Eye disorders that may affect your child’s vision can be divided into two groups:
- refractive errors: eye disorders in which the eye does not focus the light that enters the eye, resulting in blurred vision
- non-refractive errors: eye disorders that are caused by eye diseases
What are refractive errors?
Refractive errors are seen in almost 20 percent of children. The most common refractive errors, all of which affect vision, are:
- Myopia or nearsightedness: Myopia is the most common refractive error seen in children. Myopia means that a child can see close up but has problems with seeing things far away.
- Hyperopia or farsightedness is a type of refractive error in which a child can’t see things close to him or her, but he or she does not have a problem seeing things far away. This is usually uncommon in children. Most children normally have a small degree of this until they are 7 years of age.
- Astigmatism is a condition in which an abnormal curvature of the cornea occurs, resulting in decreased vision. This can start in childhood or as an adult and can be easily corrected if it is causing problems. Some signs and symptoms of astigmatism may include headache, eye strain, difficulty reading and fatigue.
- Amblyopia or lazy eye is characterized by decreased vision that occurs in one eye, usually as a result of another problem in which that eye is not receiving proper visual stimulation. This is usually preventable if the underlying cause is treated before the child is 6 years old.
Strabismus or crossed-eyes is one of the most common eye problems in children in which the eyes are misaligned. One or both eyes may turn inward (crossed-eyes), outward (wall eyes), turn up or turn down. At times, more than one of these conditions is present.
- Children younger than 6 months old may have a common form of strabismus that comes and goes. This type of strabismus may be normal. Strabismus can be a result of poor muscle strength in the eye, while some children are simply born with crossed-eyes.
The signs and symptoms of strabismus may include:
- a child squinting his eyes
- a child who cannot properly judge distance to pick up objects
- a child who closes one eye to see better
- a child who experiences dizziness
- a child whose eyes move inward or outward.
- Early diagnosis of the underlying problem is essential in preventing vision loss. Treatment of strabismus may include patching the stronger eye in order to increase the strength in the weaker eye, eyeglasses, surgery to straighten the eyes or eye exercises.
What are non-refractive errors?
- Glaucoma is a condition in which the normal fluid pressure inside the eyes (intraocular pressure or IOP) slowly rises as a result of the fluid aqueous humor -- which normally flows in and out of the eye -- not being able to drain properly. Instead, the fluid collects and causes pressure damage to the optic nerve (a bundle of more than 1 million nerve fibers that connects the retina with the brain) and loss of vision.
Glaucoma is classified according to the age of onset. Glaucoma that begins before the child is 3 years old is called infantile or congenital (present at birth) glaucoma. Glaucoma that occurs in a child is called childhood glaucoma.
- A cataract is a clouding or opaque area over the lens of the eye, an area that is normally transparent. As this thickening occurs, it prevents light rays from passing through the lens and focusing on the retina, the light-sensitive tissue lining located in the back of the eye. This clouding is caused when some of the protein that makes up the lens begins to clump together and interferes with vision.
Cataracts can affect either one eye (unilateral) or both eyes (bilateral). Cataracts in children are uncommon. A child may be born with the disease (congenital), or it may develop later in life (acquired). Possible causes of cataracts include:
- steroid use
- other childhood diseases, such as rheumatoid arthritis
- complications from other eye diseases, such as glaucoma
The majority of congenital cataracts (those present at birth) are present in children who also have other eye problems or other health problems. In approximately 25 percent of children born with congenital cataracts, the condition is due to a genetic cause, such as a metabolic disorder (caused by an inherited enzyme deficiency) or a chromosome abnormality (i.e., Down syndrome).
Signs and symptoms of a cataract may include:
- cloudy or blurry vision
- decreased vision
- lights appearing too bright and/or presenting a glare or surrounding halo
- white pupil upon flashlight examination
- double vision
- colors seem faded
- increased nearsightedness, increasing the need to change eyeglass prescriptions
Treatment of cataracts usually involves surgery.
- Retinoblastoma is a rare cancer of the retina. The retina is the innermost layer of the eye, located at the back of the eye that receives light and images necessary for vision.
About 250 children in the United States are diagnosed with this type of cancer each year. It mostly occurs in children under the age of 5; the highest incidence of the disease occurs between infancy and age 2. Both males and females are affected equally. Retinoblastoma can occur in either eye, but in about 25 to 30 percent of the cases, the tumor is present in both eyes.
Signs and symptoms of retinoblastoma may include:
- leukocoria: a white light reflex that occurs at certain angles when light is shown into the pupil
- strabismus (also called "wandering eye" or "crossed-eyes"): a misalignment of the eyes in which one or both eyes do not appear to be "looking" in the same direction
- pain or redness around the eye(s)
- poor vision or change in child's vision
Treatment for retinoblastoma may include one, or more, of the following:
- enucleation (removal of part or all of the eye or eyes involved with the tumor)
- radiation therapy
- phototherapy (uses light to destroy the blood vessels that supply the tumor)
- cryotherapy (uses a freezing process to destroy the tumor)
- fitting and training for a prosthesis
- blind or decreased vision adaptation training
- supportive care (for the side effects of treatment )
- antibiotics (to prevent/treat infection)