Laser Vision Correction

The aim of laser vision correction is to reshape the front of your cornea to be a better focusing lens – in place of your glasses.

The major visual aim is independence from wearing spectacles or contact lenses on a day-to-day basis. This has special relevance to patients who are totally dependent on their glasses.

Laser vision correction is a proven and very successful procedure. Our results show that 98% will end up 6/12 (20/40) or better and of these 98% there will be 90% who end up with 6/6 (20/20) vision or better. Depending on your individual eye health, some patients still find that a “fine tuning” pair of weak spectacles is necessary for demanding tasks such as night driving, but they are free of spectacles for everyday activities like walking, working, swimming, and going out with friends.

Each surgeon providing laser vision correction has their own laser technology and a good argument as to why they are using this technology.

Most surgeons use lasers made by: Schwind, VISX, Ladarvision, Technolas, MEL80 or Wavelight and all are very good technologies, and all are of excellent quality.

These are all surface laser techniques which use no blade and create no corneal flap.

10 years ago, this was the only laser reshaping available and was applied directly to the surface of the cornea after the skin (epithelium) of the eye was removed. There was no flap created because the techniques for making flaps were not accurate enough in those early days. This is called PRK.

It fell out of favour because the resultant ulceration was uncomfortable and took several days to heal. Visual recovery was slow, taking a week or two as the cornea healed. Also, because the healing response of the eye varies between people, the results were difficult to estimate. Patients occasionally experienced hazy vision and more chance of scarring and regression (slip-back towards the old spectacle error).

It fell from favour and was largely replaced by LASIK in the late 1990’s.

However, with improvements in excimer laser technology, faster computer software and understanding of corneal wound healing, PRK has improved greatly and has had a renaissance. It is now used in approximately 10-20% of cases. The results are equal to LASIK but the recovery takes a week longer and most patients still notice a stinging sensation, hence the uptake by only 10-20% of patients despite the safety advantages of no flap creation.

If the skin (epithelium) is replaced onto the eye afterwards, it gets called LASEK (note the similarity to the word LASIK). ASLA was developed as a term to replace PRK due to the negative connotations of the original PRK.

With LASIK a very thin sliver, called a “flap” is created using a laser called intralase.

The shave is not completed right across the cornea, thus creating a thin hinge upon which the sliver (flap) can be folded back to expose the ‘stroma’ of the cornea.

The laser is applied to this exposed stroma and then the flap is closed to restore the normal surface of the eye.

LASIK is essentially painless and provides a faster visual recovery (2-7 days with LASIK compared with 1-2 weeks with PRK / LASEK).

The main disadvantage of LASIK is the thin flap itself. Whilst it usually slides straight back into position, there is the rare case of “flap slippage” after the patient has gone home, which can cause a wrinkle in the flap. This is why you are asked to avoid rubbing your eyes and rest quietly in the early post-operative period.

Another rare event is an inflammation process which occurs within the thin space between the flap and the stroma. This is called DLK and is usually mild and responsive to steroid eye drops.

Overall, flap complications account for problems in 1-2% of patients in which their best spectacle corrected vision is reduced by one or two reading lines from the level it was preoperatively.

The other disadvantage of LASIK is that the creation of the flap can weaken the cornea and cause a condition called kerectasia (keratoconus). This usually occurs only in patients who already have a predisposition to this condition. We screen patients thoroughly for this predisposition during the clinical assessment and can nearly always screen out the patients who are at risk. Unfortunately, not every patient who will ultimately develop kerectasia is detectable in the earliest stages and therefore it is a possibility that kerectasia could develop in the years following LASIK surgery and could in fact be hastened by having had the surgery. Kerectasia can badly harm the vision and may require a corneal transplant operation to repair the vision if it becomes severe.

Laser vision correction has passed the 10 million patient mark worldwide.

The results are excellent with over 90% of patients achieving 6/6 vision (the old 20/20) without the need for spectacles.

98% of patients are sufficiently improved that even without spectacles they are living glasses free in their everyday life activities such as walking, working, swimming, and going out with friends.

The chances of a visually significant problem are 1-2% but the problem is only rarely severe (loss of more than 2 lines of spectacle vision).

The statistical chances are that you will have a great result.

However, patients have the right to know of any downside to help in their decision making and it is important to remember that there are never any guarantees in medicine or surgery because the human body is sometimes unpredictable.

If you wish to arrange an appointment for assessment, we look forward to answering any questions you have.

Laser vision correction has passed the 10 million patient mark worldwide.

Results are excellent with over 90% of patients achieving 6/6 vision (the old 20/20) without the need for spectacles.

98% of patients are sufficiently improved that even without spectacles they are living their everyday life such as walking, working, swimming, and going out with friends.

The chances of a visually significant problem are 1-2% but the problem is only rarely severe (loss of more than 2 lines of spectacle vision).

The statistical chances are that you will have a great result. However, patients have the right to know of any downside to help in their decision making.

The eye may continue to change over the years after the operation. The operation cannot make time stand still! Therefore, we always ask you whether your eyes have been stable for the few years prior to the operation.

Reading glasses will still be needed in middle life when the eye loses its ability to focus on near objects. The exception to this is obviously the middle-aged patients who are having the laser to treat their near vision reading problems in the first place.

• Dry eye: more so with LASIK than PRK / LASEK – often improves after 6 months and requires tear supplements. A common post operative problem.
• Night glare: especially if large pupils or a large spectacle error is being treated. Can be treated with eye drops. May need night spectacles. Seen less with Wavefront treatments.