Transorbital postcaruncular endoscopic surgery as an alternative to orbital exploratory surgery: A cadaveric study and case report in a dog with an orbital sarcoma.

Objective: To describe a postcaruncular approach for transorbital endoscopy as an alternative, minimally invasive technique to access the orbital apex.

Study Design: Ex vivo and prospective clinical case report.

Animals: A 12-year-old male castrated cocker spaniel and three cadaver heads (one large breed dolichocephalic, one medium-sized breed mesocephalic, and one small breed brachycephalic).

Methods: Transorbital endoscopy was performed to obtain biopsies of an orbital apex mass by using a postcaruncular approach. A 2.7-mm 30° rigid endoscope fitted with a cystoscope working sheath was used with the aid of a blunt suction-dissector and fluid ingress. This procedure was first performed on three cadavers to assess feasibility and later performed in a clinical case.

Results: By using a transorbital postcaruncular approach, it was possible to visualize and obtain biopsies from structures within the orbital apex with minimal perioperative morbidity. Dissection and expansion of the working space was facilitated with the aid of fluid ingress; however, judicious use of fluids is recommended because secondary orbital edema and chemosis can occur.

Conclusion: Transorbital endoscopy via a postcaruncular approach is feasible.

Clinical Significance: This technique should be considered in cases in which a histological diagnosis is required prior to definitive treatment as a method to obtain biopsy samples of the orbital apex region without major surgical dissection.