Coloboma eyelid in cats - treatment with carbon dioxide cryosurgery

ABSTRACT

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.