Galactosemic cataract

An extremely rare case of developmental cataract due to an inborn metabolic error

Galactosemic cataract

A 3-year-old male was brought to us by his parents with complaints of bilateral progressive lenticular opacity since early childhood. Elsewhere child was diagnosed to have a developmental cataract and referred here for a detailed workup. Antenatal and postnatal periods were uneventful. Full-term normal delivery to a non-consanguineous parent. Lately, the child failed to thrive with recurrent episodic abdominal pain associated with diarrhoea. 

On general examination, the child was drowsy and apathetic. Generalised wasting noted and poorly nourished. The child’s visual functions were age-appropriate. The lens showed a central typical oil droplet like amber coloured opacity within the substance of the nucleus in both eyes. The fundus examination was essentially normal. Based on digestive history and corroborative distinctive lenticular opacities were highly s/o galectosemic cataract. 

On further inquiry, parents did reveal that child has an abdominal pain associated with chronic diarrhoea since the age of 6 months and he was also investigated for coeliac sprue. Elsewhere; duodenal and jejunal biopsy done which revealed nonspecific mild inflammatory changes. 

The child’s general condition improved significantly after the galactose free diet. Nevertheless, lenticular opacities did not show any evidence of reversal or progress after galactose free diet. The child is now on close surveillance. 

Galactosemia: A mysterious metabolic disorder

Galactosemia is an inherited autosomal recessive inability to convert galactose to glucose. Galactosemia can result from defects in 1 of 3 enzymes involved in the metabolism of galactose: galactose 1-phosphate uridyltransferase (Gal-1-PUT), galactokinase, or UDP galactose 4-epimerase. The most common and the severest form, known as classic galactosemia, is caused by a defect in Gal-1-PUT.

Of patients with classic galactosemia, 75% will develop bilateral cataracts, usually within the first few weeks of life. Accumulation of galactose and galactitol within the lens cells leads to an increase in intracellular osmotic pressure and an influx of fluid in the lens. Typically, the nucleus and deep cortex become increasingly opacified, causing an “oil droplet” appearance on retroillumination.

If the disease remains untreated, the cataracts progress to total opacification of the lenses. Treatment of galactosemia includes the elimination of milk and milk products from the diet. In some cases, early cataract formation can be reversed by timely diagnosis and dietary intervention, according to the American Academy of Ophthalmology.

The author is Head of Rare Eye Diseases, The Cornea Institute, L V Prasad Eye Institute, Hyderabad.

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