side effects. Mild cases may show only minimal macular changes by Amsler grid, blurred vision or some constriction of the visual field. Zahn et al (1981) showed that early ERG may be normal, however in late ERG, scotopic b-wave and a-waves are altered. Hustead (1991) has shown that in individuals hypersensitive­ to quinine, a granulomatous uveitis may occur. Segal et al (1983) reported shallowing of the anterior chamber precipitating narrow-angle glaucoma. Schuman (1997) reported a case of acute bilateral transitory myopia. Worden et al (1987) and others have noted that chronic overuse of tonic water (which contains quinine) can cause toxic quinine effects in the eye.

According to the evidence presently available, the etiology of the toxic effect of quinine seems to involve not only an early effect­ on the outer layers of the retina and pigment epithelium, but also probably a direct effect on retinal ganglion cells and optic nerve fibers.

Quinine can cause optic nerve hypoplasia and decreased vision, including blindness, in the offspring secondary to prenatal maternal ingestion.

References and Further Reading

Birch J, et al. Acquired color vision defects. In Pokorny J Congenital and Acquired Color Vision Defects. Grune & Stratton, New York, 1979, p 243–350.

Boland MD, Roper SMB, Henry JA. Complications of quinine poisoning. J Ir Med Assoc 67: 46–47, 1974.

Brinton GS, Norton EW, Zahn JR, et al. Ocular quinine toxicity. Am J Ophthalmol 90: 403, 1980.

Dyson EH, Proudfoot AT, Prescott LF, et al. Death and blindness due to overdose of quinine. BMJ 291: 31, 1985.

Dyson EH, Proudfoot AT, Bateman DN. Quinine amblyopia: is current management appropriate? Clin Toxicol 23: 571, 1985–1986.

Fisher CM. Visual disturbances associated with quinidine and quinine. Neurology 31: 1569, 1981.

Fong LP, Kaufman DV, Galbraith JEK. Ocular toxicity of quinine. Med J Austr 141: 528, 1984.

Friedman L, Rothkoff L, Zaks U. Clinical observations on quinine toxicity. Ann Ophthalmol 12: 641, 1980.

Gangitano JL, Keltner JL. Abnormalities of the pupil and visual-evoked potential in quinine amblyopia. Am J Ophthalmol 89: 425,

1980.

Grant WM, Schuman JS. Effects on the eyes and visual system from chemicals, drugs, metals and minerals, plants, toxins and venoms; Systemic side effects from eye medications. Toxicology of the

Eye. 4th edn. Charles C. Thomas, Springfield, IL, 1993.

Horgan SE, Williams RW. Chronic retinal toxicity due to quinine in Indian tonic water (letter). Eye 9(Pt.5): 637–638,

1995.

Hustead JD. Granulomatous uveitis and quinidine hypersensitivity. Am J Ophthalmol 112(4): 461–462, 1991.

Kaeser HE. Drug-induced myasthenic syndromes. Acta Neurol Scand 70(Suppl 100): 39, 1984.

Rheeder P, Sieling WL. Acute, persistent quinine-induced blindness. A case report. So Afr Med J 79: 563–564, 4 May 1991.

Schuman JS. Acute bilateral transitory myopia associated with open angle glaucoma. Chandler and Grant’s Glaucoma. 4th edn. Epstein DL, Allingham RR, Schuman JS (eds), Williams and Wilkens, Baltimore, p 341, 1997.

Segal A, Aisemberg A, Ducasse A. Quinine transitory myopia, and angle-closure glaucoma. Bull Soc Ophtalmol Fr 83: 247–249, 1983.

Waddell K. Blindness from quinine as an antimalarial (letter). Trans Roy Soc Trop Med Hygiene 89(4): 331–332,

1996.

Worden AN, Frape DL, Shephard NW. Consumption of quinine hydrochloride in tonic water. Lancet 1: 271–272, 1987.

Zahn JR, Brinton GF, Norton E. Ocular quinine toxicity followed by electro­ retinogram, electro-oculogram, and pattern visually evoked potential. Am J Optom Physiol Optics 58: 492, 1981.

Class: Antiprotozoal Agents

Generic name: Metronidazole.

Proprietary names: Flagyl, Flagyl ER, Flagyl IV, Metrocream, Metro IV, Metrogel, Metrogel-vaginal 3M, Metrolotion, Noritate, Vandazole.

Primary use

This nitroimidazole derivative is an antibacterial and antiprotozoal agent effective in the treatment of trichomoniasis, amebiasis, giardiasis and anaerobic bacterial infections.

Ocular side effects

Systemic administration

Certain

1. Decreased vision

2. Photophobia

3. Visual field changes – scotoma

4. Eyelids or conjunctiva

a.Erythema

b.Conjunctivitis – non-specific

c.Edema

d.Photosensitivity

e.Angioneurotic edema

f.Urticaria

Probable

1. Retrobulbar or optic neuritis

2. Visual hallucinations

3. Diplopia

4. Myopia – reversible

Possible

1. Subconjunctival or retinal hemorrhages secondary to druginduced anemia

2. Eyelids or conjunctiva

a.Stevens-Johnson syndrome

b.Toxic epidermal necrolysis

Conditional/Unclassified

1. Oculogyric crises

2. Abnormal red-green color vision

3. Abnormal visual evoked potential

Local ophthalmic use or exposure

Certain

1. Irritation

2. Erythema

3. Epiphora

Ocular teratogenic effects

Conditional/Unclassified

1. Telecanthus

Clinical significance

Ocular side effects from systemic use of metronidazole are unusual, and most are reversible on discontinuation of treatment. Putnam et al (1991) reported seven patients on metronidazole who developed optic or retrobulbar neuritis. This is associated with color vision defects, decreased vision and various scotomas. This may

nfectivesi -Anti ectiS • 1on