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This is almost certainly referring to seniors who continued to wear corrective lenses but had cataracts hindering their vision, as is extremely common in old age. While LASIK can be an excellent long-term solution for myopia, it is not a preventative measure against cataracts.

Cataracts are fairly treatable, no?

Judging by my family some older people are reluctant to have doctors poking about in their eyes.

They straight up replace the lens of your eyeball with a plastic one, and as result you can often see better than ever, without glasses. That was the outcome for my dad, anyway.

My dad's side of the family has eye problems: myopia, glaucoma, detached retina, and wet macular degeneration. Hoping my mom's genes spare me the worst of it.

Yes, depending on your access to treatment.

I would speculate they are measuring the decline in visual processing in the brain and optic nerve in this case, not the impactful of poor sight on cognitive decline.

I read it differently. It sounds to me like it’s saying that it was people “who weren’t able to see well when they were using their prescription lenses.” As in, they have prescription lenses, but their vision is not actually corrected.

I agree, and to me it hints at a couple of possibilities...

Perhaps they are receiving sub-standard vision care (and are thus unable to get updated eyeglass prescriptions, cataract surgery, etc), and this might be associated with other forms of sub-standard care.

Or perhaps a person suffering from dementia is less likely to notice and/or less able to pursue treatment for their own declining vision...

I assumed the article meant that this was people whose vision had changed (so no longer had correct prescription) or cataracts.

> LASIK surgery has been widely popular for just over 20 years now. I'd be interested to see how permanently corrected vision factored into this study, and how the results might change over time as we have more elderly who underwent LASIK at younger ages.

Lasik can correct an astigmatism or other curvature problem but cannot do anything about presbyopia (which by definition affects older people) as that is a loss of ability to change the shape of the eyeball. That's why older people need reading glasses even if they otherwise still have 20/20 vision.

You don't have to be that "old". Late 30's it is possible

Obstetricians call having a first baby at 35 "geriatric primagravida" too...

From the conclusion of the study the article cites:

> In this survey study, all types of objectively measured VI were associated with a higher dementia prevalence. As most VI is preventable, prioritizing vision health may be important for optimizing cognitive function.

In other words, the association is dementia and uncorrected visual impairment.

EDIT: I'll add that the study does not show causality. Even people like myself who are well aware that correlation != causality often still assume it does. It doesn't help that the authors themselves imply that correcting VI would ward off dementia. It might; it might not. People with dementia might just be less likely to get glasses.

I think people get away with that kind of thinking more easily when the intervention being proposed seems generally unobjectionable anyway.

"Correcting vision problems for older adults" sounds like a good idea in its own right, so when someone adds a "and maybe it'll reduce dementia!" thought to the equation, even though the relationship might very well not be causal, people kind of shrug out a, "Sure, that'd be nice," in reply.

> It also builds on previous work about cataract surgery that showed lower rates of dementia over time in adults who had had their distance vision restored by having surgery.

This study does not (by what I read) directly address your question, since it doesn't say anything about whether the participants in this study had cataract surgery, LASIK, or anything else, or whether they even factored that in. But, evidently some other studies have been done on this.

The study is looking at best corrected vision. That is, the best vision achievable with refractive (glasses, contacts, lasik) correction.