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

Impact of in vitro lens deposition and removal on bacterial adhesion to orthokeratology contact lenses

PURPOSE

The purpose of this study was to explore the impact of several contact lens (CL) care solutions on the removal of proteins and lipids, and how deposit removal impacts bacterial adhesion and solution disinfection.

METHODS

Lysozyme and lipid deposition on three ortho-k (rigid) and two soft CL materials were evaluated using an ELISA kit and gas chromatography respectively. Bacterial adhesion to a fluorosilicone acrylate material using Pseudomonas aeruginosa with various compositions of artificial tear solutions (ATS), including with denatured proteins, was also investigated. The impact of deposition of the different formulations of ATS on biofilm formation was explored using cover slips. Finally, the lysozyme and lipid cleaning efficacy and disinfection efficacy against P. aeruginosa and Staphylococcus aureus of four different contact lens care solutions were studied using qualitative analysis.

RESULTS

While maximum lysozyme deposition was observed with the fluorosilicone acrylate material (327.25 ± 54.25 µg/lens), the highest amount of lipid deposition was recorded with a fluoro-siloxanyl styrene material (134.71 ± 19.87 µg/lens). Adhesion of P. aeruginosa to fluorosilicone acrylate lenses and biofilm formation on cover slips were significantly greater with the addition of denatured proteins and lipids. Of the four contact lens care solutions investigated, the solution based on povidone-iodine removed both denatured lysozyme and lipid deposits and could effectively disinfect against P. aeruginosa and S. aureus when contaminated with denatured proteins and lipids. In contrast, the peroxide-based solution was able to inhibit P. aeruginosa growth only, while the two multipurpose solutions were unable to disinfect lenses contaminated with denatured proteins and lipids.

CONCLUSION

Bacterial adhesion and biofilm formation is influenced by components within artificial tear solutions depositing on lenses, including denatured proteins and lipids, which also affects disinfection. The ability of different solutions to remove these deposits should be considered when selecting systems to clean and disinfect ortho-k lenses.

Profile of contact lens prescribing in GCC countries

PURPOSE

This study aimed to report the pattern of contact lens prescribing from the Gulf Cooperation Council (GCC) countries.

METHODS

Optometrists in the GCC region were contacted to participate in a web-based survey hosted on Qualtrics XM (Provo, Utah, USA). The survey methodology was adapted from the International Contact Lens Prescribing Consortium, and participants were asked to report their last five lens fits. It collected information on practitioner demographics (age, gender, nationality, qualification, country of practice, and number of years of experience), CL user demographics (age and gender) and on lens specific details such as lens type, lens design, lens material, replacement plan, and modality of lens wear. Descriptive statistics were used to analyse and report the data.

RESULTS

This study reports 739 contact lens fits by 174 practitioners from six GCC countries. The average age of the patients was 29.72 ± 9.07 (Mean ± SD) years and 64 % of them were females. The majority (80.2 %) were fitted with soft contact lenses, with 59 % preferring silicone hydrogels, 20 % wearing them for cosmetic purposes and nearly half of them disposed of their lenses daily (55 %). Among the RGP lenses, 41 % were scleral lenses. This survey demonstrated a greater proportion of new lens fits (55 % vs. 37 %), disposable hydrogel lens use (21 % vs. 13 %), and a preference for cosmetic contact lenses (20 % vs. 4 %) compared to the international data.

CONCLUSION

The pattern of CL prescriptions in the GCC region closely resembled the global trend. The survey observed a higher preference towards frequent replacement soft lenses, a greater proportion of silicone hydrogel lenses, a higher percentage of rigid lens fits, a greater affinity for cosmetic contact lenses, and a higher percentage of new fits. These trends suggest that contact lens prescription habits in the region are likely to continue evolving in the future.

Eyecare practitioner perspectives and attitudes towards myopia and myopia management in the UK

OBJECTIVE

Many children with progressive myopia are still prescribed single-vision correction. An investigation into UK eyecare practitioners' (ECPs) perceptions of myopia management was carried out to ascertain factors which may be limiting its implementation and uptake within clinical practice.

METHODS AND ANALYSIS

Online focus groups were held with UK ECPs. Participants were encouraged to discuss their knowledge of the available myopia management options, their perception of how myopia management is being delivered in the UK and any barriers limiting ECPs' prescribing of these management options in practice. The discussions were transcribed and analysed thematically.

RESULTS

Focus groups were held with 41 ECPs from primary and secondary eyecare. ECPs felt that provision of myopia management in the UK is variable. Most ECPs believe they have sufficient knowledge, but felt a lack of confidence in decision-making and practical experience. Less experienced ECPs sought more definitive guidance to support their decision-making. ECPs desired clarity on their duty of care obligations and were concerned over possible future litigation if they had not offered, or referred for, myopia management when indicated. The greatest barrier appears to be financial-treatment is expensive and ECPs are uncomfortable communicating this to parents. Many barriers were indicative of systemic problems within UK eyecare, such as commercial pressures, inadequate National Health Service funding and poor public awareness of paediatric eyecare.

CONCLUSION

Myopia management is not implemented consistently across the UK. To improve accessibility, changes are required at multiple levels, from individual ECPs through to wider stakeholders in UK eyecare provision.

Comparison Between Ocular Biometric Parameters and Intraocular Pressure With and Without Contact Lenses

OBJECTIVES

To compare the values of central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), vitreous length (VL), axial length (AL), and corneal-compensated intraocular pressure performed with and without contact lenses (CL).

METHODS

Forty volunteer participants (16 men and 24 women, 24.2±2.9 years) were recruited. In a single visit, participants underwent autorefraction, keratometry, biometry, topography, pachymetry, and tonometry with the naked eye (without CL). Then, biometry, pachymetry, and tonometry were repeated twice wearing two CL (somofilcon A and nesofilcon A) fitted in a random order.

RESULTS

Many of the ocular biometric values were affected by the use of CL during measurements (paired t test; all P ≤0.003), except for LT and VL (Wilcoxon test; both P ≥0.272). Corneal-compensated intraocular pressure was also affected by contact lens wear during measurements, obtaining lower values when wearing them (Wilcoxon test; all P ≤0.001).

CONCLUSIONS

Central corneal thickness, ACD, AL, and corneal-compensated intraocular pressure measurements cannot be performed while wearing CL. However, LT and VL measurements were not affected by any contact lens use. In addition, it was observed that ACD results from both devices are not interchangeable either when measured with the naked eye or using any contact lens.

Clinical Investigation of Flat Pack Toric Contact Lenses and Wearer Attitudes to Environmental Impact

OBJECTIVES

To investigate the performance of a novel flat pack toric daily disposable contact lens compared with traditionally packaged toric lenses in a randomized, crossover study. Environmental attitudes to contact lens wear were also explored.

METHODS

Habitual contact lens wearers were recruited to wear a hioxifilcon A (Miru 1 day Flat Pack Toric, Menicon, Nagoya, Japan) test lens and a control lens: either nelfilcon A (Dailies AquaComfort Plus, Alcon, Geneva, Switzerland) or etafilcon A (1-Day Acuvue Moist, Johnson & Johnson, New Brunswick, NJ). Objective lens performance was assessed at fitting, and participants wore lenses in a randomized order for three consecutive days. Subjective measures of lens performance (comfort, vision, and handling) were then assessed by a questionnaire, with further questions on overall lens preference and environmental perceptions.

RESULTS

Objective measures of lens fit were similar for the test and control lenses, except for distance VA which was better with the control lenses ( P <0.05; difference of two logMAR letters). End of day comfort was greater with the test lens, but this did not reach significance. Both lenses demonstrated similar scores for overall satisfaction. 87.5% of participants indicated the environmental impact of contact lenses to be important/extremely important to them, with 100% of participants identifying the flat pack packaging as having a smaller environmental impact.

CONCLUSION

Overall, the lenses used in the study performed to similar levels. Environmental credentials are important to contact lens wearers, which may contribute to overall lens preference.

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.

Comparative Evaluation of Pseudomonas aeruginosa Adhesion to a Poly-(2-Methacryloyloxyethyl Phosphorylcholine)-Modified Silicone Hydrogel Contact Lens

Pseudomonas aeruginosa is the most common causative agent associated with microbial keratitis. During contact lens wear, pathogens may be introduced into the ocular environment, which might cause adverse events. Lehfilcon A is a recently developed contact lens with a water gradient surface composed of polymeric 2-methacryloyloxyethyl phosphorylcholine (MPC). MPC is re-ported to impart anti-biofouling properties onto modified substrates. Therefore, in this in vitro experimental study, we tested the capability of lehfilcon A to resist adhesion by P. aeruginosa. Quantitative bacterial adhesion assays using five strains of P. aeruginosa were conducted to compare the adherence properties of lehfilcon A to five currently marketed silicone hydrogel (SiHy) contact lenses (comfilcon A, fanfilcon A, senofilcon A, senofilcon C, and samfilcon A). Compared to lehfilcon A, we observed 26.7 ± 8.8 times (p = 0.0028) more P. aeruginosa binding to comfilcon A, 30.0 ± 10.8 times (p = 0.0038) more binding to fanfilcon A, 18.2 ± 6.2 times (p = 0.0034) more binding to senofilcon A, 13.6 ± 3.9 times (p = 0.0019) more binding to senofilcon C, and 29.5 ± 11.8 times (p = 0.0057) more binding to samfilcon A. These results demonstrate that, for various strains of P. aeruginosa, lehfilcon A reduces bacterial adhesion compared to other contact lens materials.

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.