Congenital cataracts are a clouding of the natural lens of the eye that is present at birth or that develops shortly after birth. In most congenital cataracts, no specific cause for the cataract is found; however, congenital cataracts that occur in only one eye are rarely associated with systemic problems but are typically caused by some local problem. Congenital cataracts that occur in both eyes are associated with a systemic disease approximately 5-10 percent of the time according to the Ophthalmic Consultants Philippines website. For bilateral cataracts, it is key to determine if there is a systemic cause that may need to be treated. There are multiple disorders that are associated with the development of congenital cataracts.
Problems with Eye Development
Congenital cataracts that occur in only one eye are often caused by a problem in the development of the eye; a unilateral cataract requires a very thorough ocular examination according to Dr. Harley in the textbook "Harley's Pediatric Ophthalmology." Some conditions that may cause congenital cataracts—such as congenital glaucoma or aniridia in which the iris is not fully developed—affect the anterior chamber or the front of the eye. Other conditions like retinitis pigmentosa or persistent hyperplastic primary vitreous where the vitreous jelly in the back of the eye does not develop correctly affect the back part of the eye. It is important to fully evaluate the eye to make a determination of the potential vision that the eye may have.
Interuterine Infections
Certain infections in the pregnant woman can cause bilateral congenital cataracts such as rubella, toxoplasmosis, varicella and herpes simplex infections. According Dr. Robison Harley and colleagues in the 2005 textbook Harley's Pediatric Ophthalmology, rubella is the most common cause but with the increased use of the rubella vaccine, the number has decreased. Rubella infection is typically part of a syndrome that involves other parts of the eye as well as other parts of the body.
Chromosomal Disorders
Several hereditary or chromosomal disorders that involve problems with the entire body are related to the development of congenital cataracts in both eyes. Some of these syndromes include Down syndrome or trisomy 21 and Turner's syndrome where the female has an incomplete chromosome. Many of these syndromes have other characteristic systemic characteristics so the diagnosis of the cataract may not be the end of the evaluation.
Metabolic Diseases
Some metabolic disorders where an enzyme in the body does not work properly or is not present are associated with bilateral congenital cataracts. One disorder is galactosemia where the sugars in milk are not digested properly; another is Fabry's Disease where a specific enzyme is missing in the body causing the accumulation of fat-like substances in various parts of the body according to Dr. Harley in the textbook Harley's Pediatric Ophthalmology. Most infants are tested for many of these types of metabolic disorders at birth because many of these conditions can be managed if caught early; however, not all metabolic diseases can be treated.
References
- Lighthouse International: Congenital Cataracts
- Ophthalmic Consultants Philippines: What are the causes of congenital cataract?
- "Harley's pediatric ophthalmology"; Harley RD, Nelson LB, Olitsky SE; 2005
