Soft lens wearers should leave their lenses out for up to 2 weeks while hard or gas permeable wearers up to 6 weeks.

While this can be carried out by your own optometrist or eyecare specialist it might be preferable to go to someone who is affiliated to a clinic or clinics as this may enable you to ask more searching and in depth questions.

Orthokeratology
The process of altering the corneal curvature to neutralise the distance prescription, including astigmatism by wearing a rigid lens overnight.

Clear Lens Extraction
In layman’s terms is a cataract operation before the cataract has formed (the removal of the healthy lens inside the eye). A new artificial corrective lens is then implanted thus eliminating the original distance prescription. The drawback is that a pair of reading spectacles will be required regardless of age as a result in the loss of the eyes focusing system. However, researchers are close to perfecting a multifocal implant.

Certainly no clinic should contemplate operating while there is a risk of a prescription change hence the guideline of 21 years of age being the lower age limit.

However, it is worth noting that the guidelines from the Royal College of Ophathmologists recommending against this date back to 1997 and have now been superseded by accepted general practice worldwide.

There are very few conventional optical practices that offer “on site” surgery therefore you will have to attend a specialist clinic which will probably mean an overnight stay in a local hotel however, this is usually arranged by the clinic.

Do not allow a general surgeon or a GP to attempt the operation. If in doubt check the register of ophthalmic surgeons. In the UK you can contact The Royal College of Ophthalmology on 020 7935 0702.

It is also recommended that you use a clinic where you are able to speak directly to the surgeon concerned and that they have performed in excess of 1,000 operations of this nature.

However, a clinic that operates a stringent screening procedure rather than an “accept all” policy driven by finance has to be commended. The final result will often depend upon the complexity of the original prescription and no one will be able to guarantee 100% success.

If nothing less than perfection will satisfy you do not take the risk.

Even if your prescription is regarded as being too high some surgeons may consider a prescription reduction as being worthwhile.

PRK has a 6 to 8 week period of visual stabilization requires protective padding for 48 hours and can produce a visual imbalance between the eyes while waiting for the second eye to be corrected [with Lasik you can have both eyes operated on the same day] and as a result may be unsuitable for some people.

As a general overview it is somewhat easier to list the unsuitable rather than the suitable as individual suitability will vary however, if any of the following apply you should not proceed :- pregnancy or breast feeding uncontrolled diabetic mellitus active or severe vasculitis active collagen vascular disease systemic medications steroids cytotox therapy still experiencing prescription changes monocular vision cataract keratoconus severe dry eyes nystagmus have or have had herpes zoster ophthalmicus or pemphigoid increased corneal thickness binocular vision of less than 6/12 active iritis exposure keratopaphy proliferative retinopophy and finally either too old or too young.

Clinics will vary in their upper age limit from on average 50 to 75 years while some set no upper age limit. 27 is often regarded as lower limit for PRK and 21 for Lasik.

However here are some of the questions you ask the clinic:

1. Can I expect the same standard of vision I achieve with my fully corrected spectacles or contactlenses?
2. What are the risks of haloes or infections?
3. What is the procedure policy regarding a less than successful operation?

All clinics should have a standard of equipment and hygiene no less than you would expect in any advanced operating theatre. However, ask the clinicians what their success rate is and how they measure success and failure. A phone-call to another clinic will then enable you to compare.