A modified subconjunctival enucleation technique in dogs and cats

A modified subconjunctival enucleation technique in dogs and cats

These clinicians describe an alternative method of subconjunctival enucleation that may be ideally suited for some patients seen in general practice.


1. A lateral canthotomy is performed, and the upper eyelid margin is excised 5 mm posterior to the mucocutaneous junction in a single continuous fashion.
An enucleation is the most common orbital surgical procedure performed by veterinary ophthalmologists and general practitioners.1 In veterinary medicine, enucleation is defined as the removal of the globe, nictitating membrane, eyelids, and, depending on the technique, conjunctiva. Globe removal is indicated in patients with blind, painful eyes or patients with nonresectable intraocular tumors.1


2. The lower eyelid margin is excised in a similar manner as shown in Figure 1.
The three most commonly described enucleation techniques are the subconjunctival, lateral, and transpalpebral approaches. The main objectives of the subconjunctival technique are to remove the globe, nictitating membrane, and eyelid margins, in that order, while preserving as much soft tissue as possible to minimize subsequent orbital depression.2,3 The lateral approach removes the tissues in a similar order but first involves partially excising the eyelids for better surgical exposure.4 The transpalpebral technique is often used in patients with associated ocular surface infection or neoplasia. This method involves suturing the palpebral fissure closed and removing the globe, nictitating membrane, and conjunctiva as one encased unit to prevent contact between the remaining ocular surface and orbital contents.5


3. The excised eyelid margins.
In this article, we describe a modification to the subconjunctival enucleation technique that provides improved exposure of the globe, extraocular muscles, optic nerve, and vascular structures of the orbit.

TECHNIQUE


4. The nictitating membrane is excised at its base with Mayo scissors.
After premedication, induce general anesthesia, and aseptically prepare the periorbital skin and eyelids for the procedure by clipping the periorbital area and irrigating the periorbital tissues and globe with 5% povidone-iodine ophthalmic solution. For better pain control, consider administering retrobulbar injections6 (0.5 to 1 ml) of a combination of lidocaine hydrochloride 2% and bupivacaine 7.5% with or without epinephrine 1:1,000.


5. The nictitating membrane including the gland of the third eyelid before the final cut at the medial canthus.
Perform a lateral canthotomy, and excise the eyelid margins 5 mm posterior to the mucocutaneous junction in a single continuous fashion (Figures 1-3) with Mayo scissors. Then grasp the nictitating membrane with tissue forceps (e.g. Bishop Harmon), and excise it at its base with Mayo scissors (Figures 4 & 5). Next, incise the bulbar conjunctiva 3 to 5 mm posterior to the limbus, and transect the extraocular muscles near their scleral attachments (Figure 6). Sever the retractor bulbi muscle fibers and optic nerve (Figure 7) with curved enucleation scissors, and excise the remaining conjunctiva. Before excising the globe, a ligature may be placed around the optic nerve and the associated short and long posterior ciliary vessels before they enter the sclera. We do not perform this step; it is a matter of surgical preference.