OBJECTIVE To develop and assess a novel ex vivo corneal culture technique involving an agarose-based dome scaffold (ABDS) for use as a model of in vivo corneal wound healing in dogs and rabbits. SAMPLE Corneas from clinically normal dogs (paired corneas from 8 dogs and 8 single corneas) and rabbits (21 single corneas). PROCEDURES 8 single dog corneas (DCs), 1 DC from each pair, and 10 rabbit corneas (RCs) were wounded with an excimer laser; 1 DC from each pair and 11 RCs remained unwounded. Corneas were cultured for 21 days on ABDSs (8 pairs of DCs and all RCs) or on flat-topped scaffolds (8 single DCs). The surface area of corneal fluorescein retention was measured every 6 (DCs) or 12 (RCs) hours until full corneal epithelialization was detected. Changes in corneal clarity were evaluated at 0, 7, 14, and 21 days. RESULTS Median time to full epithelialization for wounded dog and rabbit corneas was 48 and 60 hours, respectively; among wounded DCs, time to full epithelization did not differ by scaffold type. After 21 days of culture on ABDSs, all DCs and RCs that epithelialized developed a circular, diffuse, cloud-like pattern of optical haze, whereas DCs cultured on flat-topped scaffolds developed a focal, crater-like region of optical haze. All corneas on the ABDSs maintained convex curvature throughout the study. CONCLUSIONS AND CLINICAL RELEVANCE Wounded ex vivo DCs and RCs cultured on ABDSs reliably epithelialized, formed optical haze (consistent with in vivo wound healing), and maintained convex curvature. This culture technique may be adaptable to other species.

OBJECTIVE To characterize the distribution and intensity of cyclooxygenase (COX)-2 expression in the eyes of cats with and without uveitis and to determine whether COX-2 expression is correlated with severity of inflammation. SAMPLES Archived ocular tissue specimens from 51 cats with and 10 cats without ocular disease. PROCEDURES Specimens from only 1 eye were evaluated for each cat. Specimens were stained with H&E stain or immunohistochemical stain for detection of COX-2 and reviewed. For each eye, the type, severity, and distribution of inflammation and the distribution and intensity of COX-2 expression were determined for the uvea and other ocular tissues. Correlation between COX-2 expression and inflammation severity was also assessed. RESULTS COX-2 was not expressed in any nondiseased eye. Of the 51 diseased eyes, 20 had histologic evidence of lymphocytic-plasmacytic uveitis, 13 had neutrophilic uveitis, 11 had diffuse iris melanoma with uveitis, and 7 had diffuse iris melanoma without uveitis. Of the 44 eyes with uveitis, COX-2 was detected in the uvea of 16, including 11 eyes with lymphocytic-plasmacytic uveitis, 4 with neutrophilic uveitis, and 1 with diffuse iris melanoma–induced uveitis. Inflammation was severe, moderate, or mild in 10, 5, and 1 of those eyes, respectively. Cyclooxygenase-2 was detected in the cornea of 21 eyes with uveitis and 1 eye with diffuse iris melanoma without uveitis. Uveitis severity was positively correlated with COX-2 expression in both the uvea and cornea. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that COX-2 is an inflammatory mediator in feline uveitis but not diffuse iris melanoma.

OBJECTIVE To determine the efficacy of Bdellovibrio bacteriovorus 109J for the treatment of calves with experimentally induced infectious bovine keratoconjunctivitis (IBK). ANIMALS 12 healthy dairy calves. PROCEDURES For each calf, a grid keratotomy was performed on both eyes immediately before inoculation with Moraxella bovis hemolytic strain Epp63–300 (n = 11 calves) or nonhemolytic strain 12040577 (1 calf). For each calf inoculated with M bovis Epp63–300, the eyes were randomly assigned to receive an artificial tear solution with (treatment group) or without (control group) lyophilized B bacteriovorus 109J. Six doses of the assigned treatment (0.2 mL/eye, topically, q 48 h) were administered to each eye. On nontreatment days, eyes were assessed and corneal swab specimens and tear samples were collected for bacterial culture. Calves were euthanized 12 days after M bovis inoculation. The eyes were harvested for gross and histologic evaluation and bacterial culture. RESULTS The calf inoculated with M bovis 12040577 did not develop corneal ulcers. Of the 22 eyes inoculated with M bovis Epp63–300, 18 developed corneal ulcers consistent with IBK within 48 hours after inoculation; 4 of those eyes developed secondary corneal ulcers that were not consistent with IBK. Corneal ulcer size and severity and the time required for ulcer healing did not differ between the treatment and control groups. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that B bacteriovorus 109J was not effective for the treatment of IBK; however, the experimental model used produced lesions that did not completely mimic naturally occurring IBK.

OBJECTIVE To compare the anticollagenase efficacy of fresh feline, canine, and equine serum and plasma on in vitro corneal degradation. SAMPLE Grossly normal corneas from recently euthanized dogs, cats, and horses and fresh serum and plasma from healthy dogs, cats, and horses. PROCEDURES Serum and plasma were pooled by species and used for in vitro experiments. Corneas were collected and stored at −80°C. Sections of cornea were dried, weighed, and incubated in saline (0.9% NaCl) solution with clostridial collagenase and homologous fresh serum or plasma. Corneal degradation was assessed as the percentage of corneal weight loss and hydroxyproline concentration, compared with results for positive and negative control samples. RESULTS Homologous fresh serum and plasma significantly reduced the percentage of corneal weight loss, compared with results for positive control samples. No significant difference was found in percentage of corneal weight loss between incubation with serum or plasma for feline, canine, and equine corneas. Canine serum and plasma significantly reduced hydroxyproline concentrations, whereas inclusion of feline and equine serum or plasma did not, compared with results for positive control samples. Hydroxyproline concentrations were moderately correlated with percentage of corneal weight loss for feline samples and weakly correlated for equine samples, but they were not correlated for canine samples. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the anticollagenase efficacy of fresh feline, canine, and equine serum was not different from that of plasma. Plasma should be an acceptable substitute for serum in the topical treatment of keratomalacia.

Objective—To compare the anesthetic efficacy and adverse effects associated with peribulbar injection of ropivacaine (1% solution) performed with and without ultrasound guidance (UG) in dogs. Animals—15 dogs without ophthalmologic abnormalities. Procedures—Each dog was sedated and anesthetized. A peribulbar injection of ropivacaine (1% solution; 0.3 mL/kg) was performed with UG in 1 eye and without UG in the contralateral eye (control). For each eye, the intraocular pressure (IOP) immediately after eye centralization and number of punctures were recorded; ophthalmic complications, postinjection corneal sensitivity (determined by Cochet-Bonnet esthesiometry), durations of the sensory and motor blockades (the latter determined as the interval to restoration of the vestibuloocular reflex, pupillary light reflex, and conjugate eye movement), and blockade quality were assessed in both eyes following anesthetic recovery. Results—Needle placement was fully visualized in 8 of the 15 eyes injected with UG. For eyes injected with or without UG, there was no difference with regard to the number of punctures, postinjection corneal sensitivity, and sensory or motor blockade duration and quality; however, restoration of conjugate eye movement occurred later in control eyes. For eyes injected with UG, mean IOP was 18.6 mm Hg, compared with 23.3 mm Hg for control eyes. Incidence of subconjunctival hemorrhage was higher for control eyes; severity of chemosis and hyperemia varied over time within both groups of eyes. Conclusion and Clinical Relevance—In dogs, peribulbar injection of ropivacaine with UG is feasible in dogs and provides effective sensory and motor blockades similar to those achieved with conventional techniques.

The purpose of this study was to manually measure corneal thickness in canine eyes using a spectral-domain optical coherence tomography (SD-OCT) device and to assess intra- and inter-observer reliability of this technique. Twenty healthy dogs with a mean age of 4.7 y were examined. A 6-mm corneal pachymetry protocol was carried out by 1 operator using 1 SD-OCT device in both eyes of each animal. Measurements were obtained manually and in duplicate by 2 independent investigators (> 24 h apart), using the built-in caliper function. Measurements included epithelial thickness (ET), non-epithelial thickness (NET), and central corneal thickness (CCT). The overall mean ET, NET, and CCT for all eyes examined were 72.3 ± 4.6 μm, 538.9 ± 42.5 μm, and 611.2 ± 40.3 μm, respectively. There was no significant difference in ET, NET, or CCT based on the eye examined [oculus dexter (OD) versus oculus sinister (OS)], age, or gender of the animal. There was no significant difference in replicate measurements of ET, NET, or CCT done by the same operator, although a small but significant difference was noted between operators for ET measurements only. The mean difference in ET between operators was 0.6 μm (P = 0.03). The coefficient of variation ranged from 0.5% to 9.27% and intraclass correlation coefficient ranged from 0.35 to 0.97. Based on these results, manual measurements of corneal thickness in canine eyes using a portable SD-OCT device provided ET, NET, and CCT measurements with clinically acceptable intra- and inter-observer reliability.

Objective—To assess the anesthetic efficacy and local tolerance of topically applied 0.4% oxybuprocaine ophthalmic solution to in dogs and compare its effects with those of 1% tetracaine solution. Animals—34 ophthalmically normal Beagles. Procedures—Dogs were assigned to 2 groups, and baseline corneal touch threshold (CTT) was measured bilaterally with a Cochet-Bonnet aesthesiometer. Dogs of group 1 (n = 22) received a single drop of 0.4% oxybuprocaine ophthalmic solution in one eye and saline (0.9% NaCl) solution (control treatment) in the contralateral eye. Dogs of group 2 (n = 12) received a single drop of 0.4% oxybuprocaine ophthalmic solution in one eye and 1% tetracaine ophthalmic solution in the contralateral eye. The CTT of each eye was measured 1 and 5 minutes after topical application and then at 5-minute intervals until 75 minutes after topical application. Results—CTT changes over time differed significantly between oxybuprocaine-treated and control eyes. After instillation of oxybuprocaine, maximal corneal anesthesia (CTT = 0) was achieved within 1 minute, and CTT was significantly decreased from 1 to 45 minutes, compared with the baseline value. No significant difference in onset, depth, and duration of corneal anesthesia was found between oxybuprocaine-treated and tetracaine-treated eyes. Conjunctival hyperemia and chemosis were detected more frequently in tetracaine-treated eyes than in oxybuprocaine-treated eyes. Conclusions and Clinical Relevance—Topical application of oxybuprocaine and tetracaine similarly reduced corneal sensitivity in dogs, but oxybuprocaine was less irritating to the conjunctiva than was tetracaine.

Objective: To determine whether an applanation tonometer and rebound tonometer can be used to detect similar intraocular pressure (IOP) measurements in eyes of dogs undergoing phacoemulsification. Animals: 24 dogs (40 eyes) undergoing elective phacoemulsification. Procedures: IOP measurements were obtained from each eye by use of both the rebound tonometer and applanation tonometer. Central corneal thickness was measured by use of an ultrasonic pachymeter 3 hours before surgery and 2 and 24 hours after surgery. Statistical analysis was performed by use of paired t tests. Results: Mean ± SD IOP 3 hours before surgery, 2 hours after surgery, and 24 hours after surgery was 11.9 ± 4.7 mm Hg, 15.5 ± 11.7 mm Hg, and 10.9 ± 6.7 mm Hg, respectively, as measured with the rebound tonometer and 12.2 ± 5.3 mm Hg, 15.7 ± 12.5 mm Hg, and 12.4 ± 5.4 mm Hg, respectively, as measured with the applanation tonometer. Measured IOP did not differ significantly between the 2 tonometers 3 hours before surgery and 2 hours after surgery, but measured IOP differed significantly between the tonometers 24 hours after surgery. Conclusions and Clinical Relevance: Use of a rebound tonometer underestimated IOP, relative to results for use of an applanation tonometer, by 1.65 mm Hg in eyes 24 hours after phacoemulsification. Caution should be used when IOP measurements obtained with a rebound tonometer are in the high part of the reference range, and verification of these values with an applanation tonometer would be advised.

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.

Objective: To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry. Animals: 9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age. Procedures: A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates. Results: Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species. Conclusions and Clinical Relevance: The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.