Galactosemia is a rare inherited metabolic disorder that prevents the body from effectively processing galactose, a sugar found in dairy and many other foods. This inability leads to a buildup of galactose and its byproducts, which can cause significant health problems. Among these complications, cataracts, characterized by a clouding of the eye’s natural lens, are a common consequence of uncontrolled galactosemia. Recognizing this connection is important for early diagnosis.
How Galactosemia Leads to Cataracts
Galactosemia arises from a deficiency in specific enzymes responsible for breaking down galactose into glucose, a usable energy source. When these enzymes are missing or don’t function properly, galactose accumulates in various tissues.
This accumulated galactose is then shunted into an alternative metabolic pathway, converting it into a sugar alcohol known as galactitol. The lens of the eye is particularly susceptible to this process, as galactitol cannot easily exit lens cells. Consequently, galactitol concentrations within the lens begin to rise significantly.
The increased concentration of galactitol inside the lens creates an osmotic imbalance. Water is drawn into the lens cells from the surrounding fluid to equalize the solute concentration. This influx of water causes the lens fibers to swell and eventually rupture, disrupting their uniform arrangement.
The disruption and aggregation of lens proteins lead to the lens becoming opaque, which is the physical manifestation of a cataract. This process can occur rapidly in affected infants if the condition is not identified and managed promptly.
Identifying and Diagnosing Galactosemia Cataracts
Cataracts in infants with galactosemia often present with a distinctive “oil droplet” appearance, visible at the center of the lens. These cataracts typically affect both eyes and can develop very early in life. Parents might observe general symptoms of galactosemia, such as poor feeding, lethargy, or jaundice, alongside a noticeable cloudiness or haziness in the infant’s eyes.
The diagnosis of galactosemia usually begins with routine newborn screening programs, which are mandated in many regions. These screenings involve testing a small blood sample, often collected from a heel stick, to detect elevated levels of galactose or enzyme deficiencies. A positive screening result warrants immediate confirmatory blood tests, which typically involve measuring the activity of the specific enzymes, such as GALT, directly in red blood cells.
An ophthalmological examination is then performed to confirm the presence of cataracts. During this examination, an eye care specialist can visualize the characteristic lens opacities using specialized instruments. Early detection through newborn screening and prompt ophthalmological assessment are important for timely intervention and to mitigate further damage.
Treatment and Management Approaches
The primary and most effective treatment for galactosemia, and consequently for preventing or managing its associated cataracts, involves strict adherence to a galactose-free diet. This dietary management requires completely eliminating all sources of lactose and galactose, including milk, dairy products, and certain other foods containing galactose. For infants, this means using specialized formulas that are free of lactose and galactose instead of breast milk or standard infant formulas.
Consistent dietary restriction can prevent the accumulation of galactitol, thereby halting the progression of cataract formation. In some cases, if the dietary intervention is initiated very early, during the first days or weeks of life, early-stage cataracts may even regress or disappear entirely. This highlights the importance of timely diagnosis and immediate dietary changes.
For cataracts that are already well-established and significantly impair vision, surgical removal becomes necessary. Cataract surgery for galactosemic cataracts is similar to that performed for other types of cataracts, involving the extraction of the clouded lens. Following surgery, an artificial intraocular lens may be implanted to restore vision. Ongoing dietary adherence and regular ophthalmological follow-ups are important for individuals with galactosemia to monitor for any recurrence of cataracts or other ocular complications, ensuring long-term eye health.