Researcher: Consider reading addition in young people with reduced near vision

Academy 2010 studies address low vision in pre-presbyopes and binocular vision in the elderly.

Results from two studies presented at Academy 2010 in San Francisco showed the benefits of reading additions in pre-presbyopes with low vision and the high prevalence of binocular vision anomalies among the elderly.

Near additions in pre-presbyopes with low vision

In a study of 18 pre-presbyopic patients, researchers measured accommodation with dynamic retinoscopy at various reading distances and trialed a reading addition based on the result.

Susan J. Leat

The study authors concluded that a reading addition would be beneficial for young adults and children with reduced accommodation and reduced near vision. The results of the study were shown in a poster presentation at Academy 2010.

“Although the prevalence of visual impairment is lower in young people than in older adults, the visual impairment is a lifelong condition and therefore has more significance if we consider it in ‘visual impairment years’,” Susan J. Leat, PhD, FAAO, FCOptom, said in a follow-up interview with Primary Care Optometry News.

Participants in the study, all between the ages of 8 and 34 years old, were asked to read sentences with and without reading additions, at 25 cm, 12.5 cm and their habitual reading distance, according to the poster.

The number of correct words per minute was plotted against print size and the maximum reading speed, and logMAR reading acuity thresholds were determined.

“In this study, we only included participants from 8 years upwards, so they could read our printed sentences,” Dr. Leat said. “But, clinically, such a reading addition could be tried for children as soon as they are in school if they are using a closer-than-normal reading distance.”

Without a reading addition, participants’ reading thresholds were significantly poorer at 12.5 cm compared with 25 cm. This difference was no longer significant with the reading addition at 12.5 cm, the study poster said.

Also, with the reading addition, there was an improvement in thresholds at 12.5 cm and at the habitual distance.

“Because we didn’t find any factors that easily predicted which participants would benefit from a reading addition, we suggest that all young patients with reduced visual acuity should have a reading addition trialed during a low vision assessment,” Dr. Leat said in the interview. “This could be done subjectively for those who are able to respond, such as adding positive power in diopter steps while the person observes a reading chart at their habitual reading distance.”

Researchers were surprised to find the reduced accommodation and improvements with reading additions were not predicted by visual acuity or age, as might be expected, she added. Therefore, even patients with near normal acuity should be given a trial of a reading addition.

Binocular vision anomalies

Another study assessed the prevalence of binocular vision anomalies in elderly patients, because of the known link between poor stereopsis and dangerous falls.

Dr. Leat and colleagues conducted a retrospective look at patients 60 years and older. They reviewed 500 patient files and analyzed the data for presence of binocular vision or ocular motility impairments, including phoria, strabismus, incommitancy and poor pursuits.

Researchers concluded that binocular vision and oculomotor anomalies had a prevalence of at least 35% in patients 60 and older, Dr. Leat said.

The presence of binocular vision disorders may lead to symptoms such as reduced function and compromised stereopsis, which could lead to an increase in falls or injuries, she said.

“Although ocular and systemic disease management are important in the older adult population, this study indicates that eye care practitioners should also attend to binocular vision and oculomotor disorders, which have a high prevalence,” Dr. Leat said.

The prevalence of such disorders is approximately 27% in 60- to 69-year-olds and increases to 38% in those older than 80 years, she said.

Though the incidence of binocular vision disorders tends to increase with age, they can be more strongly predicted by measures of general health, she added. Dr. Leat suggested treating these conditions as early as possible in life, and not waiting until they become more established.

“Some binocular vision disorders are treatable with prisms or with vision therapy, and optometrists should consider these options with older adults, as well as with their younger patients,” Dr. Leat said. “By doing this, we may be able to improve functional vision and even reduce the risk of falls in older adults.”

Further research

In Dr. Leat’s lab at University of Waterloo School of Optometry, researchers are now investigating whether there is a direct link between binocular vision disorders and a history or fear of falling.

“If this direct link is found, it will give more emphasis to the importance of treating these conditions as far in advance as is possible,” she said.

“It is possible that binocular vision assessment has received less attention, but this may have to change,” she added.

The results of these studies should eventually change clinical practice, Dr. Leat said. In young people with low vision, measuring accommodation and trialing a reading add should become a standard part of the low vision assessment and primary care, she said.

“Improving a child’s access to print may have an impact on his/her education, thus having a lifelong impact,” Dr. Leat said. – by Alexandra Harcharek

References:

• Leat SJ, Briand K, Hamaed N. The impact of near additions on reading performance in pre-presbyopes with low vision. Poster presented at Academy 2010, November 2010. San Francisco, CA.
• Leat SJ, Maharaj P, Hrynchak PK, et al. The prevalence of binocular vision anomalies in the elderly. Presented at Academy 2010, November 2010. San Francisco, CA.

• Susan J. Leat, PhD, FAAO, FCOptom, can be reached at School of Optometry, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1; (519) 888-4567, ext 32040; leat@uwaterloo.ca.