=Indications.= Since the operation for conical cornea is not without serious risks, it should only be undertaken when the vision cannot be improved with glasses to 6/18; high + or - cylinders will often yield satisfactory results. The object of all forms of operation is the flattening of the cone. =Operation.= This may be carried out either by excision of the apex of the cone or by cauterization. =Excision of the apex of the cone= is probably the more satisfactory method, although it is somewhat more difficult to perform. The object of the operation is to remove an elliptical portion of the whole thickness of the cornea from the apex of the cone, the long axis of the ellipse being placed horizontally. It leaves the eye with only a minute scar as compared with the nebula produced by the cautery, which is often so great as to require an optical iridectomy to restore vision. =Instruments.= Speculum, fixation forceps, a narrow Graefe’s knife, straight iris forceps, and scissors. The operation is done under cocaine, atropine having been previously instilled. _First step._ The apex of the cone is transfixed by the Graefe’s knife with the blade directed slightly upwards and forwards, the knife being made to cut out. The cornea in this situation is extremely thin, being often not more than 1 mm. in thickness. The length of the incision should not exceed 2 mm. _Second step._ The flap of corneal tissue thus made is seized with the straight iris forceps and removed with iris scissors, producing a small elliptical opening. The chief difficulty of the operation is the seizing of the corneal flap, which is most difficult to hold; care must be taken not to injure the lens capsule with the iris forceps or scissors when the cornea has collapsed as the result of the evacuation of the anterior chamber. The eye should be firmly bandaged subsequently, and the patient kept in bed until the anterior chamber has re-formed. =Complications.= _Slow re-formation of the anterior chamber._ The anterior chamber will often take two or three weeks to re-form, owing to the hole in the cornea not closing. During this time the eye is open to septic infection and therefore the greatest care should be taken to keep it aseptic when dressing it. For this reason and also because the following complications are due to the same cause, it is desirable to remove as little corneal tissue as possible in performing the operation. It is probable that conjunctivoplasty (see p. 245) would considerably facilitate the rapid closure of the wound. _Anterior polar cataract_ may result from prolonged contact of the lens with the wound in the cornea. As a rule this seldom interferes much with vision. _Anterior synechiæ_ from incarceration of the iris in the wound occasionally result and may require subsequent division.