Impaired vision is one factor that contributes to loss of balance and falls. So it seems logical that correction of vision should prevent falls. But in our What’s New in the Patient Safety World columns for June 2010 “Seeing Clearly a Common Sense Intervention” and June 2014 “New Glasses and Fall Risk” we noted that sometimes new glasses and correction of vision may paradoxically result in increased falls.
What about cataract surgery? How does it impact the risk of falls? A recent Australian study (Meuleners 2014) used large linked population databases to examine the possible relationship. The authors note that the previous literature on the impact of cataract surgery on falls is conflicting, with some studies showing a reduction in falls and some showing an increase in falls. They then addressed the risk of injurious falls requiring hospitalization in patients undergoing bilateral cataract surgery, which is typically done one eye at a time in Australia. Compared to the 2 years prior to surgery the risk of injurious falls requiring hospitalization was over twice as high (RR 2.14) between first- and second-eye cataract surgery. And there was still a 34% increase in injurious falls requiring hospitalization after the second-eye cataract surgery compared to the 2 years prior to surgery.
So what does this mean? One obvious problem is the before-after design of the study. What we don’t know are the before and after rates of injurious falls requiring hospitalization in patients with bilateral cataracts who did not have surgery (though even those rates would be subject to selection bias when compared to the rates in the current paper). The point is that we might very well anticipate an increase in the fall rate over time in this population, which is largely elderly and has multiple comorbidities, regardless of whether they have cataract surgery.
Also, we don’t know anything about the activities in these patients. The authors acknowledge that it is quite possible that patients with improved vision after cataract surgery become more active and may take risks they would not have previously taken and therefore increase their chances of a fall.
We have long been advocates of falls with injury being a more important measure than simple fall rates so we have no problem with the measures they chose. A randomized controlled trial to see whether cataract surgery reduces or increases falls with injury is very unlikely to ever happen. So we’ll probably never know for sure but have to presume that cataract surgery might possibly increase the risk of falls with injury.
But the main message of the study is that the period of time between surgeries is one in which the patients are particularly vulnerable to injurious falls requiring hospitalization. The authors recommend patients be informed of this risk and that ophthalmologists take into consideration the timeliness of the second eye surgery.
Cataract surgery clearly improves multiple aspects of vision and improves quality of life. So the message here is not to avoid cataract surgery but rather recognize that there could be an increased risk of serious falls, particularly in the period between surgeries.
Another example that even interventions having positive results may also have unintended consequences!
Meuleners LB, Fraser ML, Ng J, Morlet N. The impact of first- and second-eye cataract surgery on injurious falls that require hospitalisation: a whole-population study. Age Ageing 2014; 43(3): 341-346
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