Of the Operation of the Fistula Lachrymalis.
This Operation is perform'd when there is a Fistulous Ulcer in the great Corner of the Eye, after this manner: The Patient being plac'd in a convenient Posture, and having his sound Eye bound up, to take away the sight of the Instruments; the Operator causeth the other Eye to be kept steady with a Bolster held with an Instrument, and makes an Incision with a Lancet in form of a Crescent upon the Tumour, taking care to avoid cutting the Eye-Lid and the little Cartilage which serves as a Pulley to the great Oblique Muscle. If the Bone be putrify'd with a Caries, an Actual Cautery may be apply'd thereto, using for that purpose a small Funnel or Tube, thro' the Canal of which the Cautery is convey'd to the Bone.
But the Bone must not be pierc'd, for it is exfoliated entire by reason of its smallness; and so the Hole is made without any Perforation.
The Dressing and Bandage of the Fistula Lachrymalis.
The Wound is fill'd with small dry Pledgets, and cover'd with a Plaister and Bolster: The Bandage is made with an Handkerchief folded triangular-wise, the ends of which are fasten'd behind the Head. If the Flesh grows too fast, it may be consum'd with the Lapis Infernalis; and if there be occasion to dilate the Wound, to facilitate the Exfoliation, it may be done with little pieces of Spunge prepar'd, and put into it. Afterward Causticks are to be us'd, to eat away the Callous Parts, which may be mingled with Oily Medicines, to weaken their Action, taking care, nevertheless, that the Eye receive no dammage by 'em. If the Bone be corrupted, a little Euphorbium may be apply'd; or else the small Pledgets steept in the Tincture of Myrrh and Aloes; then the Ulcer may be handled as all others.
C H A P. III.
Of the Operation of the Cataract.
This Operation is perform'd when there is a small Body before the Apple of the Eye, which hinders the Sight from entring into it; but it is undertaken only in Blew, Green, and Pearl-colour'd Cataracts, or in those that are of the Colour of polish'd Steel; and not in Yellow, Black, or Lead-colour'd. To know whether the Cataract be fit to be couch'd, the Patient's Eye must be rubb'd; so that if the Cataract remains unmoveable, it is mature enough; but if it changeth its place, it is requisite to wait till it become more solid. The Spring and Autumn are the most proper Seasons for performing the Operation.