<prompt> The toxic agent in Tobacco amblyopia isNicotineCyanideCarbondioxideDinitrozol  <response>: Cyanide: Ref: 296-KH 92-PTOBACCO AMBLYOPIA: -Toxic agent involved cyanide fond in tobacco.Excessive tobacco smoking Decreased cyanide detoxification due to alcoholics dietary deficiency of sulphur rich proteins Excessive cyanide in blood Degeneration of ganglion cells particularly of the macular region Degeneration of papillo-macular bundle in the nerve Toxic amblyopia Bilateral gradually progressive impairment in the central vision Visual field examination - Bilateral centrocaecal scotomas Fundus examination is essentially normal or there may be slight temporal pallor of the disc. 