Of the many pieces of gear needed for triathlons, there's one that I tried to ignore for a while: prescription lenses. Sunglasses for the bike, but more importantly goggles for the swim. In a pool, my nearsightedness is only a minor nuisance to be not be able to read a clock; but for open water swimming I would be waaay more comfortable if I could clearly see my surroundings.
I assumed that they would be hard to find, and super expensive. While in googling I have found some sources for truly prescription goggles, costing about the same as actual glasses. I also found ideas on pinterest to glue old glasses lenses onto goggles - presumably to save money, and perhaps needed as a cheaper option if you have a very extreme prescription (though it seems like it'd be super clunky and potentially unsafe, in my opinion), but not necessary, it turns out, for the average glasses wearer. In a forum discussion, someone mentioned prescription goggles on swimoutlet.com (I've also found them on Amazon). While not truly "prescription", these are generic corrective lenses, along the lines of generic reading glasses, and are in the same price range as regular goggles.
Awesome! However - what about the fact that each eye needs different correction, and generic goggles - like reading glasses - come with the same in both lenses? I suppose that's also where the homemade glasses lenses option might come in handy, but there's actually a really simple workaround.
I do want to acknowledge that I didn't come up with this idea, but found it in comments in product reviews of the goggles I was looking at. However, if you didn't know about this solution you might not get far enough along that path of looking to purchase to come across it, so I wanted to put it out there in another format, not just in product reviews. My eyes are close enough (-2.0 and -3.5) that I was planning to just get enough correction for my stronger eye, and it'd still be much better than nothing, but being able to get reasonably close on both sides was a great bonus.
1. Pick a model of generic prescription lenses, making sure it's of a type that the nosebridge can be fully removed. (So you can remove and replace the lense.) (Swim Outlet, Amazon.) I went with a TYR one, just because that's the brand I've been using for my regular goggles, and they've been working.
2. Determine the diopter strength you need. This page has a good explanation of how this is determined.
3. If, based on #2, you need a different diopter for each eye, order a pair of goggles in each diopter.
4. Remove a lense from each pair and swap. (Although the diopter is impressed on the side of each lense to confirm any time, take care that the brand on the nosebridge is right side up when the lenses are on the correct sides, to make it easy to put on the right way with a mere glance.) Ta da! You have a usable pair + a backup pair of lenses with custom correction for both eyes.