News reports from the conference

Uncorrected vision a major issue in Canada, pilot study suggests

Uncorrected refractive error is a significant issue and major cause of reversible vision loss in Canada data from a Brantford, Ontario pilot study suggest.

Results from the study, involving 768 residents ages 39-94 years, showed that 16.4% had reduced distance visual acuity even when wearing corrective lenses, and that a significant number of the total study population had some type of presumed ocular pathology.

Results of the Canadian Uncorrected Refractive Error Study (CURES) were presented by Keith Gordon, vice president of research and service quality for the Canadian National Institute for the Blind (CNIB) on behalf of the research team from CNIB Research and the University of Waterloo School of Optometry.

Study rationale

Uncorrected refractive error is one of the leading causes of global avoidable blindness and published studies from the United States, Australia and the United Kingdom have documented a high prevalence of this issue in adult populations, Gordon said.

However, no population-based data are available in Canada. Researchers and policy makers rely on self-reported survey data and registration data, which Gordon notes are quite problematic.

CURES was undertaken as a pilot project to redress this deficiency with Branford being chosen as the study location for logistical reasons and because its population largely mirrors that of Canada as a whole.

Study design

Participants were recruited using a cluster sampling technique and door-to-door recruitment was aided by a local publicity campaign. Of these participants, 68% wore corrective lenses for distance and 83% had corrective lenses for near vision.

All subjects underwent measurement of presenting distance and near visual acuity when wearing their regular corrective lenses, if any. Best corrected visual acuity was measured for all participants presenting with distance visual acuity of less than 20/25 in either eye. Study subjects also underwent eye examination using a direct ophthalmoscope.

Findings

The study found that 126 participants (16.4%) had presenting distance visual acuity of less than 20/25 in their better seeing eye. Of those with glasses, 2.9% of the study population had presenting visual acuity of less than 20/40 in the better eye.

The study also found that 203 participants (26.4%) had near visual acuity less than 20/25.

Visual acuities improved by one to five lines for 85 of the 126 participants with reduced distance visual acuity (67.5%) and for 76.9% of those with reduced near visual acuity.

Although not part of the main study outcomes, eye exams revealed that 35% of study participants had some form of presumed ocular pathology whether already known or not. Of those aged over 60 years, this percentage climbed to 60% with conditions such as glaucoma and age-related macular degeneration being the most frequent.

Conclusions

The study concluded that despite the widespread availability of eye care coverage, a high prevalence of uncorrected refractive error was seen in this population.

Gordon noted that, in most cases, these deficiencies in visual acuity could be corrected with lenses.

In addition, he said that the study found that participants with both good and poor visual acuity were at risk for having ocular pathologies.