Diamond burr debridement of calcific band keratopathy in 24 eyes of 22 horses.

PURPOSE: To evaluate the safety and effectiveness of diamond burr debridement (DBD) for the treatment of calcific band keratopathy (CBK) in horses. METHODS: Medical records from horses with CBK were reviewed over a period of 4 years. Diagnosis of CBK was based on slit-lamp examination findings, and DBD was performed on standing sedated horses. Follow-up was obtained by clinical reevaluation of the treated eyes or a telephone survey with the referring veterinarian. RESULTS: Twenty-two horses of different ages (median: 11 years; range: 5-23) representing 24 CBK-affected eyes (14 left eyes and 10 right eyes) were included in the study. The patients had a medical history of chronic and recurrent uveitis, which required repeated long-term treatments with various combinations of ophthalmic corticosteroids. DBD alone cleared the cornea in 22 affected eyes (92%), but it was combined with blade scraping in two cases with thick calcium plaques. The postoperative medication included a topical antibiotic, atropine drops, and oral flunixin meglumine. Corneal healing was achieved in 21 eyes (87%), 5-21 days (median time 13 days) postoperatively. The three remaining horses were lost to follow-up. Recurrence occurred in 5 of the 21 (24%) reexamined eyes, 3-12.5 weeks (median 8 weeks) postoperatively, and required a second DBD. Four of the 21 eyes ended up being enucleated due to sequelae of uveitis. The main limitations of the study include those inherent to all retrospective clinical data collections. CONCLUSION: Mechanical DBD can readily and safely clear the cornea in horses with CBK, but recurrence of calcium deposition is possible.

Pyogenic granuloma of the cornea in a pony: Uncommon complication of corneal wound healing.

A 6-year-old miniature Shetland pony mare was referred for evaluation of a left corneal mass, which developed from the healing tissue of a corneal traumatic ulceration that had occurred 4 weeks previously. On gross examination, a spherical, smooth-surfaced, and pink-colored lesion of about 1 cm in diameter was protruding from the left palpebral fissure. Ophthalmic examination revealed that it was attached to the scar tissue of the cornea, and that one corpora nigra was adherent to the posterior face of corneal wounded area, without sign of uveitis. The remainder of the ophthalmic examination was unremarkable. The mass was excised, and cryotherapy was used as an adjunctive therapy. Histopathology of the resected mass was consistent with a pyogenic granuloma on the basis of radially oriented proliferating capillaries, embedded in immature granulation tissue containing an infiltrate of neutrophils, plasma cells and eosinophils. There were no histological features of malignancy. 2 months after surgery, the ventral part of the fibrotic corneal scar was slightly raised by a pink tissue, suggesting possible recurrence of the initial lesion. A second cryotherapy was performed over the leukoma area. No recurrence has been noted for a follow-up period of more than 25 months. Pyogenic granuloma is a benign proliferative fibrovascular response that typically develops after trauma or surgery. Corneal involvement is rare in humans, and to the authors' knowledge has never been documented in veterinary ophthalmology.

Conjunctival calcinosis circumscripta in a dog: Treatment combining surgical resection and amniotic membrane grafting.

This report describes the clinical features, histopathology, and surgical treatment of a case of conjunctival calcification in a 5-month-old female English Setter, referred with a history of recurrent conjunctivitis in the right eye (OD). The ophthalmic findings were limited to multifocal white plaques embedded in a markedly inflamed conjunctiva of the eyelids and the anterior nictitating membrane OD. Calcification was suspected. The blood cell count, blood chemical profile, and urinalysis were within normal limits, and long-bone radiographs appeared normal. After removal of the affected area by means of a large conjunctivectomy, cryopreserved canine amniotic membrane (AM) was transplanted to fill in the defect. Multifocal ectopic calcium deposits in the conjunctival lamina propria were confirmed histopathologically. The postoperative healing was uneventful, and no recurrence was observed during a follow-up period of five years. Conjunctival mineralization is uncommon in canine ophthalmology, and the cause remained undetermined in the present case, for which AM transplantation was able to promote conjunctival healing after a large surgical excision.

Corneal anesthesia associated with topical application of 2% lidocaine nonophthalmic gel to healthy canine eyes.

OBJECTIVE: To assess the degree and duration of corneal anesthesia induced by topical application of 2% lidocaine gel to the healthy canine eye. ANIMALS: Nineteen adult Beagles free of ocular abnormalities. PROCEDURES: Baseline corneal touch threshold (CTT) was measured bilaterally with a Cochet-Bonnet aesthesiometer. The 2% lidocaine gel (0.1 mL) was applied to one eye, randomly assigned, and the same volume of a lubricant gel was applied to the opposite eye. The CTT measurements were repeated bilaterally within 1 minute, after drug application, and every 5 minutes, until the baseline corneal sensitivity was restored. The potential for local adverse effects was evaluated. RESULTS: Complete desensitization of the cornea (CTT = 0) was achieved one minute after lidocaine gel application and was maintained during 25.3 ± 12.5 minutes. Overall, the corneal sensitivity was significantly decreased for 58.4 ± 16.6 minutes compared with baseline level. Minor and reversible punctate epithelial erosions of the cornea were observed in the two treatment groups and were attributed to the anesthetic effect and the aesthesiometry procedure. CONCLUSIONS: In the current study, the 2% lidocaine gel provided a sustained, deep and well-tolerated corneal anesthesia in ophthalmically normal dogs.

Subconjunctival nodule due to Setaria equina erratic migration in a horse: First case report.

An 18-month-old Arabian-English filly resident in southwest France was referred for evaluation of a conjunctival mass in the right eye (OD). A pink, solid, and mobile nodular formation, measuring approximately 1.2 × 0.8 cm was found under the superior nasal bulbar conjunctiva during an ophthalmic examination that was otherwise normal. The mass was surgically removed using a standing procedure. Cytological examination of fine-needle aspirates from the mass revealed a mixed eosinophilic-lymphocytic inflammation. Histological examination confirmed the dense and diffuse eosinophilic-lymphocytic infiltrate of the mass, and it revealed several cross sections of a parasitic nematode. The morphometric diagnosis identified an immature form of a filarial worm, and molecular analysis of the mitochondrial cytochrome c oxydase subunit 1 (cox1) and 12S rRNA gene sequences led to further identification of the specimen as Setaria equina. Microfilaremia was not observed on fresh blood smears. There have been no signs of local recurrence after 18 months, nor any evidence of intraocular involvement. To the authors' knowledge, this is the first documented case of subconjunctival setariasis due to S equina in a horse.

Congenital lacrimal fistula in two prim'Holstein calves.

Two 4- and 8-month-old prim'Holstein calves were presented for chronic epiphora. Examination of the affected eyes revealed an abnormal duct opening inferonasal to the medial canthus. A diagnosis of congenital lacrimal fistula was made based on conventional and computed tomographic-dacryocystography findings. These revealed an ectopic channel connecting the nasolacrimal duct to the skin opening near the medial canthus. Both of the calves were surgically treated with resection and closure of the ectopic duct and placement of a nasolacrimal stent.

Changes in pupil size and intraocular pressure after topical application of 0.5% tropicamide to the eyes of dogs sedated with butorphanol.

OBJECTIVE: To assess changes in pupil size and intraocular pressure (IOP) following topical application of a 0.5% tropicamide solution in the eyes of healthy butorphanol-sedated dogs. ANIMALS: 12 healthy adult Beagles. PROCEDURES: In a randomized crossover study consisting of 2 treatment periods with a 1-week washout between periods, dogs received an IM injection of butorphanol (0.2 mg/kg) or an equal volume of sterile saline (0.9% NaCl) solution. For each dog, 1 drop of 0.5% tropicamide ophthalmic solution was topically instilled in one eye and 1 drop of artificial tear solution was topically instilled in the other eye 10 minutes after the IM injection and again 5 minutes later. Extent of sedation, pupil size, and IOP were evaluated from 20 minutes before to 80 minutes after the IM injection and compared among treatment combinations. RESULTS: Butorphanol induced mild (n = 9) or moderate (3) sedation in all dogs and slightly delayed the onset of, but did not prevent, tropicamide-induced mydriasis. Butorphanol caused a significant increase in IOP, which was not exacerbated by tropicamide-induced mydriasis; however, that increase was generally not sufficient to exceed the upper limit of the IOP reference range. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that butorphanol did not prevent tropicamide-induced mydriasis but did increase the IOP in ophthalmologically normal Beagles. Although the butorphanol-induced increase in IOP did not appear clinically relevant for the dogs of this study, that may not be true for dogs with glaucoma, and care should be taken when butorphanol is administered to such dogs.

Effect of topical application of 2% lidocaine gel on corneal sensitivity of clinically normal equine eyes.

OBJECTIVE: To assess the degree and duration of corneal anaesthesia provided by topical application of a non-ophthalmic 2% lidocaine gel in horses. STUDY DESIGN: Experimental, 'blinded', randomized prospective study. ANIMALS: Twelve adult horses without relevant ocular abnormalities. METHODS: Baseline corneal touch threshold (CTT) measurements were obtained bilaterally by use of a Cochet-Bonnet aesthesiometer just prior to topical treatment. A volume of 0.2mL of 2% lidocaine gel was administered in one randomly selected eye and the same volume of a viscous lubricant in the other eye to serve as control. The CTT value was measured on both eyes 5, 10, 20, 30, 45, 60, 75 and 90 minutes after drug application. The potential for local adverse effects following lidocaine gel application was also evaluated. RESULTS: Mean CTT baseline measurements were not significantly different (p>0.05) between the control eyes (3.41±0.56cm) and those subsequently treated with the lidocaine gel (3.50±0.64cm). In control eyes, no significant changes in corneal sensitivity (p>0.05) occurred over time during the study period. By contrast, a marked reduction in corneal sensitivity was observed after lidocaine application, with mean CTT values significantly lower (p<0.001) than those of the control eyes from 5 to 75 minutes. A steady-state maximal corneal anaesthesia was present from 10 to 45 minutes after lidocaine gel application with mean CTT values ranging from 0.21 to 0.45cm. Corneal epithelial irregularities were detected in three lidocaine-treated eyes, but spontaneous resolution occurred within 24hours. CONCLUSIONS AND CLINICAL RELEVANCE: Deep and sustained corneal anaesthesia is achieved after application of 2% lidocaine gel to the equine eye, with minimal changes in the corneal epithelium. It might be useful for minor ophthalmic surgeries performed in the standing sedated horse.

Effect of sedation with butorphanol on variables pertaining to the ophthalmic examination in dogs.

OBJECTIVE: To evaluate whether sedation with intramuscular butorphanol can interfere with different variables of the ocular examination in dogs. ANIMALS: Twenty-two beagles without ophthalmic abnormalities. PROCEDURES: Each dog was examined 20 min prior to and again just before administration of butorphanol to establish baseline data. The globe and nictitating membrane position was evaluated, and the following were recorded: menace response, dazzle reflex, corneal blink reflex, phenol red thread tear test (PRT), Schirmer tear test-1 (STT-1), pupil size (PS) measurement, and rebound tonometry. Then, butorphanol was injected intramuscularly at a dose of 0.2 mg/kg and these procedures were repeated 10, 20, 30, and 45 min postadministration. A sedation score graded 0 to 3 was also established at these time points. Statistical analyses were performed on quantitative data using ANOVA. RESULTS: The sedative effect was not associated with any changes in globe and nictitating membrane position; did not affect the results of the menace response, dazzle reflex, and corneal blink reflex; and had no significant effect on PRT values. However, butorphanol administration was associated with a statistically significant decrease in STT-1 and PS values (P < 0.005), and a statistically significant increase in IOP (P < 0.05). All these variations remained in the range of normal values. CONCLUSIONS AND CLINICAL RELEVANCE: Butorphanol administered intramuscularly at 0.2 mg/kg provided a degree of sedation allowing eye examination, but was found to interfere with STT-1, PS, and IOP values among the diagnostic tests studied. However, these values remained within normal limits.

Preliminary study of the safety and efficacy of medium-chain triglycerides for use as an intraocular tamponading agent in minipigs.

PURPOSE: To date, only silicone oils and gases have the appropriate characteristics for use in vitreo-retinal surgery as vitreous substitutes with intraocular tamponading properties. This preliminary study evaluated the safety and efficacy of medium-chain triglycerides (MCTs) for use as a tamponading agent in minipigs. METHODS: In 15 minipigs, 15 right eyes underwent vitrectomies followed by injection of MCT tamponade (day 1). Two groups were defined. In Group A (ten eyes), the surgical procedure before MCT injection included induced rhegmatogenous retinal detachment (RRD), retina flattening, and retinopexy. In Group B (five eyes), MCT was injected without inducing RRD; in these eyes, MCT was removed on day 90. Pigs were sacrificed on day 45 (Group A) or 120 (Group B). Eyes were examined on days 1, 5, 15, and 45 in both groups and on days 90 and 120 in Group B. In Group B only, we performed bilateral electroretinography examinations on days 1 and 120, and histological examinations of MCTs and controlateral eyes were performed after sacrifice. RESULTS: In Group A eyes (n = 9; one eye was non-assessable), on day 45, the retina was flat in seven eyes and two RRD detachments were observed in insufficiently MCT-filled eyes. In Group B, electroretinography showed no significant differences between MCT eyes and controls on days 1 or 120. Histological analyses revealed no signs of retinal toxicity. CONCLUSIONS: This study showed that MCT tamponade seems to be effective and safe; however, additional studies are needed before it becomes commonly used as a tamponading agent in humans.

Submicroscopic deletions at 13q32.1 cause congenital microcoria.

Congenital microcoria (MCOR) is a rare autosomal-dominant disorder characterized by inability of the iris to dilate owing to absence of dilator pupillae muscle. So far, a dozen MCOR-affected families have been reported worldwide. By using whole-genome oligonucleotide array CGH, we have identified deletions at 13q32.1 segregating with MCOR in six families originating from France, Japan, and Mexico. Breakpoint sequence analyses showed nonrecurrent deletions in 5/6 families. The deletions varied from 35 kbp to 80 kbp in size, but invariably encompassed or interrupted only two genes: TGDS encoding the TDP-glucose 4,6-dehydratase and GPR180 encoding the G protein-coupled receptor 180, also known as intimal thickness-related receptor (ITR). Unlike TGDS which has no known function in muscle cells, GPR180 is involved in the regulation of smooth muscle cell growth. The identification of a null GPR180 mutation segregating over two generations with iridocorneal angle dysgenesis, which can be regarded as a MCOR endophenotype, is consistent with the view that deletions of this gene, with or without the loss of elements regulating the expression of neighboring genes, are the cause of MCOR.

Corneal anesthesia following application of 0.4% oxybuprocaine hydrochloride ophthalmic solution to normal feline eyes.

OBJECTIVE: To evaluate the loss and recovery of corneal sensitivity after instillation of 0.4% oxybuprocaine hydrochloride solution in the normal feline eye. ANIMAL STUDIED: Eighteen European shorthair cats free of ocular disease PROCEDURES: Baseline corneal touch threshold (CTT) readings were obtained bilaterally with a Cochet-Bonnet aesthesiometer prior to treatment. Subsequently, each cat received a single drop of 0.4% oxybuprocaine ophthalmic solution in the right eye and one drop of sterile 0.9% NaCl in the left eye to serve as control. The corneal touch threshold (CTT) of both eyes was then measured 1 min after drug administration and every 5 min for 60 min. The potential for ocular irritation following oxybuprocaine application was also evaluated. RESULTS: Baseline CTT readings were not significantly different (P > 0.05) between the control and oxybuprocaine-treated eyes with values of 1.75 ± 0.31 cm and 1.75 ± 0.30 cm, respectively. In control eyes, mean CTT did not significantly change (P > 0.05) during the study period. By contrast, after oxybuprocaine application mean CTT was significantly reduced from baseline (P < 0.05) for 45 min. Maximal corneal anesthesia, with a CTT value of 0, was achieved at 1 and 5 min in all treated eyes. A markedly reduced mean CTT of 0.14 ± 0.23 cm was still present at 20 min. Age and gender did not significantly affect corneal anesthesia. No clinically relevant ocular side effects occurred during the observation period. CONCLUSION: This is the first study that provides objective information on the depth and duration of corneal anesthesia following instillation of oxybuprocaine in healthy feline eyes.

Degree and duration of corneal anesthesia after topical application of 0.4% oxybuprocaine hydrochloride ophthalmic solution in ophthalmically normal dogs.

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.

Florfenicol concentrations in ovine tear fluid following intramuscular and subcutaneous administration and comparison with the minimum inhibitory concentrations against mycoplasmal strains potentially involved in infectious keratoconjunctivitis.

OBJECTIVE: To measure florfenicol concentrations in ovine tear fluid after IM and SC administration and determine minimum inhibitory concentrations (MICs) of florfenicol against field isolates of Mycoplasma organisms potentially involved in infectious keratoconjunctivitis. ANIMALS: 9 healthy adult Lacaune ewes. PROCEDURES: Animals received an IM and SC administration of florfenicol (20 mg/kg) in a 2-way crossover design. Samples of blood and tear fluid were collected before and for 24 hours after administration. Concentrations of florfenicol in plasma and tear fluid were measured via high-performance liquid chromatography. The MIC of florfenicol for various Mycoplasma strains cultured from sheep and goats was determined via an agar dilution method. RESULTS: Mean florfenicol concentration in tear fluid for the 24-hour period was significantly higher after IM administration (0.70 µg/mL) than after SC administration (0.22 µg/mL) and was maintained for a longer duration. The lacrimal fluid-to-plasma concentration ratio was not different between the 2 routes of administration, with mean values of 40.2% and 32.5% after IM and SC administration, respectively. The MIC for Mycoplasma agalactiae, Mycoplasma conjunctivae, and Mycoplasma mycoides isolates ranged from 0.5 to 8 µg of florfenicol/mL. Two strains of M agalactiae could be considered resistant to florfenicol. CONCLUSIONS AND CLINICAL RELEVANCE: Florfenicol readily penetrated the preocular tear fluid of sheep after IM and SC administration. For both routes of administration, doses > 20 mg/kg would be necessary to achieve tear fluid concentrations of florfenicol greater than the MICs for most strains of Mycoplasma organisms.

Infectious sacroiliitis: a retrospective, multicentre study of 39 adults.

BACKGROUND: Non-brucellar and non-tuberculous infectious sacroiliitis (ISI) is a rare disease, with misleading clinical signs that delay diagnosis. Most observations are based on isolated case reports or small case series. Our aim was to describe the clinical, bacteriological, and radiological characteristics of ISI, as well as the evolution of these arthritis cases under treatment. METHODS: This retrospective study included all ISI cases diagnosed between 1995 and 2011 in eight French rheumatology departments. ISI was diagnosed if sacroiliitis was confirmed bacteriologically or, in the absence of pathogenic agents, if clinical, biological, and radiological data was compatible with this diagnosis and evolution was favourable under antibiotic therapy. RESULTS: Overall, 39 cases of ISI were identified in adults, comprising 23 women and 16 men, with a mean age at diagnosis of 39.7 ± 18.1 years. The left sacroiliac joint (SI) was affected in 59% of cases, with five cases occurring during the post-partum period. Lumbogluteal pain was the most common symptom (36/39). Manipulations of the SI joint were performed in seven patients and were always painful. Mean score for pain using the visual analogue score was 7.3/10 at admission, while 16 patients were febrile at diagnosis. No risk factor was found for 30.7% of patients. A diagnosis of ISI was only suspected in five cases at admission. The mean time to diagnosis was long, being 43.3 ± 69.1 days on average. Mean C-reactive protein was 149.7 ± 115.3 mg/l, and leukocytosis (leukocytes ≥ 10 G/l) was uncommon (n = 15) (mean level of leukocytes 10.4 ± 3.5 G/l). Radiographs (n = 33) were abnormal in 20 cases, revealing lesions of SI, while an abdominopelvic computed tomography (CT) scan (n = 27) was abnormal in 21 cases, suggesting arthritis of the SI joints in 13 cases (48.1%) and a psoas abscess in eight. Bone scans (n = 14) showed hyperfixation of the SI in 13 cases. Magnetic resonance imaging (MRI) (n = 27), when focused on the SI (n = 25), directed towards the diagnosis to ISI in 25 cases. Pathogenic agents were isolated in 33 cases (84.6%) by means of articular puncture (n = 16), blood culture (n = 14), cytobacteriological examination of urine (n = 2), or puncture of the psoas (n = 1).Gram-positive cocci were the mostly isolated common bacteria, with a predominance of staphylococci (n = 21). The most frequently isolated gram-negative bacillus was Pseudomonas aeruginosa (n = 3). Evolution was favourable in 37 out of 39 patients under prolonged antibiotic therapy (mean duration 3.01 ± 1.21 months). CONCLUSION: Our series confirmed that the clinical manifestations of ISI usually lead to delayed diagnosis. Based on our results, we suggest performing an MRI of the spine and SI in clinical situations characterised by lumbogluteal pain and symptoms of an infectious disease, such as fever.

Histopathologic features of canine distichiasis.

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.

Clinical, electroretinographic and histomorphometric evaluation of the retina in sheep with natural scrapie.

BACKGROUND: The retina is part of the diencephalon in a peripheral location and may be involved in prion diseases. Retinal function and structural changes were assessed in naturally scrapie-affected red face Manech ewes presenting the classical signs of the disease, and clinically healthy age-matched subjects for controls. Ophthalmic examination was done prior to electroretinography (ERG), which was carried out under conditions that allowed photopic and scotopic activities to be assessed. Histomorphometry of the inner and outer retinal layers was performed post-mortem, and retinas were also examined for evidence of abnormal prion protein (PrPSc) accumulation and glial fibrillary acidic protein (GFAP) upregulation as a marker of gliosis. Scrapie status was determined by examination of brain tissue RESULTS: Ocular reflexes and ophthalmoscopy did not reveal any difference between scrapie affected and control animals. Although the light-and dark-adapted ERG responses of both rod-and cone-mediated functions had a similar waveform in scrapie-affected and control sheep, a significant reduction in the amplitude of the ERG a-and b-waves was observed in affected animals compared to controls. These functional alterations were correlated with a substantial loss of cells in the outer nuclear layer (ONL), lengthening and disorganization in photoreceptor segments, and substantial reduction in cellularity and thickness of the inner nuclear layer (INL). The degenerative changes in the INL and ONL were most marked in the central and paracentral areas of the scrapie retinas, and were accompanied in all scrapie retinas by PrPSc deposition in the ganglion cell and synaptic layers. GFAP immunoreactivity was mainly increased in the ganglion cell and inner plexiform layers. CONCLUSIONS: No appreciable fundoscopic changes were observed in the scrapie-affected ewes although reproducible changes in retinal function as measured by ERG were observed in these animals. The alterations in the receptoral and post-receptoral pathways corresponded to the degenerative lesions observed in the ONL and INL of the scrapie retinas. The retinal degeneration was associated with prion protein infectivity which presumably spread via the optic nerve.

Choroidal melanocytoma in a cat.

An 11-year-old male, neutered European cat was presented for anisocoria due to pupillary dilation in the right eye. Ophthalmic findings were restricted to this eye and consisted of a raised, darkly pigmented, retrolental mass associated with retinal detachment. Ultrasonography identified the mass lesion protruding into the vitreous cavity from the posterior pole of the eyeball and confirmed the detachment of the retina. A tentative diagnosis of an intraocular tumor was made. Radiographic evaluation and retromandibular lymph node cytology did not reveal evidence of distant metastasis. Orbital exenteration of the affected eye was performed and the tumor was diagnosed as a choroidal melanocytic tumor with no criteria of malignancy (melanocytoma). The cat died 5 months later from renal lymphoma, and necropsy did not detect metastasis of the melanocytic tumor. To our knowledge this is the first reported case of feline choroidal melanocytoma.

Keratoprosthesis with retrocorneal fixation: preliminary results in dogs with corneal blindness.

OBJECTIVE: To evaluate the use and complications of a penetrating keratoprosthesis implantation in the management of corneal opacification in dogs. METHODS: A retrospective clinical study describes the indications for the surgical technique utilized and the outcomes of this procedure in 20 eyes of 19 dogs with blindness of corneal origin. A successful surgical outcome was defined as a clear keratoprosthesis optic and improvement or restoration of functional vision over a follow-up period ranging from at least 8 months to a maximum of 7 years. RESULTS: Eyes with total corneal opacification resulting from chronic superficial keratitis (n = 11), keratoconjunctivitis sicca (n = 5), endothelial dystrophy (n = 3) and chemical burn (n = 1) were treated by unilateral (n = 18) or bilateral (n = 1) full-thickness implantation of a keratoprosthesis. Keratoprostheses were retained in 15 eyes (75%) which regained vision to the date of reporting. Among these eyes, six had uncomplicated postoperative course, five developed retroprosthetic membranes and four developed granulation tissue over the optic of the keratoprostheses. These complications were successfully removed surgically in the nine eyes. The five remaining eyes (25%) developed serious early postoperative complications, for which enucleation had to be performed. CONCLUSION: In keratopathies in which the corneal opacification could not be treated by standard medical or surgical procedures, this keratoprosthesis appears to be promising to restore vision in chronic superficial keratitis and deep corneal dystrophy. It appears to have a poor prognosis in keratoconjunctivitis sicca in brachycephalic dogs. The post operative complications retro-prosthetic membranes and granulomatous overgrowth could be treated well.