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. [Illustration: FIG. 132. PRINCE’S FORCEPS FOR ADVANCEMENT. Care should be taken to see that the spring catch holds satisfactorily.] 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. =Operation.= Under adrenalin and cocaine. _First step._ The patient is made to look away from the side on which is the muscle to be advanced, and the conjunctiva over the muscle is freely divided with scissors, by a curved incision with the convexity towards the cornea, and dissected back. _Second step._ The capsule of Tenon is button-holed by a small incision well above or below the tendon. A tenotomy hook is passed beneath the tendon and its expansion and brought out through a small hole in Tenon’s capsule on the opposite side of the tendon. The smooth blade of Prince’s forceps is then inserted in place of the hook, and the tendon with its expansion is grasped between the blades. The forceps are given to an assistant, who should avoid all traction on the muscle. The eye is then rotated in the direction of the muscle to be advanced, and tenotomy of the opposing muscle is performed by the open method.