Amblyopia--commonly referred to as "lazy eye"--is a condition common among young children that occurs when the vision in one eye deteriorates, rendering it unable to focus equally with the other. As the brain blocks out the poor signals from the affected eye, it forces the child to favor the "good" eye Some of the conditions that cause amblyopia run in families; however, many affected children have no family history at all. This condition can be treated, and early screening and intervention by school age are critical.
Strabismus
Strabismus is a condition in which one or both eyes are turned inward or outward. Constant strabismus, in which the right or left eye faces in or out all of the time, is the most common cause of amblyopia according to the Optometrist's Network. When an eye is misaligned, it cannot focus normally on objects. According to the Pediatric Glaucoma & Cataract Family Association, poor vision in that eye leads the brain to ignore the signals from the misaligned eye and instead focus on the healthy eye. This process leads to the development of amblyopia.
Glaucoma and Cataracts
Glaucoma is the name for a group of diseases characterized by optic nerve damage as a result of high intraocular pressure. Though more common in adults, glaucoma can develop congenitally and be present at birth, or it may develop anytime during infancy or childhood, according to the American Association for Pediatric Ophthalmology and Strabismus. Likewise, cataracts--cloudy spots on the lens of the eye--can also develop in young children. Both glaucoma and cataracts can caused blurred, distorted vision or loss of vision in the affected eye. According to the Pediatric Glaucoma & Cataract Family Association, poor vision can cause the brain to ignore signals from the affected eye, thereby leading to the onset of amblyopia.
Astigmatism
Astigmatism is a common eye condition characterized by blurred vision that is caused by an abnormally shaped cornea. In a review published in the June 2009 issue of "Optometry and Vision Science," Dr. E.M. Harvey at the Department of Ophthalmology and Vision Science and The College of Public Health at The University of Arizona concludes that uncorrected astigmatism in very young children can cause amblyopia and meridional amblyopia--a type of amblyopia in which vision in the affected eye is clear at some angles. Further research is needed to determine the most effective time during a child's early visual development to intervene with treatment.
Anisometropia
Anisometropia is the general term for the condition in which each eye has a different refractive power. For example, someone who is nearsighted in one eye but has normal vision or is farsighted in the other is considered to be anisometropic. According to the Optometrist's Network, anisometropia interferes with the eyes' ability to focus together and therefore can lead to the development of amblyopia.
Ptosis
Ptosis is the medical term used to describe a drooping eyelid. According to the Optometrist's Network, ptosis can block the vision in one eye and cause the development of amblyopia. Ptosis may be caused by trauma or injury to the eye, a congenital defect, or other diseases that affect the nerves and muscles of the eye, like diabetes and certain cancers.
References
- National Institutes of Health: Amblyopia
- Pediatric Glaucoma & Cataract Family Association: Strabismus & Amblyopia
- Optometrist's Network: All About Amblyopia
- "Optometry and Vision Science;" Development and treatment of astigmatism-related amblyopia; Harvey EM; June 2009
- American Association for Pediatric Ophthalmology and Strabismus: Glaucoma in Children
