On amaurosis and dimness of vision. Galen and Aëtius give a very circumstantial account of the causes and treatment of amaurosis. They state that the disease either comes on suddenly, in which case they refer its origin to obstruction and paralysis of the optic nerve, or gradually, when they believe it occasioned by a thickening of the coats of the optic nerve, or a change of the spirits, or of the humours of the eye. They enumerate various causes of it, such as injuries of the head, heat or cold, indigestion, or the like. When the disease occurs suddenly, they approve of general or local bleeding, such as cupping the back part of the head, and active purging. In the other case general depletion is not required, but the treatment is otherwise nearly the same, attention being particularly paid to the state of the bowels. They forbid emetics after food, but approve of errhines. They recommend in certain cases sinapisms to the head.
The Arabians treat the disease upon the same principles. Haly Abbas describes amaurosis among the affections of the optic nerves, and recommends for it general bleeding, purging, and the saffron collyrium. Alsaharavius remarks that it often arises from the state of the stomach, which, in that case, will require the principal attention. Avenzoar blames Galen for giving up as desperate cases of amaurosis which occur suddenly. He recommends general and local bleeding, with repellent applications to the head.
On strabismus. See Galen (de Causis Morborum); Oribasius (Synops. viii, 49.)
Avicenna properly remarks that squinting is occasioned by debility or spasm of some of the muscles of the eye. He and Rhases recommend the same treatment as our author. Avicenna also makes mention of a mask. Haly Abbas, who appears to have been intimately acquainted with anatomy, of which his work contains a valuable compendium, explains minutely the cause of the disease, which he attributes to an unequal contraction of the muscles of the eye. See also Alsaharavius and Jesu Haly. Jesu, like our author, directs us to fasten a piece of black or red cloth on the angle of the eye at the temples, when the eye inclines towards the nose. He correctly explains that the complaint arises from spasms or paralysis of some of the muscles of the eye.
On ecpiesmus, or protrusion of the eyes. This section is taken from Oribasius. (Syn. viii, 50.)
Aëtius, Avicenna, and Rhases recommend the same treatment for this complaint, which can only arise from suffocation, violent straining, or swelling of the eye.
On synchysis, or confusion of sight. Aëtius and Oribasius treat of this affection in nearly the same words.
Rowley defines synchysis to be “a solution of the vitreous humour into a fine attenuated aqueous fluid.” It does not appear to us that the ancients understood it in this sense, or that they meant anything more by it than a confusion or disorder of the eye occasioned by a blow.
On myopia. This section also is taken from Oribasius or Aëtius.
Alsaharavius treats of it by the name of alhayn. He says it sometimes arises from external causes, such as exposure to snow and cold, in which case he directs us to apply stimulant fumes to the eye and refrigerants to the head. Although the ancients were aware of the magnifying powers of specula (as appears from Seneca, ‘Quæst. Natur.’), it is doubtful if they ever thought of applying this knowledge to any useful purpose; and hence none of the Greek, Latin, or Arabian medical authors make any mention of spectacles or magnifying glasses as a remedy for this complaint, or for weakness of sight. Dutens, however, maintains that they were not unacquainted with telescopes. (p. ii, 10.) From a passage in Iamblichus it has been supposed that they also used microscopes. (Vit. Pyth. 26.)