Omar asked:

Good Afternoon Mr Allamby,
I’m considering getting some treatment on my eyes, but am very worried about the long-term effect cutting the cornea can have. As i get older and my eyesight deterioates. will the my eyesight be worse off than if i had just kept wearing glasses?

Omar, I think this is one of the most common worries that prospective candidates have when considering laser eye surgery be it LASIK or PRK. It is just over 20 years since we first performed PRK for short-sight, and just under 20 years for LASIK, so we have considerable experience of long-term results.

The long-term outcomes have been excellent to date. Regression is seen in the London PRK study in 1-2% of patients, with a partial return to myopia, but not as bad as the vision had been before without glasses.

Cutting the cornea (e.g. to create a flap or flap disc) has been around for decades. Lamellar cuts were made in the 50s, and the first mechanical keratome was first used in 1963. No long term problems were seen, except when too little thickness was left in the cornea. At my clinic, we use a high safety standard of leaving 300 microns in the corneal bed, after creating the flap with a femtosecond laser and using the excimer laser to reshape the cornea.

The main worry is in excessive weakening of the cornea. However, the incidence of bending of the cornea through weakness in post-LASIK patients is the same as the incidence of bending from a disease known as keratoconus (KC). So in normal LASIK where all the safety parameters are observed, we are not sure if LASIK actually contributes to corneal bending post-operatively.

The key here, as always, is rigorous screening pre-operatively and visiting a centre where you get sufficient time for your consultation. Some clinics do consultations in 30 minutes, or even less. Others (mine included) spend much longer. Focus consultations take at least 2 hours.

Choose carefully.

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Here are the answers to one of today’s questions:

From Ian, who said:

A fantastic site, very informative.  A quick (but naive) question.  I am very excited about the prospect of having intra Lasik to correct a minus 5 prescription.  However, I have read some scare stories on US web sites which suggest that it is possible that the cornea can be irreparably damaged during the flap creation process.  How often have you seen this happen?

Thanks Ian. Correcting a -5.00D prescription is quite routine and should give you no problems. You mentioned IntraLASIK, which is a brand name when the Intralase femtosecond laser is used to create a Lasik flap. I don’t know whether you refer to femtosecond Lasik in general or you are looking at the Intralase machine for treatment. Manufacturers AMO now refer to iLasik rather than IntraLASIK. Other version are Z-LASIK when the Ziemer femtosecond laser is used, and Visumax and Femtec systems from other companies.

The femtosecond lasers have replaced the blade-cut keratome Lasik procedures in many clinics. One of the reasons to do this is to eliminate the possibility of a seriously damaged flap from a keratome, which I have seen happen (although it’s occurrence is rare). I have never seen this occur with a femtosecond laser and it is not possible to ‘mangle’ a flap with these technologies, so added safety.