Amblyopia, or lazy eye is the result of strabismus that has gone untreated. A child who has strabismus will eventually learn to focus on the vision produced by the stronger eye and ignore the vision of the weaker, or lazy, one. This causes the vision in the weaker eye not to develop fully and can result in reduced sight in that eye.
Amblyopia can be caused by a condition called ptosis, which is a drooping of the eyelid. An impairment of color vision is usually the result of toxic or some other influence.
- Nutritional amblyopia, as the name suggests, occurs as a result of vitamin and mineral deficiencies. Lack of vitamin A in the diet leads to blindness. A lack of zinc prevents the body from using adequate amounts of vitamin A stored in the body. Thiamine (B1) and B12 deficiencies may cause optic neuropathy and vision loss. Generally, intensive vitamin therapy and proper nutrition can restore lost vision. It is often seen in alcoholics and those with severe nutritional deficiencies, especially in pernicious anemia, which is caused by a vitamin B12 deficiency. Complete recovery is possible with an improvement in diet and nutritional supplementation, but a prolonged deficiency can result in permanent loss of central vision. It is estimated that about two to three percent of children in the US have amblyopia.
- Alcohol amblyopia is a visual condition unique to those who have a history of chronic, severe drinking problems. The disorder involves lost vision, including scotomas (blind spots) and decreased visual acuity within the central portion of the visual field. The painless, bilateral sight loss gradually worsens. The disorder is caused by the toxic effects of alcohol on the optic nerve causing optic neuropathy, a condition in which the optic nerve swells. Because alcohol depletes the entire body system of nutrients, alcohol amblyopia is easily linked to a thiamine (vitamin B1) deficiency, a condition that can lead to optic-nerve damage. The condition can be treated with proper diet and vitamin supplementation. It is generally reversible, but may lead to permanent vision loss if untreated.
- Tobacco amblyopia is a condition in which the vision is lost because of the use of tobacco. The toxic effects of tobacco constrict the vessels of the body and interfere with circulation. The optic nerve is very sensitive to tobacco and can be easily irritated by excessive smoke. As a result, the optic nerve swells, a condition known as optic neuritis. Early symptoms of tobacco amblyopia include painless blurring or loss of central vision that may be accompanied by numbness or tingling in the fingers. If allowed to progress, the blurring may spread to the peripheral visual fields, and optic nerve damage may result. Reduction or elimination of tobacco usage in conjunction with proper nutrition usually restores sight. Alcohol and tobacco amblyopia are common conditions. Overuse of either compound affects the optic nerve and optic disc, causing optic atrophy. A slow, progressive loss of central vision and, often, color vision follow. Both conditions are associated with poor nutrition and diet, which also affects ocular function. Treatment with vitamins and minerals, especially that of vitamins B1 and B12, as well as the reduction in the use of both substances often restores sight.
- Toxic amblyopia is a condition in which vision is lost as a result of the absorption of toxic agents. The condition is usually bilateral, and except in the case of wood alcohol and arsenic poisoning when the vision loss is irreparable, generally tends not to be permanent. Some poisons induce a central vision blurring or scotoma, a blind spot. These include tobacco, ethyl alcohol, methyl alcohol, carbon disulphide, halogenated hydrocarbons, aromatic amino and nitro-compounds, such sedatives as barbiturates, opium, and morphine, anti-infective compounds and other drugs, and such heavy metals as lead and thallium. Other compounds produce a reduction of the peripheral field, or tunnel vision. These include organic arsenic, quinine, carbon tetrachloride, methyl iodide, and the drugs salicylic acid, hydrocupreine derivatives, ergot, and aspidium.