The 36th British Contact Lens Association (BCLA) clinical conference and exhibition was held in Birmingham, UK this past May 24-27. With about half of its 1,203 delegates from the United Kingdom and the remainder from another 44 countries, the four-day conference included multiple sessions with lectures from prominent experts Lyndon Jones, B.Sc., Ph.D., and Stuart Richer, O.D., Ph.D., as well as workshops, posters and competitions.
Given the meeting’s heavy emphasis on contact lens care, I thought it might be appropriate to review its highlights and abstracts this month. This research certainly will impact our everyday clinical practices, and perhaps even trigger new ideas in research. This year’s presentations dealt with a broad array of topics, ranging from novel drug delivery systems and controlled molecule release to the impact of cosmetics on the physical dimensions and optical performance of silicone hydrogel lenses.
The following summaries are based on abstracts from the printed material provided by the BCLA. Take note, the materials were submitted in advance of the meeting and may not entirely represent the final conclusions of the authors.
• Characteristics of the ocular surface in normal and marginally dry eyes, including sensitivity, tear osmolarity and ocular symptoms.
There often is a disconnect between symptoms and clinical signs when a patient complains of ocular discomfort. Practitioners tend to focus on the cornea, but research shows that lids and conjunctiva are important—especially regarding contact lens-related discomfort, meibomian gland dysfunction and sensations associated with ocular dryness.
Fiona Stapleton, B.Sc., M.Sc., Ph.D., of the University of South Wales in Australia, examined 76 subjects (of whom 37 were contact lens wearers) to investigate the relationship between clinical indications of dry eye, symptoms of discomfort and ocular surface sensation during a single visit.
Conjunctival staining was associated with higher tear osmolarity, lower tear volume, reduced tear film quality, more corneal staining and an increased incidence of lid wiper epitheliopathy. The latter condition was associated with increased tear osmolarity, corneal staining and conjunctival staining. Ocular surface sensitivity was associated with higher levels of conjunctival staining and lid wiper epitheliopathy.
Contact lens wear was associated with more reporting of symptoms, lower tear volume and tear film break-up time and more staining of cornea, conjunctiva and lid wiper. No difference was found between contact lens wearers and non-lens wearers with respect to sensitivity.
The take-home message: when evaluating ocular health and symptoms, the conjunctiva and lids are just as important as the cornea.
• Controlled release of comfort molecules from silicone hydrogel contact lenses through the use of molecular imprinting.
Conventional eye drops have limitations in relieving ocular discomfort associated with contact lens wear: they are inconvenient to apply, have a low residence time on the eye and produce some side effects from inactive ingredients. Using molecular imprinting, graduate student Charles White, of Auburn University, described lenses that were designed to incorporate and elute a “comfort agent” from within the polymer network of the lens during wear.
Using rabbit eyes in an in vivo study, researchers found that the imprinted lens released a comfort agent in a slow, controlled manner for up to 26 hours. The non-imprinted lenses were depleted after 10 hours; conventional eye drops washed out of the eye in just six to 30 minutes.
The research team was able to incorporate comfort molecules into a commercial extended wear silicone hydrogel lens, achieving a tailored release of 50 to 52 days. Release rates are adjustable, as well as the size of the reservoir of comfort agent within the lens.
The lab also created a microfluidic device able to mimic natural tear flow; lenses were able to release a comfort agent for 60 days. These lenses had a 90% degree of optical clarity at the conclusion of the 60-day period.
Better contact lens comfort may be achieved with this new technology, which may make its way to market in the future. Comfort molecules are delivered before symptoms of discomfort occur. Further developmental work is ongoing.
• Dry eye in contact lens wear: a perennial problem?
Estimated contact lens dropout rates range from 15% to 30% in multiple countries. Dropout and discomfort are two closely related themes that have remained constant despite improvements in lens material and design. In 2012, are we any closer to addressing concerns of dry eye symptoms associated with contact lens wear? Alan Tomlinson, M.Sc., Ph.D., D.Sc., D.C.L.P., D.Orth., of Caledonian University in Scotland, reviewed the research and provided an overview of factors contributing to this problem.
Once a contact lens (comprised of any material) is placed in the eye, a cascade of events follows, often ending in symptoms of discomfort. These events result in loss of conformity between the lid and globe, which changes the blink pattern and tear distribution. In addition, the tear film splits into post- and pre-lens components. Dr. Tomlinson noted that if the average tear film volume is 0.728mm3 and the volume of a lens is 34.603mm3, the tear film now has to cover double the original surface area.
Interference with the lipid layer, resulting in an up to 50% increase in evaporation and rapid drying of the tear film and contact lens, adds to the problem. This increased evaporation is one of the main causes of contact lens-associated dryness.
Lens dehydration can be characterized in two stages: onset lateness (first tear break-up) and drying duration (at which point the lens has already dried out). Both stages are important in learning about contact lens-related dryness and attempting resolution. Remember that there are different drying patterns for each lens. For example, a hydrogel lens begins drying in one spot and extends over time, and a silicone hydrogel dries out in scattered areas that extend and coalesce over time. Wetting characteristics also vary, depending on the lens material and solution used.
Contact lens discomfort actually may be a symptom of vision changes communicated by means of a feedback loop. The eye has only a limited number of responses to stress, and they do not necessarily relate to their physical cause. One must not assume a contact lens wearer has dry eye simply because he or she reports symptoms of dryness. Don’t diagnose dry eye or contact lens dryness based on symptoms alone. Consider recommending different lens materials, care solutions, emulsion eye drops and breaks from contact lens wear.
• The impact of cosmetics on the physical dimension and optical performance of silicone hydrogel contact lenses.
Cosmetics are safe for periocular use, but what is their impact on contact lenses? An in vitro experiment conducted by Doerte Luensmann, Ph.D., Dip. Ing., of the University of Waterloo assessed the effect of common cosmetics (liquid make up remover, make up remover wipes, hand cream, waterproof mascara and water-soluble mascara) on contact lens shape, power and optical performance of seven hydrogel lenses. Recovery of the changes was measured after cleaning the lenses with a hydrogen peroxide regimen.
Some cosmetics can change the shape of contact lenses as well as the quality of vision they provide. Overall, balafilcon A, enfilcon A and galyfilcon A lenses demonstrated a stronger change in parameters; plasma surface lotrafilcon A and lotrafilcon B were impacted the least by cosmetics. Liquid make-up remover and both waterproof and water-soluble mascara had a strong impact on image quality. Cleaning with peroxide provided minor recovery of different lens parameters, although its efficacy varied with different cosmetics.
Practitioners should advise patients to insert contact lenses prior to applying make up and remove their lenses prior to removing eye make up.
Contact lens wearers who exhibit problems that appear to be related to cosmetics may need to be switched to a different lens type.
• Predicted reduction in high myopia for various degrees of myopia control.
In this study, Noel Brennan, Ph.D., of Johnson & Johnson Vision Care in Jacksonville, Fla., calculated the proportion of people who may avoid becoming high myopes with varying degrees of myopia control.
Refractive error frequency distribution samples were studied to identity the proportion of individuals with various levels of myopia, especially those frequencies of different degrees of myopia greater than -5.00D. Refractive errors were multiplied by a correction factor, depending on the degree of myopia control under consideration. The change in the proportion of the population with greater than -5.00D of myopia was then calculated.
Results showed that reducing the rate of myopia progression by 33% would lead to a 73% reduction in the frequency of high myopia. Reducing the rate of progression by 50% would lead to a 90% reduction in frequency of high myopia.
Myopia control that leads to a modest reduction in progression rates could have a major impact on the risk of sight-threatening complications. Development and adoption of methods for reducing myopia progression by as little as 33% are justified from a public health perspective. Novel contact lens designs, such as multifocals, may aid in reducing the rate of myopia progression.
• Cytotoxic and inflammatory effects of contact lens multipurpose solutions on human corneal epithelial cells.
Multipurpose solutions may cause damage to the ocular surface. In this study, researchers at Hadassah University Hospital in Jerusalem examined the cytotoxic and inflammatory effects of multipurpose solutions (MPS) and hydrogen peroxide disinfection systems on cultured human corneal epithelial (HCE) cells.
HCE cells were exposed to eight commercially available MPS products (MPS A to H) at concentrations of 30% v/v and 50% v/v for 12 hours. Cytotoxic effects and protein contents of pro-inflammatory cytokines were examined using numerous lab tests.
Incubation of HCE cells showed that all MPS examined did induce some levels of pro-inflammatory cytokines compared to the negative control. MFB immunoassay demonstrated that five MPS stimulated the highest levels of pro-inflammatory cytokines in HCE cells. In contrast, insignificant differences were noted between the hydrogen peroxide systems and the negative control.
Taken together, these data suggest hydrogen peroxide is a preferable disinfecting and sterilizing system for contact lenses compared to most commercially available MPS.
• Do people really care for contact lens cases in the correct way?
The purpose of the study, conducted by Katharine Evans, B.Sc., Ph.D., Magdalene James, B.Sc., and Christine Purslow, B.Sc., Ph.D., was to investigate contact lens case hygiene among contact lens wearers in a university population. All university staff and students were emailed an online contact lens case hygiene questionnaire investigating demographics, wearing history, last aftercare and practitioner lens case hygiene questions. Compliance scores were calculated from responses about daily case emptying, rinsing, drying, no use of water and frequent case replacement.
Of the 745 contact lens wearers who completed the questionnaire, 683 wore soft lenses and wore 62 gas-permeables (GP). Less than 6% of respondents were fully compliant. Compliance scores were similar in the two gender groups. GP wearers reported significantly poorer case hygiene than soft lens wearers, with mean compliance scores of 2.19 and 2.76, respectively. Superior hygiene was observed in those wearing lenses for less than 12 months. Compliance scores were better where the practitioner questioned lens case hygiene during aftercare. Wearers with more recent aftercare, or where the practitioner went on to explain the consequences of poor lens case hygiene, had better compliance (although differences did not reach statistical significance). In soft lens wearers, compliance tended to be worse in those wearing internet-purchased lenses (2.49) compared to practitioner-purchased lenses (2.78).
This study highlights poor case hygiene in contact lens wearers; like other aspects of lens wear, compliance decreases with increasing wearing history. These results reinforce the importance of regular aftercare and the influence of the practitioner on lens case hygiene.
• Evaluation of change in comfort and vision from two to four weeks of monthly replacement silicone hydrogel contact lenses.
This study by Peter Bergenske, O.D., of Alcon and Barry Eiden, O.D., and Robert Davis, O.D., M.B.A., of EyeVis examined changes in comfort and vision between two weeks and one month for wearers of lotrafilcon B lenses. One hundred twenty current wearers of lotrafilcon B lenses each wore a new pair of lenses for one month, using their habitual lens care system, and were evaluated after two weeks and at one month. In addition to clinical ratings, subjects responded to agreement statements regarding perceived differences in comfort or vision over the month of wear.
No differences were noted in biomicroscopy scores between two weeks and one month. Comfort and vision ratings were evaluated for non-inferiority of the one month compared to the two week rating, using a margin of 0.50 on a 1-10 scale. Non-inferiority was established for ratings of visual clarity and ocular redness. The four agreement statements using a Likert scale comparing comfort between the two-week visit and the four-week visit were all found to be significant.
Subjective comfort ratings showed a small decrease between two weeks and one month; however, subjects expressed strong agreement with statements regarding consistency of comfort and vision throughout the month of wear. Wearers of lotrafilcon B lenses do not perceive substantial drops in comfort or vision over the recommended wearing interval. The small decrease in comfort supports compliance with monthly replacement of these lenses.
The annual BCLA conference is almost entirely dedicated to contact lens-related practice and research, and this year was no exception. The meeting provided valuable data and clinical insights that help all of us provide better care to our contact lens wearers. Due to space constraints, it is impossible to cover all the posters and abstracts, but I do urge our readers to visit
www.bcla.org/uk for more information.