Medical student Peter Cassar explains how the eyes work and why they may not do so properly. He gives solutions and discusses the pros and cons of cosmetic eye surgery.
The eye is an organ which converts light into a neural signal which the brain can read as an image. This occurs thanks to the retina which is found at the rear surface of the eye covering it from the inside.
The retina is made of special cells called ‘photoreceptors’ which sense light and convert it into a message which the brain can understand.
When light passes through the cornea and lens of an eye, the light rays are bent on a precise point on the retina in order for the brain to have the best visual image. When this does not happen, vision is blurred as is in the case of people who are far-sighted, short-sighted or have astigmatism. But why do we have blurry vision in the first place?
When one is far-sighted (hyperopia) the eyeball is too short. This means that light rays reach a point of focus beyond the retina. This results in blurry images up close. But when the eye is too long as in the case of nearsightedness (myopia), light rays reach a point of focus before they even reach the retina. This means that objects appear blurred in the distance.
Some eyes have an irregular-shaped cornea which is the clear part in front of the eye’s surface. When this happens, the light rays can have several different points of focus. This is called astigmatism, which also results in distorted images as light rays are prevented from meeting at a common focus.
Eye glasses and contact lenses sharpen focus by bending light and altering the way it enters the eye, changing the point of focus in the most appropriate way. For example, in people who are far-sighted, contact lenses and glasses cause light to bend more, resulting in a greater focus on the retina. The opposite occurs in nearsightedness, as contact lenses and glasses help to bend light in a way to point it further away, focusing on the retina.
Apart from contact lenses and glasses, there is another solution for the problems mentioned above and this is laser eye surgery. There are many types of eye laser surgery but the most common is known as LASIK, standing for Laser Assisted In Situ Keratomileusis. Recently, tremendous advancements have been made in this field, making it in most cases an effective, safe and permanent alternative to contact lenses and glasses.
The procedure is carried out by an ophthalmologist who uses laser to reshape the cornea on the surface of the eye, with the procedure itself only lasting about 10 minutes per eye.
By reshaping the cornea in a certain way, the surgery allows for light rays to properly focus on to the retina and therefore increases visual acuity and thus removes the blurriness in one’s vision.
Laser eye surgery offers minimal discomfort and fast recovery time, with most patients able to resume normal activities within 24 hours
The laser corrects far-sightedness by making the cornea steeper and, on the other hand, corrects nearsightedness by making the cornea more flat. Astigmatism is also corrected by making the cornea smoother, removing any irregularities on its surface and giving it a more normal shape.
Unfortunately, people who suffer from severe cases of nearsightedness in most cases cannot be treated with laser surgery but there are alternatives.
For example, by changing the eye lens, but this is less desirable as it will hinder the ability of the eye to ‘accommodate’, meaning that the eye wouldn’t be able to focus well on objects particularly when reading and doing close-up activities.
The procedure starts by first placing a few drops of anaesthetic on the eyeball along with an antibiotic in order to create a general comfortable feeling for the patient. Then a small flap is cut open on the corneal surface of the eye in order to expose the corneal stroma, which is found right under the surface of the cornea – this procedure is carried out with a very small and sharp blade, or else with a laser.
This part of the process can at times be uncomfortable for the patient.
The flap is then opened and another type of laser consisting of high pulses of ultraviolet light is used to remodel and alter the corneal stroma, according to the patient’s needs. In most cases, this part of the procedure is painless. After the laser, the flap is closed carefully and is left to heal naturally.
As with any other procedure, there are risks involved but thanks to the huge advancement in laser technology, these complications are rare and not that serious.
Some of the most common risks of laser eye surgery are overcorrections and undercorrections, meaning that the laser may remodel the corneal stroma too much or too little, which may then be corrected by doing follow-up laser eye surgery.
Also, there is a very small risk that, if the procedure is successful, the vision can revert to the way it was before the operation after some time.
This occurs because the eye is a living organ that alters along the years, which may lead to changes in one’s eyesight.
Another risk is that the corneal flap may not close and heal well after the procedure and this may cause inflammation in the cornea and distorted vision.
Furthermore, other minor complications are temporary dry eyes and eye infections. These situations are very rare but it all depends on how experienced the ophthalmologist is and how modern the laser is.
A global review of LASIK published in 2009 showed that 95 per cent of patients were completely satisfied with the results after the procedure withthe other five per cent experiencing some type of complication – of whom, less than a fifth being of a serious nature.
Laser eye surgery offers minimal discomfort and fast recovery time, with most patients able to resume normal activities within 24 hours.