Types of Blindness
Types of Blindness
Albinism involves the absence or reduction of pigment in the eyes, skin, and hair. It may affect only the eyes. Effects on vision may include decreased visual acuity, photophobia, nystagmus, and strabismus.
Aniridia is a hereditary condition where the iris of the eye is underdeveloped. The effects on vision include decreased visual acuity, photophobia, nystagmus, cataracts, and underdeveloped retinas.
A congenital cataract is a hereditary condition in which there is opacity of the lens. The effects on vision include decreased visual acuity, photophobia, nystagmus, cataracts, and underdeveloped retinas.
Coloboma is a hereditary condition in which various parts of the eye may be deformed. The effects on vision include decreased acuity, nystagmus, and strabismus.
CORTICAL VISUAL IMPAIRMENT (CVI)
Cortical visual impairment is a result of damage to the vision center of the brain due to trauma, anoxia, or malformation. The effects on vision include decreased acuity, nystagmus, and strabismus.
Congenital glaucoma is a hereditary condition in which the tissue of the eye is damaged from increased intraocular pressure. The effects on vision include excessive tearing, photophobia, opacity or haze on the lens, buphthalmos, poor visual acuity, and constricted visual fields.
OPTIC NERVE ATROPHY
Optic nerve atrophy is caused by damage to the optic nerve. It can be hereditary or may result from trauma, inadequate blood or oxygen supply before or shortly after birth, or hydrocephalus. Effects on vision include decreased visual acuity, decreased central vision, decreased sensitivity in all visual fields, and nystagmus.
OPTIC NERVE HYPOPLASIA (ONH)
ONH is generally of unknown cause. It may appear by itself or in conjunction with neurological or hormonal abnormalities. The effects on vision may include decreased visual acuity, peripheral field loss, poor depth perception, and mild photophobia.
Nystagmus is an involuntary, rhythmic side-to-side or up-and-down eye movement that often accompanies other visual disorders.
RETINOPATHY OF PREMATURITY (ROP)
Retinopathy of Prematurity is a condition in which the retinas are scarred due to an unusual growth of blood vessels in the retina and vitreous. This is usually found in premature infants, but may also be found in full-term infants. The effects on vision include retinal detachments, severe myopia, decreased visual acuity, and blindness.
Trachoma is an inflammation of the eye that can cause blindness if left untreated. Almost six million people have been blinded by trachoma and approximately 150 million more are in need of medication or surgical treatment. The contagious disease is spread through direct contact and is common in areas where many people live in cramped, unhygienic quarters and poor climatic conditions. Trachoma can be successfully treated with a course of antibiotics and operations on the eyelids.
VITAMIN A DEFICIENCY (Child Blindness)
Each year approximately 350,000 children go irreversibly blind and two million die as a result of Vitamin A deficiency.
Along with undernourishment, the main causes of this deficiency in developing countries are infectious diseases such as measles and conjunctivitis in newly born children.