PENETRATING CYCLODIATHERMY
Weve (1) introduced the concept of cyclodestructive surgery in 1933, using nonpenetrating diathermy to produce selective destruction of ciliary processes. Vogt (2,3) modified the technique by using a diathermy probe, which penetrated the sclera, and this became the standard cyclodestructive procedure. The technique involved penetration of the sclera 2.5 to 5 mm from the corneolimbal junction with a 1.0- to 1.5-mm electrode and the application of a diathermy current of 40 to 45 mA for 10 to 20 seconds (3). This could be done with or without preparation of a conjunctival flap. One or two rows of diathermy lesions were generally placed several millimeters apart for approximately 180 degrees. The mechanism of permanent IOP reduction was probably cell death within the ciliary body (4). In addition, it may be that the more posteriorly placed lesions created a draining fistula in the region of the pars plana.
Early reports of experience with cyclodiathermy were encouraging (5,6). However, subsequent study revealed a low success rate and a significant incidence of hypotony. In a review of 100 cases, 5% had lasting, useful reduction in IOP, whereas about the same number developed phthisis (7). Results undoubtedly vary with the technique, and experience with a newer one-pole diathermy unit was said to be encouraging (8).
β-Irradiation Therapy
In 1948, Haik and co-workers (9) reported the experimental application of radium over the ciliary body in rabbit eyes and in one clinical case. Although this was shown to produce a reduction in the vascular supply of the ciliary body, it also caused damage to the lens, and the technique was never adopted for clinical use.
Cycloelectrolysis
Berens and co-workers (10) in 1949 described a technique that employed the use of low-frequency galvanic current to create a chemical reaction within the ciliary body. This led to the formation of sodium hydroxide, which is caustic to the tissue of the ciliary body. Although this was shown in rabbit studies to produce destruction of ciliary processes (11), the procedure did not seem to have significant advantages over penetrating cyclodiathermy and never achieved widespread clinical popularity.
CYCLOCRYOTHERAPY
The use of a freezing source as the cyclodestructive element was suggested by Bietti (12) in 1950. Cyclocryotherapy was generally thought to be somewhat more predictable and less destructive than penetrating cyclodiathermy and gradually replaced the latter technique as the most commonly used cyclodestructive operation. It is still used by many surgeons, especially when laser technology is not available.
