Retina quinine

Because central vision tends to recover spontaneously even without treatment, patients with acute quinine toxicity should generally be managed by supportive measures alone. Hyperbaric oxygen has been used in an attempt to increase oxygen delivery to the retina. The use of oral activated charcoal or any other gastric decontamination procedures does not improve clinical outcome and may, in fact, be harmful to the patient. It is important to emphasize preventive measures, such as patient education and dispensing of quinine in child-resistant containers. 

Quinine The antimalarial agent quinine is derived from the bark of the cinchona tree along with several other alkaloids and salicylate (aspirin). Many of these agents produce similar toxic features (cinchon-ism) in patients with excessive intake, but only quinine produces blindness. Cinchonism consists of abdominal pain and vomiting, ringing in the ears (tinnitus), and confusion. Visual loss after quinine overdose is due to direct retinal toxicity, although until recently it was believed to be due to spasm of the arterial blood supply to the retina. Treatment is difficult, but limited evidence suggests charcoal hemoperfusion may be beneficial (hemoperfusion is similar to hemodialysis, except in place of a semi-permeable membrane to filter the toxin from the blood, charcoal is used to bind the toxin). 

I. Mechanism of toxicity. The mechanism of quinine toxicity is believed to be similar to that of quinidine (see p 324) however, quinine is a much less potent car-diotoxin. Quinine also has toxic effects on the retina that can result in blindness. At one time, vasoconstriction of retinal arterioles resulting in retinal ischemia was thought to be the cause of blindness however, recent evidence indicates a direct toxic effect on photoreceptor and ganglion cells. 

Ocular electrophysiologic examinations are occasionnally required to evaluate the functional capability of the retina of laboratory animals treated with a test article which may have a detriments effect on retinal function. In order to test the sensitivity of the SYNTHELABO RECHERCHE electroretinograph and to quantify potential fonctional changes, an ocular electrophysiologic study was performed in beagle dogs which received quinine hydrochloride by intravenous infusion at different dose levels. Quinine is known to affect the visual capability to decrease the amplitude and to increase the... 

M.T. Carapancea, Synchronic quinine toxicity in visual retina and superior nervous... 

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