Vision and Comfort Remain Top Priorities for Contact Lens Wearers
Innovative Packaging and Proper Disinfection Can Keep Eyes Safe
Worldwide, more than 140 million people wear contact lenses. This number is sure to increase, due to the rising rates of myopia and an aging population developing presbyopia.
Commercially available since the late 1980s, numerous soft contact lenses (CLs) have been introduced with the aim of improving upon the previous version’s vision and comfort. However, contact lens “dropout” still occurs — at a rate between 12 and 27.4% in developed countries. In established CL wearers, discomfort is cited as the top reason for dropout; factors contributing to ocular discomfort can include CL material, design, wear modality and lens care solution. Meanwhile in new CL users, vision was the main reason, followed by handling. As such, selecting CLs with more eye- and user-friendly designs and packaging could be beneficial.1
During the recent American Academy of Optometry annual meeting (Academy 2021 Boston), one session titled Improving Contact Lens Comfort Without Changing the Lens or Modality covered just this. In fact, the presenters, including Lyndon Jones, Centre for Ocular Research & Education (CORE), agreed that issues with handling is one of the main reasons that new CL wearers might dropout and stop wearing their lenses. Specifically, in new wearers, there are other drivers [other than comfort and vision] that stop them from wearing their lenses.
With handling, hygiene and safety are other also important issues to consider. Thus, several papers investigated both bacterial and viral contaminants in CLs during a session called Contact Lens Antimicrobials. These included the efficacy of contact lens care solutions and the impact of the rub-and-rinse step on CLs, as well as interesting data on bacterial movement and adhesion.
Disinfect to protect
The proper disinfection and storage of CLs is critical to ensure wearers don’t introduce bacteria or viruses to the ocular surface. To further understand the movement of these pathogens, a paper called Novel Method of Acanthamoeba Movement Quantification to Determine Efficacy of Contact Lens Solutions was presented at Academy 2021 Boston.
Acanthamoeba keratitis is a serious ocular infection — it’s difficult to treat and can lead to permanent corneal damage, or even blindness. Infection occurs when the pathogen comes into contact with the CL which is then placed into the eye. The presenting author shared that by quantifying the motility of Acanthamoeba, they might be better able to understand the efficacy of lens disinfection — and what they found was interesting, indeed.
In all controls, the amoeba maintained consistent movement, even without nutrients. However, contact lens solutions that contained polyquad/aldox and polyquad/alexidine were associated with the largest cessation of movement; meanwhile, solutions using PHMB (polyhexamethylene biguanide) had the least effect on movement. The authors concluded that compared to controls, all the CL solutions either completely halted or severely impaired Acanthamoebamotility.
This data is highly relevant to CL prescribers and wearers — especially when choosing a CL solution. For example, MeniCare Soft (Menicon, Nagoya, Japan) disinfecting solution begins to work against bacteria and fungi within 20 minutes and against amoebas within 6 hours of soaking. The solution also contains polyhexanide disinfectant, for better safety and higher disinfection.
Of course, this all assumes the wearer is disinfecting and storing the lenses properly. Another paper presentation focused on this crucial step: The Impact of a Rub and Rinse Step on the Removal of Enveloped Viruses from Contemporary Lens Material.
“The rub-and-rinse step is known to be highly effective for removing bacterial bioburden from reusable contact lenses. However, it is not known whether rubbing or rinsing lenses has a similar impact on viral load that may be present on contact lenses,” began presenting author Dr. Scott Boegel, University of Waterloo, Ontario, Canada. Therefore, the aim of this paper was to assess the effectiveness of the rub-and-rinse step for removing viral particles from various soft (2 hydrogel, 6 silicone hydrogel) and 4 rigid gas permeable CLs.
All CLs were incubated with either a baculovirus or human coronaviruses (common cold) for 6 hours after which they were either subjected to no rinsing or rubbing; rinsing only; or a rinse-rub-rinse cycle. To determine the virus titre, an end-point dilution assay was used.
When there was no rub or rinse step, viruses were recovered from all 12 tested lenses. For CLs with the baculovirus, a rinse step significantly reduced the number of infectious viral particles, and the rinse-rub-rinse step eliminated them to below the limit of quantification (virus titre: no rinse or rub 1,720 PFU/mL; rinse only 61.6 PFU/mL). For human coronaviruses, the single rinse step was able to eliminate viral particles below the quantification limit in all 12 tested CLs.
“In conclusion, contact lens wearers should maintain a rub-and-rinse step when cleaning their lenses if they wish to remove attached viral particles,” said Dr. Boegel.
Improving CL hygiene with packaging
Packaging can also play a role in creating a more hygienic — and patient-friendly — contact lens experience. Fingertips and hands, even when washed, can still carry bacteria and small fibers to the contact lens which can then transfer onto the ocular surface. To minimize any hassles associated with handling — while increasing hygiene —Menicon has designed packaging with SmartTouch™ for some of its CL products, including Miru 1day UpSide and Miru 1day Flat Pack.
This “flat” innovative packaging keeps the inner surface of the lens facing downward: Users simply pinch the lens’ outer surface between two fingers and insert the CL into the eye — all without touching the lens’ inner surface. This helps ensure a more hygienic process and as such, this type of Smart Touch™ packaging could also alleviate some of the handling issues new CL wearers face. This might not only improve vision, but overall eye health as well.
Vision and comfort for the presbyopic patient
As mentioned above, vision and comfort are also key factors for keeping patients in their lenses. This could be especially so for presbyopic patients, where discomfort and poor vision are the primary reasons for discontinuing CL use. [1]
Building on the blocks of comfort and vision for CL wear, overall vision satisfaction has been noted as a key predictor of willingness to purchase multifocal CLs. And over the last decade, many new and improved multifocal CLs have been introduced — however, despite 41% of the U.S. population aged 40-74, only 20% of American CL wearers were prescribed multifocal CLs. [2]
To see how Miru 1month multifocal compares with other existing multifocals, a poster by Tilia et al., investigated patient satisfaction and vision. [2]
Miru 1month multifocal has 2 add powers and a center-near design. This provides near correction in the central optical zone and incorporates negative spherical aberrations to provide distance correction in the periphery of the optic zone.
In a prospective, single-masked, cross-over study in Sydney, Australia, the clinical performance of Miru 1month multifocal (center-near) was assessed in comparison with a center-near multifocal CL (Air Optix, Alcon; 3 near adds) and a center-near/center-distance combination multifocal CL (Biofinity, CooperVision; 4 near adds in both center-near and center-distance). During the study, experienced CL wearers with presbyopia wore all three lenses in random order, as well as daily wear (for about one month) in conjunction with PureMoist (Alcon) as lens care solution. During the three fitting visits, high and low contrast visual acuities (HCVA and LCVA) at varying distances were recorded, as well as the participant’s subjective comfort rating. At assessment visits, both HCVA and LCVA were assessed, as well as other subjective ratings, including clarity of vision, comfort, overall vision satisfaction and total satisfaction with CLs, among others.
The investigators then used a linear mixed model to analyze the differences between the lenses; a chi-square test was used to analyze participants’ willingness to purchase. Results showed that Miru 1month multifocal showed better distance performance (Figure 1), while the Biofinity CL showed better near vision (Figure 2). Although there was no significant difference between Miru 1month multifocal and the other CL designs in regard to overall satisfaction, comfort or willingness to purchase, the Miru 1month was rated higher for both day and night driving (Figure 3).
“The results from this study suggest all three designs performed well and Miru 1month multifocal has clinical performance that is comparable with Air Optix and Biofinity,” stated Tilia et al., noting that Miru only has 2 near additions, compared to 3 near additions with Air Optix and 8 near additions with Biofinity. “Therefore, Miru 1month multifocal offers comparable clinical performance to other multifocal contact lenses, but with a simpler fitting criterion,” they concluded.
These results show that with the variety of multifocal CLs currently available, presbyopic patients have more choice than ever before when selecting a lens to maximize both comfort and vision.
Editor’s Note: The American Academy of Optometry Annual Meeting (Academy 2021 Boston) took place from Nov. 3-6 in Boston, Massachusetts, USA. Reporting for this story took place during the meeting.
Figure 1: Differences between designs for HCVA.
Results are presented as means and error bars are 95% confidence intervals. All P-values are relative to Miru.
Figure 2: Differences between designs for LCVA.
Results are presented as means and error bars are 95% confidence intervals. All P-values are relative to Miru.
Figure 3: Differences between designs for clarity of vision and vision when driving.
Results are presented as means and error bars are 95% confidence intervals. All P-values are relative to Miru.
References:
[1] Pucker AD, Tichenor AA. A Review of Contact Lens Dropout. Clin Optom (Auckl). 2020; 12: 85–94.
[2] Tilia D, Diec J, Sugimoto K, Nishimura S, Ueda M. Assessment of a New, Monthly Replacement Center-Near Multifocal Contact Lens. Poster presented at the American Academy of Optometry Annual Meeting; Nov. 3-6, 2021; Boston, Massachusetts, USA.