Effect of immediate postoperative intracameral tissue plasminogen activator (tPA) on anterior chamber fibrin formation in dogs undergoing phacoemulsification.

OBJECTIVE: To evaluate the postoperative effect of intracameral tPA (alteplase; Activase®, Genentech, San Francisco, CA), administered at immediate conclusion of phacoemulsification, on anterior chamber fibrin formation in dogs. PROCEDURES: Forty-one dogs (82 eyes) undergoing bilateral phacoemulsification received 25 µg/0.1 mL intracameral tPA in one eye and 0.1 mL unmedicated aqueous vehicle in the contralateral eye immediately after corneal incision closure. Intraocular pressure (IOP) was measured, and severity of anterior chamber fibrin formation, aqueous flare, pigment precipitates on the intraocular lens (IOL) implant, posterior capsular opacification (PCO), and corneal edema were graded at approximately 1 week, 2-3 weeks, 4-6 weeks, 8-12 weeks, and greater than 3 months postoperatively. RESULTS: Anterior chamber fibrin developed postoperatively in 68.3% of dogs (28/41) and 50% of eyes (41/82). In tPA-treated eyes, 53.7% (22/41) developed fibrin compared to 46.3% of control eyes (19/41). Some degree of postoperative ocular hypertension (POH) occurred in 53.7% of dogs (22/41) and 36.5% of eyes (30/82). In tPA-treated eyes, 34.1% (14/41) experienced POH compared to 39% of control eyes (16/41). Additional intracameral tPA injection was later required in 29.3% of both tPA-treated (12/41) and control eyes (12/41). CONCLUSIONS: Administration of intracameral tPA at immediate conclusion of canine phacoemulsification had no clinically observable effect on anterior chamber fibrin incidence at any time point. tPA-treated eyes showed no prophylaxis against POH or secondary glaucoma compared to control eyes and received late postoperative tPA injections at the same frequency as control eyes.

The effects of topical aqueous sirolimus on tear production in normal dogs and dogs with refractory dry eye.

PURPOSE: To evaluate the effect of twice daily aqueous 0.02% sirolimus drops on tear production in normal dogs and dogs with refractory keratoconjunctivitis sicca (KCS). METHODS: Two groups of dogs were studied. Ten normal dogs with no signs of ocular disease were administered topical 0.02% sirolimus ophthalmic solution in right eye, and a vehicle control in the left eye twice daily for 4 weeks. Complete ophthalmic examinations, including Schirmer tear test were performed weekly. Eighteen dogs with refractory KCS were randomly assigned to receive 0.02% sirolumus ophthalmic solution or 0.02% tacrolimus ophthalmic solution twice daily. Complete ophthalmic examinations were was performed at 2 and 6 weeks following treatment. RESULTS: Tear production in the sirolimus-treated eyes of normal dogs was greater when compared to vehicle controls with a mean difference over all time points of 3.46 mm (95% CI 1.17, 5.75; P = 0.006). After 4 weeks of treatment, the mean difference was 5 mm (95% CI 1.95, 8.05; P = 0.002). In dogs with refractory dry eye, 37.5% of eyes treated with sirolimus exhibited increased tear production >4 mm/min after 6 weeks of treatment, compared to 20% of eyes receiving tacrolimus (P = 0.433). One normal dog experienced topical irritation to both sirolimus and vehicle-treatment. Side effects were not reported in any treated eyes with chronic KCS. CONCLUSION: Topical 0.02% sirolimus might be an alternative treatment for canine patients with keratoconjunctivits sicca. The drug appears safe when applied topically in an aqueous suspension for up to 6 weeks. While initial results are promising, further studies are warranted.

Preoperative findings and visual outcome associated with retinal reattachment surgery in dogs: 217 cases (275 eyes).

OBJECTIVE: Report the correlation of pre-operative findings with visual outcome in dogs undergoing retinal reattachment surgery for giant retinal tears. PROCEDURES: Retrospective analysis of dogs that underwent pars plana vitrectomy (PPV) with silicone oil (SiO) tamponade and endolaser retinopexy at one institution. Recorded parameters included signalment, etiology, and duration of retinal detachment, observable retinal tissue architecture, visual reflexes, lens status, presurgical aqueous flare, visual status postoperatively, and complications. RESULTS: Two hundred and seventeen patients (275 eyes) were included. Common etiologies of detachment were primary vitreoretinal disease (50.5%), lens surgery (35.3%), and hypermature cataracts (6.2%). Immediate postoperative anatomic success was noted in 98% of operated eyes. Maintenance or return of vision was noted in 74.2% of patients (72% of eyes) through the last known follow-up, with return of vision on average 18.5 days postoperatively. In those eyes that regained vision, 71.7% had retained vision at the last known recheck examination, with an average follow-up time of 550 days. Pre-operative findings correlated with postoperative vision included presence of a dazzle reflex, presence of a menace response, and retinal tissue architecture. The most common complications included migration of SiO into the anterior chamber (49.4%), corneal ulceration (25.7%), glaucoma (25.7%), and cataract formation (24.5%). CONCLUSION: Giant retinal tears in dogs can be successfully managed via PPV with SiO tamponade and endolaser retinopexy. Vision was maintained in the majority of cases with long-term follow-up. Patient history and thorough ophthalmic examination with attention to retinal tissue architecture are important in assessing surgical candidacy.

Analysis of the transport of and cytotoxic effects for nalbuphine solution in corneal cells.

OBJECTIVE: To assess the in vitro effects of various nalbuphine concentrations on viability and wound healing ability of corneal cells and potential drug transport through the corneal epithelium. SAMPLE: Cultured canine and human corneal epithelial cells (CECs) and cultured canine corneal stromal fibroblasts. PROCEDURES: CECs and stromal fibroblasts were exposed to nalbuphine (concentration of solutions ranged from 0% to 1.2%) for up to 30 minutes, and viability was assessed with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. A standard scratch test technique was used. Wound healing of CECs and stromal fibroblasts was evaluated following treatment with nalbuphine solutions < 0.1%. Liquid chromatography-mass spectrometry-mass spectrometry analysis was used to evaluate drug transport across a monolayer and a multilayer of human CECs. RESULTS: A progressive decrease in viability was detected in canine CECs for all nalbuphine treatment groups, whereas treatment with only 0.5% or 1.2% nalbuphine significantly reduced corneal stromal fibroblast viability, compared with results for control cells. Within 24 hours, treatment with 0.1% nalbuphine solution significantly altered the healing rate of both canine CECs and stromal fibroblasts. Continuous increases in transport rates of nalbuphine were detected with time for both the monolayer and multilayer of human CECs. CONCLUSIONS AND CLINICAL RELEVANCE: In vitro, nalbuphine potentially could penetrate through corneal tissue, but it may cause damage to the corneal epithelium and stromal fibroblasts. Therefore, nalbuphine potentially may impair corneal wound healing.