Optometric researchers report results of myopia, driving, AMD trials

TAMPA, Fla. – Researchers from optometric institutions around the world as well as industry-based scientists presented a wide range of clinical data through podium and poster presentations here at the annual meeting of the American Academy of Optometry. A few researchers were also chosen to present their study results to the media at an AAO-sponsored press conference.

Changes in the myopic eye

Donald O. Mutti, OD, PhD, FAAO, reported that the posterior segment of an eye that becomes myopic follows a different pattern of development compared to the emmetropic eye, characterized by accelerated axial growth and changes in shape. Dr. Mutti, of the Ohio State University, and colleagues from other universities sought to investigate the behavior of the length and shape of the eye before, during and after the onset of myopia in children by evaluating patients involved in the 14-year Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study, which began in 1989 and continues.

Researchers looked at 928 subjects, measuring their refractive error by cycloplegic autorefraction, their ocular shape by relative peripheral refraction and their axial length by A-scan ultrasonography. Four hundred eighty-two children became myopic while being examined; 450 did not.

“The emmetropic kids stayed emmetropic,” Dr. Mutti said at the press conference. “The myopic kids started slipping, with the fastest change starting the last year before they became myopic.”

Two years before the onset of myopia, the eye starts to become more prolate, then the prolate trend stops and stays that way, he said. “Differences are apparent before the onset of myopia, so we can now better identify who’s at risk and predict who will become myopic,” Dr. Mutti reported. “Some of the differences are apparent 2 or 4 years before onset, so we don’t have much time to figure out what’s going on in these kids.”

This study was supported by grants from the National Eye Institute, the Ohio Lions Eye Research Foundation and the EF Wildermuth Foundation.

Older vs. younger drivers

Researchers at the Queensland University of Technology found that older drivers perform worse than younger drivers on most measures of performance when they compared a group of younger patients to a group of older patients.

Joanne M. Wood, PhD, FAAO, associate professor of the School of Optometry, reported at the press conference that older drivers make up the fastest growing segment of the driving population and have high crash rates. The goal of this study was to “investigate the effects of age, simulated impairment and multitasking on driving performance measured under real-world conditions,” she said.

Dr. Wood and colleagues looked at 28 patients: 14 young (19 to 34 years old) and 14 older (63 to 77 years old). Visual impairment was simulated using goggles modified to replicate the effects of cataracts and blur, although the participants still satisfied the visual requirements for driving when wearing the goggles.

Participants were tested on a real road course, were assigned three tasks and experienced computer-generated distractions in the car. The “real-world” driving tasks included detection and recognition of road signs and large low-contrast road hazards, judgment of cone gaps, lane-keeping and time taken to complete the road course. According to the study abstract, a secondary task “required participants to verbally report the sums of pairs of numbers presented either through a computer speaker (auditorally) or via a dashboard-mounted monitor while driving (visually).”

The researchers found that the older drivers performed worse than the younger drivers, with significantly more differences in the blur and cataract conditions. “Simulated cataracts had the greatest detrimental impact on older drivers,” Dr. Wood said. “The effects of simulated visual impairment on driving performance are exacerbated by performing secondary tasks.”

Dr. Wood concluded that “older drivers perform worse; driving in complex environments decreases driving performance; the use of navigation systems or mobile phones while driving negatively affects performance — and this effect is magnified by visual impairment.”

Reducing AMD risk

Patients with age-related macular degeneration make up a large segment of the optometric population 65 years and older. Because studies have identified lifestyle changes that can help prevent AMD or reduce the risk of blindness from it, it is important that optometrists are aware of these strategies, reported Barbara E. Robinson, OD, MPH, PhD, FAAO, of the University of Waterloo.

At the AAO press conference, Dr. Robinson said that AMD is the leading cause of blindness among older white people in North America, causing 54.4% of the cases of legal blindness in people older than 40. This number will double by 2020 and will total about 3 million people, she said.

Dr. Robinson’s study was based on data collected a few years ago when looking at asymptomatic disease in an optometric population in 133 practices across Canada. She looked at data from 24,570 patients (57.2% women, 42.8% men) over a period of about 3 months. The overall prevalence of AMD was 3.21% in the population, slightly higher in women, Dr. Robinson reported. In patients older than 65, the prevalence was 12.17%, and in those 85 and older, it was 25%.

Dr. Robinson urged practitioners to be aware of proven strategies to reduce the risk of this disease. “Not smoking, having a healthy diet — all those things you’re being told to do for your heart, you’re doing for your vision, too,” she said.

“If you smoke, you increase the risk of dry AMD by 2.5 times and for wet AMD by 4.5 times,” she continued. “If you smoke, your risk of having this disease at a younger age is greatly increased.”

She added that eating fish twice a week and three fruits per day can help decrease risk. Dr. Robinson also noted that the results of the Age-Related Eye Disease Study showed that people with moderate AMD who used antioxidant and zinc supplements decreased their risk of advanced AMD by 25%.

This study was supported by the Canadian Association of Optometrists.

Proview vs. Goldmann for kids

Amelia G. Bartolone, OD, FAAO, of the State University of New York, reported at the AAO press conference that children preferred the Proview Eye Pressure Monitor (Bausch & Lomb, Rochester, N.Y.) over Goldmann tonometry, and that the Proview is a reliable and repeatable method of measuring intraocular pressure in children.

Dr. Bartolone said that because the Goldmann method requires an anesthetic eye drop that can sting, the experience can be traumatic for children. “Kids must sit still and keep their eyes open while you bring a probe close to their eyes,” she said.

She and her colleagues sought to determine the validity and repeatability of Proview measurements as well as whether or not children can appreciate the pressure phosphene necessary for using the Proview method.

Ninety-two children between 5 and 12 years old completed the study, reported Dr. Bartolone. The average age was 7.5 years, and they were equally split between boys and girls. The first subset did the Proview, then Goldmann; the second subset did the Goldmann, then the Proview.

“The mean average in Goldmann was 14.5 mm Hg, and it was about 4 points higher on the Proview,” Dr. Bartolone said. “Yes, kids can appreciate phosphene, it is repeatable, but there is a large variability among subjects.”

Dr. Bartolone said that no prediction of Goldmann measurements can be made from the Proview measurements. However, “kids who were normal with Proview were normal with Goldmann,” she added.

Her final recommendation: Use the Proview first. “If you get a high measurement, repeat it on Goldmann,” she said.

Tear viscosity and TBUT

Allergan researchers found that high-viscosity artificial tears increase tear break-up time (TBUT) to a greater extent and for a longer period of time than either a low-viscosity drop of similar composition or a low-viscosity drop of different composition.

Peter A. Simmons, PhD, FAAO, and Joseph Vehige, OD, looked at three different formulas of tears in patients with mild to moderate dry eye symptoms and reduced TBUT.

According to the study abstract, the researchers randomly dosed 39 subjects on 3 successive weeks with three different artificial tear formulas: private label brand artificial tears (0.3% hydroxypropyl methylcellulose), Refresh Tears (0.5% carboxymethylcellulose, Allergan) and Refresh Liquigel (1% CMC, Allergan).

They recorded TBUT after 5, 10, 15, 20, 30, 45 and 60 minutes. They also recorded blink rate at the beginning and end of each testing period, and the inter-blink interval was determined to calculate the ratio of TBUT-to-blink interval.

The pre-drop TBUT averaged 3.8 seconds, according to the study abstract. All drops increased TBUT at 5 minutes, with significantly higher TBUT for the Refresh Liquigel group than the others.

“At later time points, only the [Refresh Liquigel] drop significantly increased TBUT compared with baseline,” the abstract said. “The number of eyes with TBUT/blink interval ratio >1.0 was greater for the [Refresh Liquigel] drop than the others up to 30 minutes after instillation.”

In addition to showing that the high-viscosity drop increased TBUT to a greater extent and for a longer period of time than the other drops, “the TBUT/blink interval ratio results indicate that the use of a higher-viscosity drop protects the ocular surface for a longer time following instillation” said the abstract.

The study was performed in collaboration with Ophthalmic Research Associates.

For Your Information:

• Donald O. Mutti, OD, PhD, FAAO, can be reached at the Ohio State University, 338 West 10th Ave., Columbus, OH 43210-1240; (614) 247-7057; fax: (614) 247-7058; e-mail: dmutti@optometry.ohio-state.edu.
• Joanne M. Wood, PhD, FAAO, can be reached at the Queensland University of Technology School of Optometry, Victoria Park Rd., Red Hill, QLD 4059, Australia; (617) 3864 5701; fax: (617) 864-5665; e-mail: j.wood@qut.edu.au.
• Barbara E. Robinson, OD, MPH, PhD, FAAO, can be reached at the University of Waterloo, Waterloo, ON N2L 3G1, Canada; (519) 888-4567, ext. 2057; fax: (519) 725-0784; e-mail: robinson@sciborg.uwaterloo.ca.
• Amelia G. Bartolone, OD, FAAO, can be reached at the State University of New York, State College of Optometry, 33 West 42nd St., New York, NY 10036; (212) 780-4976; fax: (212) 780-4980; e-mail: abartolone@sunyopt.edu.
• Peter A. Simmons, PhD, FAAO, can be reached at Allergan, 2525 Dupont Dr., Irvine, CA 92612; (714) 246-5514; fax: (714) 246-4002; e-mail: simmons_peter@allergan.com.
• Joseph Vehige, OD, can be reached at Allergan, 2525 Dupont Dr., Irvine, CA 92612; (714) 246-6847; fax: (714) 246-4002; e-mail: vehige_joseph@allergan.com.