A 9-year-old female domestic shorthair indoor-only cat was presented to the ophthalmology referral consultation at the Teaching Hospital of the Faculty of Veterinary Medicine, Lisbon University with a right globe lesion that had started 6 months ago. The cat had been undergoing long-term treatment for conjunctivitis by the referring veterinarian, and showed no improvement or change in the clinical appearance of the lesion. Oral and topical antibiotics and topical anti-inflammatory drugs, including steroids, had been prescribed. Complete physical examination revealed no other abnormalities. On ophthalmic examination, the cat presented with an extensive elevated pink mass that covered two-thirds of the cornea of the right eye (OD) (). The left eye (OS) had no clinical signs of disease. In the OD the dazzle reflex was positive, the menace response was absent and palpebral closure was impossible owing to the presence of the mass, leading to lagophthalmos. The corneal reflex was decreased, probably due to changes of the termination of corneal nerves. In the OD, direct and indirect pupillary light reflexes were impossible to evaluate owing to the large mass and grey opacity in the remaining cornea that rendered visualisation of the pupil impossible. In the OS, menace response and all the remaining ocular reflexes were present. In the OS both direct and indirect pupillary light reflexes were present, as light could pass through the opaque cornea, so a functional retina in the right eye could be expected. Schirmer tear test (Dina strips Schirmer-Plus; Luneau SAS) was 11 mm/min in the OD and 18 mm/min in the OS. Intraocular pressure measurement obtained by applanation tonometry (Tono-Pen XL; Medtronic Solan) following instillation of a topical anaesthetic (Oxibuprocaine, Anestocil; Laboratórios Edol) was 13 mmHg in the OD and 18 mmHg in the OS. The left cornea did not stain with fluorescein dye, while the right eye mass captured some stain. Slit-lamp biomicroscopy (SL14 Kowa Company) of the OD allowed for better visualisation of the mass and showed no abnormalities in the OS. Two drops of a topical mydriatic drug corresponding to tropicamide in a 1% concentration (Tropicil Top; Laboratórios Edol) were applied in the OS. Indirect funduscopic examination (Heine Omega 180) was impossible to perform in the OD owing to the mass, but was normal in the OS. The differential diagnoses for the OD mass included eosinophilic keratitis, chronic keratitis, traumatic injury, corneal foreign body and neoplasia. Complete blood count (CBC) and serum chemistry analysis were within normal limits. Triple-view thoracic x-rays were obtained to rule out thoracic lesions. Although corneal surface cytology is an important complementary examination, it could not be performed in this patient without heavy sedation or general anaesthesia, and so surgical biopsy was considered the best option. The patient was premedicated with methadone (Semfortan; Dechra Veterinary Products) at a dosage of 0.2 mg/kg body weight subcutaneously and anaesthetised with propofol at a dose of 5 mg/kg body weight intravenously (Propofol Lipuro; B Braun Medical). Endotracheal intubation was performed following topical anaesthesia of the larynx and volatile anaesthesia was maintained with isoflurane. On induction, cephalosporin (Cefazolina Labesfal; Labesfal – Laboratório Almiro) at a dosage of 22 mg/kg body weight was administered intravenously to prevent bacterial contamination of the surgical site and meloxicam (Meloxidyl; Ceva) at a dosage of 0.1 mg/kg body weight was given subcutaneously for the control of postoperative pain. Periocular skin of the right eye was clipped and surgical asepsis was obtained with povidone–iodine 1:20 solution, followed by sterile saline. After completion of draping, a 5 mm lateral canthotomy was performed to increase corneal exposure. Surgery was performed using a surgical microscope, a Collibri forceps to grasp the mass and the corneal lamellae, and a disposable crescent blade was used to carefully dissect between collagen stromal layers. This task was difficult to accomplish because the mass was friable and difficult to grasp without tearing the tissue. An attempt was made to achieve a surgical-free margin, sparing as much corneal stroma as possible (–). The excised tissue was sent for histopathology. Lateral canthotomy was routinely closed in two layers with 5-0 simple interrupted absorbable sutures (Surgycril; B Braun Medical). Histopathology revealed that the tissue corresponded to a corneal SCC (). Postoperatively, medical treatment consisted of oral meloxicam (Meloxidyl; Ceva) at a dosage of 0.05 mg/kg body weight for 4 days, and doxycycline (Ronaxan; Pfizer) at a dosage of 10 mg/kg body weight for 7 days postoperatively. Additionally, topical tobramycin drops (Tobrex; Edol) were applied every 4 h for 14 days in the OD, along with ganciclovir 0.15% in gel form (Virgan; Laboratoires Thea) every 4 h to prevent an eventual exacerbation of a latent feline herpesvirus infection, which is endemic in Portugal. An Elizabethan collar was advised to prevent self-mutilation of the surgical site. Ten days later, the canthotomy skin sutures were removed. The cornea healed with no complications, apart from a moderate superficial neovascularisation on the surgical site. One month postoperatively, a fluorescein test was negative, the cornea had completely healed and topical mitomycin C adjuvant treatment was initiated. The drug was diluted in sterile water at a concentration of 0.04% (0.4 mg in 10 ml of sterile water), placed in commercial sterile dry tubes; three tubes were prepared – one for each treatment. Tubes were protected from light (covered with Vet Wrap) and kept at 4ºC. One drop was applied three times daily in the OD for a course of 15 days, followed by a 15-day interval with no other medication apart from artificial tear drops three times daily. Three treatment cycles were performed, one per month. The cytostatic agent was applied by the owner using chemotherapy gloves. There were no immunosuppressed owners or children at home and the cat was the sole pet and always kept indoors. There was no pruritus or signs of ocular discomfort throughout the treatment, and an Elizabethan collar was unnecessary. No secondary side effects, either systemic or local, were observed with this topical chemotherapy. By the end of the chemotherapy protocol, CBC and biochemistry profiles were within normal limits. The patient was ophthalmically rechecked every 2 weeks and the cornea was clear throughout the treatment, showing no signs of inflammation, epiphora or ocular discharge. Fluorescein tests were negative. Over the course of treatment, the cornea regained transparency and decreased its neovascularisation (). During follow-up evaluations, every 2 months after the end of treatment, an almost clear cornea was appreciated, with slight neovascularisation and discrete scarring. Symblepharon of the dorsal bulbar conjunctiva to the third eyelid was present at 2 o’clock. There was no epiphora or ocular discharge, signs of inflammation, pruritus or ocular discomfort. Intraocular pressure was normal. There was no recurrence of the neoplasm at the 1-year follow-up.