How to perform an enucleation | VETgirl Veterinary Continuing Education Videos
In this VETgirl veterinary continuing education video, we will review how to perform an enucleation. Enucleation is a common ocular surgery which may be indicated for a variety of reasons, such as nonresponsive glaucoma, perforated corneal ulceration, or intraocular neoplasia. This surgery can be therapeutic for pain relief, and also diagnostic as it provides the globe for biopsy.
There are two techniques for performing an enucleation: transconjunctival (also referred to as subconjunctival) and transpalpebral. The transconjunctival approach removes the globe via a conjunctival incision, followed by removal of the eyelid margins, conjunctiva, and third eyelid with its gland. The transpalpebral approach removes all of these structures together via incisions in the eyelids. The transpalpebral approach is recommend for patients with ocular surface infections, such as ruptured ulcers.
In this VETgirl video, the patient is placed under general anesthesia. The periocular area is clipped free of all hair approximately 2-3 inches around the globe, taking care not to excessively traumatize the delicate and thin skin around the eye. In brachycephalic patients, the nasal skin folds should be clipped as needed. The periocular skin, conjunctival surfaces ad fornix, and corneal surface are prepared for surgery with a povidone-iodine solution (dilute with sterile saline to a “weak tea” color). Traumatized corneal surfaces should be rinsed aggressively. Even though the eye is being removed, this preparation will reduce the risk of intraoperative contamination. NEVER use a detergent or alcohol-based scrub on or near the eye (e.g. Chlorhexidine, betadine scrub).
The patient is positioned in sternal recumbency with their head stabilized using either a surgical vacuum pillow, sandbags, or towels. Once positioned, a final surgical prep is performed in a similar fashion as before. Sterile cotton tipped applicators are used in the conjunctival fornices. Surgical instruments should be small and delicate, appropriate for eye tissues. The surgical site can be draped using standard material, but VETgirl loves the adhesive drapes that you cut a hole in for eye procedures! A non-absorbent patient drape secured with towel clamps provide a large sterile.
The first step in a transpalpebral enucleation is to close the eyelid edges – VETgirl likes to use a towel clamp because it is very quick, but alternatively sutures can be used. A No. 15 scalpel blade is then used to make elliptical full-thickness skin incisions about 5 mm away from the eyelid margins, from the medial to the lateral canthus. Using tenotomy scissors, blunt dissection is performed towards the orbit, staying in a plane of dissection just superficial to the conjunctiva. This dissection is performed starting dorsally, and then extending all around the globe. There are firm ligaments at the medial and lateral canthus, which may require sharp dissection with scissors or a scalpel blade. When these ligaments are fully transected, the globe will become more mobile and free. It is VERY important to avoid the large venous sinus at the medial aspect of the globe – when dissecting in this area, keep the tips of the scissors pointed towards the globe and deep orbit, not towards the nose / sinuses. Hemostats or low-power cautery can be used for hemostasis.
Once the tissue dissection is deep enough, orbital fat will become evident. The optic nerve may be easily visible in brachycephalic patients but is not likely to be easily located in cats or dolichocephalic dogs. VETgirl recommends using hemostats to clamp the optic nerve and it’s vessel but discourages trying to place a ligature around it. Curved enucleation scissors are used in this video to transect the optic nerve, releasing the globe from the orbit, but curved Metzembaums would work too! Once the globe is removed, hemorrhage from the orbit is managed using gauze and pressure applied for 3-5 minutes. If additional oozing is noted, VETgirl recommends using a hemostatic agent, such as HemaBlock or gel foam, as seen in this video.
Closure is performed in 3 layers. The first layer is a periosteal mesh pattern spanning the orbital rim using 3-0 or 4-0 monofilament polyglyconate synthetic absorbable suture. This mesh will prevent the eyelid skin from sinking too deeply into the orbit. The subcuticular layer of the eyelid skin is apposed using a continuous pattern of 3-0 or 4-0 monofilament polyglyconate synthetic absorbable suture, and the skin is closed using 3-0 or 4-0 nylon in a simple interrupted or cruciate pattern, as seen here. The patient should be sent home on appropriate analgesic therapy with an E-collar, and rechecked 7-10 days later, or as needed.