Summary

Cataract has been associated with several systemic diseases, importantly diabetes mellitus, myotonic dystrophy, atopic dermatitis and neurofibromatosis type 2. Many of these cataracts have unique, characteristic patterns.

Summarised below are the salient learning points regarding cataracts associated with systemic disease.

Diabetes mellitus

Pathophysiology

• Hyperglycaemia results in a high glucose level in the aqueous humour, which diffuses into the lens
• Glycosylation of lens proteins causes over-dehydration
• Vacuoles of cortical fluid develop, which opacity over time

Cataract features

• ‘Snowflake’ pattern ******- appear as grey-white subcapsular opacities. These cataracts can grow rapidly with the entire lens turning white. These are rare and typically occur in the young
• Age-related cataracts develop at a younger age in diabetes mellitus

Image showing bilateral posterior subcapsular ‘snowflake’ cataracts in a diabetic patient. Image courtesy of Park.

Myotonic dystrophy

Cataract features

• ‘Christmas tree’ pattern - bilateral iridescent needle-shaped cortical opacities. 90% of patients with myotonic dystrophy develop these in their 30’s.
• These grow over time into wedge-shaped or ‘star-like’ cortical and subcapsular opacities by their 50’s.