Ocular side effects

Systemic administration

Certain

1. Constriction of visual fields

2. Decreased vision

3. Visual sensations

a.Smokeless fog

b.Shimmering effect 4. Optic neuritis

5. Optic atrophy

6. Toxic amblyopia

Clinical significance

The most serious and common adverse drug reactions due to tryparsamide involve the eye. Incidence of ocular side effects varies from 3 to 20% of cases, with constriction of visual fields followed by decreased vision as the characteristic sequence. Almost 10% of individuals taking tryparsamide experience visual changes consisting of ‘shimmering’ or ‘dazzling’, which may persist for days or even weeks. If the medication is not immediately discontinued following these visual changes, the pathologic condition of the optic nerve may become irreversible and progress to blindness. Due to the severity of side effects of this drug on the optic nerve, it has generally been replaced by melarsoprol.

References and Further Reading

Doull J, Klaassen CD, Amdur MO (eds). Casarett and Doull’s Toxicology: The Basic Science of Poisons, 2nd edn, Macmillan, New York,

pp 301–302, 1980.

LeJeune JR. Les oligo-elements et chelateurs. Bull Soc Belge Ophtalmol 160: 241, 1972.

Potts AM. Duality of the optic nerve in toxicology. In: Neurotoxicity of the Visual System. Merigan WH, Weiss B (eds), Raven Press, New York, pp 1–15, 1980.

Sloan LL, Woods AC. Effect of tryparsamide on the eye. Am J Syph 20: 583613, 1936.

Walsh FB, Hoyt WF. Clinical Neuro-Ophthalmology, Vol. III. 3rd edn. Williams & Wilkins, Baltimore, 2594–2596, 2004.

Class: Antitubercular Agents

Generic name: Cycloserine.

Proprietary name: Seromycin.

Primary use

This isoxazolidone is effective against certain Gram-negative and Gram-positive bacteria and M. tuberculosis.

Ocular side effects

Systemic administration

Certain

1. Decreased vision

2. Eyelids or conjunctiva

a.Allergic reactions

b.Conjunctivitis – non-specific

c.Photosensitivity

3. Trichomegaly

Probable

1. Visual hallucinations

2. Flickering vision

Possible

1. Subconjunctival or retinal hemorrhages secondary to druginduced anemia

Conditional/Unclassified

1. Optic nerve

a.Neuritis

b.Atrophy

Clinical significance

Even though ocular complications due to cycloserine are quite rare, this drug is primarily used in combination with other drugs therefore pinpointing cause and effect for an ocular side effect is very difficult. An increased number of eyelashes (hypertrichosis) has been reported (Weaver and Bartley 1990) and may prompt the clinical suspicion of an immune system abnormality. Optic nerve damage (including optic neuritis and atrophy) has been reported, but these data are not conclusive.

References and Further Reading

Drug Evaluations, 6th edn, American Medical Association, Chicago, pp 1539–1540, 1986.

Drugs that cause psychiatric symptoms. Med Lett Drugs Ther 28: 81, 1986. Gilman AG, Goodman LS, Gilman A The Pharmacological Basis of

­Therapeutics. 6th edn. Macmillan, New York, 1980, p 1210–1211. Walsh FB, Hoyt WF. Clinical Neuro-Ophthalmology, Vol. III. 3rd edn.

Williams & Wilkins, Baltimore, 1969 p 2680.

Weaver DT, Bartley GB. Cyclosporine-induced trichomegaly. Am J Ophthalmol 109(2): 239, 1990.

Generic name: Ethambutol.

Proprietary name: Myambutol.

Primary use

Ethambutol is a tuberculostatic agent that is effective against

M. tuberculosis.

Ocular side effects

Systemic administration

Certain

1. Problems with color vision – red-green or blue-yellow defect 2. Decreased vision

3. Contrast sensitivity – decreased

4. Visual evoked potential – decreased

5. ERG changes

6. Visual fields

a.Scotomas – annular, central or centrocecal

b.Constriction

c.Hemianopsia

d.Enlarged blind spot

7. Optic nerve

a.Retrobulbar or optic neuritis

b.Papilledema

c.Peripapillary atrophy

d.Atrophy (Fig. 7.1i)

Probable

1. Optic nerve

a.Micro-hemorrhages

b.Hyperemia

ectiS • 1on -Anti

nfectivesi