This was touched upon about a decade ago.

The question remains of using LASEK or epi-LASEK to address irregular astigmatism.

In my case, I have been told the irregular astigmatism in on the surface of the cornea.

An given that the cornea has some, but little correction to vision and I am a bit overcorrected, it seems like LASEK would be a good approach.

Why can't LASEK burn off enough tissue to eliminate the damaged corneal tissue?
Original Post
Irregular astigmatism, per se, does not mean the corneal tissue is damaged. It simply means that the corneal optics are not amenable to correction by "conventional" means, i.e., glasses.

Wavefront-guided surface ablation can be used to correct irregular astigmatism plus any residual over or under correction but with certain caveats. A lot depends on how well the new treatment can "read" the irregularity and successfully adjust the ablation to create a "regular" optical surface. It will also depend on the degree of spherical aberration present and your pupil size.

While many people have had surface ablation to "correct" optical irregularities due to previous LASIK procedures, VSRN doesn't receive many reports of great satisfaction following secondary procedures. So much depends on the degree of irregularity prior to the second procedure and the relative improvement afforded by it.
Thanks for the response.

How would the irregularity be measured and localized prior to any procedure?

After all these years I am not sure where I was told the irregularity is, and never understood how that was determined. If I recall, I was told on the surface.

The pattern of the distortion looks just like the pattern one would see in the cloth, all to one side.
How is the irregularity formed? There was never an answer for this. I always assumed it was from the nose of the microkeratome. I was told by someone watching it pushed up the tissue (like catching a thread on some cloth).
The irregular surface would be mapped by a wavefront aberrometer as part of the surface ablation.

In most cases the irregular surface produced by LASIK is not from the underlying ablation (the laser burn) but from the simple fact that the flap no longer perfectly fits onto the residual cornea. The flap must cover a less voluminous cornea.

It's like you're a size 40 waist. If you lose fifty pounds and are a size 36, you will have to tighten your belt. Now the waistline on your pants is all bunched up and looks bad. In LASIK, when the flap gets re-laid over the newly-shaped cornea, it too gets bunched up. But instead of looking bad, you SEE badly.

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