Defining the truth

By Peter J. McDonnell, MD

Dr. McDonnell

Sometimes, it is hard to prove what you know to be true is actually true-like that my brother-in-law, John, is a nice guy.

Yes, he’s a bond trader, so he knows the incredibly rude jokes that fly around bond trading rooms. Presumably, he has that “go-for-the-jugular” aspect to his makeup that is part of the culture in his line of work.

But I just happen to know that deep down he is a really decent fellow-even if there’s no scientific literature I can cite to back me up on my assertion.

Reaffirming study

So, it’s nice to know there is a paper confirming something I have also known to be true: People who lose visual acuity as a result of cataracts will-if they have cataract surgery to restore their vision-live longer than those who do not have surgery.

A population-based cohort study¹ from Australia examined 354 people aged 49 or more years with visual impairment from cataract between 1992 and 2007. Correcting for other known risk factors, like diabetes and smoking, the study showed that people who underwent cataract surgery had a 40% lower long-term mortality risk than those who did not have surgery.

The study “suggests to ophthalmologists that correcting cataract patients’ visual impairment . . . results in improved outcomes beyond the eye and vision, and has important impacts on general health,” said Jie Jin Wang, one of the authors of the paper.

It strikes me this statement is one that would be obvious to any ophthalmologist. People who do not see well tend to fall, have trouble accurately drawing up their insulin, find driving difficult, and become withdrawn and sedentary.

But now we have a published study we can cite (unlike with my brother-in-law).

There’s always a caveat

The authors, however, do not know for sure whether some people did not have cataract surgery because they had other health problems that prevented this, and those other health problems might have contributed to poorer survival.

The other obvious flaw is that the study is from Australia.

I have yet to visit that great country, but enjoy watching nature programs and know Australia to be inundated with vicious animals (voracious crocodiles and deadly cassowaries to name two).

The only similar environment in my country, in which senior citizens are routinely ingested by hungry reptiles, is the golf courses of Florida.

Hence, it may simply be that cataractous Aussies don’t see the predators sneaking up on them until it is too late (as documented in the film “Crocodile Dundee”). This would make their study not generalizable to the populations of other nations (or at least the residents of my condominium).

Prospective, randomized controlled trials are always best for addressing such controversies.

One approach is to recruit retired bond traders who have cataracts, randomly assign them to either surgery or no surgery, have them golf every day for a year in Florida, and see how many in each group have not been devoured.

Reference

1. Fong CS et al. Correction of visual impairment by cataract surgery and improved survival in older persons: The Blue Mountains Eye Study Cohort. Ophthalmology. 2013;120:1720-1727.

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