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Understanding Vision Problems

Normal

Cross section of eye showing light focusing on retina.
Normal

Your eyes see an object as light coming from the object. Your cornea focuses light rays onto a layer that lines the back of your eye (the retina). If your eyes are normal, this process produces a focused image on your retina. This makes objects look clear.

Nearsighted

Cross section of eye showing light focusing in front of retina.
Nearsighted

Your cornea and your retina are too far apart if you’re nearsighted. Sometimes your cornea or your lens has an abnormal shape. This makes light rays from distant objects focus in front of your retina. These objects then look blurry.

Farsighted

Cross section of eye showing light focusing behind retina.
Farsighted

Your cornea and your retina are too close together if you’re farsighted. Sometimes your cornea or your lens has an abnormal shape. This makes light rays from close objects focus behind your retina. These objects then look blurry.

Astigmatism

Cross section of eye showing light focusing in more than one place.
Astigmatism

Sometimes your cornea or the lens inside your eye is curved abnormally. Then light rays can’t focus evenly onto your retina. This is called an astigmatism. It makes both close and distant objects look blurry.

Online Medical Reviewer: Chris Haupert MD
Online Medical Reviewer: Marianne Fraser MSN RN
Online Medical Reviewer: Raymond Kent Turley BSN MSN RN
Date Last Reviewed: 7/1/2020
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