Refractive Errors

Normal Eye

Clear vision is the result of light entering the eye, through the cornea (outer window of the eye), then passing through the lens (behind the iris), and finally focusing directly on the retina, at the back of the eye.

Nearsightedness (Myopia)

People that are nearsighted or myopic, can remove their glasses and see clearly at near, but the distance is all out of focus.

If the cornea is too steep or the eye is too long, the laser must remove tissue from the center of the cornea to reduce its focusing power.  This moves the point of focus from front of the retina to right on the retina.


Cornea is the clear dome in front of the eye and in a perfect world, it would be a perfect half sphere.  But, if the cornea is more curved in one direction than the other, similar to a half football, then there are two separate focus curves.  The laser must remove tissue so that the cornea is made more symmetrical, so that is more perfectly spherical similar to a basketball.  This eliminate multiple focal point and establishes one point of focus on the retina.

Farsightedness (Hyperopia) 

Farsighted people or hyeropes typically see clear at all distances early in life, but end up needing reading glasses earlier than others and then need glasses to see clearly for both reading and distance vision.

If the cornea is too flat or the eye is too short, the laser must remove tissue from the outer zone of the cornea (shaped like a donut area) to make it steeper and increase its focusing power.  This moves the point of focus from behind the retina to on the retina.



Presbyopia s a natural, normal process that at near age 45, one's ability to change the focus of the natural lens inside the eye is diminished.  Most people will notice that holding object further by stretching their arms longer helps initially.  Ultimately, the reading glasses or bifocals will become necessary to help with reading at near.


Monovision is a method chosen by patients with presbyopia where one eye is set to focus at near and other eye to focus at distance.  When both eyes are open, one is able to see both far and near.  Initially most patient may find the concept strange and reject the idea, however, monovision tends to be either loved or hated by most people and unless tried in contact lenses, one will not know for certain.


Contact us today to schedule a consultation!


The physicians of Modesto Eye Center and the Northern California Laser Center are renowned Modesto and Stockton lasik eye surgeons. They are also considered Modesto and Stockton cataract surgery specialists. These physicians treat LASIK Modesto and cataracts patients from their Modesto offices.

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