Subconjunctival Enucleation Surgery in Dogs & Cats
Sheryl G. Krohne, DVM, MS, DACVO, Purdue University
Enucleation surgery, a common procedure in small animal practice, is indicated when an eye is painful or infected and vision can’t be saved. However, enucleation should not be used in place of a correct diagnosis or treatment for ocular disease.
Severe corneal or scleral laceration with loss of intraocular contents
Phthisical eye with discharge accumulating in the conjunctival sac
Unresponsive painful dry eye with corneal scarring (accompanied by owner’s inability to pursue other treatment options)
Severe proptosis with extraocular muscle avulsion
Progressive intraocular tumors not involving the sclera
Blinding unresponsive infectious or inflammatory uveitis, with or without hyphema (Figure 1)
Eyes that have been irreversibly damaged from severe panophthalmitis or a retrobulbar abscess, or that have an extensive or invasive intraocular tumor, should be removed by using an exenteration or transpalpebral technique, not simple subconjunctival enucleation.
In eyes blinded from glaucoma (not caused by neoplasia) or traumatic loss of intraocular contents, evisceration and placement of an intrascleral prosthesis is an alternative to enucleation. Owners who prefer an intrascleral prosthesis should be referred to an ophthalmology practice for this procedure. However, many owners prefer enucleation to intrascleral prosthesis because it involves less postoperative care.
Step-by-Step: Subconjunctival Enucleation
What You Will Need
General surgery pack, vacuum pack for positioning the head, standard surgery room and anesthesia equipment, & adjustable-height chair (seated position for ocular procedures increases surgeon’s hand stability)
Jar of 10% neutral buffered formalin (10 parts formalin:1 part eye tissue). This volume is needed to adequately fix the eye for histopathology.
3/0 or 4/0 absorbable suture (such as PDS* II, Monocryl monofilament or Vicryl braided suture; ethicon.novartis.us) on a cutting (FS-2) needle. Monofilament sutures have less tissue drag and are preferred for this use. Skin sutures should be 2/0 to 4/0 (depending on animal size) nonabsorbable suture (such as Ethilon or Prolene; ethicon.novartis.us) on a cutting needle.
Surgical clippers, 4 × 4 sponges, mild surgical scrub, water and eye wash for rinsing, dilute 1:25 povidone-iodine solution for final surgical preparation of the skin, and cotton-tipped applicators to clean and prepare the conjunctival sac with the solution
Injectable 1/1000 epinephrine diluted to 1/10,000 (using saline) in a 6-mL syringe to be used as a subcutaneous injection or irrigation to control hemorrhage
Optional: Electrocautery with a cutting tip for the eyelid margin and cautery tip for controlling hemorrhage. A tonsil snare attachment is useful, if available, for removing the eye at the optic nerve.
Clip hair from around the eye before positioning the head. Then place the animal in lateral recumbency, with the head positioned and stabilized. Adjust the surgeon’s chair or stool so that the surgeon’s arms and hands are supported comfortably, and set the overhead light position so that all ocular structures are well illuminated.
After positioning, prepare the area for surgery by using a mild surgical scrub and solution (eye damage from a scrub is not a concern if the eye and conjunctiva will be removed at enucleation) (A).
Postoperative pressure or protective bandages are rarely necessary; however, if hemorrhage occurs, a bandage is an excellent way to apply pressure after the incision is closed. See Suggested Reading for bandage placement techniques. An Elizabethan collar is useful to prevent postoperative trauma to the surgery site.
I prefer to keep patients in the hospital for one night to monitor for hemorrhage. Owners often have emotional difficulties with enucleation surgery, and postoperative bleeding from a bruised and clipped surgery site at home the night after surgery can be a very bad experience. Owners should be warned about postoperative appearance or even shown pictures of what it will look like before they are reunited with their pet at discharge.
Postoperative analgesia can be used in the hospital (nonsteroidal antiinflammatory drugs, fentanyl, morphine) as needed, and patients can be released the next day with oral analgesic medications (carprofen, deracoxib, tepoxalin, or meloxicam in dogs; meloxicam in cats) for 3 to 5 days. Systemic antibiotics are recommended to prevent intraocular infection. Reevaluation 5 to 6 days after surgery and suture removal 12 to 14 days postoperatively are recommended.
The author wishes to thank Dr. Martin Coster and Sam Royer for providing surgical images and also Dr. Pam Mouser for providing the pathology photo for this article.