55).

CONCLUSION

Keratoconus is a topic of high interest in the clinical and scientific literature. Highly cited papers and impactful authors, institutions, countries and journals are identified.

Topical Review: Bibliometric Analysis of the Emerging Field of Myopia Management

SIGNIFICANCE

Identification of the most impactful articles, authors, institutions, countries, and journals in myopia management provides a useful baseline reference for clinicians, researchers, and funding agencies in respect of this emerging field.This work aims to assemble publication metrics for myopia management to identify the most impactful articles, authors, institutions, countries, and journals in this emerging field of research. A search of the titles of articles was undertaken on the Scopus database to identify myopia management-related articles. The 25 most highly cited articles were determined from the total list of 1064 articles found. Rank-order lists by count were assembled for the top 25 in each of four categories: authors, institutions, countries, and journals. A subject-specific myopia management-related h-index (hMM-index) was derived for the entire field, in addition to each of the four categories, to serve as measures of impact in the field. Top 15 lists were generated for each category ranked by hMM-index and tabulated for consideration. An article by Christine Wildsoet and colleagues, describing choroidal and scleral mechanisms of compensation for spectacle lenses in chicks, has generated the most citations (412); Earl Smith is the most impactful author (hMM = 19); the University of Houston produces the most impactful articles (hMM = 31); the United States is the most highly ranked country (hMM = 60); and Optometry and Vision Science is the most impactful journal. Although still in its infancy, myopia management is a topic of emerging interest in the clinical and scientific ophthalmic literature. Impactful authors, institutions, countries, and journals are identified. Optometry is revealed as the leading profession in relation to the publication of myopia management-related articles.

Effect of material and care system combination on subclinical inflammation of the ocular surface in soft contact lens wear

PURPOSE

To investigate the ocular subclinical inflammatory response in two soft contact lens materials when used in combination with two different care systems ('solutions').

METHODS

Fifteen established soft contact lens wearers wore each of two lenses: Acuvue® 2 (CH) and Acuvue® Oasys® (SiH) or no lenses in random sequence for one week. Two care systems were used: a peroxide system: Oxysept 1 Step® (P) for the right lens and Opti-Free® Replenish® (MPS) for the left lens. After one week of lens/no lens wear, in vivo confocal microscopy (IVCM) of corneal and conjunctival regions was carried out. Density of presumed dendritic cells (DC) and 'white spots' (WS) were quantified. Impression cytology of the bulbar and upper eyelid margin conjunctivae was carried out and samples were analysed for CD45+, CD3+ and CD11c+ cells.

RESULTS

The SiH + MPS combination showed a greater inflammatory response compared to SiH + P in seven out of 12 parameters investigated (p < 0.05). The remaining five were not statistically different between the two solutions. The converse was found for the CH lens, with four of the 12 parameters showing a greater response with the P solution compared to the MPS (p < 0.05).

CONCLUSION

This study suggests that the SiH lens investigated demonstrated an upregulated response when used with a MPS compared to a P solution whereas the converse is true for the CH lens which showed a reduced response when used with a MPS compared to a P solution. This finding aids in the understanding of the biological underpinnings of manifest corneal inflammatory events during contact lens wear.

On the art and science of rigid contact lens fitting

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 25' in each of four categories: authors, institutions, countries and journals. A subject-specific rigid contact lens h-index (h_RL-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 h_RL-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 (h_RL = 20; 32 papers) and Richard Hill (h = 10; 50 papers) are most impactful and prolific authors, respectively. The Ohio State University (h_RL = 24; 96 papers) is the most impactful and prolific institution and the United States (h_RL = 51; 680 papers) is the most impactful and prolific country. Optometry and Vision Science (h_RL = 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.

Use of silicone hydrogel contact lenses by Australian optometrists

BACKGROUND

Prior to the launch of silicone hydrogel (Si-H) materials in Australia in 1999, only 1.6 per cent of lenses were prescribed on a continuous wear basis.

METHODS

One thousand surveys were distributed randomly to practitioners in Australia during January 2000, 2001 and 2002 (total surveys 3000). Each anonymous survey requested data about the next 10 patients fitted with contact lenses, including date, age, gender, new fitting or refitting, lens material type, lens design, frequency of replacement, modality of wear, uses per week and care regimen.

RESULTS

Twenty per cent (599) were returned, reporting data on 5976 fittings. A total of 710 fittings used Si-H contact lenses (11.9 per cent), which represented 18.6 per cent of all soft lens fittings. During the three years, the proportion of practitioners prescribing Si-H lenses increased from 42.2 to 52.5 per cent. In 2000, 43.8 per cent were daily wear, which decreased to 32.2 per cent by 2002. The solution system of choice for daily wear lenses was multipurpose solutions (98.4 per cent); the only alternative was hydrogen peroxide systems. Continuous wear represented 11.7 per cent of all fittings, of which 85.7 per cent were Si-H, 3.0 per cent RGP lenses and 11.3 per cent conventional hydrogels. For continuous wear, 79.0 per cent of fittings were to existing wearers, whereas for daily wear, 59.4 per cent were existing wearers. More males were prescribed Si-H continuous wear contact lenses, while females were more likely to be prescribed Si-H on a daily wear basis.

DISCUSSION

Si-H contact lenses were introduced to the Australian market as a continuous wear contact lens, yet many practitioners use this product for daily wear with multipurpose solutions. By 2002, more practitioners were prescribing Si-H contact lenses for continuous wear than in 2000, suggesting a growing confidence in that product for that mode of wear. A comparison with an earlier survey shows there is an increase in continuous wear from 1.6 per cent to 11.7 per cent over a five-year period.

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

PURPOSE

To document contact lens prescribing trends in the United Kingdom over the past quarter of a century.

METHODS

An 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.

RESULTS

Over 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.

CONCLUSIONS

This 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.

CLEAR - Effect of contact lens materials and designs on the anatomy and physiology of the eye

This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia). However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation. In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.

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.

An investigation into disposal and recycling options for daily disposable and monthly replacement soft contact lens modalities

PURPOSE

To examine the annualised waste and end-of-life disposal options with two representative soft contact lens (CL) modalities.

METHODS

The component parts of two representative soft CL modalities were catalogued, separated, weighed and inspected for material identification: somofilcon A soft CLs (clariti elite, CooperVision Inc.) used with multi-purpose solution (MPS) (All in one Light, CooperVision Inc.) and somofilcon A CLs (clariti 1 day, CooperVision Inc). Using a model that assumed compliant wear and care of CLs, the mass of material solid waste generated by CL use over a year was calculated. Disposal options were explored using household and specialist recycling streams in order to develop recommendations for responsible disposal of CL waste.

RESULTS

Full-time daily disposable (DD) CL wear generates 1.06 kg of waste annually compared to 0.83 kg generated by reusable-monthly replacement daily wear ('reusable') CLs. Plastic was the dominant material in both modalities. With full-time use of DD CLs, 64% of waste by mass was plastic blister trays. For full-time use of reusable CLs, where figures from lens and MPS packaging are combined, plastics accounted for 67% of waste by mass. MPS bottles alone made up almost half the waste (45%) associated with full-time reusable CL wear.

CONCLUSION

Full-time DD wear generates 27% more waste annually than full-time reusable lens wear. Reusable CL wearers can recycle 78% of waste at home. DD lens wearers have access to recycling options that allow them to recycle 100% of CL related waste. Full-time CL lens wear represents just 0.20-0.26% of the 412 kg of household waste generated per person, per year in the United Kingdom. Worn CLs should never be disposed of down the sink or lavatory. CL wearers should be aware of responsible end-of-life recycling and disposal options for all CL waste.

Global optometrist top 200 research ranking

Clinical relevance: Clinical optometric practice is underpinned by a rigorous research base, the primary evidence for which is publications in refereed scientific journals. Leading optometrists who publish this work should be identified and celebrated.Background: This work aims to derive publication metrics of the leading optometric researchers worldwide.Methods: An extensive global search was conducted to discover leading optometric researchers; 480 names were identified. A custom-designed bibliographic search tool was developed to interrogate the Scopus database (Elsevier) and extract publication metrics using the unique Scopus Author Identifier number for each optometrist. On 13 January 2021, the full list was reduced to 200 optometrists (the 'Top 200') ranked by h-index - the 'Global Optometrist Top 200 Research Ranking'. The output from the custom tool automatically updates every 24 hours and is available at www.optomrankings.com.Results: The Top 200 have h-indices ranging from 20 to 67 and have published between 28 and 440 papers. Sixty one (30.5%) are women. Konrad Pesudovs has the highest h-index (67) and citations (51,193). The most prolific author is Robert Hess (442 papers). David Piñero is publishing at the fastest rate (17.6 papers per year). The Top 200 work in 13 nations, of whom 172 (86.0%) work in four nations: USA - 76 (38.0%), Australia - 43 (21.5%), UK - 41 (20.5%) and Canada - 16 (8.0%). Of the 72 institutions represented, the University of California, Berkeley, USA is home to the most Top 200 optometrists (17) and has the highest combined h-index of Top 200 optometrists (132).Conclusions: The optometric profession is supported by a robust research base, prosecuted by a large international cohort of optometric researchers who publish extensively on a broad range of ophthalmic issues and whose work is highly cited. The 200 most impactful optometrists in the world are identified.

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.

The association of comfort and vision in soft toric contact lens wear

PURPOSE

This work set out to investigate if there was an association between subjective comfort and both subjective and measured vision during the use of contemporary daily disposable soft toric contact lenses.

METHODS

Thirty-eight habitual soft contact lens wearers wore each of three daily disposable toric lenses for one week in a prospective, crossover, randomised, single-masked study. The following clinical measures were recorded at dispensing and follow-up visits: biomicroscopy scores, lens fitting (including rotation and rotational stability), high and low contrast visual acuity, subjective vision quality and subjective ocular surface comfort. Subjective scores were collected using 0-10 numerical grading scales. Comfort scores were analysed using a linear regression model with age, sex, visit, phase of crossover ('phase'), lens type, lens rotation, lens rotational stability, visual acuity, cylinder power and subjective vision quality as factors of interest and then refined using backward stepwise regression.

RESULTS

Thirty six participants (31.1 ± 13.5 years) completed the study. Comfort scores were found to be associated with subjective vision quality (F = 127.0 ; p < 0.0001), phase (F = 7.2; p = 0.001) and lens type (F = 4.9; p = 0.009). Greater comfort scores were observed with greater subjective vision quality scores. Visual acuity was not statistically significant in the model.

CONCLUSION

This work suggests that symptoms of ocular discomfort may be more intense if there is also perceived visual compromise in daily disposable soft toric lenses. There was a stronger positive correlation between comfort and subjective vision quality compared with comfort and measured visual acuity.

The ocular surface, coronaviruses and COVID-19

The ocular surface has been suggested as a site of infection with Coronavirus‐2 (SARS‐CoV‐2) responsible for the coronavirus disease‐19 (COVID‐19). This review examines the evidence for this hypothesis, and its implications for clinical practice. Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2), responsible for the COVID‐19 pandemic, is transmitted by person‐to‐person contact, via airborne droplets, or through contact with contaminated surfaces. SARS‐CoV‐2 binds to angiotensin converting enzyme‐2 (ACE2) to facilitate infection in humans. This review sets out to evaluate evidence for the ocular surface as a route of infection. A literature search in this area was conducted on 15 April 2020 using the Scopus database. In total, 287 results were returned and reviewed. There is preliminary evidence for ACE2 expression on corneal and conjunctival cells, but most of the other receptors to which coronaviruses bind appear to be found under epithelia of the ocular surface. Evidence from animal studies is limited, with a single study suggesting viral particles on the eye can travel to the lung, resulting in very mild infection. Coronavirus infection is rarely associated with conjunctivitis, with occasional cases reported in patients with confirmed COVID‐19, along with isolated cases of conjunctivitis as a presenting sign. Coronaviruses have been rarely isolated from tears or conjunctival swabs. The evidence suggests coronaviruses are unlikely to bind to ocular surface cells to initiate infection. Additionally, hypotheses that the virus could travel from the nasopharynx or through the conjunctival capillaries to the ocular surface during infection are probably incorrect. Conjunctivitis and isolation of the virus from the ocular surface occur only rarely, and overwhelmingly in patients with confirmed COVID‐19. Necessary precautions to prevent person‐to‐person transmission should be employed in clinical practice throughout the pandemic, and patients should be reminded to maintain good hygiene practices.

Thirty years of 'quiet eye' with etafilcon A contact lenses

Frequent replacement contact lenses made from the etafilcon A hydrogel lens material were introduced onto the market over 30 years ago, and etafilcon A remains the most widely used hydrogel lens material today. Although the prescribing of silicone hydrogel lenses is increasing, millions of lens wearers globally have been wearing hydrogel lenses for many years and exhibit a physiologically-stable 'quiet eye', with a low profile of adverse events. Hydrogel lenses are demonstrated to maintain a low inflammatory response and infection risk profile during daily wear, which in the case of etafilcon A, may be related to its low modulus, and the naturally-protective, anti-microbial, non-denatured lysozyme absorbed into the lens from the tear fluid. Although improved corneal physiology from decreased hypoxia with silicone hydrogel lenses is well accepted, equivalent levels of corneal oxygenation are maintained during daily wear of low to medium powered hydrogel lenses, which do not impede the daily corneal de-swelling process, and do not induce clinically significant changes in ocular health. Therefore, hydrogel lenses remain an important alternative for daily wear in modern contact lens practice.

Monitoring ocular discomfort using a wrist-mounted electronic logger

PURPOSE

To investigate ocular discomfort during contact lens wear using a wrist-mounted electronic 'lens awareness logger' (LAL).

METHODS

Thirty symptomatic contact lens wearers wore study contact lenses for three days. On the first two days, two lens types which are known to differ in end-of-day comfort (lens A: senofilcon A and lens B: balafilcon A), were worn as a matching pair (randomised order). On day three, a pair of lens B was worn. On each day, the participant used a LAL. On day one and two, the participant pressed a button on the LAL whenever they became aware of their lenses due to discomfort. On day three, the participant used a multiple click protocol (1 = mild awareness to 3 = severe awareness) to report discomfort.

RESULTS

LAL events were similar on days one and two (17.3 vs. 15.8 events per day). There were significantly more LAL events for lens B (21.6 events per day) in comparison with lens A (11.6 events per day) (p = 0.006). The LAL event profile highlighted peaks in awareness following lens application and towards the end of the wearing cycle. Comparison of the LAL event profile for the two lens types showed significant differences in lens awareness, particularly in the first half of the wearing cycle. LAL events on day 3, showed a uniform distribution of single and double clicks through the day, but a marked peak in triple clicks in the last two hours of lens wear.

CONCLUSION

The LAL was able to differentiate between the study lenses and demonstrated differences in their LAL event profiles. Lens awareness associated with discomfort appeared to increase not only in frequency, but also in intensity towards the end of the wearing cycle. The ability of the LAL to track lens awareness suggests it is likely to be a useful tool in furthering understanding of ocular discomfort.