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Article
March 1988

Effects of Cyclocryotherapy on Aqueous Humor Dynamics in Cats

Author Affiliations

From the Illinois Eye and Ear Infirmary, University of Illinois, Chicago (Dr Higginbotham); the Jules Stein Eye Institute, UCLA School of Medicine (Dr Lee); the Ophthalmic Pharmacology Unit, Eye Research Institute of the Retina Foundation (Dr Bartels) and Massachusetts Eye and Ear Infirmary (Dr Richardson and Mr Miller), Harvard Medical School, Boston.

Arch Ophthalmol. 1988;106(3):396-403. doi:10.1001/archopht.1988.01060130422034
Abstract

• 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.

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