An earlier report indicated that freezing the ciliary body at -80 C caused only a temporary fall in intraocular pressure, and that freezing at lower temperatures caused phthisis. Additional studies in animals were undertaken to search for a procedure that would produce a sustained hypotension short of phthisis. Animals were subjected to different combinations of temperature, time and number of applications and observed for up to 500 days. The results showed that intraocular pressure and flow can be reduced permanently by cyclocryothermy without causing critical damage to the eye. The experiments suggest that the extent ot treatment used for glaucoma patients to date has been insufficient. An encircling procedure to freeze the outer portion of the entire ciliary body is indicated. Systemic steroids has been shown to reduce the risk of phthisis.
Lincoff H, Cavero R, Nadel A, McLean JM. Cryosurgery of the Ciliary BodyPart II. Arch Ophthalmol. 1968;79(2):196-204. doi:10.1001/archopht.1968.03850040198018