AAO clinical research highlights contact lens wear, dry eye

TAMPA, Fla. — As evidenced by research presented in December here at the American Academy of Optometry meeting, clinicians are gaining a better understanding of the effects of contact lens wear in regard to corneal infiltrates, dryness and overnight hyperopia treatment. In addition, mobility training was found to benefit visually impaired individuals.

Incidence of corneal infiltrates

In a study that sought to identify risk factors associated with corneal infiltrative events (CIEs) in contact lens wearers, researchers found that “[men] and smokers appear to carry an increased risk of CIE, suggesting that careful counseling and follow-up examinations are indicated for these groups,” according to the study abstract.

Nathan Efron, PhD, DSc, FAAO, reported results of a study conducted by the optometry and ophthalmology departments at the University of Manchester, United Kingdom. At an academy-sponsored press conference, Dr. Efron, a vision scientist at the university, said that all contact lens wearers who came to a hospital clinic over the course of 12 months who were found to have a CIE were examined thoroughly. A total of 118 lens wearers fell into this category.

The study abstract specified that, in addition to a full exam, the patients provided information about their contact lens wear habits and lifestyle. “Control data were then collected using the same questionnaire with 105 randomly selected patients matched in terms of wearing modality and lens classification, from the clinical database of a university-based contact lens research group,” the abstract said.

According to Dr. Efron at the press conference, significant risk factors for CIE included the following:

• male gender (1.5 times higher risk than for female patients)
• smoking (two times greater risk than for nonsmokers)
• health problems (2.4 times increased risk for those without relevant health problems — “not sure why,” Dr. Efron said)
• eye problems (2.8 times greater risk if the eye is healthy)
• lens wearing modality/type (increased risk depending on type of lens and wearing schedule)
• season (2.4 times higher risk for late winter)

Dr. Efron added that silicone hydrogels are five times safer than traditional hydrogels for extended wear. “Based on data, the vast majority of contact lenses in next 10 years will be silicone hydrogels for all modalities,” he predicted.

Self-reported dry eye comparison

In a comparison of self-reported dry eye between contact lens and non-lens wearers, Corrie Ziegler and colleagues at the Ohio State University found that contact lens wearers are much more likely to self-report dry eye than spectacle wearers and emmetropes.

Researchers administered the Contact Lens Dry Eye Questionnaire (CLDEQ), which includes questions about dryness, light sensitivity and self-perception of dry eye.

Ms. Ziegler reported at the AAO press conference that of 893 study subjects, 28.7% reported dry eye. It was found that contact lens wearers were 12 times more likely to report dry eye than emmetropes and that spectacle wearers were twice as likely to report dry eye as emmetropes. “Why? Maybe they’re more aware of their ocular health,” Ms. Ziegler said. “Maybe they’re unable to wear contacts.

“Women were two times more likely to report dry eye than men,” she added.

The study was supported by grants from the National Eye Institute.

CRT for hyperopia

Sameena Haque, BScOptom, MCOptom, reported that she and colleagues from the Centre for Contact Lens Research, University of Waterloo, found that Corneal Refractive Therapy lenses (Paragon Vision Sciences, Mesa, Calif.) for hyperopic correction, when worn overnight, caused a greater increase in central corneal and epithelial thickness than the paracentral area.

Twenty subjects wore a CRT lens on one eye for one night. Corneal, epithelial and stromal thickness measurements were taken at baseline, immediately following lens removal, then 1, 3, 6, 12 and 28 hours after removal.

Dr. Haque reported at the press conference that corneal scans were obtained by optical coherence tomography, focusing on the cornea instead of the retina.

“An 8.8% change in corneal thickness was seen at removal; after 3 hours, there was 1.2% swelling, with 99% recovery at 28 hours,” she reported. “Regarding change in epithelial thickness, the center had thickened 23% upon removal. Twenty-eight hours later, there was 98.7% recovery.

“CRT lenses induced greater overnight swelling than no lens wear,” she continued. “We recommend using higher Dk lenses. Almost no swelling was seen 3 hours after removal. The epithelial change pattern is opposite to myopic CRT, showing central thickening and midperipheral thinning.”

The work was supported by Paragon Vision Sciences.

Restasis improves lens tolerance

In a study of contact lens-intolerant patients, Milton M. Hom, OD, FAAO, found that treatment with Restasis (cyclosporine 0.05% ophthalmic emulsion, Allergan) allowed patients to wear their lenses longer each day and require less frequent instillation of rewetting drops.

Dr. Hom, a private practitioner from Azusa, Calif., and a Primary Care Optometry News Editorial Board member, evaluated 17 patients with self-reported ocular dryness. Nine patients were administered Restasis before and after lens wear; eight patients received Refresh Contacts (carboxymethylcellulose, Allergan) before and after lens wear. All patients used Refresh Contacts as needed, up to four times daily, during lens wear. Patients were given new lenses at baseline and at week 4.

According to the study abstract, after 5 weeks, wearing time in the Restasis group increased a mean of 1.9 hours per day, while wearing time in the control group increased 0.93 hours.

Dr. Hom concluded: “Cyclosporine emulsion was safe and well tolerated, with no polymer compatibility issues. It appears to be a promising new treatment for contact lens intolerance.”

This study was supported by Allergan.

Visual training improves mobility

In a study involving visually impaired individuals, Patti W. Fuhr, OD, PhD, FAAO, and colleagues found that computerized visual searching training may improve mobility performance.

Dr. Fuhr said at the AAO press conference that 3.3 million Americans have severe visual impairment that cannot be corrected. “They walk slowly and have a higher risk of bumping into things,” she said. “Patients usually work with a mobility instructor to help them get around, but training is costly and not readily accessible.”

Dr. Fuhr and fellow researchers from the Veterans Health Administration, Lighthouse International and Northrop/Grumman Information Technology developed and studied the effects of a computerized training program on 81 low-vision patients.

“Some trained 1 hour a day for 5 days,” she said.

Both trained and untrained patients were asked to walk through indoor obstacle courses, one under photopic and the other under mesopic illumination. According to the study abstract, the assessment was repeated twice for each subject, separated by an average of 13 days.

“The untrained individuals improved in testing slightly, but trained individuals improved much more,” Dr. Fuhr said. “Trained patients walked slower through the course than the untrained.”

According to the abstract, “While both groups hit a similar number of obstacles in the first walk, the trained group hit 32% fewer obstacles in the second walk, while the untrained group hit only 18% fewer obstacles.”

Dr. Fuhr concluded: “Visually impaired patients can learn to perform more efficient visual search. Computerized perceptual training may enhance mobility in these patients.”

This study was funded by the Department of Veterans Affairs Rehabilitation Research and Development Service.

For Your Information:

• Nathan Efron, PhD, DSc, FAAO, can be reached at the Department of Optometry, University of Manchester, PO Box 88, Manchester, M60 1QD, United Kingdom; +(44161) 306-3886; fax: +(44161) 831-6625; e-mail: n.efron@manchester.ac.uk.
• Corrie Ziegler can be reached at the Ohio State University College of Optometry, 320 West 10th Ave., SL Hall Room 101, Columbus, OH 43210; (614) 292-4979; fax: (614) 292-4705.
• Sameena Haque, BScOptom, MCOptom, can be reached at Centre for Contact Lens Research, University of Waterloo, School of Optometry, 200 University Ave. W, Waterloo ON Canada N2L 3G1; e-mail: S2haque@sciborg.uwaterloo.ca.
• Milton M. Hom, OD, FAAO, can be reached at 1131 E. Alosta, Azusa, CA 91702; (626) 963-7100; fax: (626) 335-1402; e-mail: eyemage@mminternet.com.
• Patti W. Fuhr, OD, PhD, FAAO, can be reached at Birmingham VAMC, 700 South 19th St. (124), Birmingham, AL 35233; (205) 933-8101, ext. 5105; fax: (205) 558-7060; e-mail: patti.fuhr@med.va.gov.