A cataract is any cloudiness or opacity of the lens of the eye, which is normally crystal clear. Cataracts can be very tiny, in which case, they do not interfere with vision, or they can affect the entire lens, resulting in severe loss of vision. [See figure 1].
About 3 children per 10,000 children have a cataract. The incidence is variable throughout the world.
A cataract causes decreased vision by interfering with the light ray path to the retina (back part of the eye). Abnormal vision development resulting in permanent loss of vision (amblyopia) occurs when a child has a cataract. Prompt and sometimes immediate treatment is necessary to prevent permanent vision loss [See figure 2].
Pediatric cataracts often occur because of abnormal lens development during pregnancy. Lens malformations that occur in conjunction with other findings are often the result of a genetic or metabolic problems. These cataracts may be present at birth or develop during childhood. Nevertheless, most pediatric cataracts are not associated with other abnormalities.
No. Some cataracts are small and/or off-center in the lens. These cataracts do not need to be removed because vision develops normally, even if the cataract is left in place.
The human crystalline lens consists of a center part called the nucleus and outer part called the cortex, both contained within a capsule. Cloudiness can occur in one or more parts of the lens:
• A lamellar cataract is cloudiness between the nuclear and cortical layers of the lens [See figure 3].
• A nuclear cataract is cloudiness of the center part of the lens.
• A posterior subcapsular cataract is a thin layer of cloudiness that affects the back surface of the lens cortex, just inside the capsule. [See figure 4].
• An anterior polar cataract is a small, usually central opacity of the front part of the lens capsule. This type of cataract is often shaped like a pyramid. Anterior polar cataracts generally do not grow during childhood and can usually be managed without surgery [See figure 5].
• A posterior polar cataract is a central opacity at the back of the lens [See figure 6].
• Persistent fetal vasculature is often associated with a cataract. During development of the eye a blood vessel extends from the optic nerve (back of the eye) to the developing lens to provide nutrients to the young growing lens. This blood vessel normally disappears during development, but if it persists, it can result in a plaque-like cataract on the back of the lens. The persistent stalk extending from the back of the eye toward the cataract can cause retinal abnormalities.
A traumatic cataract results from either a blunt or penetrating force that damages the lens. The cataract can form shortly after the trauma or months to years after the injury [See figure 7].
Cataracts that interfere with vision should removed as soon as is safely possible, especially if the cataract is present at birth, since delay in cataract removal can interfere with normal development of the visual parts of the brain. Tiny cataracts that do not seem likely to interfere with vision may be carefully monitored, but should be removed at the earliest sign of a vision problem.
A tiny incision is made into the eye and an opening is made in the front of the lens capsule. The very soft inner part of the child's lens is suctioned out of the capsule. Younger children may require an additional opening in the posterior lens capsule with some vitreous gel removal. An intraocular lens is then sometimes placed within the lens capsule. Dissolvable stitches are used to close the wounds.
Cataract surgery performed by an experienced surgeon is generally very safe. However, no surgical procedure is without risks. The risks of pediatric cataract surgery include infection, retinal detachment, development of glaucoma, displacement of the intraocular lens, development of capsular cloudiness and development of vitreous cloudiness.
There are several methods to restore focusing ability of the eye: 1) a permanent intraocular lens implant (IOL) is sometimes placed inside the eye at the time of cataract surgery, 2) a contact lens can be placed on the surface of the eye. (contact lenses have to be removed and cleaned regularly), 3) glasses can be used to focus the light rays. Cataract glasses are often very thick and cause magnification. so they are generally not a good option when only one eye is affected.
The Pediatric Glaucoma and Cataract Family Association.
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