=Indications.= Sclerotomy is an operation undertaken for the relief of increased intra-ocular tension. It is performed-- (i) Usually as a secondary operation when iridectomy has failed. (ii) As a primary operation for the division of anterior synechiæ causing tension. A few surgeons prefer the operation to iridectomy, especially in cases of bup[h]thalmos. When practised after an iridectomy which has been done upwards, the sclerotomy is sometimes performed in a downward direction; otherwise the section is usually made upwards. The intra-ocular tension is probably relieved by the formation of a filtration cicatrix, and it is therefore probable that it may be largely superseded by the operations of cyclo-dialysis and sclerectomy. When performed for the division of anterior synechiæ the position of the incision should be planned according to the situation of the synechia to be divided. =Instruments.= Speculum, fixation forceps, Graefe’s knife with a narrow blade. =Operation.= The operation is done under cocaine. Eserine should have been previously instilled in order to contract the pupil and prevent prolapse of the iris. Graefe’s knife should be passed across the anterior chamber in the same manner and position as for a glaucoma iridectomy (see p. 221). In the _complete_ method the knife is made to cut out through the sclerotic, leaving a band of conjunctiva to hold the flap in position. In the _incomplete_ method a band of sclerotic is left in the periphery. If the operation is done in a downward direction, it is better for the surgeon to stand on the opposite side of the patient to the eye on which the operation is to be performed, operating across the patient. =Complications.= Any of the complications which follow an iridectomy for glaucoma may occur (see p. 222). Prolapse of the iris is probably the most frequent. CYCLO-DIALYSIS =Indications.= This operation has only recently come into general use in this country, so that statistical results have at present by no means been worked out, but most satisfactory results have been obtained from it in individual cases; according to German authorities about 30 per cent. are permanently cured. Although at present its performance is largely limited to blind eyes and to eyes that have undergone previous operations for glaucoma, it is probable that it may come into further use as a primary operation in the treatment of chronic glaucoma and bup[h]thalmos. It is also of service in cases of dislocation of the lens backwards, associated with increased tension, where iridectomy would certainly be followed by loss of the vitreous. [Illustration: FIG. 119. CYCLO-DIALYSIS OPERATION. Showing the method of commencing the incision in the sclerotic; it is subsequently deepened with the point of the knife. The dotted lines mark the incision for turning forward the conjunctival flap.]