The eyeball needs to maintain a certain level of tension, or pressure, within the eye to keep it from collapsing. A series of canals within the eye continually drain fluid to keep intraocular pressure, often called IOP, within this range. Children, including infants, as well as adults can develop elevated intraocular pressure. Elevated pressure in the eye can cause glaucoma, damage to the optic nerve.
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Normal Intraocular Pressure
Intraocular pressure in children is normally lower than that of adults. Under one year of age, IOP averages 8.9 mmHg, or millimeters of mercury, lead author Roberto Sampaolesi reports in “The Glaucomas: Volume 1--Pediatric Glaucomas.” The IOP in children normally rises about 0.85 mmHg per year until they reach adult levels, which should remain under 21 mmHg.
Elevated intraocular pressure can occur for two reasons. If the canals become blocked, drainage can’t occur and pressure builds up in the eye. If the eye produces more fluid than normal, fluid can’t drain fast enough and pressure within the eye rises. Glaucoma--damage to the optic nerve--can result, causing permanent vision loss. While other conditions can also cause glaucoma, elevated IOP is a common cause in children and adults. Elevated IOP in children can be congenital, or present at birth, infantile, occurring between the ages of one month and two years, or juvenile, occurring after age three.
Inherited genetic abnormalities cause many cases of congenital elevated IOP that lead to glaucoma in children. Around 1 in 10,000 children born have congenital glaucoma, the American Association for Pediatric Ophthalmology and Strabismus reports. About one-third of congenital glaucoma cases occur because of inherited autosomal recessive genes. In autosomal recessive diseases, both parents must pass on the gene for the child to have the disease. Around 66 percent of cases of congenital disease occur because of spontaneous mutations during fetal development. Genetic syndromes, acquired diseases, cancers and injury to the eye can all cause elevated IOP in children.
Symptoms of elevated IOP in children include clouding of the cornea that makes the iris--the colored part of the eye--appear dull; tearing; light sensitivity; and having one eye larger than the other. Children old enough to talk may complain of vision loss.
Around 60 percent of cases of congenital glaucoma are diagnosed before six months of age, according to Children’s Hospital Boston. Unlike adults, who can usually cooperate with an eye exam, children often require anesthesia to tolerate the eye examination for glaucoma. Older children may be able to cooperate with parts of the exam in the office.
Treatment is essential to prevent permanent vision loss. Surgery and medications can lower IOP. Surgery creates an alternative drainage route for fluid. Medications can decrease fluid production. Other eye problems such as myopia, or nearsightedness, crossed eyes or lazy eye often occur in children with elevated IOP and also need treatment.