Thursday, December 17, 2015

Second Cataract Surgery: January 6, 2016

Although the focus of this blog are issues associated with lipids and heart health, I'd like to bring in other topics as well, in particular, the choices one needs to weigh in choosing the best sight strategy for the kind of lens you choose to embed.

One can go for maximum distance vision in both eyes. But then one almost surely will need reading glasses.

Or one can go for the new "multi" lens, which go for both distance and reading. As with many other compromises, you don't get the best distance or reading correction. At least that's been the story on the street.

Or one can go for "mono-vision" (as I did). This choice takes off from the natural distribution of function your eyes already have. One eye tends to do the "up close" work, the other eye, the distance work. In my case, my left eye naturally gravitates to closer reading, my right eye is my distance eye. My optometrist and I discussed this and set this up with my last several contact lens prescriptions.

Instead of correcting both eyes to 20-20, he corrected my left eye to about 20-40, so that it was easy to read. He adjusted the right eye to the full 20-20 for distance. This worked very well. I could read small text (say on my iPhone) without reading glasses or even squinting. While driving, the brain combined the two different corrections into something like 20-20 (at least during the day). This worked very well and the idea was to continue it with similar embedded lenses when I had cataract surgery.

But cataract surgeries don't typically happen together. The cataract in my left (reading) eye matured faster than the one in my right (distance) eye. So the idea was embed a "reading" lens in that eye.

But I've left out the issue of astigmatism. Both eyes have some astigmatism, which needs to be corrected in some way. My left eye was a candidate for a "toric" implant, a lens which corrects vision, including astigmatism, but costs extra.

My surgeon, who is also a lasik specialist, suggested that he could embed a regular lens and adjust for astigmatism through lasik surgery  at the time of the implant. The idea was to come up with about 20-40 in the left eye to continue my strategy of mono-vision.. This translated to a "backing off" about 1.25 diopters. (There is not necessarily a one-to-one correspondence to the 20-20, 20-30, 20-40, etc. and the diopters of correction. 1.25, 1.50, 1.75, etc. This needs to be actually tested in a standard refraction exam at your optometrist.)

Long story made short is this: while my left eye started out at 20-40, it has continued to "back off" until, almost a year later, it is 20-80. This is no problem of course in terms of reading, but I do feel some strain in combining distance vision, say while reading labels in a museum or driving at night. On a bright day, because the aperture of the iris is contracted, you get the same "depth of field" advantage as you do with a camera, so that my left eye may be even 20-30 at that time and the illusion of a full correction in both eyes is very strong.

The optometrist at the surgeon's office said something like, "The original target was 1.50 but I see that it is 1.75 or more..." I thought the original target was 1.25 (about 20-40) and was afraid the result was more like 20-100 in that dark room, but it was later tested at 20-80, which I think corresponds to 1.75.

In retrospect, I probably should have had a toric lens for my left eye. But my current status is within the acceptable window - as I attested at the office visit.

For the future, however, especially if the left eye backs off further (a real 20-100), then I would get a contact lens for it. The question is then, "At what correction"? From a discussion with my regular optometrist, it would have to have at least 0.5 diopter correction to be worth it. For me, that would mean, I think, a 20-40 "net" correction in that eye.

The question then becomes, does that compromise reading vision. If so, it doesn't appear to be worth it. My optometrist was able to simulate what it would be to have this. I really liked how it helped my distance vision (in the relatively dark room). But I was slightly put off by how I would have to slightly distance (extend out further) my iPhone for optimum reading. A close call.

In the meantime, the surgeon is going for "the best distance" in my right eye and I will get the toric lens. ($$)

Bottom line, after the surgery  and things settle. I'll revisit this.

1 comment:

  1. I've since met with my optometrist. We went through the exercise where he gave me left eye a half-diopter correction. Great! I saw the letters below the 20/80 line. Then he showed me what my near vision would be at that correction. Ouch! Could not read my iPhone text easily. Conclusion: the surgery relaxed my eye just right! Any less relaxation, and there would have been trouble reading at close distances. I had thought it was too much relaxation. Turns out, that it was just the amount needed.