Rhases gives similar directions. He forbids emetics, and recommends attention to keeping the teeth clean. He praises the following dentifrice: Of hartshorn, of the seeds of tamarisk, of cyperus, of spikenard, of each ℥j, of the salt of gem ʒij, to be pulverised, and the teeth rubbed with it. (Ad Mansor. iv, 21.)
SECT. XXX.—FOR DULNESS OF HEARING.
Dulness of hearing may be prevented by clearing away the sordes from the meatus, and by occasionally introducing into the ear a piece of linen dipped in a calefacient ointment (dropax), pressing it down, and then drawing it out; for this completely clears the opening, and at the same time, stimulates the sense of hearing. Afterwards, the meatus is to be plugged up with a piece of wool of the size of a tare for a day; and, when it is taken out, the meatus is to be anointed with the oil of almonds, of spikenard, or of chamomile, with the fat of geese, or a small quantity of ox gall. Again, after a time, rubbing mustard and figs together, introduce the collyrium thus prepared, for two hours; and then take it out and pour in oil heated in the hollow of the root of the asphodel.
Commentary. This is taken from Oribasius. (Synops. v, 23.)
Rhases particularly directs great care to avoid indigestion, which, without doubt, is occasionally the cause of indistinct hearing. He recommends some almond oil to be introduced into the meatus, and cautions against exposure to cold wind. (Ad Mansor. iii, 23.)
SECT. XXXI.—ON DIMNESS OF SIGHT.
In order to avoid dimness of sight, when they plunge into cold water, people ought to open their eyes wide, for thereby the strength of their eyes will be much improved. They ought also to be careful not to hurt them by reading. Let them also avoid wine that is thick and sweet, such articles of food as ascend upwards, whatever is of difficult digestion, and engenders crude and thick humours, the herb rocket, leeks, and everything whose pungency ascends upwards. Let them also avoid reclining long in a supine position, cold, winds blowing direct in the face, smoke and dust; and pour daily into the eyes an infusion prepared thus: for a month and a day, put green fennels into an earthen vessel smeared with pitch on the outside, and pour in rain water, and then taking out the fennels, keep the water laid up for use.
Commentary. This is copied from Oribasius. (Synops. v, 27.)
Rhases gives very copious and sensible directions on this subject, but many of them are the same as those given by our author. He forbids all gross and diffusible articles of food, and also thick wines. Although he cautions against reading books written in small characters, he recommends exercising the eyes by looking at large letters or pictures. He also recommends various collyria, containing antimony, tutty, calamine, camphor, and the like. (Ad Mansor. iv, 22.)