A plethora of invaluable research was presented at this year’s British Contact Lens Association (BCLA) Clinical Conference & Exhibition, covering everything from corneal infection risk factors to ortho-K techniques to contact lens care. In case you missed this year’s meeting, here are our picks for some of the more stand-out abstracts presented at the UK’s premier contact lens event, and how the research presented may soon affect your practice.
1. Long term ortho-K treatments could stabilize refractive errors in myopes.
A study by Yee et al. demonstrated that patients with a median age of 10 who wore ortho-K (OK) lenses for five years showed signs of refractive error and corneal curvatures stabilizing approximately six weeks after ceasing OK lens wear. While these results may be patient dependent, no sudden changes in each patient’s myopia were observed.1
Monitoring OK wearers over time is essential to ensure the success of the treatment. The study demonstrates how critical the six-week time period is for stabilization following OK treatment. “Prior to six weeks, the cornea for some patients can still continue to change.” says Clinical Editor Joseph Shovlin, OD. “This is an important time reference, especially when considering final correction in prescribing alternative corrective options such as conventional lenses or even refractive surgery.”
2. Hand washing time is important when dealing with silicone hydrogel lenses.
Etty Bitton, OD, and Samantha Kronish conducted a two-arm pilot study using silicone hydrogel contact lenses and two different liquid hand soaps to determine the effects of hand washing on contact lens parameters. Unsurprisingly, the study demonstrated that when using liquid hand soaps, shortened hand washing times have the potential to leave behind soap residue on the lenses. This causes a visible smear or smudge on the lens surface that reduces the clarity of vision in contact lens wearers.2
The study points out the importance of educating patients on proper compliance when wearing contact lenses. “The consequences can be evident with an impact on vision, overall comfort, wettability and, somewhat surprisingly, the lens fit,” Dr. Shovlin adds.
Use this finding as a lesson to reiterate to your patients the importance of spending enough time washing their hands before handling contact lenses. Not only will it have the effect of reducing potential residue on the lenses, it will also help to lower the risk of infection as a result of improper hygiene.
3. Multifocals offer presbyopes better binocular vision than monovision lenses.
While there are many options available to help presbyopes, multifocal (MF) contact lenses may provide your patients with greater focus than monovision (MV) lenses.
A study by Pete Kollbaum, OD, PhD, et al. compared the binocular summation ratio (BSR) of monocular dominant eye performance to binocular performance using three different contact lenses: MV lenses with adds of +0.75 and +2.00D, lotrafilcon B low and high add MF lenses and omafilcon A MF lenses.
The results showed that both MF lenses had very similar median BSRs—1.12 for omafilcon and 1.19 vs. lotrafilcon B high lens and 1.15 for lotrafilcon B low lens—which were significantly higher than the median BSRs for either of the MV lenses—1.00 for the MV+0.75D and 1.02 for the MV+2.00D.3
While binocular summation varies between presbyopic correction options, MF correction provides better binocular summation for patients when compared to MV options. “Binocular summation in presbyopes wearing various forms of contact lens correction will vary depending on the type of correction used,” Dr. Shovlin explains. “Of interest, monocular defocus (i.e. monovision high add correction, +2.00D) did not show inhibition (BSR < 1).”
4. Gas permeable lenses can be used to flatten the corneas of keratoconus patients.
Various surgical options for correcting keratoconus exist, but researchers are examining the possibility of correcting the condition with the use of contact lenses. Romero-Jimenez et al. conducted a study that evaluated the effect 14 days of GP lens wear had on the anterior corneal surface of patients with keratoconus.
Thirty-one keratoconic patients with no history of lens wear were fitted with either flat or three-point-touch lenses. The changes made on each subject’s mean central keratometries (MCK), corneal asphericity, maximum corneal curvature (MK), thinnest corneal thickness and anterior corneal surface aberrations were examined for each group. The study found that the GP lenses in both groups significantly flattened the MCK and MK, reduced their corneal asphericity, corneal aberrations and also increased their corneal thickness.4
While further research is still necessary, GP lenses can be used to flatten the corneas of patients with keratoconus, providing additional support for non-surgical approaches to long-term management of irregular corneas.
5. Bandage contact lens material is more important in the healing process than once believed.
The use of conventional hydrogel and silicone hydrogel contacts as bandage contact lenses (BCLs) may be causing more damage to eyes than good. Manpreet Kaur Cooner, BSc Chemistry, et al. examined the connection between contact lens material, vitronectin removal, plasmin upregulation and wound healing using hydrogel lenses. Vitronectin, an adhesive protein, has been shown to influence the generation of plasmin in tears, which is disadvantageous in the process of ocular healing. Because vitronectin has a high affinity for hydrogel surfaces, the use of hydrogels for BCLs needs to be reevaluated.5
While hydrogel and silicone hydrogel lenses offer convenience, their specific healing capabilities are limited. This new information will prove useful to researchers in the future production of BCLs that are more conducive to the ocular healing process.
6. The presence of PQ1-ALX in contact lens solutions may help to eradicate biofilm created by Staphylococcus aureus.
The formation of microbial keratitis and corneal infiltrates has long been associated with the development of biofilms found inside of contact lens cases. A study conducted by David McCanna, PhD, and Lyndon Jones, PhD examined the antimicrobial efficacy of the contents of various contact lens solutions against Staph aureus. The antimicrobials polyquaternium-1 (PQ1) and alexidine (ALX) were shown to be the most effective in damaging the cell membranes of the bacteria present.6
The presence of PQ1-ALX was shown to cause the most damage to microbial cell membranes, and this information will prove useful in the development of future contact lens solutions. Understanding which ingredients are most effective against various bacterial cell membranes can help you when recommending solutions to your patients. Still, though, disposing of lens cases regularly in favor of a new case remains the best way to prevent bacterial infection.
7. Stenotrophomonas maltophilia and Pseudomonas aeruginosa pose a risk of forming a biofilm and adhering to contact lenses.
High levels of gram-negative bacteria can colonize contact lens cases and transfer into the eye, increasing the likelihood of infection or corneal infiltrates.
Mark Willcox, BSc, PhD, and Ajay Vijay, BOptom, PhD, examined the capabilities of Stenotrophomonas maltophilia and Pseudomonas aeruginosa to form biofilms and adhere to contact lenses. Both showed the ability to adhere to contact lenses, with S. maltophilia having a higher affinity for low Dk lenses, and P. aeruginosa adhering in higher numbers to lenses with a higher Dk. This ability of pathogens to adhere may be related to the production of diffuse corneal infiltrates in patients susceptible to Stenotrophomonas when lens disinfection is compromised, says Dr. Shovlin. “Exposure to significant lens surface bioburden exists, especially with repeated inoculation.”
Neither bacteria were affected significantly by lens wear during the study. Though further research is required, it is believed that their ability may be related to the production of corneal infiltrates.7 Ensuring that lens care provides broad-spectrum efficacy against all known pathogens will reduce risk of adverse events. These findings could aid in the development of future products designed to disinfect contact lens cases, ensuring lower rates of infection in contact lens wearers.
8. Mucin balls can cause microstructural abnormalities in the cornea.
While believed to be harmless, mucin balls can cause small changes in the cornea. Over the course of four months, 10 patients were examined after using continuous wear SiHy lenses approved for monthly wear. The study found that by the third and fourth weeks of continuous wear, mucin balls had formed around the cornea. Once the lenses were kept out of the eyes following continuous wear—one day for one-week wear, and three days for three- to four-week wear—the cornea was restored to its original state.8
“Mucin ball formation remains an interesting phenomenon whose significance clinically is still being investigated,” Dr. Shovlin says. “Debate continues on whether their presence has a detrimental or protective effect for other corneal events.” Though they don’t pose a great risk, it still remains important to communicate with your patients the importance of removing their contact lenses for a few days following continuous wear. Preventing the formation of mucin balls is just one reason among many.
9. Friction between the eyelids and lenses can cause inflammation and discomfort.
Discomfort is commonplace for many lens wearers and a motivator for dropout. Clinicians have tried to understand its underlying causes for years, but questions still remain.
A small study by Morgan et al. revealed that interaction between the lid margin and the lens surface might create friction, which then possibly leads to inflammation and discomfort. Ten non-CL wearers and 10 lens wearers broken into two groups—five in low-friction contacts, and five in high-friction lenses—were examined throughout the course of a day to measure any increase in inflammatory cells. The results showed that there was in fact an increase, with the greatest elevation occurring in the high-friction contact lens group.9
“Poor comfort may be related to the frictional interaction between the lens and lid anatomy,” Dr. Shovlin says. “Inflammatory lid margin changes are unavoidable, but strategies to lessen the mechanical influence may be a benefit to lens wearers.” Suggesting low-friction contact lenses could prove to be an effective way to decrease discomfort in patients.
10. Hyperosmolarity could lead to discomfort in lens wearers.
The need to understand the factors that cause end-of-day discomfort in contact lens wearers has led researchers to examine the impact of osmolarity. Tawnya Wilson, OD, and Kristy Canavan, OD, examined 12 subjects—six with CLIDE and six unaffected patients—to measure the difference in osmolarity with and without lens wear. The results showed that CLIDE subjects were more likely to experience hyperosmolarity than normal patients.
Three osmolarity readings were conducted at four different points—before lens wear, 30 minutes after lens insertion, eight hours after insertion and 15 minutes after the lenses were removed—using the TearLab Osmolarity system. CLIDE subjects reported higher osmolarity readings vs. normal subjects in every test.10
A Contact Lens User Experience (CLUE) questionnaire was given to each subject to determine subjective comfort levels following the tests. The differences were staggering—during the initial visit, normal subjects scored 99.69 vs. 73.07 for CLIDE subjects; following lens wear, normal subjects scored 90.86 vs. 71.18 for CLIDE subjects.
While the osmolarity bare-eye measures were repeatable, the measures may not be as predictive for evaluating CLIDE. “Osmolarity measures with a lens on the eye did not show repeatability, nor was there correlation between comfort and osmolarity,” adds Dr. Shovlin.
The BCLA is to be commended for its efforts to promote research that improves patient care and product development. Look for next year’s meeting in Birmingham, June 6-9, 2014.
1. Yee MC, Chui WS, Cho P. Stabilisation of refractive errors and corneal curvatures after long term orthokeratology. Poster session presented at BCLA 2013.
2. Bitton E, Kronish S. The impact of hand washing time and soap on the surface of silicone hydrogel contact lenses: a pilot study. Poster session presented at BCLA 2013.
3. Kollbaum P, McGiffen R, Rickert M, Tarrant J, Chamberlain P. Binocular summation of presbyopic contact lens corrections. Poster session presented at BCLA 2013.
4. Romero-Jimenez M, Santodomingo-Rubido J, Gonzalez-Meijome JM. Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches. Poster session presented at BCLA 2013.
5. Cooner MK, Tighe B, Rubinstein M. Understanding the interaction between bandage contact lenses and the cornea: potential consequences for wound healing. Poster session presented at BCLA 2013.
6. McCanna D, Jones L. The effect of contact lens solutions on membrane permeability of Staphylococcus aureus aggregates. Poster session presented at BCLA 2013.
7. Willcox M, Vijay A. Formation of biofilms of Stenotrophomonas maltophilia and Pseudomonas aeruginosa on contact lenses. Poster session presented at BCLA 2013.
8. Grupcheva C, Marinova T, Ivancheva V. The importance of the mucin balls… Poster session presented at BCLA 2013.
9. Morgan P, Petropoulos I, Read M, Malik R, Maldonado-Codina C. Confocal microscopy of the lid margin area of contact lens wearers. Poster session presented at BCLA 2013.
10. Wilson T, Canavan K. Osmolarity evaluation using TearLab with and without lenses in contact lens induced dry eye (CLIDE) and normal subjects. Poster session presented at BCLA 2013.