The major parts of the eye are listed below. Problems or malfunctions in any part of the eye cause many common eye conditions.
The cornea is a layer of clear tissue at the front of the eye that helps focus light.
The openings to the tear ducts are located in the upper and lower eyelids at the inner corner of each eye. Tears are secreted by the lacrimal gland from the outer, upper eyelid to the surface of the eye. Tears keep the cornea lubricated and clear of debris. The tear ducts drain the tears away.
Iris and pupil
The colored part of the eye is the iris. It is a set of muscles that control the pupil, which is the opening in the middle of the eye. The iris controls the amount of light coming in through the pupil.
Lens and retina
The lens is behind the pupil. It focuses light onto the retina, the light-sensitive cells on the back of the eyeball. The retina converts images into electrical signals that are sent to the optic nerve.
When light isn’t focused properly, it causes blurry vision. Glasses, contacts, or surgery can usually correct refractive errors, which include:
- myopia (nearsightedness), which is when faraway objects look blurry
- hyperopia (farsightedness), which is when close-up objects look blurry
- astigmatism, which can result in blurry vision because the cornea is not perfectly shaped to direct light into the eye
- presbyopia, which is farsightedness that’s caused by the loss of elasticity of the eye’s lens due to aging
A cataract is a clouding of the lens, causing blurry or color-tinted vision. People with cataracts often report “haloes” surrounding objects they’re looking at, particularly at night. This condition is most common in older adults.
Cataracts can be removed by surgery that replaces the damaged lens with an artificial lens.
Age-related macular degeneration (AMD) is gradual damage to the cells of the macula. This condition is most common in people over 60 years of age.
AMD causes blurry vision, especially in the center of the field of view. According to the
Amblyopia is commonly referred to as a “lazy eye.” It occurs when vision has not properly developed in the eyes, and the brain begins to favor the eye with better vision.
This happens if one of the eyes is blocked from producing clear images during the critical years from ages birth to 6. One eye may be inhibited by problems such as a lid droop, tumor, or misaligned eyes (strabismus) that are not corrected when a child is young.
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The best way to avoid these vision problems is to keep your blood sugars under control, and see your eye doctor every year for a dilated eye exam. Proper care can lessen complications.
When the retina separates from the back of the eye, it’s called a detached retina. It causes blurry vision and partial or complete loss of vision and should be treated as a medical emergency.
Dry eye is a lack of tears. It’s usually due to a problem with the tear formation, tear ducts, or eyelids, or it’s a side effect of certain medications. This condition can cause pain and blurry vision.