The practical details of cataract extraction / by H. Herbert.

  • Herbert, H.
Date:
1903
Catalogue details

Licence: In copyright

Credit: The practical details of cataract extraction / by H. Herbert. Source: Wellcome Collection.

    104/142 page 82
    the whole; it may include the whole breadth of the iris, or only its basal portion ; it is nearly always partly or entirely uncovered by conjunctiva, except where a very complete conjunctival flap has been made. Though often predisposed to by damage of the sphincter of the pupil during the passage of the lens, it may yet occur in spite of an active pupil, from any sudden bursting open of the wound, through spasm of the orbicularis, or by increase of ocular tension from muscular effort or cough. After combined extraction incarceration of the iris in, and adhesion to, the wound largely takes the place of pro- lapse. Either of these conditions may result—at one or both angles of the wound—from imperfect replacement of the pillars of the coloboma, especially if much of the pupillary zone (with the sphincter muscle) of the iris has been cut away. At other times, after either the simple or combined operation, the iris may be carried into the wound by escaping vitreous. The disadvantages and risks consequent on prolapse and incarceration of the iris are diflicult to formulate exactly. The covneal astigmatism produced varies mainly with the breadth* of the protrusion ; it can be only partly corrected by cylindrical lenses. By a very extensive prolapse the upper half of the cornea may be bent slightly forwards, a fine transverse gray line on the back of the cornea marking the division between its two portions. Small protrusions tend to flatten down within a few months, largely reducing the abnormal corneal curvature. But the loop of iris remains, permanently weakening the sclero-corneal scar ; a fistulous cicatrix is formed, with * An unusually prominent, but limited protrusion, due to pro- lapse of the whole width of the iris at one point of the wound, may lead to little or no corneal astigmatism ; whereas if a con- siderable extent of the wound be occupied by only the base of the iris, the effect upon the curvature of the cornea is often great.
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