Proceedings of: Workshop on Improving Building Design for Persons with Low Vision

Falls and Injuries

So talking about falls: Just in general, if you look at the epidemiology literature, there was actually a Safety and Seniors Act that was passed in 2007 or 2008. It was called the Act of 2007 of Putting Emphasis on Preventing Falls and Injuries in the Older Population. But a third of the people who reach 65 have fallen at least once in the preceding year (slide 64). About a third of the people over 65 have a strong fear of falling and that limits their activities. And this prevalence of both falls and fear of falling increases with age.

Well, in terms of hip fractures, 90 percent of the hip fractures occur in this population because of falls (slide 65). Visual acuity loss turns out to be a major independent risk factor for hip fractures. I’ll give you those numbers in a minute. Relative to people who have 20/20 visual acuity – if you test for all the other variables – hip fractures double in the acuity range of 20/30 to 20/40. They triple in the range of 20/50 to 20/70. We’re not even up to Medicare paying for it. And then once you get up into Medicare’s definition of low vision, it quadruples. So you have four times the risk of hip fracture if you have low vision by Medicare definition than you if you don’t – all else being equal.

Accidents [are] the leading cause of death in seniors; falls account for about 50 percent of accident of deaths, car accidents account for the other 50 percent (slide 66). The death rate from all causes increases 20 percent for people who are 20/25 relative to 20/20 (slides 67 and 68). It goes up to 25 percent more for people who are 20/32 – it’s just a small change, one line. And less than 20/30 – that’s not even into what we conventionally considered a low vision category – 20/40s kind of important. They take your driver’s license – put restrictions on your driver’s license. The death rate is 60 percent higher. So the 30 million figure might not be too far off if we’re thinking in terms of the impact it could have on safety.

So probably the reason for this is that as you age, you get nerve degeneration occurring in the vestibular apparatus. That’s the inner ear that controls your balance (slide 71). And you also get nerve degeneration occurring in the stretch receptors and appropriate receptive feedback that you’re getting from your muscles and joints (slide 70). And making your balance – three systems are involved: your vestibular system, which senses accelerations; your receptive feedback from your muscles and joints and your vision (slide 69). [These] are called flow fields that tell you that you’re moving relative to your environment. If you have two of those three systems intact, you can control your balance. If you drink a lot, that screws up the vestibular system, okay? But it also, in doing that – because of dehydration – it also induces what we call vestibular-ocular reflex that, for kind of a nice name, we call it getting dizzy. And balance tests tend to be good diagnoses that you are having too much to drink.

If you lose two of these systems, you cannot maintain your balance. If we have just neurodegeneration going on, we’re probably increasing the load on vision to maintain balance as we grow older. Added to that, neural-degenerative diseases like peripheral artery disease and things like that in this composite, and so [there is] more reliance on vision. And even so, small changes in vision seem to have a big impact on both.