Who is suitable

LASIK can correct short-sightedness (myopia), long-sightedness (hyperopia) and astigmatism.

As a scanning spot laser, the Bausch & Lomb Zyoptix 100 is not limited as to what spectacle prescriptions it can treat. The upper limit of myopia that is correctable is about minus 10 dioptres but determined by the thickness of your cornea. For hyperopia we will correct up to about plus 3 dioptres depending on age and presence of dry eye. We have successfully corrected up to 7 dioptres of astigmatism.

You must have healthy, normal eyes. The most common problem preventing people from having excimer laser surgery is an abnormal shape to the cornea called keratoconus. This is usually only detected with corneal topography. This is why we perform corneal topography at all of our free assessments to screen for keratoconus and other irregularities in the shape of the cornea. 

As you age the chance of developing cloudiness of the natural lens called cataract increases. In practice we find that most people over 60-65 years of age have some cataract. If there is significant cataract formation then cataract extraction with intraocular lens implant is the best vision correction surgery.

The normal eye works like a colour video camera. The iris (coloured part) acts as the diaphragm of the "camera", regulating the amount of light reaching the inside of the eye. The clear window of the eye (cornea) acts with the lens inside the eye to bend (refract) light rays and bring them to a point focus on the retina. The retina is a thin layer of nerve tissue at the back of the eye that is sensitive to light, like a photographic film. The image formed on the retina is converted into nerve signals that are sent via the optic nerve to the brain.

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With eyes that have myopia or short-sightedness, distant objects appear blurred while near objects may be seen clearly. Light entering the eye is bent or refracted too much for the length of the eye and comes into focus in front of the retina. This is because the ability of the cornea and lens to refract light is too great for the length of the eye. Myopia typically starts in your teens but occasionally earlier or later in life. It typically stabilises in your twenties. Myopia is the most common vision complaint treated with LASIK.

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With eyes that have hyperopia (hypermetropia) or long-sightedness, near objects are more blurred than distant objects. Light entering the eye is not bent or refracted enough for the length of the eye and light comes to a focus behind the retina. Young people with hyperopia can usually see quite well without glasses but may need reading glasses. As we age hyperopia becomes more of a problem, starting to affect distance as well as near vision. Dr Kent has been treating hyperopia since 1997. He has extensive experience with hyperopic LASIK.

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The most common reason for needing glasses only for reading at age 45 and over is presbyopia. This is the name given to the loss of ability of the lens of the eye to change focus onto objects close to the eye. Many people describe their arms as not being "long enough" to hold a book at a comfortable reading distance.

At present surgery to correct presbyopia is at the experimental stage. Fendalton Eye Clinic are taking part in an international trial of the AcuFocus ACI7000 corneal inlay for  presbyopia. See www.acufocus.com

Currently if you have presbyopia and are having laser eye surgery, the only way to avoid both reading and distance glasses is to have one eye in focus for near objects and the other eye focused for distant objects. This is called monovision or blended vision. We would be happy to discuss this option further with you to see if it will suit your lifestyle.

Astigmatism is where the curvature of the cornea is different horizontally compared to vertically. The surface of the cornea is shaped like the side of an egg instead of a round ball. This difference in curvature of the cornea causes light to focus at more than one point inside the eye resulting in blurred vision at all distances. Astigmatism often accompanies myopia or hyperopia and is corrected at the same time with the excimer laser.

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