Am I Suitable?

First Steps... Am I Suitable for Laser Eye Surgery?

After thinking about proceeding with laser eye surgery one of the first questions people ask is ‘Am I Suitable?’

Not everyone is a suitable candidate for laser eye surgery and the first step towards working out your suitability will be to call one of our friendly and professional team. Alternatively you can fill in our contact form and one of the team will be in touch.


When you call us we will often ask a few key questions about your eyesight, whether you wear glasses or contact lenses and if you are short or long sighted. David Gartry also performs refractive lens exchange surgery so therefore provides an alternative if laser eye surgery might not be the right treatment for you. Remember that only a consultation can determine whether you are in fact a suitable candidate for laser eye surgery.

If we feel that you might be suitable we will invite you in for a consultation at either The Wimpole Street Eye Clinic in Marylebone (next to Harley Street), in London’s West End or The Moorfields Private Outpatient Centre which is on City Road and part of Moorfields Eye Hospital.

Your laser eye surgery consultation is a very detailed and thorough examination of your eyes and not just a simple eye test. However it is worthwhile understanding the eye chart and also how your prescription is established.

Understanding Your Prescription

When you come for your consultation you will of course undergo an eye examination which will include an eye test to determine your prescription. Your prescription or ‘refractive error’ is a combination of numbers which may resemble this chart:


R +4.50D -2.50D 120
L +3.50D -2.00D 80


SPH represents sphere, and is the amount of short sight (-) or long sight (+), measured in dioptres. This is the figure you will probably be most familiar with.

CYL represents cylinder, and is the amount of any astigmatism present, also measured in dioptres.

AXIS is the angle of the astigmatism, measured in degrees.

The above example represents a patient with +4.50 of long sight in their right eye, combined with -2.50 of astigmatism at an axis of 120°, and +3.50 of long sight in their left eye, combined with -2.00 of astigmatism at an axis of 80°.

The dioptre sign (D) is often omitted, so a typical prescription may look like this:-
RE:-7.75/-1.25 x 10 LE: -8.50/-1.75 x 175
(BVD = 12mm)

Here, the patient has -7.75D of short sight in their right eye, combined with -1.25D of astigmatism at an axis of 10° and -8.50D of short sight in their left eye, combined with -1.75D of astigmatism at an axis of 175°.

For higher prescriptions (greater than plus or minus 4D), the optometrist will also record the distance between the test lenses and the front of the eye. This is known as the back vertex distance or BVD and is an important measurement when planning laser eye surgery. In the above example, the BVD has been measured as 12mm.

When presbyopia (a condition that affects us all as we age) is also present, the optometrist will record the extra magnifying power required for reading or close work. This is called the reading addition or ADD.