Other Eye Conditions
How the Eye Works
Your eyes are AMAZING. Understanding how your eyes function can help you determine whether it is time to visit your eye doctor.
Read below to learn about your eyes, then explore our carefully cultivated list of patient educational resources.
THE NORMAL EYE
A normal eye has a curved shape that allows light rays that hit it to bend towards the eye's center, focusing an image directly on the retina at the back of the eye.
MYOPIA
(Nearsightedness)
When the eye's shape is too long, light rays focus in front of the retina rather than on it. The result is that near objects appear clear, while distant objects do not.
HYPEROPIA
(Farsightedness)
When the eyeball is too short from front to back, light rays entering the eye focus behind the retina. Distant objects are seen clearly, but near objects are not.
ASTIGMATISM
Ideally, the surface of the cornea is uniformly rounded like the smooth, even surface of a ball. Vision becomes distorted when the surface of the cornea has an uneven curvature, rounded more like the back of a spoon than the surface of a ball. This type of irregularity causes blurred vision because light focuses on more than one spot on the back of the eye. Have you ever looked through a pane of glass that has an irregular, somewhat wavy surface? That uneven surface allows only one part of the view to be in good focus—the rest is blurred and wavy-looking.
PRESBYOPIA
(Loss of Reading Vision)
The lens of a youthful eye flexes to change shape (“accommodate”) when we change from focusing on something in the distance to something closer. Over time, the eye’s lens gradually loses its flexibility and ability to change shape to see close objects, like the page of a book. Bifocals or reading glasses are the traditional prescription for remedying this “presbyopic” loss of accommodation.
DRY EYE
Tears keep the eye moist, wash out dust and debris, and are essential to good eye health. Without this lubrication, the eyes become irritated and feel dry and scratchy. Dry eye, a chronic condition that tends to become worse over time, causes blurred and fluctuating vision.
Evaporative Dry Eye, the most common form of this problem, is caused by the dysfunction of glands that produce the oil responsible for preventing tears from evaporating too quickly.
Strangely enough, the irritating symptoms of “dry eye” can cause the eyes to water excessively. These tears are ineffective because they don’t contain one or more of the components needed to relieve the irritation.