Sometimes solutions to problems are right in front of our eyes. Pun intended or not, sometimes things that are just common sense fail to be utilized in patient safety. Ever try to walk down or up stairs wearing bifocal lenses? Or walk in any area where surfaces may have bumps or depressions? Even the healthiest of people can trip and fall while wearing bifocals. So think about the elderly who need bifocals and those who are already at risk of falling.
A study just published in the British Medical Journal (Haran et al 2010) looked at the effect of replacing multifocal lenses in patients at risk of falls with single distance vision lenses (and providing appropriate counseling about their use when going outside). This was a randomized controlled trial of community-dwelling elderly patients with presbyopia who used multifocal lenses outdoors at least 3 times a week. The intervention resulted in a 40% reduction in falls in those who regularly took part in outside activities. However, the frequency of falls actually increased in the subgroup that had little outside activity. So the seclection of patients for the intervention must be thoughtful. A couple prior studies that failed to show significant reduction in falls with single vision lenses may have had 2 subgroups “cancel each other out”. In the current study that is actually what happened, too. The overall reduction in falls for all intervention subjects was only 8%, not statistically significant. But the pre-planned subgroup analysis was what demonstrated the beneficial effect in patients who regularly do outside activities.
Actually, some previous studies had shown acute ocular interventions might increase the risk of falls and the editorial accompanying the Haran paper (Campbell et al 2010) stresses that changes should be made step-by-step in the elderly with impaired vision. That editorial also provides some thoughtful insight into problems that may arise when patients wearing transitional (polychromatic) lenses when they come inside from being outside. Since there is a delay in the change in tint of such transitional lenses, vision may become impaired when those patients initially come inside.
So a common sense approach may work. But equally importantly it shows that unintended consequences may pop up.
Haran MJ, Cameron ID, Rebecca Q Ivers RQ, et al. Effect on falls of providing single lens distance vision glasses to multifocal glasses wearers: VISIBLE randomised controlled trial. BMJ 2010;340:c2265, doi: 10.1136/bmj.c2265 (Published 25 May 2010)
Campbell AJ, Sanderson G, Robertson C. Poor vision and falls
BMJ 2010;340:c2456, doi: 10.1136/bmj.c2456 (Published 25 May 2010)