(1) Division of the thickened iris-membrane by an incision made either through the sclerotica or through the cornea. This is true iridotomy.
(2) Excision of a portion of the iris through a previously made corneal opening. This is now known as iridectomy.
(3) Separation of the iris from its ciliary attachment. This was generally known as iridodialysis, but sometimes called iridorrhexis.
(4) Simple incision of the pupillary margin, and of the free iris tissue. This has been designated sphincterotomy by some, and coretomy or iritomy by others. Either one of the latter terms is to be preferred, because it is more clearly descriptive.
(5) Detachment of the synechiæ at the pupillary margin, either anterior or posterior, thus allowing the pupil to retract. This was known as corelysis.
(6) Strangulation of the prolapsed iris in the corneal incision was called iridencleisis. The prolapse was sometimes tied with a ligature.
(7) Trephining of the iris-membrane, by passing a small trephine or punch through a corneal incision.
(8) Section and removal of a portion of the sclerotica and chorioid by knife or trephine, with replacement of the conjunctiva over this opening, the conjunctiva thus acting as a substitute for the cornea in transmitting light. This was called sclerectomy.
(9) Transplantation of the cornea for total leucoma. This was usually preceded by partial or complete trephining of this membrane.
In addition to these nine distinct methods certain combinations of these have been described and successfully practiced: