Showing papers in "Veterinary Ophthalmology in 2012"

Clinical utility of a complete diagnostic protocol for the ocular evaluation of free-living raptors

Abstract: Objective: To describe a protocol for the examination of free-living raptors and report the ophthalmic examination findings of seven raptor species native to central Illinois, namely the barred owl, Cooper’s hawk, eastern screech owl, great horned owl, American kestrel, red-tailed hawk, and turkey vulture and to determine if the findings relative to visual prognosis affected eligibility for future release. Animals studied: Seventy-nine free-living raptors. Procedures: Under manual restraint, complete ophthalmic examination including slit-lamp biomicroscopy and indirect funduscopy, applanation tonometry, rebound tonometry, ocular morphometrics, B-mode ultrasound, and electroretinography (ERG) were performed on each bird. Histopathology of enucleated globes was performed after euthanasia or death in selected cases. Results: The examination protocol was easily performed using manual restraint alone on all birds. Ocular lesions were detected in 48.1% of birds, with 47.3% affected unilaterally and 52.6% affected bilaterally. Ocular lesions were considered to be vision threatening in 29.0% of the unilaterally affected birds and 29.0% of the bilaterally affected birds. The most common case outcomes were discharge from hospital to rehabilitation facility (45.6%) followed by euthanasia (43.0%). The presence of an ocular lesion or a vision-threatening ocular lesion was not significantly associated with outcome. Reference ranges are reported for B-mode ultrasound, ocular morphometrics, and horizontal corneal diameter in all species. Conclusion: Complete ophthalmic examination can be supplemented by the use of ocular morphometrics, ultrasound, and ERG in the manually restrained raptor. These advanced diagnostic techniques may be useful in developing more objective criteria for evaluating eligibility for release following rehabilitation of free-living birds of prey.

Optical Coherence Tomography for the Evaluation of Retinal and Optic Nerve Morphology in Animal Subjects: Practical Considerations

Abstract: Optical coherence tomography (OCT) is a noninvasive, noncontact imaging technique capable of producing high-resolution images of the retina and optic nerve. These images provide information that is useful for following the progression and/or resolution of posterior segment disease. Rapid advances in OCT technology allow the acquisition of increasingly detailed images, approaching the original goal of providing in vivo histopathology. Increases in scan acquisition speeds and axial resolution enhance the clinical diagnostic value of this modality. Adapting instrumentation designed for use in human patients for use in animals can be challenging. Each species has a unique set of adjustments that need to be made but it is possible to obtain reproducible, high-quality OCT images in a variety of animals, including rodents, dogs, cats, pigs, and monkeys. Deriving quantitative measurements from OCT instruments is hindered by software algorithm errors in detecting the edges of the distinct retinal layers. These segmentation errors occur in scans of human eyes as well in other species and arise with similar frequency with each of the different OCT instruments. Manual segmentation methods to derive optic nerve head and other structural indices have been developed for several species.

Characterization of cytokines associated with Th17 cells in the eyes of horses with recurrent uveitis.

Abstract: Objective Equine recurrent uveitis (ERU) is a spontaneous disease that is the most common cause of blindness in horses, affecting up to 15% of the horse population. Th17 cells are a major cell population driving the pathogenesis in several mouse models of autoimmune inflammation, including experimental autoimmune uveitis. The purpose of this study is to investigate the role a Th17 cell-mediated response plays in the pathogenesis of ERU. Procedure Banked, Davidson’s-fixed equine globes histopathologically diagnosed with ERU (n = 7) were compared immunohistochemically with healthy control globes (n = 7). Immunohistochemical staining was performed using a pan-Leptospira antibody and antibodies against IL-6, IL-17, and IL-23. Additionally, immunostaining was performed for T-cell (CD3) and B-cell (CD79α) markers. Specificity of immunoreactivity was confirmed by western blot analysis. Results Immunohistochemical staining was positive for IL-6, IL-17, and IL-23 within the cytoplasm of nonpigmented ciliary epithelial cells and mononuclear inflammatory cells infiltrating the iris, and ciliary body of ERU horses (n = 7) but negative in controls (n = 7). ERU-affected eyes were CD3 positive (n = 7) and CD79α negative (n = 7). Staining for Leptospira was negative in all ERU and control globes. Conclusions Strong immunoreactivity for IL-6, IL-17, and IL-23, in conjunction with the fact that T lymphocytes are the predominating inflammatory cells present in ERU, suggests that IL-17-secreting helper T-cells play a role in the pathogenesis of ERU. These findings suggest that horses with ERU may serve as a naturally occurring animal model for autoimmune uveitis.

Carbon dioxide laser photoablation adjunctive therapy following superficial lamellar keratectomy and bulbar conjunctivectomy for the treatment of corneolimbal squamous cell carcinoma in horses: a review of 24 cases.

Abstract: Objective To determine the complications and nonrecurrence rates following superficial lamellar keratectomy, bulbar conjunctivectomy, and adjunctive carbon dioxide (CO2) photoablation for corneolimbal squamous cell carcinoma (SCC) in the horse. Study design Retrospective study. Sample population Twenty-four horses with corneolimbal SCC. Procedure Medical records of horses diagnosed with corneolimbal SCC that was surgically excised and where CO2 photoablation was used as an adjunctive therapy from 2000 to 2007 were reviewed. Signalment, prior therapy, tumor location and size, complications, and recurrence of SCC were recorded. Results The Thoroughbred was the most commonly (25%) represented breed. Lesions were >10 mm in diameter in 70.8% of cases. Eight horses (33.3%) had neoplastic cells extending to the deep margin of the keratectomy. All horses were available for follow-up for an average ± standard deviation of 40.7 ± 25 months. Four horses (16.7%) developed a recurrence of SCC. Three of these four horses underwent repeat keratectomy and CO2 photoablation, one each, at 4 months, 1, and 2 years following the initial procedure. One horse underwent enucleation 8 months following the initial procedure. Conclusions and clinical relevance As an adjunctive therapy, CO2 photoablation was successful in 87.5% of the horses following a single procedure and in a total of 91.7% following a second therapeutic application. CO2 photoablation appears to be effective as an adjunctive therapy following removal of large corneolimbal SCC in the horse and in cases in which all tumor cells were not excised.

Effects of intravenous administration of dexmedetomidine on intraocular pressure and pupil size in clinically normal dogs

Abstract: Objective To evaluate the effects of the intravenous administration of dexmedetomidineon the intraocular pressure (IOP) and pupil size (PS) in normal dogs.Animals studied Forty-two animals with no ocular abnormalities were included in thisstudy.Procedure Following initial readings (T 0 ) of IOP and PS, the dogs received anintravenous injection of dexmedetomidine (5 lg/kg). Both measurements wererepeated 10 min (T 10 ) and 20 min (T 20 ) later.Results There were no significant differences in IOP measurements between T 0 andT 10 , although a significant decrease was observed at T 20 . A significant miosis wasfound in the first 10 min after sedation. At T 20 , the PS slightly increased, resulting inno statistical differences with T 0 and T 10 .Conclusion Dexmedetomidine is an excellent option for surgery or diagnostic ocularprocedures in dogs when a specific control of IOP is required. However, it must beused in combination with mydriatics in ophthalmic surgical or diagnostic procedures,which require complete dilation of the pupil.Key Words: dexmedetomidine, dog, intraocular pressure, pupil size, a

Measurement of tear production in black-tufted marmosets (Callithrix penicillata) using three different methods: modified Schirmer's I, phenol red thread and standardized endodontic absorbent paper points.

Abstract: Objective: To report normal tear production of healthy adult black-tufted marmosets and propose a novel alternative for the measurement of the aqueous portion of tear production in animals with small eyes. Animal studied: Black-tufted marmosets (Callithrix penicillata). Procedures: Tear production of 19 animals was evaluated by the following methods: modified Schirmer’s I, phenol red thread and the novel use of standardized endodontic absorbent paper points. These methods and results were compared. Additionally, blink frequency and palpebral fissure length were measured. Results: Modified Schirmer’s test I, mean = −0.46 ± 3.41 mm/min; Phenol red thread, mean = 13.27 ± 5.41 mm/15 s.; Standardized endodontic paper points, size 30, mean = 9.32 ± 3.09 mm/min; Mean palpebral fissure length = 7.83 ± 0.72 mm. Blink frequency, mean = 20.27 ± 5.92/5 min. Conclusions: Normal parameters for blink frequency, palpebral fissure length and tear production measurement are presented. The palpebral fissure of black-tufted marmoset is very small and tear production is one of the lowest reported for all animal species. A novel and practical alternative for tear production measurement using standardized endodontic absorbent paper points is presented and is indicated for animals with small eyes.

Diagnosis of Borrelia-associated uveitis in two horses.

Abstract: Borrelia burgdorferi, the etiologic agent of Lyme disease is a tick born spirochetal infection. Clinical signs of Lyme borreliosis are uncommon in horses, but when present they are often vague and nonspecific. In horses, Lyme borreliosis has been implicated in musculoskeletal, neurological, reproductive, and ocular disorders, including uveitis, but definitive diagnosis can be challenging as the causative agent is rarely isolated and serologic tests can be unreliable and do not confirm active disease. Here, we report two cases of equine uveitis associated with B. burgdorferi based on the identification of spirochetes within ocular fluids and confirmed with PCR testing. The two cases illustrate some of the challenges encountered in the recognition and diagnosis of equine Lyme borreliosis. Although only one of many possible causes of equine uveitis, Lyme disease should be considered a differential diagnosis, especially in endemic areas. Given the possibility for false negative results of serum tests during uveitis associated with B. burgdorferi and the failure of such tests to confirm active infection, a combination of cytologic assessment, antibody, and/or PCR testing of ocular fluids may be worthwhile if the clinical suspicion for Lyme uveitis is high.

Congenital stationary night blindness is associated with the leopard complex in the miniature horse

Abstract: Objective To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit-lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ2 = 22, P << 0.0005) and CSNB status (χ2 = 11, P < 0.0005). Conclusions The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.

Ocular consequences of blunt trauma in two species of nocturnal raptors (Athene noctua and Otus scops).

Abstract: Objective To determine the type, prevalence, and prognosis of ocular and periocular lesions in free-living little owls (LO) and scops owls (SO), injured by blunt trauma Procedures Medical records from LO and SO with ocular or periocular lesions secondary to blunt trauma were reviewed A complete ophthalmic examination was performed in all birds Short protocol electroretinography (ERG) and ocular ultrasound were performed as dictated by the case Results During the study period, a total of 158 LO and 99 SO with blunt trauma were admitted Among these, 43 LO (278%) and 27 SO (273%) had ocular or periocular lesions Bilateral injuries (721% LO and 815% SO) were more common than unilateral Common findings in both species were: corneal erosions/superficial ulcers, anterior and posterior uveitis, cataracts, hyphema, posterior synechia, vitreal hemorrhage, and retinal detachment Electroretinography was performed in 32 LO and eight SO, which had posterior segment lesions or opacity of the transparent media Normal to nonrecordable b-wave amplitudes were observed Follow-up was available in 13 LO and 11 SO Among these, nine LO (14 eyes) and 10 SO (17 eyes) had resolution of the clinical signs following medical treatment Conclusions Ocular lesions are common in LO and SO injured by blunt trauma Electroretinography is a valuable diagnostic tool to assess the severity of retinal dysfunction secondary to blunt trauma and to determine the response to medical treatment A complete ophthalmic examination is a determining factor in the early management of trauma in these species

A retrospective comparison of surgical removal and subsequent CO2 laser ablation versus topical administration of mitomycin C as therapy for equine corneolimbal squamous cell carcinoma

Abstract: OBJECTIVE: To compare the complications and nonrecurrence rate following topical mitomycin C (MMC) therapy vs. CO(2) laser ablation for treating equine corneolimbal squamous cell carcinoma (SCC). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Twenty-five horses with corneolimbal SCC. PROCEDURES: Medical records of horses undergoing surgical tumor resection followed by either topical MMC therapy (0.04%) or CO(2) laser ablation between the years of 2004 and 2010 were reviewed. Recurrence and complications were compared between groups and within MMC subgroups defined by the time at which treatment was initiated relative to surgery. RESULTS: Therapy with topical MMC resulted in a nonrecurrence rate comparable to that achieved with CO(2) laser ablation (82.4% vs. 85.7%, respectively). Initiation of MMC following epithelialization of the surgical site a mean of 15 days postoperatively did not result in increased recurrence rates relative to treatment in the immediate postoperative period. Vision- or globe-threatening complications tended to occur with greater frequency in horses receiving topical MMC in the immediate postoperative period (5 of 6 major complications) relative to following epithelialization of the surgical site (1 of 6 major complications). CONCLUSIONS: Horses receiving adjunctive topical MMC therapy were no more likely to experience tumor recurrence than were horses undergoing CO(2) laser ablation in the horses in this study. Initiation of two to three rounds of MMC following epithelialization of the surgical site results in fewer major complications and achieves comparable disease resolution relative to treatment in the immediate postoperative period.

Traumatic corneal laceration with associated lens capsule disruption: a retrospective study of 77 clinical cases from 1999 to 2009.

Abstract: Objective Examine prognostic factors that may indicate when surgical lens removal is indicated to prevent vision-threatening complications in patients presented following traumatic perforating corneal laceration with associated lens capsule disruption. Procedures Seventy-seven patients (10 cats and 67 dogs) were evaluated with this injury; of these, 47 were presented acutely and treated surgically and/or medically. Successful outcome was defined as functional vision in the treated eye. Results The 47 patients with acute injuries were divided into 3 treatment groups A-C for comparison; A - corneal repair/lens removal (n = 15), B - corneal repair/no lens removal (n = 9), C – medical management (n = 23). Groups A and B showed a significantly greater rate of vision loss compared to Group C that was most obvious greater than 18 months post-injury (P = 0.029 and 0.0097, respectively). Cox proportional hazards regression analysis found a significantly higher increased rate of vision loss in Group A (HR = 4.5; P = 0.023) and a higher but nonsignificant increased rate of vision loss in Group B (HR = 3.0; P = 0.23) compared to Group C after controlling for age and cause of injury. The length of the corneal laceration and time interval from injury to referral were also relevant prognostic factors. Conclusions Medical management is an appropriate therapy for patients of all ages suffering perforating corneal injuries with associated lens capsule disruption. Patients with corneal injuries requiring surgical repair or managed by lens removal following corneal repair suffered vision-threatening complications approximately 3 to 4.5 times the rate of patients treated by medical management, respectively. Favorable prognostic signs for treatment by medical management include good corneal wound apposition and a formed anterior chamber without uveal prolapse or continued aqueous leakage.

Characterization of structure and function of the mouse retina using pattern electroretinography, pupil light reflex, and optical coherence tomography.

Abstract: Objective To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes. Animal Studied Adult C57BL/6 male mice (n = 37). Procedures Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT). Results The average pERG amplitudes were found to be 11.2 ± 0.7 lV (P50-N95, mean ± SEM), with an implicit time for P50-N95 interval of 90.4 ± 5.4 ms. Total retinal thickness was 229.5 ± 1.7 lm (mean ± SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean ± SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7 ± 0.9 lm (temporal), 46.1 ± 0.9 lm (superior), 45.8 ± 0.9 lm (nasal), and 48.4 ± 1 lm (inferior). The baseline pupil diameter was 2.1 ± 0.05 mm in darkness, and 1.1 ± 0.05 and 0.56 ± 0.03 mm after stimulation with red (630 nm, luminance 200 kcd/m 2 ) or blue (480 nm, luminance 200 kcd/m 2 ) light illumination, respectively.

Comparison of intraocular pressure measurements between the Tono-Pen XL® and Perkins® applanation tonometers in dogs and cats.

Abstract: Objective To compare the accuracy between two applanation tonometers, Tono-PenXL and Perkins , in ophthalmoscopically normal dogs and cats.Animals Both eyes of 25 conscious and healthy dogs and cats were evaluated. Botheyes of five dogs and cats immediately after sacrifice were used as controls for thepostmortem study.Procedure In conscious animals, the tonometry was performed with topical anesthesiausing 0.5% proxymetacaine eye drops for both tonometers and 1% fluorescein eyedrops for the Perkins tonometer. Readings of intraocular pressure (IOP) in thepostmortem study were taken using manometry and tonometry by Tono-Pen XLand Perkins .Results The correlation coefficient (r 2 ) in dogs between manometry and applanationtonometers Tono-Pen XL and Perkins were, respectively, 0.896 and 0.981 and incats were 0.905 and 0.988. The mean IOP values in conscious dogs with Tono-PenXL and Perkins were, respectively, 17.5 ± 3.7 mmHg (10.0–25.0 mmHg) and15.3 ± 2.1 mmHg (12.0–19.8 mmHg) and in conscious cats were 16.8 ± 3.6 mmHg(10.5–24.5 mmHg) and 15.5 ± 1.3 mmHg (13.0–18.5 mmHg).Conclusion There was a strong correlation between the IOP values obtained by directocular manometry and the Tono-Pen XL and Perkins tonometers in dogs and cats.There was no statistically significant difference between the mean IOP obtained withboth tonometers in conscious animals, there was, however, a difference between theminimum and mainly in the maximum values that were on average 5–6 mmHg higherwith Tono-Pen XL than those measured with Perkins , which justifies a table ofnormal values differentiated for each tonometer.Key Words: applanation tonometer, cats, dogs, intraocular pressure, Perkinstonometer, Tono-Pen XL tonometer

The protective effects of Lycium barbarum and Chrysanthemum morifolum on diabetic retinopathies in rats

Abstract: The effects of Lycium barbarum and Chrysanthemum morifolum extracts on diabetic retinopathy were evaluated. The diabetes model was induced by streptozotocin. Animals were divided into six groups: the control group received only vehicle; diabetic animal models received no treatment, insulin treatment, Lycium extract, Chrysanthemum extract, or a combination of Lycium and Chrysanthemum extracts, respectively. Retinal function was evaluated by electroretinography, and the diabetic progression was monitored by blood test for hyperglycemia. In addition, retinal histopathology and retinal glial reactivity were also investigated. The electroretinographic amplitudes of the a- and b-waves were significantly decreased in the diabetic animals, and the implicit time of the b-wave was also delayed, compared to the control group. However, reductions in the a- and b-wave amplitudes were not observed in the Lycium-treated group. Histopathological studies showed no significant differences between the Lycium-treated, Chrysanthemum-treated, Lycium/Chrysanthemum-treated groups, and the control group. The results of this study suggest that L. barbarum may have protective effects in diabetic retinopathy.

Use of a combined slit‐lamp SD‐OCT to obtain anterior and posterior segment images in selected animal species

Abstract: Objective To obtain images of anterior and posterior segments of the eye using a slit-lamp (SL)/spectral domain (SD) optical coherence tomography (OCT) integrated system designed for the human eye, in the cat, dog, minipig and monkey. Animals studied One healthy adult monkey, one healthy adult minipig, one healthy adult dog, one healthy adult cat, and three cats and four dogs affected by corneal or retinal diseases. Procedure A SL SCAN-1 SD-OCT, which is a slit-lamp SL-D7 that contains an integrated OCT module and a fundus viewer, was used to generate OCT images (512-2048), while simultaneously taking 'en-face' slit-lamp images (efSL). OCT images were obtained under sedation or anesthesia. These images were compared to histological retinal sections obtained from a monkey, a minipig, a dog, and a cat. Results 'en-face' slit-lamp images and OCT images of the ocular tissues were obtained allowing for the identification of different corneal and retinal layers in all animal species. Measurements of the total retinal thickness (TRT) from the inner limiting membrane to the retinal pigment epithelium were performed in various regions throughout the retina. Reduction in TRT was consistent with clinical features of retinal degeneration identified in dogs and cats. Conclusion This noninvasive procedure is useful for both experimental and clinical assessments of ocular tissue damage. Images of anterior and posterior segments are readily obtained under routine clinical conditions. Future studies are warranted to establish normal OCT data in our patients with this new instrument.

The morphology of the pecten oculi in the common buzzard (Buteo buteo).

Abstract: Objective The pecten oculi are an intraocular, vascular, and pigmented structure peculiar to the avian eye. In this study, we investigated the pecten oculi of the common buzzard (Buteo buteo) using stereomicroscopy and light and scanning electron microscopy (SEM). Procedures Twenty eyes from 10 adult buzzards were studied. Specimens from each buzzard were preserved in 10% buffered formalin and observed stereomicroscopically before being embedded in paraffin, sectioned, and stained with three stains: Mallory’s triple staining technique as modified by Crossman, Hematoxylin-Eosin (HE), and Safranin O, and for examination by light microscopy. Specimens from two buzzards were also prepared for SEM. Results Stereomicroscopy and SEM examination showed the pecten oculi in the common buzzard to be pleated—consisting of 17–18 100 μm thick folds. These folds are connected to one another by bands of connective tissue extending vertically between the plications. Blood vessels, approximately 30–40 μm in diameter, were seen on the surface of the each fold. These vessels arise from the base of pecten, becoming thinner toward the apical end of the structure. A network of capillary vessels at the base of the plicated structure resembles contour lines. At high amplification, melanin granule accumulations were observed around the vascular structures of the plica on SEM images. Light microscopy supported the SEM observations. Conclusions These findings reveal that the pecten oculi in the common buzzard are plicated and are remarkably similar to that of the other diurnal raptors.

Pharmacokinetics of famciclovir and penciclovir in tears following oral administration of famciclovir to cats: a pilot study

Abstract: Objective To validate a means of collecting tears from cats, develop an assay for quantifying famciclovir and penciclovir in tears, and to assess famciclovir and penciclovir concentrations and pharmacokinetics in the tears of cats being treated orally with famciclovir for suspected herpetic disease. Animals Seven client-owned cats. Procedures Cats were treated orally with a median (range) dose of 40 (39–72) mg of famciclovir/kg three times daily for at least 24 h. At various time points following famciclovir administration, tear samples were collected using Schirmer tear test strips. Tear famciclovir and penciclovir concentrations were measured using liquid chromatography-mass spectrometry, and concentration-time profiles were analyzed noncompartmentally. The relationship between famciclovir dose and tear penciclovir concentration near its maximum was evaluated using least squares linear regression. Results Maximum tear famciclovir concentration of 0.305 lg/mL occurred at 2.64 h; elimination half-life was 2.28 h. Maximum tear penciclovir concentration (0.981 lg/ mL) occurred 2.25 h following oral administration of famciclovir; elimination half-life was 2.77 h. A significant positive correlation was noted between famciclovir dose and tear penciclovir concentration at various time points between 0.5 and 3.75 h following drug administration ( P= 0.025). Tear penciclovir concentration exceeded the concentration shown to have in vitro efficacy against feline herpesvirus (FHV-1) (0.304 lg/mL) in about half of samples collected. Conclusions Oral administration of 40 mg of famciclovir/kg to cats resulted in a tear penciclovir concentration-time profile that approximated the plasma penciclovir concentration-time profile and frequently achieved a penciclovir concentration at the ocular surface likely to be effective against FHV-1.

Gender differences in iridocorneal angle morphology: a potential explanation for the female predisposition to primary angle closure glaucoma in dogs

Abstract: Objective Female dogs have approximately twice the risk of males for developing primary angle closure glaucoma (PACG). The cause of this gender difference is unknown, but one theory proposes that the gender differences in iridocorneal angle morphology are involved in this risk differential. Procedures Fifty beagles (25 males, 25 females) were included into this study and had normal baseline ophthalmic examinations. Normal dogs were selected so as to avoid any potentially confounding influence of goniodysgenesis. Standardized 20-MHz high-resolution ultrasound images of the iridocorneal angle were acquired from one eye of each dog with the scan plane perpendicular to the limbus in the superior temporal quadrant. Images were imported into ImageJ, and the angle opening distance (AOD) and angle recess area (ARA) were measured by a masked observer, and the analysis of variance method was used to compare differences. Results The mean (±SD) AOD was significantly smaller for female dogs (0.847 ± 0.241 mm) vs. male dogs (1.058 ± 0.322 mm) P-value = 0.012. The mean (±SD) ARA tended to be smaller for female dogs (0.584 ± 0.278 mm) vs. male dogs (0.748 ± 0.385 mm), but this difference was not significant (P-value = 0.092). Conclusions Female dogs have a significantly smaller AOD vs. males. This difference may render the female iridocorneal angle more susceptible to closure and may partially explain the 2:1 female/male predisposition to PACG. Further studies using goniodysgenic dogs are warranted.

Morphology of retinal vessels in the optic disk in a Göttingen minipig experimental glaucoma model

Abstract: Objective To compare the morphology of normal, healthy Gottingen minipig retinal vessels of the optic disk with experimentally induced glaucomatous optic disks in order to identify the glaucomatous excavation. Present results were compared to human glaucoma findings. Procedure Sixteen eyes from eight Gottingen minipigs were studied using fundoscopic photography and fluorescein angiography. Experimental glaucoma was then induced in the left eyes over 14 months, and changes in the optic disk vessels were assessed using fundoscopic photography and fluorescein angiography. The changes were compared with those previously reported in humans. Results Regarding the number of vessels, the location from where they emerge and the sectors of the optic disk that they cross, arterial and retinal vessels in Gottingen minipigs present a more asymmetric layout than in humans. The central excavation is filled by the central venous ring. Changes in the glaucomatous optic disk include arteriolar incurvation, and sometimes, nasal, and peripheral displacement of the arterioles that emerge between the ganglion cell axons of the neuroretinal ring. No angiographic changes were observed in the experimental glaucoma model. Conclusions The changes in the glaucomatous optic disk of the minipig imply a predominant involvement of the arterioles. However, in humans with primary open- angle glaucoma (POAG), both the arterioles and the venules are displaced, and the central excavation is easier to distinguish, because of the absence of a central venous ring.

Canine neurogenic Keratoconjunctivitis sicca: 11 cases (2006-2010)

Abstract: Objective To describe the clinical data of dogs with neurogenic Keratoconjunctivitis sicca (KCS) and an ipsilateral dry nose without other neurologic deficits. Procedure The retrospective case study included 11 dogs diagnosed with neurogenic KCS and an ipsilateral dry nose between 2006 and 2010. Medical records were reviewed for breed, age, sex, history, suspected cause of neurogenic KCS, clinical signs, and treatment modalities. Follow-up information was obtained by re-examination of patients or completion of a telephone survey with the referring veterinarian or the owners. Results Mean age of the dogs was 6.6 ± 4.5 years. Neurogenic KCS was diagnosed in three females, five spayed females, one male, and two castrated males representing 10 different breeds. Ophthalmic signs of KCS (mean Schirmer tear test [STT] value of 1.9 ± 2.9 mm/min) combined with an ipsilateral dry nose were diagnosed in seven left and four right eyes. The suspected cause of neurogenic KCS was idiopathic in nine and trauma in two cases. Systemic therapy consisted of oral pilocarpine 1–2% eye drops combined with case-specific topical treatment with cyclosporine 0.2% and tear substitutes. Duration of systemic treatment with pilocarpine until healing was 125 days (range 84–204, median 98 days) for five dogs. One dog was lost to follow-up, and the remaining five dogs are still under systemic treatment with pilocarpine. Conclusions Neurogenic KCS with an ipsilateral dry nose seems to be a predominantly idiopathic disease of middle-aged female dogs without breed predisposition, which may be self-limiting in some cases.

Parotid duct transposition in dogs: a retrospective review of 92 eyes from 1999 to 2009.

Abstract: Objective The aim of this study was to perform a retrospective review of parotid duct transposition (PDT) in the dog to determine the rate and nature of complications, the success and failure rates and to evaluate owner satisfaction. Methods Medical records of 56 dogs (92 eyes) that underwent PDT and subsequent follow-up by a veterinary ophthalmologist were reviewed. Forty owners (40 dogs/66 eyes) were contacted by telephone and 37 owners (37 dogs/60 eyes) also completed a visual analog scale questionnaire. Statistical evaluation included Wilcoxon Signed Rank tests, one-way analysis of variance and Kaplan–Meier survival analysis with Wilcoxon and Log-rank tests. Results The mean follow-up was 38.7 months (range 1–109 months). The surgical success rate was 92% (85/92 eyes). Total failures (8%, 7/92 eyes) were because of severe saliva intolerance (n = 5 eyes) and PDT failure (n = 2 eyes). The complication rate was 50% (46/92 eyes) of which 61% (28/46 eyes) were managed medically and 39% (18/46 eyes) required further surgery. Ninety percent (36/40) of owners indicated that they would proceed with surgery again. Statistically significant improvements in owner perception of ocular comfort, number of daily topical treatments, ocular wetness, and postoperative vision were identified. Conclusions This study shows that PDT is a successful procedure based on clinical findings and in terms of owner perception. It has also demonstrated that PDT improves ocular comfort and vision in medically refractive cases of keratoconjunctivitis sicca, and that a low level of on-going management is required in 33% of cases.

Histopathologic features of canine distichiasis.

Abstract: Objective To describe the histologic features of canine distichiasis using excised tarsoconjunctival specimens that included roots of distichiatic cilia. Procedures The study group included 21 strips of cilia-bearing tarsoconjunctiva resected from 20 dogs with distichiasis. Eyelid tissue specimens were also collected from 11 euthanized dogs without distichiasis to serve as controls. All flat mount preparations were processed for histologic examination, and serial sections were stained with hematoxylin-eosin (H&E). A total of 157 slides were examined for the study group to describe the follicles and path of the distichiatic hairs and determine their potential connection with the tarsal glands. A total of 82 slides were examined for the control group. Results In 19 of the 20 dogs with distichiasis, serial sections of the specimens identified anatomic segments of hair follicles located abnormally in the eyelid tarsus and associated with the aberrant cilia. They appeared as hair bulbs adjacent to tarsal glands, middle portions of hair follicles located between sebaceous lobules, and single or multiple hair shafts present within the sebaceous duct. The tarsal glands in the cilia-bearing tarsoconjunctiva were not different from those of the controls, in which no distichiatic hair bulbs or shafts were observed. Conclusions These results demonstrate that adventitious cilia are not associated with histologic changes of the tarsal glands, and appear to arise from ectopic hair follicles present in the tarsus. Canine distichiasis may result from anomalous regulation of morphogenesis of hair follicles in the mesenchymal tissue of the tarsal plate.

Aqueous humor vascular endothelial growth factor in dogs: association with intraocular disease and the development of pre-iridal fibrovascular membrane.

Abstract: Objective To examine the concentrations of vascular endothelial growth factor (VEGF) in aqueous humor of dogs with intraocular disease and to evaluate the association of aqueous humor VEGF with pre-iridal fibrovascular membrane (PIFM) formation. Procedures Two hundred and twenty six aqueous humor samples and 101 plasma samples were collected from 178 dogs with a variety of intraocular diseases (including cataract, primary glaucoma, uveitic glaucoma, aphakic/pseudophakic glaucoma, retinal detachment, lens luxation, and intraocular neoplasia), and aqueous humor was collected from 13 ophthalmically normal control dogs. Systemic disease status and administration of select medications were recorded. Aqueous and plasma VEGF was assayed via enzyme-linked immunosorbant assay validated for canine VEGF. Available histopathology samples were examined for the presence of PIFM. Where present, PIFMs were categorized as none, cellular, vascular or fibrous, and fibrovascular. Data were evaluated by mixed model ANOVA, with application of Tukey‐Kramer adjustment for multiple comparisons. Results There was no association between aqueous humor and plasma VEGF levels. Compared with normal controls, aqueous humor VEGF was significantly elevated for all intraocular diseases (P < 0.05) except for primary and diabetic cataracts. Systemic disease and administered medications had no significant effect on aqueous humor VEGF concentration. Compared to dogs without PIFM, aqueous humor VEGF was significantly higher in dogs with fibrovascular PIFM (P = 0.001), but not cellular (P = 0.1704) or fibrous/vascular PIFM (P = 0.0667). Conclusions These findings confirm that VEGF is commonly elevated in aqueous humor of dogs with intraocular disease and likely plays a role in the causation or progression of a variety of intraocular disorders, including the development of PIFM.

Effect of mydriasis induced by topical instillations of 0.5% tropicamide on the anterior segment in normotensive dogs using ultrasound biomicroscopy

Abstract: Objective To determine the effect of 0.5% tropicamide and the resultant mydriasis on the anterior segment in normotensive dogs using ultrasound biomicroscopy. Procedure Twenty-four dogs without ocular disease underwent ultrasound biomicroscopic examination of both the eyes under general anesthesia. Pharmacologic mydriasis was induced in the right eye of each dog by the topical instillation of 0.5% tropicamide. Ultrasound biomicroscopic examinations were performed and the anatomical parameters of the anterior segment were evaluated including the geometric iridocorneal angle (ICA) - formed by the plane of the iris root and the internal corneoscleral limbus - the width of the opening of the ciliary cleft (CC), the width of the mid-CC, the length of the CC, and the anterior chamber (AC) depth (distance between the corneal endothelium and the anterior lens capsule). Results Mydriasis resulting from the topical use of 0.5% tropicamide is associated with an increase in the geometric ICA and a decrease in the opening of the CC, without any effect on the width of the mid-CC, or on the length of the CC, or on the AC depth. Conclusions Mydriasis induced by topical 0.5% tropicamide results in modification of the anterior segment which may influence the drainage of aqueous humor.

Feline calicivirus: a neglected cause of feline ocular surface infections?

Abstract: Objective To investigate the prevalence of feline calicivirus (FCV) infection in relation to ocular surface lesions in cats with upper respiratory tract diseases (URTD). Animals studied Ninety-nine cats with ocular surface infection and symptoms or recent history of URTD were examined at various rescue shelters and hospitals. Procedure A complete general and ophthalmic examination was performed including Schirmer tear test, slit-lamp biomicroscopy, fluorescein and lissamine green staining. Clinical and ocular symptoms were scored and recorded. Conjunctival samples were collected using a cytobrush, and nucleic acid extraction using RT-PCR was carried out to analyze for the presence of various infectious agents. Results RT-PCR detected either FCV, feline herpes virus type 1 (FHV-1), Chlamydophila felis or Mycoplasma spp. in 63/99 samples. 30/63 samples were positive for FCV, 23/63 for C. felis, 21/63 for Mycoplasma spp., and 16/63 for FHV-1. Out of the 30 FCV-positive samples, 11 were positive only for FCV and in 19 samples FCV was seen in combination with other agents. FCV infection was highest in animals examined at the rescue centers and in the age group of 0–2 months. Erosive conjunctivitis was an important ocular finding. Oral ulcers were detected in all FCV-infected cats. Conclusion Results indicate that FCV is highly prevalent in cats with URTD either as a sole infectious agent or in combination with other pathogens and therefore is a potential cause for ocular surface lesions during the URTD.

Astrocytic responses in the lateral geniculate nucleus of monkeys with experimental glaucoma.

Abstract: Objective To investigate the responses of lateral geniculate nucleus (LGN) astrocytes to experimental glaucoma in monkeys. Animal studied Rhesus monkeys (Macaca mulatta). Procedures Unilateral chronic elevation of intraocular pressure (IOP) was induced in six rhesus monkeys by laser photocoagulation of the trabecular meshwork. Four normal monkeys were used as controls. Immunohistochemistry with antibodies to glial fibrillary acidic protein (GFAP), S100β and parvalbumin was used to specifically label astrocytes and neurons in the LGN. The relative immunointensity (RI) of GFAP was defined as the ratio of intensity between each region of interest to a reference field and compared between the experimental and control groups as a function of percentage optic nerve fiber loss. Ultrastructural changes of LGN astrocytes were examined by transmission electron microscopy. Results An increase in GFAP and S100β immunoreactivity was observed in the LGN layers receiving projections from the experimental glaucoma eyes. Quantitative analysis revealed that the RI of GFAP in both the magnocellular and parvocellular layers connected to the glaucomatous eyes increased in a linear fashion with increasing optic nerve fiber loss. Compared to controls, the RI of GFAP was also moderately elevated in LGN layers connected to the fellow nonglaucomatous eyes. Ultrastructurally, accumulation of glial filaments that occurred throughout the perikaryon and extended into the process in reactive astrocytes was observed in LGN layers of glaucomatous monkeys. Conclusions Reactive astrogliosis occurs in the magnocellular and parvocellular LGN layers of monkeys with unilateral glaucoma. Astrocytes may play an important role in the regulation of LGN microenvironment in glaucoma.

Canine multifocal retinopathy in the Australian Shepherd: a case report

Abstract: A 1-year-old Australian Shepherd (AS) was presented for a routine hereditary eye examination. During the examination multiple raised, brown to orange lesions were noted in the fundus, which could not be attributed to a known retinal disease in this breed. As they clinically most closely resembled canine multifocal retinopathy (cmr) and no indication of an acquired condition was found, genetic tests for BEST1 gene mutations were performed. These showed the dog to be homozygous for the cmr1 (C73T/R25X) gene defect. Furthermore, ultrasound (US), electroretinography (ERG), and optical coherence tomography were performed, confirming changes typical for cmr. Subsequently, the AS pedigree members were genetically and clinically tested, demonstrating autosomal recessive inheritance with no clinical symptoms in carrier animals, as was previously described for cmr. To our knowledge, this is the first reported case of canine multifocal retinopathy in the AS breed. Further investigations are under way.

Ultrastructure features of camel cornea--collagen fibril and proteoglycans.

Abstract: Introduction The uniform distribution of collagen fibrils and proteoglycans maintain the transparency of normal cornea. We describe the ultrastructural features of camel cornea including collagen fibrils and proteoglycans (PGs). Methods Camel corneas (of 6-, 8-, and 10-month-old animals) were fixed in 2.5% glutaraldehyde containing cuprolinic blue in sodium acetate buffer and processed for electron microscopy. The ‘AnalySIS LS Professional’ program was used to analyze the collagen fibril diameter. Results The camel cornea consists of four layers: the epithelium (227 μm), stroma (388 μm), Descemet’s membrane (DM), and endothelium. The epithelium constituted 36% of the camel cornea, whereas corneal stroma constituted 62% of the corneal thickness (629 μm). The PGs in the posterior stroma were significantly larger in number and size compared with the anterior and middle stroma. The collagen fibril diameter was 25 nm and interfibrillar spacing 40 nm. Fibrillar structures are present throughout the DM. Conclusion The structure of the camel cornea is very different from human and other animals. The unique structure of the cornea might be an adaptation to help the camel to survive in a hot and dry climate. The camel cornea may also be a good model to study the effect of hot and dry climates on the cornea.

Acute primary canine herpesvirus-1 dendritic ulcerative keratitis in an adult dog.

Abstract: We present a report of dendritic ulcerative keratitis in a 4-year old locally immunosuppressed dog suspected to result from acute primary canine herpesvirus-1 (CHV-1) infection. The dog was presented for evaluation of mild blepharospasm and conjunctival hyperemia in the right eye (OD) shortly after attending a public boarding facility. For approximately 3 months, the dog had been receiving topical prednisolone acetate 1.0% and tacrolimus 0.02% in both eyes (OU) q12h for treatment of follicular conjunctivitis. Ophthalmic examination revealed three regions of corneal fluorescein retention OD. The lesions had a dendritic pattern, were approximately 2-3 mm in length, and were located at the dorsomedial, lateral, and ventromedial aspects of the cornea. No additional abnormalities were noted on complete ophthalmic and physical examinations. CHV-1 was identified in conjunctival samples OD by polymerase chain reaction, and paired CHV-1 serum virus neutralization antibody titers were positive and consistent with acute infection. Topical prednisolone acetate and tacrolimus were discontinued. The dog was treated with cidofovir 0.5% OU q12h for a period of 4 weeks, with resolution of corneal disease noted within 1 week of treatment. In conjunction with previous studies, this case report supports a central role for alterations in host immune status in the pathogenesis and clinical manifestations of CHV-1 ocular disease in dogs.

Eosinophilic keratoconjunctivitis in two rabbits

Abstract: The purpose of this case report is to describe the clinical course and cytologic findings, treatment, and outcome of eosinophilic keratoconjunctivitis in two rabbits. Ophthalmic examination revealed ocular discharge, dacryocystitis, blepharitis, conjunctivitis, white conjunctival and corneal plaques, corneal vascularization, and stromal infiltration with different degrees of severity in each case. In case 2 there was also ulcerative disease of the cornea. Computerized tomography scan of the head, corneal biopsy for histopathologic examination with additional Luna and Giemsa stain were performed in case 2 and conjunctival as well as corneal specimens were obtained for bacteriologic culture and cytologic examination in case 1. Based on test results, a diagnosis of eosinophilic keratoconjunctivitis was made in case 2 and a tentative diagnosis of eosinophilic keratoconjunctivitis was made in case 1. Response to treatment with a topical steroid and topical cyclosporin was supportive of the diagnosis in both cases and shared many similarities with the response to treatment previously described in cats. Eosinophilic keratitis should be considered as part of a differential diagnosis list in rabbits with a history of keratitis.