Neodymium:yttrium-aluminum-garnet laser treatment of cystic granula iridica in horses: eight cases (1988-1996).

摘要

An ophthalmic neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was used to deflate cysts in 8 horses diagnosed with cystic granula iridica. The horses were tranquillized with xylazine hydrochloride and detomidine hydrochloride. An auriculopalpebralblock was performed with lidocaine hydrochloride. Laser treatment was performed with the horses standing. The spot-size diameter of the laser was 50μm and produced pulses of energy in the range 1 to 10 mJ, either singularly or in a burst of 5 pulses/burst. A mean of 3.6 laser bursts (range 3 to 8 bursts) per cyst was used to rupture cysts. Mean laser energy was 36.2±17.5 mJ/cyst. Generally, 1 well placed burst of laser energy was sufficient to deflate each cyst. Additional bursts were applied to enlarge the hole in the cyst or to create additional perforations. One horse had a small haemorrhage when the laser was directed near the base of the cyst at its attachment to the iris, therefore subsequent bursts were directed towards the apex of the cyst. Antiinflammatory or cycloplegic drugs were found not to be necessary. Clinical signs associated with cysts resolved in all horses after treatment. No complications developed, and cysts did not recur. It is concluded that cystic granula iridica may cause vision impairment in horses and that treatment with an ophthalmic Nd:YAG laser appears to be safe and effective.