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Cataracts are clouding of the eye's natural lens. They can affect one or both of the eyes. Since the lens in a healthy eye is clear like a camera lens, light has no problem passing through the lens to the back of the eye to the retina where images are processed. When a cataract is present, the light cannot get through the lens as easily and, as a result, chickens often become blind.

There are several different causes of cataracts in chickens:
  • Genetics: Chickens of the Light and Dark Brahma breed are predisposed to developing cataracts. In 1991, one study revealed that 69% of the cockerels and 15% of the pullets in an inbred flock of approximately 200 dark and light Brahma chickens had cataracts in one or both of their eyes, and crooked toes; the chickens had been normal until all of a sudden at six months of age they developed cataracts, with or without crooked toes.
  • Certain diseases: avian encephalomyelitis or Marek's disease
  • Diet: Nutritional deficient diet, especially one that lacks sufficient antioxidants and omega 3 fatty acids.
  • Environment: Exposure to continuous lighting or ammonia.

Clinical Signs

Cloudy eye(s)
Visible whiteness in pupil
Sensitivity to light
Loss of eyesight


  • History
  • Clinical signs
  • Physical exam


Supportive care: as needed. Refer to care of blind chickens.:



Ensure birds are receiving enough riboflavin and vitamins A and E in their diet


Good as long as they are provided support.

Scientific References

Good Overviews

Risk Factors

  • History of avian encephalomyelitis
  • Chickens of the Light Brahma breed
  • Older birds

Case Stories