Resumo

Background: The treatment of glaucoma often requires numerous therapeutic modalities to achieve the desired reduction in intraocular pressure (IOP). Cyclodestructive procedures or ciliary body destruction have been performed using techniques with considerable differences in efficacy and complication rates. Among these methods, cyclocryotherapy is non-invasive and simple for the management of uncontrolled glaucoma in dogs and cats. The objective of this case report is to describe the technique of carbon dioxide cyclocryotherapy to reduce intraocular pressure in dogs and cats with glaucoma. Cases: Nine canine patients and one cat with glaucoma were treated with cyclocryotherapy performed under general anaesthesia. Clinical signs patients included blepharospasm, ocular pain, episcleral congestion and ocular hypertension. The patients showed higher levels of IOP, higher than 30 mmHg. Surgical treatment with general anaesthesia was applied. The pre-anaesthesia protocol included acepromazine 0.05 mg/kg with methadone 0.2 mg/kg, followed by intravenous propofol and maintenance with isoflurane and oxygen. An ophthalmological cryocautery unit was used with carbon dioxide as the cryogenic agent and a retinal cryoprobe of 3.2 mm diameter tip for the procedure. The method used was a double cycle of freezing and thawing for 60 s in each site. The cryoprobe was centred approximately 5 mm posterior to the corneoscleral limbus over the ciliary body. The temperature of each cyclocryotherapy spot was between -60°C and -80°C and each site was maintained in place for 60 s; 4 to 6 spots of the double freeze-thaw cycle were made. This technique did not have any serious complications during or after the application of cryotherapy, but chemosis and hyperaemia of the bulbar conjunctiva developed. Subconjunctival anti-inflammatory steroids were injected to minimise swelling and patient discomfort. Satisfactory results were observed; in all cases, the intraocular pressure decreased, with the usual result being a cosmetic and painless eye. Discussion: Even with recent surgical and medical advances, pain and blindness are still common occurrences in glaucoma in human and veterinary practice. The cyclodestructive procedures included cyclodialysis, cyclodiathermy, cyclocryotherapy, and cyclophotocoagulation. The cryosurgery in veterinary ophthalmology has many indications for the treatment of ocular diseases and is effective at decreasing intraocular pressure in patients with persistent uncontrolled glaucoma. Cyclocryotherapy has been shown to reduce intraocular pressure in dogs, cats, rabbits and humans with normotensive and glaucomatous eyes. The application of a cryoprobe over the ciliary processes results in ablating ciliary tissue so that aqueous humour inflow is reduced to acceptable levels. In the clinical cases evaluated, there was a reduction in intraocular pressure reaching acceptable levels, with the usual result being cosmetic and painless eye. Medical therapy remains the predominant method for treating glaucoma in veterinary patients; therefore, cyclocryotherapy is an effective, simple way to lower IOP and is a reasonable treatment option for glaucoma management. Cyclocryotherapy has shown good results, with a low learning curve and it can also be repeated if necessary.

Resumo

Background: Eyelid colobomas are congenital and developmental disorders. Generally, they affect the temporal portion of the upper eyelids of cats, bilaterally. This ocular defect is accompanied by trichiasis associated with pain and ulcerative keratitis. Any breed can be affected and it has been reported in Domestic Shorthair, Persian, Burmese, Mongrel cats and captive felids. The objective of this case report is to describe the technique of dioxide carbon cryosurgery for the treatment of eyelid coloboma in felines. Cases: Seven mongrel cats (14 eyes) with bilateral eyelid coloboma were included in this study, 5 females and 2 males, with a median age of 5 months (range 6-8 months). The patients presented with blepharospasm, bilateral mucopurulent ocular discharge and eyelid coloboma extension of 30-50% in the upper eyelid, resulting in severe trichiasis of both eyes. In 5 cats, 1 or both eyes were diagnosed with keratitis and superficial corneal ulcers. Surgical treatment with general anaesthesia was applied. The pre anaesthesia protocol included acepromazine 0.05 mg/kg with methadone 0.2 mg/kg, followed by intravenous propofol and maintenance with isoflurane and oxygen. An ophthalmological cryocautery unit was utilised with carbon dioxide as the cryogenic agent and a retinal cryoprobe of 3.2 mm diameter tip, reaching -50ºC for the procedure. The method used was a double cycle of freezing and thawing for 60 s in the margins of eyelid agenesis. Epilation of hairs was made after freezing with eyelash tweezers. Immediately after the surgical procedure, an Elizabethan collar was placed to safeguard the area and anti-inflammatory therapy with meloxicam 0.1 mg/kg once daily for 3 days was prescribed. Antibiotic ointment every 6 h (chloramphenicol and associations) was also prescribed for topical application. Two weeks post-operatively, hyperaemia, oedema and skin wounds at the margins were observed. After 30 days these clinical signs were minimal. No signs of pain were observed post-operatively. The follow-up was 90 days and the trichiasis was resolved in all cats. Discussion: Usually, young cats are affected with eyelid colobomas. The age of the patients in this study was between 6-8 months. Eyelid colobomas are repaired with a variety of blepharoplastic procedures and the choice depends on the size and position of the defect. Generally, larger defects require more extensive reconstructive procedures. All techniques can have post-operative complications. Suture dehiscence, skin flap necrosis and facial deformation can occur with traditional surgical techniques. Furthermore, posterior hair growth in the margins can lead to new trichiasis. Cryosurgery was chosen and performed as the temperature of -20°C is sufficient to destroy hair follicles, without surgical incisions, avoiding scar formation. Hence, sutures are not necessary in cryosurgery procedures. Carbon dioxide is a good cryogenic agent for the purpose of this procedure. In the cases described, no recurrence of hair growth was observed in the follow-up period of 90 days. Nevertheless, a good aesthetic appearance was maintained. Therefore, the use of carbon dioxide cryosurgery is an effective and safe alternative for treatment of eyelid coloboma in cats. To our knowledge, no paper has described the use of carbon dioxide cryosurgery for the correction of palpebral agenesis in felines and other species as a single treatment. This technique is easy to perform, has good aesthetic and functional results and can be considered a treatment option for this congenital condition.

Resumo

Corneal pigmentation and vascularization eventually result in blindness in dogs. Pigmentary keratitis describes a relatively common presentation comprising the deposition of melanin in the cornea and conjunctival surface associated with chronic inflammation. Cryosurgery is indicated as a treatment for pigmentary keratitis in dogs. Due to melanocytes sensitivity to cold, cryosurgery is a viable treatment for severe refractory corneal pigmentation. The aim of this work was to evaluate the use of dimethyl ether in the treatment of pigmentary keratitis in 14 eyes of seven Pug dogs. Follow-up occurred after 30 days in four animals and six months in three animals. In all treated animals, there was a reduction in corneal pigmentation. Cryosurgery causes intracellular and extracellular ice crystal formation and other mechanisms that result in rupture and death of the melanocytes. The technique used was easy to perform, has a low cryogen cost and has few undesirable or serious side effects. However, after 30 days repigmentation occured in treated patients. Cryosurgery shows good results in the first four weeks, but partial recurrence occurred in all cases.

A pigmentação e a vascularização da córnea eventualmente resultam em cegueira em cães. A ceratite pigmentar é descrita com uma apresentação relativamente comum que compreende a deposição de melanina na córnea e na superfície conjuntival associada à inflamação crônica. A criocirurgia é indicada como tratamento para ceratite pigmentar em cães. Devido à sensibilidade dos melanócitos ao frio, a criocirurgia é um tratamento viável para pigmentação corneana refratária grave. O objetivo deste trabalho foi avaliar o uso do éter dimetílico no tratamento da ceratite pigmentar em 14 olhos de sete cães da raça Pug. O acompanhamento foi de 30 dias em quatro animais e seis meses em três animais. Em todos os animais tratados, houve redução da pigmentação da córnea. A criocirurgia causa a formação de cristais de gelo intracelular e extracelular e outros mecanismos que resultam na ruptura e morte dos melanócitos. A técnica utilizada foi de fácil execução, baixo custo de criogenia e poucos efeitos colaterais indesejáveis ou graves. No entanto, após 30 dias, ocorreu repigmentação nos pacientes tratados. A criocirurgia apresenta bons resultados nas primeiras quatro semanas, mas ocorreu recidiva parcial em todos os casos.