Comment by rms | Hacker News Reader

Comment by rms | Hacker News Reader

I had LASIK 1.5 years ago...

I went from not being able to see the big E at the top of the chart (worse than 20/500, but still only 80th percentile bad for people getting LASIK) to having 20/25 vision.

My world looks fundamentally different to me than my pre-corrected vision. All around, it's substantially more like being on LSD all the time. Lights are brighter. Way, way brighter. Blacks are deeper. The contrast has been turned up on my vision by at least an order of magnitude. At night, it makes big light installations more interesting and driving not that much harder.

My ability to perceive 3 dimensional detail is much improved. I can perceive the intricate structure of the leaves of a tree in a way that was previously impossible for me. Current LASIK is good at fixing higher order aberrations and this is what results in the improved 3d vision.

No matter what your doctor tells you, accept that sometimes, LASIK doesn't quite stick and once your vision gets worse than 20/60 or so, you'll need corrective lenses or another surgery. I expect that sometime in the next 10 or 20 years, I will get a LASIK touch-up, then a while after that, a lens replacement. Maybe a lens replacement instead of another LASIK surgery if medical technology improves exponentially or something.

If you can afford it, I would suggest getting LASIK (or PRK or computer-automated derivation of PRK if you don't mind suffering for a week or so, in exchange for not leaving never healing wounds in the middle of your eyes), especially if your vision is significantly worse than normal or you have moderate astigmatism. The world really does just look better.

I'm also a mediocre outcome of modern LASIK surgery! A lot of people get to 20/15 vision. A lot of the bad press for LASIK came 10 years ago or more, before wavefront-guided LASIK. As it stands, LASIK tech these days is brilliant elective surgery.

This notation 20/* is very interesting: in Brazil they never tell you a number like that.

People tell you about how well they see by saying that they don't need glasses, or by giving their prescriptions, like "hyperopia, 2.5 on right eye, 1.0 on left, plus astigmatism of 1.0 on the right eye..."

It's an American think afaict. I still don't quite get how it works, just that it has something to do with feet.

It's a ratio of distances -- the benchmark distance is 20 feet but that's non-essential. 20/10 means you can see the same level of detail at 20 feet that somebody with "normal" vision can see at 10 feet.

That seems problematic, how is normal vision defined?

With dioptres, the definition is very clear and based on optical properties of the eye.

Prescription and acuity are not the same thing. Many people do not get "perfect" acuity even with optimal prescription.

Ie prescription tells what kind of corrections you need to get the best possible vision, but doesn't tell how good your best possible vision is. Acuity on the other hand tells you what's the smallest detail you can distinguish over some distance (such as 20 feet in the normal 20/xx expression).

Are there other people here with heavy corrections that have undergone LASIK surgery?

I was always told that heavier corrections (I have about -10 dioptrics) were tricky because they would have to laser away to much of your eyes' "back wall". This would make the eye structure weaker which could result in eye deformation (bulging eyes?). Truth to be told: that sounded possible and scary enough so I didn't investigate further. I'm ready to be proven wrong :)

I was about -6.5.

I think the answer to the question is that it depends on how thick your cornea are, and how far the surgeon is willing to push it. Some surgeons are more comfortable working with thinner margins of error than others. You want a doctor that is conservative on this metric. I would go in and get a (free) scan to find out whether or not you're a good candidate.

Yes, there is a limit to how much correction you can do to an eye with that method. I have a -8 correction and it seems that it's already too much.

Also heavier correction gives not as precise results as small corrections : it depends of the cicatrisation of the eye. You might end up having a better vision but still requiring to have glasses.

It seems there exists alternatives like putting a lens inside the eyes which gives really good results and is also reversible. The lens is visible if you look closely. I didn't try the method though.

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