• The effects of graded cyclocryotherapy were studied using pneumatonometry, fluorophotometry, and light and electron microscopy. Cats were treated with either 90°, 180°, or 270° of cyclocryotherapy and were followed up for six weeks. The response of the eyes to treatment was evaluated in terms of intraocular pressure (IOP) response, aqueous humor flow rate, and permeability of the blood-aqueous barrier compared with the untreated fellow eye. The average IOP response was determined to be −20%, −44%, and −47% for the 90°, 180°, and 270° treated eyes, respectively. The aqueous humor flow rate was estimated to be −14%, −44%, and −52% for each of the groups, respectively. Finally, the permeability of the blood-aqueous barrier, measured 60 minutes after injection of fluorescein, was estimated to be a percent increase of 22%, 332%, and 285% for each of the groups, respectively. Histologically, the maximally treated eyes (270°) demonstrated greater disruption of the ciliary body compared with the control eyes. Thus, graded cyclocryotherapy causes graded destruction of the ciliary epithelium and proportionally related changes in IOP and aqueous humor dynamics.
Higginbotham EJ, Lee DA, Bartels SP, Richardson T, Miller M. Effects of Cyclocryotherapy on Aqueous Humor Dynamics in Cats. Arch Ophthalmol. 1988;106(3):396-403. doi:10.1001/archopht.1988.01060130422034