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by Dr. Steven Mattas, Ophthalmologist Maxicare, Inc.
Editor's Note: The following is reprinted from the VIPS Parents Newsletter, Louisville, Kentucky.
There are many causes for loss of vision in infancy and childhood. Infections, tumors, and developmental problems take a definite toll in eyesight. Although quite dissimilar among themselves, there are several eye problems of infancy or childhood which present themselves with the same sign -- leukocoria. Leukocoria means "white pupil." Several eye problems of children are first discovered because they cause a white or opaque pupil. Congenital cataract, retinoblastoma, retinopathy of prematurity, nematode endophthalmitis, persistent hyperplastic primary vitreous, and Coat's disease all may be first discovered by observing that the child has a white or opaque pupil.
Cataract might be our first thought when we see leukocoria. Congenital cataract can appear alone or associated with other eye or body system problems. If examination determines that the eye has potential for vision and the child's health permits, congenital cataracts should be removed soon after birth. An infant with cataracts can develop a very profound amblyopia. This would mean that even if successful surgery were performed later in life, vision may not improve. Once the cataracts are removed the infant must use contact lenses or eyeglasses to properly focus light on the retina. Often there are tactical difficulties fitting an infant with contacts or glasses. The doctor might then recommend epikcratophakla. In this procedure a donor cornea is ground to the power of a contact lens and is sutured onto the child's cornea. In a way of thinking the graft becomes a living contact lens.
A white pupil might also be caused by retinoblastoma. Retinoblastoma is the most common eye malignancy of childhood. The tumor arises from the retina and appears in approximately 1 in 20,000 live births. About 6% of these tumors are inherited. With the inherited form of the tumor there is a 50/50 chance that each child of the affected parent may develop the tumor. About 3 in 10 cases will affect both eyes. The average age for diagnosis of retinoblastoma is 18 months, and 90% are discovered by age 3 years. As with any malignancy, discovering the tumor when it is confined to the retina is favorable. Today, about 90% of patients who develop retinoblastoma survive their disease. Removing the eye is recommended in most cases of retinoblastoma. Radiation and chemotherapy may also be used.
A relatively new cause of developing a white pupil is retinopathy of prematurity (ROP). ROP was first described in the 1940's and reached a peak in the 1950's. The damage in ROP is caused by oxygen toxicity to immature retinal blood vessels. Naturally, a premature infant also has immature lungs and must receive oxygen therapy. However, now the incidence of ROP has been stabilized because pediatricians carefully monitor the amount of oxygen in the premature infant's blood. Oxygen toxicity to immature retinal blood vessels can cause scar tissue to develop within the eye. This scar tissue can apply a constant traction to the retina and cause it to detach. In the most severe cases the retina may completely detach and form a whitish mass behind the pupil. Retinal detachment surgery is a benefit to some of these children.
Another disease of retinal blood vessels which can cause leukocoria is Coat's disease. Coat's disease usually affects one eye, usually involves males and it is restricted to the eye with other body systems unaffected. In Coat's disease retinal blood vessels are abnormally leaky. Blood plasma usually confined to the vessel permeates through the wall of the abnormal vessel. This leakage can progress to the point where fluid detaches the retina. Doctors try to control these abnormal vessels by photocoagulation with a laser or freezing them with a cryoprobe. Retinal detachment surgery may be necessary in severe cases.
An infectious cause of leukocoria is nematode endophthalmitis. This childhood eye disease is caused by ingesting soil or perhaps vegetables contaminated by the parasitic worm, Toxocara. Toxocara can be found in the feces of puppies and this is thought to be a main source of contamination. Once the parasite is ingested it can travel through the bloodstream to the retina. As bodily defenses fight the infection, inflammatory cells and debris can cloud the vitreous jelly of the eye. Scarring and the development of traction membranes might detach the retina. Once identified, the inflammation Toxocara causes can be combatted with cortecosteroid medication. The condition usually affects just one eye.
A developmental problem secondary to leukocoria is persistent hyperplastic primary vitreous (PHPV). The vitreous is the clear jelly which fills the back of the eye. Sometimes the proper development of the vitreous is interrupted and instead of a clear jelly an opaque membrane develops behind the lens of the eye. This membrane can cause a cataract and glaucoma to develop. Cataract surgery can be successful in these children if PHPV is the only problem affecting the eye. The eye involved with PHPV is usually smaller than the fellow eye, and 90% of the time only one eye is involved.
The variety and scope of these various eye problems underscore the importance of discovering a white pupil in an infant. In addition to the problems described there are still other conditions which may cause leukocoria. Once the parent or doctor discovers a white pupil, a diagnostic investigation is initiated as there are many different conditions which may be responsible and many different therapies which may follow.
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