I had -10 dpt on both eyes before lasik. 6 Months post OP 80 % (right eye 1,25 astigmatism) and 90 % (left eye 0,25 dpt Astigmatism) uncorected vision due to astigmatism wich I feel to cause very little triple vision on the right eye (with artificial small lights at night only, not visible otherwise or othertime). Topography doesn`t confirm the irregular-astigmatism- impression, but one thinner area at both corneas. Contrast-visibility declined a bit in dawn. My M.D. suggests an enhancement. The thinnest area is 280-300 micrometers, while 320-340 surounds. He says, he would need about 40 microms. How low can/should I go?

Ectasia is a serious complication with LASIK. The only way to know how thin your cornea is would be for your doctor to actually measure your residual corneal thickness just before he applies the laser surgery. So the surgeon would lift the flap, and then measure the remaining amount of cornea. It turns out that the depth of the flap is very variable - and if you were unlucky and had a very thick flap, then the extra laser treatment may cause ectasia.
Remember also that the 250 micron level of untouched cornea has not been proven - it may be slightly more or less - we just do not know yet.
I hope this helps

Bill Trattler, MD
Miami, FL

Thanks very much, it helped a lot, especialy the medical term ectasia was helpfull for further research in the net.
If the remaining bed of cornea is more important for structural stability than the flap, wouldn`t it be better to do a prk (on the flap) instead of lasik (on the bed) as an enhancement with thin cornea left?

No one answered this question and it is a good one. Will there be a future wavefront surgery that can remove the irregular astigmatism from the surface so people with thin residual beds can be helped?

PRK can not be performed over a LASIK flap, as it can induce scarring. So this is not even an option.
The key is not to have LASIK if you are going to end up with a thin residual bed. If someone already has a thin residual bed, then they have to consider other treatment options, such as contact lenses or glasses for now.

I hope this helps

Bill Trattler, MD
Miami, FL

What are the visual symptoms for ectasia?

What is the treatment plan for ectasia?

Progressive blurring of vision is the only symptom of ectasia. Examination will reveal progressive steepening of the cornea - which is ectasia.
At this point, the only treatment is a contact lens - so the key is to avoid ectasia.

Best of luck

Bill Trattler, MD
Miami, FL

There is a thread on the surgical eyes board where Mermaid had a lamellar corneal transplant using an interlease laser by a Dr. Feinerman in California to fix her various problems from lasik. The doctor mentioned that with the graft he increased her corneal thickness from 425 to 573. It looks like similar procedures will someday be able to fix lasik induced ectasia. There is one patient there who had the same procedure a few years ago (before the laser assisted part) who was able to get to a crisp, clear 20/25 in that eye with glasses. It seems that Mermaid may be able to do a bit better since the transplant part was able to be lasered to the exact size rather than hand cut. The doctor said that her corenea was really clear now with all the lasik-induced irregularities gone.