Extraction of the lens in its capsule is also performed when the lens is dislocated and causing irritation. If the lens be in the anterior chamber immediate extraction is called for, as glaucoma is a usual complication. Eserine is first instilled in order to contract the pupil and prevent the lens passing back into the posterior chamber; an incision is then made as for a cataract extraction and the lens removed by means of the vectis. Complete dislocation of the lens into the vitreous rarely requires operation, as the patient is able to see. Partial dislocation (luxation) occasionally calls for extraction, the vectis usually being employed for delivering the lens, but before undertaking the operation an attempt should be made to get the lens into the anterior chamber by dilating the pupil and making the patient lie face downwards; if this is successful eserine should be instilled to contract the pupil behind the lens and so retain it in the anterior chamber, from whence it can more easily be extracted. Some surgeons prefer to fix the lens with a needle passed through the sclerotic behind the ciliary body before making the incision. =Subconjunctival extraction.= In order to diminish the risks of sepsis, more especially in cases in which the conjunctiva is affected with trachoma, some continental surgeons deliver the lens into a pocket beneath the conjunctiva, whence it is subsequently removed. The operation has the additional advantage of a better blood-supply to the corneal flap, which is also held in better position after the operation. _Operation._ A section upwards is made with a Graefe’s knife as in the ordinary method of extraction previously described, the lens capsule being opened with the point of the knife as it is passed across the anterior chamber. When the section through the sclerotic has been completed and the knife lies entirely beneath the conjunctiva it is withdrawn. The wound in the conjunctiva on the outer side is then enlarged upwards with scissors, and an iris spatula is passed beneath the conjunctiva from the small wound on the inner side and the point made to appear in the wound on the outer side; by this means the conjunctiva is raised on the spatula, and by means of sharp-pointed scissors a pocket is made in an upward direction by undermining the conjunctiva (Fig. 101). Delivery of the lens is then performed into this pocket, from which it is subsequently removed, the conjunctival wound on the outer side being closed with a stitch. The advantage of this form of subconjunctival extraction over other forms which have been devised is that if difficulty is met with in delivering the lens, &c., the operation can be readily converted into an ordinary extraction by completing the division of the conjunctival flap.