LASIK surgery can treat myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (football-shaped cornea). It cannot treat presbyopia or the need for reading glasses when one turns forty.
The animated videos below will help illustrate the optical principles involved in focusing errors of the eye and how LASIK surgery can correct those errors permanently, painlessly, and safely.
Nearsighted individuals typically have problems seeing well at a distance and are forced to wear glasses or contact lenses. The nearsighted eye is usually longer than a normal eye and the cornea may also be steeper. As a result when light passes through the cornea and the lens, it is focused in front of the retina making distant images appear blurred.
Farsighted individuals have shorter than normal eyes and have problems seeing up close before the age of forty. The light of distant objects focuses behind the retina and these images are blurred. Eventually, their distant vision also starts to blur as they age. If you didn’t have close up vision problems until you reached your forties, you may be experiencing presbyopia. Differentiating between the two can be confusing.
Astigmatism (Football-shaped Cornea)
Astigmatism is a common vision condition where the corneal surface is not evenly shaped causing one to see ghosting or shadowing of images. With astigmatism the cornea is not a perfect sphere like a basketball but is steeper in one direction and flatter in the other like a football. Astigmatism can occur alone but is most often combined with nearsightedness or farsightedness.
Presbyopia (Reading Difficulty)
All people will experience difficulty with reading usually beginning in their forties. There is a lens in the eye that accommodates light so that we can see at near distances. But with presbyopia light from a near object enters the eye, the cornea refracts the light and the lens changes shape to accommodate for the decreased focal length of a near object. This is exactly the same process that occurs when focusing your camera on a near object. Unfortunately, this lens within the eye as it ages losses its ability to focus for us and we need reading glasses or bifocals. Presbyopia can be dealt with in a number of ways so please contact our staff to better understand your options if this is something you think you are experiencing.
LASIK (Laser Vision Correction)
With the LASIK procedure a thin protective flap of corneal tissue is gently folded back.
If treating nearsightedness, the excimer laser removes tissue from the center of the cornea making it flatter and reducing its focusing power. This moves the point of focus in front of the retina, to on the retina.
If treating farsightedness, the corneal is made steeper as the laser removes tissue from the outer margins of the cornea. This helps the cornea bend light more, moving the point of focus somewhere behind the retina, to on the retina.
If treating astigmatism, the laser removes tissue from the steeper meridian thereby making the cornea more spherical. This allows all the light images to focus on the retina.
The protective flap is then folded back in place where it bonds without the need for stitches.