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    Most people need to use corrective lenses to improve their eyesight at some point in their lives. Myopic people usually start early, as do people with astigmatic vision. People who are far-sighted can manage until they get older, when their eyesight deteriorates and they need glasses for reading.

Less than perfect vision is caused by a change in the focal length of the optic system that is the eye. If the focal length is too long it needs to be reduced in order for the image to be seen sharply; if it is too short, it needs to be lengthened.

    Spectacles have been used for ages (the Chinese invented them) and besides being useful, they have evolved into fashion accessories. But there are disadvantages to having to wear glasses. In sports they can be hazardous, in jungles or the Dubai summer they fog up. And along with car keys, they always are misplaced! They are expensive and scratching or breaking easily damages the lenses.

    The advent of the contact lenses in the 50’s addressed some of the inconveniences of glasses. The apparent invisibility of contacts was great for people who were self-conscious about wearing glasses. They also could engage in activities that were previously prohibitive with glasses – such as athletics and physically active careers.

    Especially when the long-wear lenses came onto the market, people happily exchanged their specs for these flimsy bits of transparent material. Still, even lenses get lost Infections of the eye are sometimes caused and certainly exacerbated by the wearing of lenses.

    It was only a matter of time until someone came up with the idea that the correction needed to improve vision could be applied to the eye itself. Before the appearance of computers and laser beams, the main tools available to an ophthalmologist were a scalpel, a steady hand, a medical background and perhaps some engineering knowledge. The premise was that they could modify the shape of cornea, and then possibly they could effect permanent improvement to their patient’s vision. (The cornea is the clear dome on the front of the eye; it is in reality a lens, which provides about 80% of the focus power of the eye). The first procedure to show the possibility of achieving a positive result was called radial keratotomy or RK. This is method, in which the qualified eye surgeon would make series of cuts (usually 4 to 8) in the cornea with a scalpel, in a pattern that resembles a spoke wheel. These cuts are fairly deep, more than 90% of the thickness of the cornea. Later on lasers have been used to make these cuts, but with little improvement on the result. Unfortunately there were many limitations and complications - some of them resulting in permanent blindness. It was not something that I ever recommended as elective surgery.

    In the last decade new technology has brought better solutions for poor vision. Photorefractive keratectomy (PRK) is a procedure, in which the cornea is re-shaped to provide the correction that the eye needs for sharp vision. It sculpts the focussing power of correcting glasses or lenses directly into the cornea. This is done with lasers, which produce an intense beam of energy with a very precise wavelength.  Lasers were first used in 1960 and have undergone many technological changes since that time, becoming ever more precise and controlled. The excimer laser can be precise to 0.25 nm, which is one quarter of a micron. The surgery needed for myopia consists of removing tissue from the centre of the cornea, while the correction for hypermetropia occurs in the periphery, leaving the central cornea untouched. Astigmatism can also be corrected by removing extra tissue in a specific axis of the eye.

    In the early days there were a few drawbacks to having PRK done. There used to be quite a bit of postoperative pain and there were also problems with haze afterwards. Recuperation took several days to weeks. Recently there has been progress in treatment of these two problems, so that the procedure is now virtually painless and haze is rarely encountered. The recuperation time is now considered to be around two to five days.

    A new method was developed that is called LASIK or "Laser assisted in situ keratomileusis" (sometimes also referred to as ALK-E). In LASIK surgery the cornea is cut from the side to form a lid that remains hinged at one end.  The sculpting of the cornea is carried out below this lid, which is then closed over the area and grows back on. The advantage of this procedure is that fewer nerve endings are cut so that the post-operative pain is reduced. There is very little trouble with haze and glare and the recuperation period is measured in hours and days rather than weeks.

      The disadvantage of the LASIK surgery is that in order to cut the lid, the pressure of the eye has to be raised more than 60 mmHg (while the normal pressure is less than 20 mmHg) in order to be able to make a clean and smooth cut into the cornea. This is done by applying a suction cup around the top of the eye. Even though the pressure is only raised for a few minutes, it can already do harm in eyes that are specifically sensitive to raised pressure. Another risk is in the cutting of the lid itself. If the cut is made too shallow the lid will have a hole in it and if it is cut too deep the eye may be perforated. In the postoperative phase, the flap may become unhinged and can be lost or it heals off-centre, creating vision disturbances. The debris created by the cutting and abrading process can accumulate along the edge of the flap creating a sand-ripple effect, known as the "Sands of the Sahara" effect - again a visual disturbance that is unpleasant. There is more chance of an infection festering underneath the lid and scarring is also a possibility.

    Photorefractive Keratectomy (PRK) has been done in Dubai for almost ten years by Dr. Niaz Ahmed Khan, Consultant Ophthalmologist at the Al Zahra Medical Centre on Sheikh Zayed Road, who is one of the leading Eye specialists in the Middle East. Dr. Khan did his medical studies in Pakistan and his specialty post-graduate education in London, UK. Having more than 30 years of experience, Dr. Khan was the pioneer in introducing the RK and PRK to the Middle East. “ I have started with RK back in 1987,” says Dr. Khan. “This procedure was only OK for patients, who had to correct low grade of Myopia, maybe up to –3.0 or –3.5, but could not address the problems of hyperopia (farsightedness) at all. Due to the deep incisions in the cornea, there were a lot of postoperative complications, but thank God, we didn’t loose any eye.”  In 1993 Dr. Khan was the first Eye Specialist to introduce the PRK to the Middle East. He has by now treated more than 1600 patients in UAE with PRK and more than 5000 case from abroad and has not had any serious complications. He estimates that the risk of the only complication (haze) is less than 1 %. “The PRK is a procedure that takes only about a minute on each eye,” continues Dr. Khan. “ The technology now days is so advanced and the laser is so precise, that the postoperative complications that can occur a very minor and very rear (under-correction or over-correction) and can easily be treated.. I also should stress, that besides cleaning the eye (after inserting unaesthetic drops) the surgeon is not touching the eye at all, the whole procedure is done by the laser beam and is totally painless.  The prognosis of a person with Myopia of up to –6.0 to have a 20/20 vision after the surgery are very good. For higher dioptries sometimes a second minor correction is needed”  

    A consultation for refractive eye surgery starts with a medical history and a general eye exam, at which time the exact level of loss of vision is assessed. The eye pressure is measured and the eye is examined minutely for any sign of superficial or deep infection or abnormality. Then a special examination is done in which the topography of the cornea is recorded on a chart; this is done by computer. Every irregularity of the surface of the eye, specifically of the central part that is the cornea, is represented on a colourful map showing "ups" and "downs" just as in a topographical map of a landscape.

    For the actual procedure, the data are fed into a computer, which directs the laser beam. The patient lies back on a chair looking up into a beam of green light that shines down into his eye. The eye is anaesthetized with eye drops and the eyelids are fixed in a clamp to prevent blinking. The laser beam is centered on the exact spot of the cornea by two separate beams of red light that have to meet the green beam at the exact level of the cornea. Then the laser beam is used to take away the precise amount of tissue from the exact locations determined beforehand in the topographical exam. The procedure takes only a few minutes. Both eyes are usually done in the same session. The abraded area is covered with a clear contact lens, which covers the nerve endings that have been cut in the procedure and therefore reduces post-operative pain.

    Afterwards the patient is given painkillers, antibiotic and anti-inflammatory eye drops and checked again after a few days, at which time the contact lens is removed.  Most people are back into their normal routine within a week. The visual acuity is immediate.

    In eyes that need corrections of more than 6 or 7 dioptries some haze can develop, which is treated with steroid drops for three months.  Dr. Khan has treated eyes with Myopia of  - 0.75 as well as - 25(!) and hypermetropic eyes from +1 to +8. Now Astigmatism is easily corrected too.

    So now can we all have lives without spectacles? Alas, that is not the case. Some people with myopia can read without glasses even in old age. After PRK treatment they would be able to spot eagles in the sky without glasses, but they would need reading glasses for the newspaper.

    There is a solution even for this: mono-vision treatment, in which only one eye is corrected by surgery and the other not. That enables a person to see into the distance with the operated eye and read without glasses with the untreated eye. It does reduce depth vision, for which you need both eyes. Several of dr. Khan's patients have had this done and are happy with it.

    At the end of the day, this is elective surgery, which means it is not necessary to save a person's life or cure a nasty disease. However, it can do a lot to improve the quality of life and it is great that people nowadays have the choice to do the surgery or continue to live with their (minor) handicap.



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