Toxic Amblyopiæ.
TOBACCO AND ALCOHOL.—These two lesions strongly resemble each other, and it is impossible to differentiate them when we find them in persons who are addicted to the abuse of both of these drugs; consequently, for a time, in Germany, there was a disposition to underrate the potent destructive agency of the latter drug, but every practitioner of experience in eye disease must have seen cases of tobacco amblyopia in which there has been no abuse of alcohol. The best proof of the deleterious influences of tobacco on the eyesight is the improvement which results by simple abstinence from its use where the vision has been seriously affected by its influence. In the earlier stages of both forms of amblyopia there is a contracted pupil and a slight dimness of vision, the patients claiming that they see better in feeble light and twilight. The ophthalmoscope shows a slight oedema of the disc with tortuosity of the veins, the rest of the eye-ground appearing normal. Later, the usual appearances of blue-gray atrophy set in. In the earlier stage there are often color scotomata, which are usually ovoid in form and lie between the disc and the macula lutea. Unless carefully looked for with color squares of one to two millimeters in diameter, they are apt to be overlooked. Later, there is a marked reduction of central vision. When the atrophy has progressed farther, there is decided contraction of the field.
LEAD-POISONING.—The deleterious effects of lead on the eyesight are undoubted, although rare in proportion to the cases of colic and wrist-drop produced by this metal. When amaurosis develops, it is usually either in acute lead-poisoning or after a gradual saturation of the system, as is shown by repeated attacks of lead colic. In either case the amaurosis is usually accompanied by dilatation of the pupils, delirium, and convulsions. The amaurosis generally passes off, and the pupils contract with the return of vision, although it may remain permanent, and leaves the patient with atrophic nerves, as in a case observed by Trousseau, where the patient was subsequently transferred to the Salpêtrière. The only two cases which the writer has had an opportunity of witnessing showed marked choking of the discs and severe cerebral symptoms. One of these cases died and one recovered: both were results of the use of white lead as a cosmetic. Rognetta307 quotes Vater as reporting a case of hemianopia produced by lead-poisoning, which recovered when the lead colic was cured. Trousseau308 quotes Andral as giving a case of diplopia due to the same cause, and disappearing as the patient recovered.
307 Recherches sur la Cause et la Siège d'Amaurose.
308 Thèse de Concours.
QUININE.—Over-doses of quinine seriously impair the eyesight, and in some cases have produced temporary but absolute blindness. The usual symptoms are a deterioration of central vision and a contraction of the field. The ophthalmoscopic examination reveals a pallid disc with marked diminution in the size of the retinal arteries and veins. In many of the reported cases it is difficult to decide positively how much of the amaurosis is due to the quinine and how much to the disease for which the patient is under treatment. This is especially true where the patient has been suffering from severe intermittent fever or from exhausting hemorrhages complicating uterine disease, which are well known frequently to produce more or less complete atrophy, with shrinking of the vessels. There are, however, a sufficient number of well-observed cases on record to satisfactorily establish the lesion. One of the most striking is a case of poisoning recorded by Giacomini, where the patient took at one dose three drachms of sulphate of quinia by mistake for cream of tartar. This was followed by severe headache, pain in the stomach, dizziness, unconsciousness, with slow and scarcely perceptible pulse and infrequent respiration. The pupils were widely dilated. On regaining consciousness the patient found that he was almost blind, the weakness of sight lasting a long time. As the poisoning occurred in the preophthalmoscopic era, there is of course no description of the eye-ground. In all recorded cases, while central vision has been either partially or entirely regained, the field of vision has remained permanently contracted.
SANTONIN.—In very large doses santonin produces dilatation of the pupil, amblyopia, and complete color-blindness. Smaller doses produce a shortening of the violet end of the spectrum and cause yellow vision. The disturbance of vision usually lasts only a few hours. The poison seems to be eliminated by the urine, as the sight is said to become normal while traces of the drug can still be seen in the secretion of the kidneys. Rose has given us a most careful study of this subject in his papers entitled "Color-Blindness from Santonin"309 and "Hallucinations in Santonin Intoxication."310
309 Virch. Arch., Bd. xx., 1860 (Separat Abdruck, S. 48).
310 Ibid., Bd. xxviii., 1863 (Separat Abdruck, S. 12).
SALICYLATE OF SODIUM.—Gatti311 reports a case of transient amblyopia, due to the ingestion of one hundred and twenty grains of salicylate of sodium, in a sixteen-year-old peasant-girl who had acute articular rheumatism. There were no changes in the eye-ground except a fulness of the veins, which persisted after the eyesight had returned. There was mydriasis. No phosphenes could be produced. As the urine did not present any traces of salicylate of sodium, it would seem to show that it was not eliminated by the usual emunctories.