Key Points

• Colour vision can be affected by changes in the different components involved in visual stimulation: the retina (cones only, or more diffuse damage); optic nerve transmission; and integration of visual information. Abnormal colour vision may be hereditary (such as colour blindness) or acquired.
   
• Acquired colour vision disorders are often asymmetric. The manifestations are highly variable, with predominance of a particular colour, difficulty distinguishing between colours, decreased perception of colour shades. Patients are aware of them and may report them spontaneously.
   
• Acquired colour vision disorders are sometimes a component of serious ocular or neuro-ophthalmic disorders, often preceding other symptoms. They may also occur during the course of various metabolic or neurological disorders, or during drug therapy.
  
  
• Some drugs lead to mild and transient changes in colour vision. Other drugs may cause irreversible eye damage preceded by impaired colour vision. The disorders sometimes depend on the dose and duration of treatment.
   
• When patients complain of altered colour vision, measures should be taken to prevent other, more severe ocular or systemic disorders. When the role of a drug is plausible, the dose should be reduced rapidly, or the drug withdrawn.
   
• Drugs belonging to a wide variety of pharmacological classes can affect colour vision. Most cause retinopathy or neuropathy, but the mechanisms are not always known. The drugs most often implicated include: phosphodiesterase type 5 inhibitors such as sildenafil; digoxin; anti-infectives such as interferon alfa; ethambutol; metronidazole; and antimalarials.  

©Prescrire 1 May 2012

"Drug-induced colour vision disorders" Prescrire Int 2012; 21 (127): 126-128. (Pdf, subscribers only)