1. The capsulo-muscular, in which the tendon, together with the attachment of the capsule of Tenon to it, is advanced.
2. The tendon only is isolated, shortened, and advanced.
3. The tendon is shortened by folding it upon itself.
The first operation is by far the most satisfactory of these, owing to the fact that a broader new insertion of the muscle is obtained, which is less likely to yield subsequently; it is the operation usually performed in this country.
The chief cause of unsatisfactory results after advancement operations is the cutting through of the sutures holding the tendon in position. The various operations, which are some fourteen in number and have mostly their respective surgeon’s name attached, differ principally in the method of insertion of these sutures. Whichever method of inserting sutures be used, the main factors which aim at preventing the stitches from cutting out are (1) that the stitches should take a good hold in the scleral and episcleral tissues on the corneal side of the wound, for the passing of which it is most essential that the needles should be sharp; (2) that complete rest of the muscles should be ensured by bandaging both eyes for the first seven days after the operation; (3) that the opposing muscle should be tenotomized so as to prevent traction on the sutures.
Of the many operations that have been devised the capsulo-muscular advancement or some modification of it is most frequently used.
Instruments. Speculum, straight scissors, fixation forceps, Prince’s advancement forceps (Fig. 132), four sharp needles and strong silk, needle-holder.
Fig. 132. Prince’s Forceps for Advancement. Care should be taken to see that the spring catch holds satisfactorily.