Ciliary body temperatures during cyclocryotherapy in the clinically normal dog

Area of Science:

• Veterinary Ophthalmology
• Cryosurgery Techniques
• Ocular Physiology

Background:

• Cryosurgery is a therapeutic modality used in ophthalmology.
• The ciliary body is a key structure involved in aqueous humor production and intraocular pressure regulation.
• Understanding the thermal effects of cryosurgery on the ciliary body is crucial for its clinical application.

Purpose of the Study:

• To compare the efficacy of three cryosurgical units in freezing the canine ciliary body.
• To evaluate the thermal profiles and histological outcomes of cyclocryosurgery in canine eyes.

Main Methods:

• Comparison of three cryosurgical units based on their ability to freeze the ciliary body of enucleated canine eyes.
• Application of cryosurgery to the ciliary body of 25 dogs for 5 minutes, with continuous temperature monitoring.
• Daily monitoring of intraocular pressure and anterior uveitis, with histological evaluation at multiple time points post-surgery.

Main Results:

• The coldest average temperatures achieved by the cryosurgical units ranged from -4.3 C to -17.6 C.
• In situ and ex vivo cyclocryosurgery resulted in similar coldest average temperatures of approximately -13.4 C to -13.8 C.
• Intraocular pressure normalized within 1-2 weeks, anterior uveitis resolved in 7-10 days, and ciliary body epithelium showed histological normality by 6 months.

Conclusions:

• Cryosurgery is an effective method for freezing the canine ciliary body.
• The procedure leads to temporary changes in intraocular pressure and inflammation, with complete histological recovery observed within six months.
• These findings support the potential of cyclocryosurgery as a treatment modality in veterinary ophthalmology.