March 2009

 

OPHTHALMOLOGY NEWS

 

Vision screening not a good idea?


by Matt Young EyeWorld Contributing Editor

   

Study results buck common perceptions but corroborate other results

Vision screening for frail older people doesn’t work. It doesn’t help improve vision or vision-related quality of life, according to an Australian study. Findings were based on comprehensive vision and eye examinations, conducted by an optometrist, of 616 men and women 70 years or older. “This somewhat surprising finding is consistent with a previous randomized trial done in the U.K., which found that community visual screening as part of a multicomponent assessment was of no benefit in terms of visual acuity or vision-related quality of life,” wrote study co-investigator Robert G. Cumming, M.D., Ph.D., and colleagues, Centre for Education and Research on Ageing, Concord Hospital, Sydney, Australia. The study was published online in July 2008 in the British Journal of Ophthalmology. Why didn’t vision screening work in this study? Because a control group that didn’t undergo screening reported seeing an eye care professional anyway during the follow-up period. Although Dr. Cumming referred to this as a kind of study “contamination,” it nonetheless points to an interesting conclusion: Promoting frequent eye checks in a community isn’t helpful.

Some strange findings

In this study, an optometrist conducted a comprehensive vision and eye exam of 309 subjects, with 146 deemed to need eye treatment. Ninety-two patients received new glasses, 24 got a home visit by an occupational therapist, 17 received glaucoma treatment, and 15 were recommended cataract surgery. The study also involved 307 control subjects that did not undergo vision screening. Given that about half of the screened patients were recommended some treatment, you might think that the intervention helped. Not so, compared with controls. “After 12-months follow-up, the mean (logMAR) distance visual acuity was 0.27 in the intervention group and 0.25 in the control group,” Dr. Cumming wrote. “The mean (logMAR) near visual acuities were –0.01 in the intervention group and –0.03 in the control group. The mean composite score on the National Eye Institute Visual Function Questionnaire was 84.3 in the intervention group and 86.4 in the control group.”

Why were acuities and scores so similar? “Of the 258 subjects in the control group at follow-up, 187 (72%) reported having been seen by an eye care professional in the preceding 12 months,” Dr. Cumming reported. Thirty-six percent of screening patients had their glasses changed in the 12-month timeframe, but 29% of control patients also did. Control patients also saw an eye care professional and had glasses changed closer to the 12-month follow-up interval than screening patients. “Our findings would probably have been different if we had conducted follow-up assessments after a shorter period of time, as immediately after receiving their new glasses, subjects in the intervention group would be likely to have had improved visual acuity,” Dr. Cumming noted. “However, findings after a short period of follow-up would have little public health or clinical relevance.”

Very surprisingly, Dr. Cumming further suggested that more frequent vision checks might even be damaging. “In a previous paper from this study, we reported the possibility that vision screening might increase the risk of falls and fractures,” Dr. Cumming reported. “While the mechanism for any increased risk of falls remains unclear, it may be that older people take a considerable time to adjust to wearing new glasses and that falls risk may be increased during this period of adjustment.”

Dr. Cumming suggested that these results—again, supported by various studies at this point—still might only apply to populations where vision testing is easily available. So vision screening may still benefit those living in “rural and remote” areas, for example. Mohan Rajan, M.D., Rajan Eye Care Hospital, Chennai, India, suggested that vision screening is beneficial in India. In his country, vision screening centers are critical to reduce workloads on ophthalmologists. It’s necessary, therefore, to have vision screening for school children, in which teachers themselves are trained to check vision, Dr. Rajan said. Vision centers also are manned by optometrists that simply check vision—not even at the slitlamp. If they are not able to improve patient vision by means of refraction, then they are referred to a hospital, he said. “In the future we’re going to take it one step further,” Dr. Rajan said. “We’re going to provide non-mydriatic fundus cameras to all vision centers. They do not require training.”

Editors’ note: Dr. Cumming has no financial interests related to this study. Dr. Rajan has no financial interests related to his comments.

Contact information

Cumming: 61-2-9767 6818, bobc@health.usyd.edu.au
Rajan: rajaneye@vsnl.com

Vision screening not a good idea? Vision screening not a good idea?
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