Tobacco amblyopia

• Tobacco amblyopia is a toxic amblyopia seen in people who are smoke heavily, consume alcohol and have a diet deficient in proteins and vitamins

Pathogenesis:

• Cyanide present in tobacco smoke causes degeneration of ganglion cells in the macula
• There is also degeneration of the papillomacular bundle of nerves

Relation to alcohol consumption:

• Alcoholics have a dietary deficiency of sulphur rich proteins
• This results in decreased ability to detoxify cyanide, thus having a synergistic effect

Clinical features:

• Usually seen in men of 40-60 years of age
• Visual loss is:
  • gradually progressive
  • painless
  • bilateral
  • affecting central vision (damage to the macula and papillomacular bundle results in centrocecal scotoma)
  • greater defect for red vs white colour
• Fundus examination reveals a normal fundus (there may be slight temporal pallor of disc)

Treatment:

• Stop smoking and alcohol intake
• Intramuscular injections of hydroxycobalamine – 1mg – weekly – for 10 weeks
• Good nutrition
• Vasodilators

Prognosis:

• Good prognosis if there is cessation of smoking and alcohol intake
• Recovery of vision is slow – takes weeks to months