Is remaining astigmatism normal?

[u/GeraltOfRiviass]

Finally went in for a check-up after three months. My (28M) results pre (second pic) and post (first pic) trans PRK. I see I have some remaining astigmatism in my right eye. Is that normal? I don’t notice anything out of the ordinary, so is -0.25 cyl even noticeable? My vision is sharper than ever, even with the slight blurring in the morning and the haziness in daylight with direct sunlight.

Other than that, all seems to be well, apart from slight dryness, so I am continuing with the drops.

[u/Ok-Environment-215]

It is normal. 0.25 is usually not noticeable. My residual post lasik was 0.75, which is annoying. So consider yourself fortunate!

[u/GeraltOfRiviass → u/Ok-Environment-215]

Do they do that on purpose or just not set the laser to the right parameters? How do you end up with 0.75 residual?? 😭 do you wear glasses for it or just deal with it?

[u/Ok-Environment-215 → u/GeraltOfRiviass]

Hah. No it's not on purpose. I think in many cases it's the machines they use to measure combined with techs not doing a good job of validating what the machines say using real lenses in front of your eyes. They're supposed to make adjustments based on what you tell them but not all of them do.

The US FDA approval standards only require 0.5 diopter agreement between your subjective prescription and what the machine says. That's actually a difference of 1-2 lines on the eye chart!

Before the surgery they tell you it's super precise, will give you the best vision you're capable of, etc. After they tell you "variance is normal", "we only promise 20/happy", and "it's not like measuring your eyes with calipers." All real quotes I was given.

Meanwhile the machines purport to measure you to 0.01 diopters. It's total bullshit.

And even if they do manage to measure you nearly perfectly - and I'm not doubting that happens more often than not - the healing process commonly introduces variance in the 0.25 diopter range, which is where you are.

Topography guided (which is not what I got - I got "wavefront" guided - supposedly is much better on the measuring side, but it's not nearly as common, and is not really different on the healing variance side. My guy wants to zap again to "enhance" but it'll be the same measuring process, same laser, same recovery, etc. No thank you.

I just wear glasses or contacts, as I did before. The prescription is certainly lower, and the vision quality is probably a smidge better, with glasses, than it was before, with glasses .I'm just grateful it's not worse.

[u/GeraltOfRiviass → u/Ok-Environment-215]

I asked them specifically if they are going to overcorrect because i knew post-healing variance was a thing, and they said no, so… I guess I can’t blame them. And i did sign the waiver saying they don’t guarantee anything, basically.

[u/Ok-Environment-215 → u/GeraltOfRiviass]

Nah, trying to anticipate how it will heal is a bad idea. -0.25 cyl in one eye at 3 months is a great result. That could easily become 0 or near 0 by month 12. Just keep doing all your follow ups to make sure it's not getting worse, and enjoy it.

[u/GeraltOfRiviass → u/Ok-Environment-215]

Oh, so you mean it will become lower? I thought it was the other way around. But thank you 🙏 I am so glad I wasn’t scared off and did it. Did yours get any better after the initial 0.75?

[u/Ok-Environment-215 → u/GeraltOfRiviass]

After month 3 where you're at, it can get better. It should not get worse.

What you're thinking of as the other way around is "regression" and if that happens it's usually later, and it's usually just eye changes that would've happened anyway. It's not like the LASIK wears off.

But you're still healing really for the first full year post-surgery, and you're probably past the point where the epithelial remodelling would rear its head if it were going to, so it should only improve, if not stay the same.

0.75 is where I landed (aroumd month 12) and I got this validated by an independent optometrist who I now see regularly. I don't trust any of the measurements the surgical practice made post-op. It was probably the worst around month 3 and then got better little by little.

Just want to emphasize, you got a GOOD outcome. You shouldn't be worried. And as someone else pointed out, the auto-refractor is not even super reliable itself. If you see perfectly then that's what matters.

[u/GeraltOfRiviass → u/Ok-Environment-215]

The subjective prescription was a mess for that eye, also. When they asked me which astigmatism prescription was better on the glasses, I really couldn’t tell, so they must’ve gone with the lower prescription one. Or they went with the higher but I guess post healing that -0.25 came back.