Corneal anesthetic effect and ocular tolerance of 3.5% lidocaine gel in comparison with 0.5% aqueous proparacaine and 0.5% viscous tetracaine in normal canines.

OBJECTIVE: To compare the degree and duration of corneal anesthesia of a novel viscous ophthalmic lidocaine hydrochloride preparation vs. two commonly used ophthalmic anesthetic preparations. METHODS: Each subject was randomly selected to receive 2 of 4 treatments at 2 different time periods separated by a 1 week washout: 3.5% lidocaine hydrochloride gel (Akten® ; Akorn Inc., Lake Forest, Illinois, USA), 0.5% aqueous proparacaine hydrochloride (Akorn Inc.), 0.5% viscous tetracaine hydrochloride (TetraVisc™; Ocusoft Inc., Richmond, Texas, USA), or 0.9% saline eyewash as a negative control. Corneal sensitivity was determined using a Cochet-Bonnet aesthesiometer (Luneau® , Chartres Cedex, France) prior to instillation of each treatment; at 1 and 5 min post treatment; and at 5-min intervals thereafter for 90 min total. Ocular side effects were recorded on a scale of 0-3. RESULTS: Twenty-four normal dogs (48 eyes) were entered into the study. Mean duration of maximal anesthesia was significantly greater at 34.2 min with tetracaine compared to 21.5 min and 19 min with proparacaine and lidocaine respectively. Corneal sensitivity was significantly decreased from baseline for up to 70 min with tetracaine and 55 min with both proparacaine and lidocaine. All lidocaine-treated eyes had transient blepharospasm and conjunctival hyperemia. Ten out of 24 tetracaine-treated eyes had conjunctival hyperemia with 4 of these having concurrent chemosis. CONCLUSIONS: Tetracaine provided a significantly longer duration of corneal anesthesia than proparacaine or lidocaine. Tetracaine and lidocaine were associated with more ocular side effects than proparacaine, although these were mild and transient. None.

Clinical and histological characteristics of canine ocular gliovascular syndrome.

OBJECTIVE: To characterize the clinical, diagnostic, and histopathologic findings in dogs with canine ocular gliovascular syndrome (COGS). PROCEDURES: The archives at the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) were used to identify eyes with COGS. Histopathological inclusion criteria included: a neovascular membrane extending from the optic nerve head or retina, clusters of spindle cells lacking vascularization within the vitreous, and histological signs of glaucoma. Special and immunohistochemical (IHC) staining techniques were performed. Clinical data, treatments, and outcomes were obtained from case records and information provided by submitting veterinarians. RESULTS: Thirty-seven eyes of 36 dogs were identified with COGS. The average age at diagnosis was 8.8 years (±2.2). The relative risk for a Labrador retriever affected by COGS was significantly greater (9.3 times) (P < 0.0001) when compared to all other dog breeds within the COPLOW database. Most dogs presented with hyphema and secondary glaucoma; average intraocular pressure was 39 mmHg (±19). Average time to enucleation or evisceration was 27 days. Vitreal cells stained positive with IHC for glial fibrillary acidic protein in 14 of 17 globes, and vascular endothelial growth factor was expressed in the vitreal cells in five of five globes. CONCLUSIONS: We have defined a syndrome associated with vitreal glial cell aggregates and neovascular proliferation from the optic nerve or retina, which leads to neovascular glaucoma. The inflammation and secondary glaucoma resulting from this syndrome appear poorly responsive to conventional medical therapies. The exact etiology of COGS remains undetermined, but a systemic etiology is unlikely.

Postoperative glaucoma in the Labrador Retriever: incidence, risk factors, and visual outcome following routine phacoemulsification.

OBJECTIVE: To evaluate the incidence and risk factors associated with development of postoperative glaucoma in the Labrador Retriever following routine phacoemulsification. METHODS: Medical records from Labradors and a randomly selected population of non-Labradors were retrospectively evaluated. Signalment, diabetic status, cataract stage, gonioscopic findings, presence of preoperative lens-induced uveitis, development of postoperative hypertension (POH), postoperative glaucoma and postoperative visual status were recorded for each patient. Survival curves were developed using the Cox proportional hazards model. RESULTS: Forty-two Labradors (66 eyes) and 199 non-Labradors (314 eyes) were included. The incidence of POH was significantly higher in Labradors (33%) than non-Labradors (18%). Labradors were at significantly increased risk of postoperative glaucoma and blindness compared to non-Labradors. Estimated probabilities of postoperative glaucoma in Labradors were 23%, 25%, 30% and 35% at weeks 4, 26, 52 and 104, respectively, compared with 5%, 6%, 7% and 9% at weeks 4, 26, 52 and 104, respectively, in non-Labradors. Estimated probabilities of postoperative blindness in Labradors were 5%, 9%, 15% and 27% at weeks 4, 26, 52 and 104, respectively, compared with 2%, 3%, 5% and 10% at weeks 4, 26, 52 and 104, respectively, in non-Labradors. Risk factors for the development of glaucoma in Labradors included increasing age and development of POH. No statistically significant risk factors for the development of glaucoma were identified in non-Labradors. CONCLUSIONS: Labradors are at increased risk of glaucoma and blindness following phacoemulsification compared with non-Labradors. POH and increasing age represent risk factors for the development of postoperative glaucoma in Labradors.

Canine conjunctival mast cell tumors: a retrospective study.

OBJECTIVE: To describe signalment, clinical presentation, treatment, recurrence rate, and outcome of canine conjunctival mast cell tumors (MCTs). DESIGN: Retrospective study. PROCEDURES: Canine cases were selected from the Comparative Ocular Pathology Laboratory of Wisconsin, Eye Path Lab of the UK, and California Eye Care for Animals. Thirty-two canine patients were identified as having a MCT presumed to be arising primarily from the conjunctiva. Data were collected from pathology submission request forms; additional information was collected by means of a questionnaire distributed to the veterinary ophthalmologist or veterinarian who performed the surgery. Data collected included age, gender, breed, location of tumor, dimensions of tumor, duration and growth rate, additional diagnostics, surgical descriptions, adjunctive treatment, histologic description, special stains, number of recurrences, and final outcome. RESULTS: Thirty-two dogs with 33 conjunctival MCTs meeting search criteria were identified. All dogs underwent surgical excision as the primary treatment. Surgical margins were evaluated for 30 tumors and were reported as: incomplete margins in 25 cases, narrow in four cases and complete in one case. Histologic grade was provided for 33 of 33 MCTs and included 10 low (30%), 18 intermediate (55%) and five high-grade (15%) tumors. Follow up information was received for 25 dogs. Four died of unrelated causes, two had local recurrence, 15 were currently disease free (mean 21.4 months postoperatively) and four were reported to be disease free at the reported rechecks but were lost to long term follow up (mean 13 months postoperatively). No dogs in the study were identified that died of MCT related disease.

Central corneal thickness in koi fish: effects of age, sex, body length, and corneal diameter.

OBJECTIVE: To establish the central corneal thickness (CCT) of normal koi fish by ultrasonic pachymetry, and its relationship to age, sex, body length and corneal diameter. METHODS: Age, sex and body length of 33 koi fish (17 male and 16 female fish) were recorded. Horizontal and vertical corneal diameters of each eye were obtained using Jameson calipers. Central corneal thickness of all eyes was measured by ultrasonic pachymetry. Intraocular pressure (IOP) by rebound tonometry was obtained for a subgroup of nine koi (18 eyes). RESULTS: Mean central corneal thickness was 325.9 microm. Central corneal thickness of female koi was greater than CCT of male fish (P < 0.01). Central corneal thickness increased with increasing age overall and within both sexes (P < 0.01). Central corneal thickness increased with increasing body length (P < 0.001). For male and female fish, CCT increased with increasing horizontal and vertical corneal diameters (P < 0.01). Mean horizontal corneal diameter (HCD) was 8.05 mm, mean vertical corneal diameter (VCD) was 7.38 mm, and HCD was consistently greater than VCD. Mean IOP of a subgroup of these koi was 4.9 mmHg by rebound tonometry. CONCLUSIONS: Koi CCT increases with increasing age, body length and corneal diameter.

Corneal sensitivity and aqueous tear production in dogs undergoing evisceration with intraocular prosthesis placement.

OBJECTIVE: To determine whether there is an association between evisceration with intraocular prosthesis placement via a dorsal scleral approach and decreased corneal sensitivity or aqueous tear production in dogs. DESIGN: Prospective study. PROCEDURE: Twenty-one dogs scheduled to undergo unilateral evisceration with intraocular prosthesis, and with a normal normotensive contralateral eye, based on slit-lamp biomicroscopy, indirect ophthalmoscopy and applanation tonometry, were included in the study. Central corneal sensitivity was measured with a Cochet-Bonnet esthesiometer prior to (week 0) and 2, 7, 14 and 28 weeks following surgery. Other pre- and postoperative data collected were Schirmer's tear test (STT I), Schirmer's tear test with topical anesthesia (STT II), corneal fluorescein retention, and intraocular pressure (IOP; postoperative control eye only). Axial globe length was determined for both eyes. Scleral incision length in the surgery eye was also recorded. RESULTS: Corneal sensitivity was significantly lower in eyes undergoing evisceration with intraocular prosthesis than in control eyes both preoperatively and postoperatively at all time points. There was no significant difference between preoperative and postoperative corneal sensitivity within the two groups. There was no significant difference in STT I or STT II-values between control eyes and surgery eyes preoperatively. There was a significant difference between preoperative and 2-week postoperative STT I in the surgery eye. There was a significant difference between the preoperative and 28-week postoperative STT II in the surgery eye. The 28-week postoperative STT I-values differed significantly between control and surgery eyes. Corneal sensitivity tended to decrease with increased degree of buphthalmos or with increased scleral incision length, although neither relationship was statistically significant. CONCLUSIONS: Eyes that have sustained chronically elevated intraocular pressure had decreased axial corneal sensitivity compared to normal eyes, which persisted even after intraocular pressure was reduced. The presence of buphthalmos appeared to be a factor in globes developing decreased corneal sensitivity. Evisceration via a dorsal scleral incision did not result in a significant further reduction in axial corneal sensitivity. A mild reduction in aqueous tear production occurred over time in globes following evisceration with intraocular prosthesis.

Feline periocular peripheral nerve sheath tumor: a case series.

The objective of this retrospective study was to describe signalment, clinical presentation, surgical treatment, outcome, histopathologic, and immunohistochemical characteristics of periocular peripheral nerve sheath tumor in a series of cats. Six cats with a histologic diagnosis of peripheral nerve sheath tumor of the eyelid and/or conjunctiva were identified from 3997 feline ocular histopathologic submissions to the Comparative Ocular Pathology Laboratory of Wisconsin between 1976 and 2002. Medical records were reviewed and data were collected for signalment, eye affected, location, duration, and history of tumor recurrence. Ancillary diagnostic tests, surgical approach, and histopathology were also described. Special stains and immunohistochemistry panels were performed on the tissue. Follow-up information was obtained through telecommunications with the owner and local veterinarian. The mean age of the cats was 8 years (range: 5-15 years). There was an equal distribution of males and females. Breeds represented were two Domestic Long-haired (DLH) cats, three Domestic Short-haired (DSH) cats, and one Manx. The right eye was affected in four cats and the left eye in two cats. The superior eyelid was affected in four cats, the superior conjunctiva in two cats, and the inferior eyelid in one cat. All of the cats that underwent surgical excision, cryoablation, or laser ablation had an average of three recurrences of the tumor. Four of six cats undergoing wide excision with enucleation, exenteration or rhomboid flap had no recurrence of the tumor. Histomorphologically, all of the tumors were of spindle cell type with five of six tumors showing histologic features of Antoni type B tissue. All six tumors stained positive for vimentin. Five of six tumors stained positive for S-100 and laminin. All six tumors were negative for smooth muscle actin. Definitive histologic diagnoses of spindle cell tumors can be difficult. The presence of Antoni A and B histologic patterns as well as immunohistochemical reactivity for vimentin, S-100, and laminin suggest a diagnosis of peripheral nerve sheath tumor. Our findings suggest that local aggressive recurrence is common and that wide surgical excision combined with enucleation or exenteration may be indicated.