Myopia (Click to View)
Myopia is commonly called short-sightedness and occurs when an eye is too long or strong for the light-bending ability of the cornea. Light rays entering the eye do not come to a sharp focus on the retina as they should, and instead focus in front of the eye, producing a blurred distance image.
Short-sighted people can often see reasonably clearly at short distances, but will not be able to see distant objects clearly. They find it hard to read road signs and scoreboards and to play ball games. Recognising people in the distance may be a problem for many short-sighted people. Often a person will not realise that they cannot see clearly but an eye examination by an optometrist will reveal the problem. This can be corrected with spectacles or contact lenses.
Hyperopia (Click to View)
Hyperopia is the medical term for long-sightedness. It occurs when an eye is too short to power the light-bending ability of the cornea. Light rays entering the eye dont come to focus sharply on the retina. Instead, they focus back behind the eye, producing a blurred image. Hyperopic individuals, however, can use their focusing muscles to pull the image forward onto the retina, often resulting in the ability to see far but not very well at near.
If there is a significant amount of hyperopia, the effort of focusing (called accommodation) can lead to blurry vision , especially for close objects, because the closer the object the more focusing is required. Hyperopic people may experience fatigue in their eyes or headaches after a lot of visual work. Reading is more difficult and school work can be affected. This can be corrected with spectacles or contact lenses.
Presbyopia (Click to View)
Maybe youve noticed difficulty seeing clearly at close distances, especially while reading or computing. Or is it more difficult to see while driving at night, or following the news ticker at the bottom of your TV screen? Dont worry. Just like our bones and our brains, eyes and vision change over time. This is normal, just one of the joys of aging, and a clear sign that its time for an eye test.
Presbyopia is easily the most common eye condition; its a normal change in the eyes ability to focus, due to a gradual thickening of the natural lens in our eyes. Usually occurs around age 40, whether youve had good vision or been wearing corrective eyewear for years. People in this age group often find that they have to hold things further away to see them clearly. Reading glasses can help in mild cases. Bifocals or multifocal lenses are usually prescribed for patients already wearing spectacles.
Astigmatism (Click to View)
Astigmatism is a very common refractive (focusing) error. It occurs when the front curvature portion of the cornea has an oval shape (like a rugby ball) rather than a round shape (like a netball ball). The two different curves in such a corneal surface each bend light rays to a separate focus point. This causes images to appear distorted. Certain letters may be more difficult to read than others, depending on the orientation of the lines within them.
Objects at all distances are indistinct or blurred and the eye cannot focus. Even slight degrees may encourage headaches, fatigue and reduce concentration. This is because the eyes may try, without success, to correct the blurred vision. Astigmatism correction in the form of spectacles or contact lenses makes all the rays of light focus at the same distance so that they all fall correctly on the retina.