Amniotic membrane transplantation for corneal surface reconstruction after excision of corneolimbal squamous cell carcinomas in nine horses

OBJECTIVE: The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate. STUDY: The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone or combined with strontium-90 irradiation and followed by placement of a permanent amniotic membrane graft in the surgical defect. The level of scarring (i.e. the clarity of the cornea) resulting with the use of amniotic membrane was subjectively compared to cases where a permanent bulbar conjunctival graft was performed following keratectomy combined with strontium-90 irradiation or cryotherapy (n = 3 eyes). Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe. RESULTS: The nine horses that received an amniotic membrane graft after keratectomy alone or combined with irradiation showed a minimal level of scarring in a cornea that regained a greater transparency in comparison to the horses that were treated with a bulbar conjunctival graft. All of the horses that received an amniotic membrane graft had 226 +/- 218 days of follow-up without tumor recurrence (mean +/- SD), ranging from 21 days to 778 days. CONCLUSIONS: The combination of superficial keratectomy alone or associated with beta-irradiation and permanent amniotic membrane transplantation is an effective treatment of corneal or corneolimbal SCC in horses. The placement of an amniotic membrane material represents an alternative surgical procedure to bulbar conjunctival grafts, especially if there is a lack of bulbar conjunctiva tissue available after tumor resection or if a particularly large corneal resection is necessary. The amniotic membrane is incorporated into the corneal defect and seems to create noticeably much less scarring than a corneal defect covered by bulbar conjunctiva.     

Corneal dermoid in a beef calf

A 10-mm circumscribed nodule, containing hair, was noted on the ventral cornea, limbus and conjunctiva of the right eye of a 6-month-old male Hereford calf. With the animal restrained in a chute and proparacaine used as a topical anesthetic, superficial keratectomy was performed to remove the mass. The edge of the bulbar conjunctival wound was sutured to the limbus with 6-0 Vicryl. Chloramphenicol ophthalmic ointment was applied TID for 5 days. Recovery was uneventful.     

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.     

Pigmented squamous cell carcinoma of the conjunctiva of a horse

Abstract A heavily pigmented tumor was removed from the lateral, perilimbal, bulbar conjunctiva of a bay Thoroughbred horse. Excision was incomplete and the base of the tumor was lasered on the assumption that the tumor was a melanoma. No other ophthalmic lesions were seen. Histology showed the mass to be a pigmented squamous cell carcinoma (SCC). The prognosis and recommended treatment protocols are different for SCC and melanoma. This is, to the best of our knowledge, the first report of an ocular, pigmented SCC in the veterinary literature.     

Structural and Histochemical Studies on the Teleostean Bulbus Arteriosus

The structure and histochemical properties of the bulbus arteriosus in two species from an evolutionary old teleost family, Characidae, and in three modern teleosts, family Cichlidae, are described. The bulbar wall was composed of an outer layer, a middle layer and a strongly folded inner layer covered by a thick, granule‐rich endothelial cell layer towards the lumen. One of the cichlid species (Thorichthys meeki) was injected intraperitoneally with horse ferritin; the endothelial cell layer of the heart atrium and ventricle displayed high ability to endocytose ferritin particles from the blood stream, but the corresponding layer in the bulbus arteriosus displayed no such uptake. This finding suggests that the bulbar endothelial cell layer plays no scavenger or immunological blood cleansing roles in this species. The bulbar endothelial cell granules were strongly coloured by periodic acid–Schiff (PAS) in the present cichlids, but weakly coloured by PAS in the present characids. These cell layers were uncoloured by alkaline carmine in ethanol in both cichlids and characids. The negative carmine test combined with a positive PAS test for the bulbar endothelial cell layer in the present cichlids indicates that these cells contain only small amounts of polysaccharides. The weak PAS‐colouring for the bulbar endothelial cell layer in characids indicates a very low content of sugars in these cells. These findings together with the fact that this cell layer in the present cichlids and characids was nearly uncoloured when treated with orcein, Heidenhain’s Azan or Schmorl’s solutions for elastic materials suggest that the bulbar endothelial granules do not play any role in the blood cleansing or in the rebuilding or maintenance of the ground substance or elastic material in the bulbar wall. Probably, the granules in the bulbar endothelial cell layer in the present species contain mainly proteins, connected to some PAS‐positive polysaccharides to enhance their solubility.     

Penetrating keratoscleroplasty and bimodal grafting for treatment of limbal melanocytoma in a dog

A 6-year-old, male neutered, German Shepherd dog presented for evaluation of a dark limbal mass OS. Based on the signalment and clinical findings, a presumptive diagnosis of limbal melanocytoma was made. Additionally, OU demonstrated corneal changes consistent with chronic superficial keratitis. Full thickness en bloc resection of the limbal mass was followed with reconstruction and grafting using both frozen cornea and bulbar conjunctiva. Nitrous oxide cryotherapy was utilized as an adjunctive modality for residual neoplastic cell destruction. Histopathologic evaluation confirmed the presumptive diagnosis. At 18 months postoperatively, there was no evidence of recurrence of the limbal melanocytoma. The dog was treated long-term with both topical steroid and tacrolimus 0.03% for control of the chronic superficial keratitis.     

Subconjunctival Dirofilaria repens infection in a dog resident in the UK

Dirofilaria repens infection was diagnosed in a 5‐year‐old female German shepherd crossbreed, originally from Romania but brought into the UK in February 2014. The dog presented with conjunctivitis in March 2014 and then again 2 months later with additional ocular and nasal mucopurulent discharge. Bacterial cultures from the nasolacrimal duct were negative for bacterial growth. The case was referred in August 2014 for ophthalmic examination, which revealed abnormalities in both eyes, especially the left. They included mild palpebral conjunctival hyperaemia and marked follicular conjunctivitis, as well as a dorsonasal bulbar conjunctival mass. Serum biochemistry was unremarkable and a conjunctival biopsy taken from the dorsonasal bulbar conjunctival mass revealed eosinophilic/lymphoplasmacytic conjunctivitis. At re‐examination, nematodes were found in the area of the previous biopsy site and in the ventral palpebral conjunctival fornix. Polymerase chain reaction and sequencing confirmed these to be D. repens. Treatment with 10% imidacloprid and 2·5% moxidectin (Advocate Spot‐On) was successful, and clinical signs resolved over a 6‐week period. This case report indicates that D. repens infection should be considered as a possible aetiological cause of ocular lesions in dogs in the UK, especially those with a history of foreign travel. Implications for establishment and spread of D. repens in the UK are discussed.     

Primary conjunctival mast cell tumor in a Labrador Retriever

A 4-year-old, intact male Labrador Retriever with a rapidly progressive conjunctival mass was evaluated. Ocular examination showed a 2-cm elongated mass arising from the superior bulbar conjunctiva of the left eye. The mass resulted in distortion of the palpebral fissure and contacted the superior aspect of the cornea without modifying its structure; no adhesion to the sclera was detected. The superior palpebral conjunctiva was unaffected, and the remaining ocular examination was normal. The initial diagnostic work-up included CBC, serum biochemical analysis, urinalysis, and fine needle biopsy of the mass. A poorly differentiated mast cell tumor was diagnosed by cytology. Immunocytochemistry was performed to evaluate Ki-67 proliferation index, and 54/1000 tumoral nuclei showed a dark red staining. After a complete clinical staging, the mass was excised and identified histologically as a grade-II mast cell tumor. An adjuvant treatment with prednisone and vinblastine was instituted because of the limited excisional margins. No evidence of local recurrence or metastasis has been apparent during the 29-month follow-up period. This report contributes to the current literature pertaining to canine conjunctival mast cell tumors; unfortunately, the paucity of case reports and the absence of large studies regarding this tumor make conclusions regarding its biologic behavior impossible.     

Evaluation of a soluble sustained-release ophthalmic delivery unit in the dog.

A 5-mg hydroxypropyl cellulose soluble ocular insert was evaluated by placement in the upper and the lower conjunctival and bulbar nictitating membrane fornices in normal dogs. The insert was easily placed in the conjunctival fornices, but was difficult to place in the bulbar nictitating membrane fornix. The conjunctival inserts did not produce irritation of the cornea and the conjunctiva. Placement of the inserts beneath the nictitating membrane produced local irritation and chemosis. The sites of highest to lowest retention for the insert were upper conjunctival fornix, bulbar nictitating membrane fornix, and lastly, lower conjunctival fornix. Dissolution was nearly complete in 8 hours.     

Isolated lepromatous conjunctivo-corneal granuloma in a cat from Italy

Objective  To describe a case of a conjunctivo-corneal mass in a cat associated with acid-fast bacilli.
Methods  A 2-year-old female black European Short-Hair cat, living outdoors in a suburban environment in Italy, was referred for evaluation of a nodular, vascularized mass of 2 weeks duration. The mass involved the dorsal bulbar conjunctiva at the temporal canthus of OS and invaded the sclera and cornea. Routine ophthalmic and systemic examination, serologic testing, cytology and histology of the mass were performed. Mycobacterium specific polymerase chain reaction (PCR) of variable regions 1, 2 and 3 of the 16S ribosomal RNA (rRNA) gene was also performed.
Results  Neutrophils, lymphocytes, macrophages and giant cells with intracytoplasmic acid-fast bacilli were seen on cytological examination. The histological examination confirmed the presence of a granulomatous lesion with acid-fast bacilli within macrophages. Bacteriological culture of the material from the lesion was negative for Mycobacterium spp. Mycobacterium 16S rRNA gene specific PCR was positive.
A diagnosis of feline leprosy was made. The owners refused any treatment, and 1 year later the lesion was still present.
Conclusions  Veterinary ophthalmologists should be aware of conjunctivo-corneal leproma as an unusual symptom of leprosy.     

Treatment of bilateral corneal ulceration in a Peregrine Falcon (Falco peregrinus) using 360 degree conjunctival flaps

A wild Peregrine Falcon (Falco peregrinus) was presented with extensive bilateral fluorescein positive corneal damage. Local therapy and bilateral tarsorrhaphies resulted in slow improvement over 5 weeks. When bilateral 360 degree conjunctival flaps were used subsequently, healing proceeded more rapidly over the next 8 weeks. Although bulbar conjunctival flaps have been reported as difficult in birds due to their small size and relatively immobile bulbar conjunctiva, 360 degree conjunctival flaps made from palpebral rather than bulbar conjunctiva were found to be technically feasible in a larger bird species such as the Peregrine Falcon.     

Co-existing squamous cell carcinoma and hemangioma on the ocular surface of a cat

A 14-year-old spayed female domestic short-haired cat was presented for evaluation of a mass in the right eye. Ophthalmic examination revealed a blind right eye and presence of two distinct masses: a pink and a red-to-brown mass, the latter occupying most of the cornea and part of the conjunctiva. Exenteration was performed under general anesthesia, and the ocular tissues were processed routinely for histopathology. Upon microscopic examination, a malignant epithelial neoplasm and a benign vascular neoplasm were present in the cornea. The conjunctiva and the third eyelid were also affected. Upon immunohistochemistry, the epithelial tumor was positive for cytokeratin and negative for vimentin and the endothelial tumor was negative for cytokeratin and positive for vimentin. A diagnosis of squamous cell carcinoma (SCC) and hemangioma was made. The SCC was affecting the cornea, bulbar conjunctiva (lateral and inferior) and the base of the third eyelid, whereas the hemangioma was affecting the cornea and medial limbus. To the authors' knowledge, this is the first report of concomitant SCC and hemangioma affecting the ocular surface in a cat.     

Mast cell tumor invading the cornea in a horse

A 3‐year‐old Marwari mare was presented for evaluation of an irregular, reddish mass protruding from behind the right third eyelid. The mass appeared to arise at the ventral limbal area, involved the perilimbal bulbar conjunctiva and widely extended into corneal tissue. No other ocular or systemic abnormalities were detected at the time of presentation. The mass was surgically removed by lamellar keratectomy, with defocused CO₂ laser used as adjunctive therapy to treat the surgical exposed area and its surroundings. Histopathologic evaluation showed sheets of densely packed, well‐differentiated neoplastic mast cells separated by fibrovascular connective tissue. Nuclear staining for Ki‐67 was performed, and an average of 370 cells were positive per 1000 counted cells. Two months postoperatively, the surgical site was filled with flat fibrovascular and pigmented tissue, while the surrounding cornea was transparent with no superficial vascularization around the fibrotic scar. Thirty‐two months after treatment, no recurrence of the neoplasia was reported.     

The conjunctival crypt of the equine third eyelid

The purpose of this study is to characterise the gross anatomy of a relatively large, cryptic structure within the bulbar conjunctival surface of the equine third eyelid that has commonly been observed by the authors during equine ophthalmic examinations. In this study, cadaveric eyes and adnexa were obtained from 13 Quarter Horses without history of ocular disease. The gross anatomy of the bulbar surface of the third eyelid was characterised by digital macrophotography and with an image capture system using an operating microscope. A well-defined cryptic structure was readily identified in the majority of eyes (17/26). The location of the crypt varied but was most commonly observed within the central aspect of the bulbar surface of the third eyelid, often in close proximity to prominent blood vessels oriented perpendicular to the leading edge of the third eyelid. A patch of lymphoid follicles was often observed surrounding the crypt. The rectangular shape and upward facing orientation of the crypt was akin to a shirt's breast pocket. Width and depth were variable but ranged between 1 and 8 mm in either dimension. Some crypts were complex, with multiple channels observed within the primary opening. In conclusion, this study confirms the presence of a well-organised mucosal crypt within the bulbar surface of the equine third eyelid capable of harbouring foreign material and ocular irritants. Additional anatomical characterisation of the macro-crypt by light microscopy, immunohistochemistry and electron microscopy is underway. Evaluation of this structure by equine practitioners and veterinary ophthalmologists should be performed during the routine ophthalmic examination to better understand its role in ocular disease.     

Feline conjunctival melanoma: histopathological characteristics and clinical outcomes

Purpose  We report on the histopathology and clinical features of 21 cases of feline conjunctival melanoma.
Methods  A total of 18 cases are from the COPLOW collection and three cases from Antech Diagnostics. We tabulated the location of the tumor, pigmentation, cell shape, mitotic index and presence of multinucleated tumor cells. Surveys were sent to referring ophthalmologists to obtain further information about each case.
Results  The mean age of the cats was 12.4 years. A total of 11 cases were neutered males, six spayed females, and one each of intact female and male. Thirteen of the 21 cases were located on the bulbar conjunctiva, three on third eyelid only, three on palpebral conjunctiva. Sixteen tumors were pigmented while five were amelanotic. Seventeen of the cases consisted of round cell only while four cases were mixed populations of round and spindle cell. Fourteen of the cases contained multinucleated cells. The mitotic index ranged from 0 to 45 mitotic figures/10 HPF. Of the 13 cases with adequate follow-up information, four showed local recurrence while three reported metastasis. Eight cats had died at the time of the survey. Survival time post-diagnosis ranged from 0.5 to 36 months. Two cases had metastasized to the submandibular lymph nodes and in a third case, an abdominal mass was detected.
Conclusions  Feline conjunctival melanoma is most frequently found on the bulbar conjunctiva, are mostly round cells and suggest that conjunctival melanoma in cats has a poorer long term prognosis than the same neoplasm in dogs.     

A case of conjunctival melanoma in a cat

Since 1985, 5 cases of feline conjunctival melanoma have been reported in the literature. Information on feline conjunctival melanoma epidemiological features, localizations, macroscopic features and histological features is limited. We are describing the clinical, histopathologic features and outcomes in a cat that presented clinically with a slow developing dark brown mass located under the upper eyelid of the left eye. Pertinent literature is reviewed; and the recognizable clinical features and treatment are discussed. The mass was surgically resected. Despite its size, the lesion was easily separated from underlying tissues, making possible a macroscopic complete resection that left intact the adjacent conjunctiva. The tumour histological examination has showed a pigmented melanoma lacking encapsulation, but presenting a clear zone delimiting the lesion. It was exclusively composed of epithelioid cells, and presented mild cellular anaplasia and weak mitotic activity. These features allowed it to be classified as a quite differentiated melanoma with few signs of potential malignancy. In accordance with these histologic features, no recurrence has been registered 34 months after surgery. Thus, a favorable outcome is now reported for two out of six cases of conjunctival melanoma in the cat. This report also confirms the predilection for this neoplasm to arise from the bulbar conjunctiva.     

Suprascleral removal of a foreign body from the retrobulbar muscle cone in two dogs

The successful application of a suprascleral approach to remove a foreign body within the retrobulbar muscle cone in two dogs is described. The episcleral space was entered through a small opening in the paralimbal conjunctiva and bulbar vagina. Under ultrasound guidance, a curved haemostat with a fine tip was advanced along the scleral surface to the foreign body, which was then carefully grasped and removed using gentle traction. The conjunctival incision was left to heal secondarily. The suprascleral approach may allow the quick removal of non-cutting and non-barbed foreign bodies from the episcleral space or the retrobulbar muscle cone, without the need for extensive tissue dissection. To reduce the risk of damaging extraocular tissues, the procedure must be performed cautiously and under ultrasound guidance. The globe should be continuously observed for any movement suggesting traction or pushing forces on bulbar or adjacent anatomical structures.     

Bilateral palpebral reduction and concurrent mycoplasmosis in a wild Agassiz's desert tortoise (Gopherus agassizii)

A wild Agassiz's desert tortoise, Gopherus agassizii, with bilateral eyelid reduction and plaques of tissue covering the superior surface of both corneas was examined in the field and subsequently submitted to the University of Florida for diagnostics. Polymerase chain reaction (PCR), from a swab of both corneas, was positive for Mycoplasma agassizii. Two months later, the tortoise was euthanatized and necropsied. There was increased bulbar exposure associated with dermal excoriation of periocular scales in both superior and inferior palpebra resulting in an increased palpebral fissure opening. Concurrently, there was bilateral conjunctivitis of the nictitating membranes and squamous metaplasia of the bulbar conjunctiva. Using PCR, Mycoplasma testudineum, another pathogen of tortoises, was identified in both nasal cavities, and the upper respiratory tract histopathological findings were consistent with those described for M. testudineum in Agassiz's desert tortoises. Although eye disease has been reported in desert and gopher (Gopherus polyphemus) tortoises with mycoplasmosis, widespread loss of palpebral tissue, conjunctivitis of the nictitans, and squamous metaplasia of the bulbar conjunctiva have not been reported in tortoises.