Partial or complete loss of vision in one eye caused by conditions that affect the normal development of vision. These conditions include strabismus, in which the eyes are crossed inward (esotropia) or turned outward (exotropia) and anisometropia, in which there is a major difference in refractive error between the two eyes from nearsightedness, farsightedness, or astigmatism. Less common causes of amblyopia include ptosis (drooping) of one eyelid, disease of the cornea (preventing light from entering the eye), congenital cataract, and injury to the eye of a young child.
In amblyopia, the brain favors one eye over the other. The other eye is ignored. It is not adequately stimulated and the visual brain cells do not mature normally. Amblyopia is the most common cause of monocular blindness, partial or complete blindness in one eye. Amblyopia affects 2 to 3% of children in the US.
Treatment of strabismus may involve surgical correction of the eye muscle imbalance. In the case of severe refractive error, it should be corrected by glasses, contact lenses or, if appropriate, lasix. Wearing an eye patch over the stronger eye is a hallowed treatment for amblyopia. Another option is atropine eye drops to blur the vision temporarily in the stronger eye. Weekend atropine provides an improvement in visual acuity of a magnitude similar to that provided by daily atropine in treating moderate amblyopia
Inflammation of the eyelids.
Blepharitis occurs in two forms, anterior and posterior:
Anterior blepharitis affects the outside front of the eyelid, where the eyelashes are attached. The two most common causes of anterior blepharitis are bacteria (Staphylococcus) and scalp dandruff.
Posterior blepharitis affects the inner eyelid (the moist part that makes contact with the eye) and is caused by problems with the oil (meibomian) glands in this part of the eyelid. Two skin disorders can cause this form of blepharitis: rosacea and seborrheic dermatitis of the scalp (scalp dandruff).
Both types of blepharitis can cause a foreign body or burning sensation, excessive tearing, itching, sensitivity to light (photophobia), red and swollen eyelids, redness of the eye, blurred vision, frothy tears, dry eye, or crusting of the eyelashes on awakening. Complications from blepharitis include:
Stye: A red tender bump on the eyelid that is caused by an acute infection of the oil glands of the eyelid.
Chalazion: This condition can follow the development of a stye. It is a usually painless firm lump caused by inflammation of the oil glands of the eyelid. Chalazion can be painful and red if there is also an infection.
Problems with the tear film: Abnormal or decreased oil secretions that are part of the tear film can result in excess tearing or dry eye. Because tears are necessary to keep the cornea healthy, tear film problems can make people more at risk for corneal infections.
Treatment for both forms of blepharitis involves keeping the lids clean and free of crusts. Warm compresses should be applied to the lid to loosen the crusts, followed by a light scrubbing of the eyelid with a cotton swab and a mixture of water and baby shampoo. Because blepharitis rarely goes away completely, most patients must maintain an eyelid hygiene routine for life. If the blepharitis is severe, an eye care professional may also prescribe antibiotics or steroid eyedrops
A clouding of the lens of the eye. The normally clear aspirin-sized lens of the eye starts to become cloudy. The result is much like smearing grease over the lens of a camera. It impairs normal vision.
There are many causes of cataracts including cortisone medication, trauma, diabetes, many other diseases and simply aging. Cataracts will affect almost all people if they are fortunate enough to live long enough.
The symptoms of cataracts include double or blurred vision and unusual sensitivity to light and glare. Cataracts can be diagnosed when the doctor examines the eyes with a viewing instrument.
The ideal treatment for cataracts is surgical implantation of a new lens. Wearing sunglasses can help prevent cataracts.
The floating specks you sometimes see in front of your eyes are not on the surface of your eyes, but inside them. These floaters are bits of cellular debris that come and go without treatment. To some people, these "floaters" look like spots. To others, they look like tiny threads.
A person with floaters sees abnormal shapes or shadows that move across the field of vision.
Floaters are usually black or gray. They are most noticeable when gazing at a light-colored background, such as the sky or a white sheet of paper.
A hole in the macula, the tiny oval area made up of millions of nerve cells located at the center of the retina responsible for sharp, central vision.
The eye contains a jelly-like substance called the vitreous. Shrinking of the vitreous usually causes the hole. As a person ages, the vitreous becomes thicker and stringier and begins to pull away from the retina. If the vitreous is firmly attached to the retina when it pulls away, a hole can result.
The size of the hole and its location on the retina determine how much it affects vision. Generally, people notice a slight distortion or reduction in their eyesight. However, if the hole goes all the way through the macula, you can lose a lot of your central vision and therefore your detailed fine vision.
Eye strokes occur when blockages (occlusions) within veins and arteries cause decreased or distorted vision. Severity of vision loss depends on the extent and location of the problem.
Just as strokes occur in other parts of the body because blood flow is blocked, your eye also may suffer damage when vital structures such as the retina and optic nerve are cut off from nutrients and oxygen flowing through your blood.
Besides having an eye exam to detect signs of an eye occlusion, you'll also need your family doctor or internal medicine physician to evaluate you for high blood pressure, artery disease or heart problems that may be responsible for the blockage.
If a blockage is found, the type of eye occlusion you have is categorized by its location.