The human eye is like a camera where the cornea (transparent front window of the eye) and the natural crystalline lens (the human natural lens inside the eye and behind the pupil) both act like the zooming lens in a camera. The cornea and the lens work together to focus the image on the retina (the very back layer inside the eye which act like the film in the camera). The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.
Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina. The length of the eyeball (longer or shorter), changes in the shape of the cornea or aging of the lens can cause refractive errors.
Types of refractive errors
The most common types of refractive errors are myopia, hyperopia, presbyopia and astigmatism.
Myopia (nearsightedness) is a condition where objects up close appear clearly, while objects far away appear blurry. With myopia, light comes to focus in front of the retina instead of on the retina.
Hyperopia (farsightedness) is a common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects at any distance, near or far.
Astigmatism is a condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out.
Presbyopia is an age-related condition in which the ability to focus up close becomes more difficult. As the eye ages, the lens can no longer change shape enough to allow the eye to focus close objects clearly.
The most common method of correcting refractive errors is the use of eye glasses or contact lenses. The prescribed lenses will help to put the light rays (the image) on the retina. Over the last decade, a variety of surgical procedures collectively known as refractive surgery has become increasingly a popular method in correcting refractive errors. In most cases these procedures ultimately alter the shape of the cornea so light rays are refocused on the retina to give good version.
The most common effective surgical procedures are:
Phakic Intraocular Lenses (IOLs): Implantable Contact Lens ICL, and Artisan Iris-Clip IOLs
Refractive Lens Exchange (RLE)
Each of these procedures offers different technique for refocusing light more accurately on the retina. For many people with refractive errors who are content to wear glasses or contact lenses there is no need to consider refractive surgery. However, millions of people have elected to have refractive surgery to reduce their dependence on glasses or contacts. If you are considering refractive surgery then we advise you to have full consultation with Mr Samer Hamada and have a complete eye exam to determine which procedure is appropriate for your particular eyes.