Enucleation, or eye removal, is similar to limb amputation; it is a salvage procedure. Despite valiant efforts to save an eye, all hope may be lost for vision, and an enucleation may be necessary.
We asked John S. Sapienza, a board certified veterinary ophthalmologist at Long Island Veterinary Specialists in Plainview, N.Y., to share a few pearls of wisdom about the art and pitfalls of enucleation.
Do you feel that an enucleation is a specialized surgery?
I don’t think that every enucleation requires a specialist’s surgical skills. In the case of ocular or periocular neoplasia, the procedure may be a little trickier. Either way, I would encourage general practitioners to follow some important guidelines if they elect to perform the procedure.
When is an enucleation indicated?
• Here is a list of 10 reasons:
• In case of severe, intractable pain.
• When the eye is blind.
• With severe proptosis.
• In case of endophthalmitis.
• With chronic, blinding glaucoma.
• When there is severe ocular trauma with hemorrhage.
• In case of intraocular neoplasia.
• In case of intractable infection.
• In case of chronic active uveitis (painful globe).
• With Phthisis bulbi (small shrunken globe) with excessive ocular discharge.
• In these cases, the patient is best served with removal of the globe.
What are the options to perform an enucleation?
You can either remove the globe by a subconjunctival (or transconjunctival) approach or by a transpalpebral (through the eyelids) approach. I typically perform a subconjunctival procedure because less extraocular tissue is removed, resulting in a more “full-looking” post-enucleation orbit. I perform a transpalpebral approach when there is severe orbital contamination, infection or an extension of ocular neoplasia.
Is it acceptable to discard the eye when there is no neoplasia?
You should always, always, always biopsy the globe, or even better, submit the entire globe. If you take the time to remove an eye, you also need to absolutely document the cause of the underlying ocular disease.
In the case of ocular neoplasia, the prognosis for metastatic disease cannot be adequately evaluated without proper histopathologic analysis. The biopsy submission takes little time to do, and in the hands of an experienced pathologist (ideally one who is dedicated to ocular disorders), the information learned from the histologic sample is priceless.
Do you ligate the optic nerve?
Controversy exists over the need to ligate the optic nerve stalk—or more importantly, its associated vessels. Many ophthalmologists do not to ligate it. Personally, I still routinely place a Hemoclip around the optic nerve vessels. This step takes a few seconds and results in a bloodless surgical field. You could also ligate with 3-0 to 4-0 polydioxanone.
How about the glandular tissue?
Remember to remove all epithelial lined or glandular structures. This includes the third eyelid, the gland of the third eyelid, the palpebral conjunctiva, and the lacrimal caruncle (located at the medial canthus). I have explored several eye sockets because of the formation of an orbital cyst from failure to remove these glandular, adjunctive ocular structures.
Leaving the conjunctival tissue and the gland of the third eyelid will lead to an orbital cyst, as in this Pekingese.
What do you suggest to improve cosmesis post-op?
You could place an orbital implant in dogs. The typical sunken appearance of the skin into the orbit is apparent in many post-enucleation cases that I examine. I routinely place an orbital sphere made of silicone in the hollow orbit. In addition, I create a periosteal flap over the implant in the shape of a diaphragm. This allows the enucleated orbit to appear flatter, and it minimizes postoperative orbital depression.
In cats, I avoid orbital implants altogether because there is an increased incidence of sphere extrusion. I have examined two cats with post-operative implant extrusion. So in cats, I use the periosteal flap to serve as a “diaphragm” under the skin incision. The post-operative cosmesis of the periosteal flap in cats is generally good to excellent.
Another option is to place a few non-absorbable sutures from the dorsal to the ventral periorbital periosteum to create a mesh effect.
Please walk us through the different steps of an enucleation.
First, I excise approximately 2 mm from the eyelid margins while the globe is still in the orbit. This allows me to make an accurate incision on the eyelids while there is normal orbital conformation and pressure. Then a 360 degree peritomy (conjunctival incision) is made several millimeters posterior to the limbus. The extraocular muscles are identified and resected at their insertion. Bleeding is controlled by pressure and delicate electrocautery.
The optic nerve is gently clamped with a curved hemostat or a right-angled enucleation hemostat or snare. Don’t pull too hard on the optic nerve, especially in cats—big issue!—because you can damage the optic nerve chiasm and cause a contralateral blindness.
The stalk is then severed by sharp dissection with a curved tenotomy scissors. The globe is removed. Again, I typically ligate the optic nerve stalk with a Hemoclip, but others ligate or simply apply pressure.
I ensure that all conjunctival tissue is removed, and then remove the eyelid margin, following the previously made periocular incision. Care is taken to remove all the pigmented tissue and the caruncle at the medial canthus. An orbital implant is placed in the anophthalmic socket of most canine patients.
Photo by Dr. John Sapienza
After the enucleation, a Hemoclip is placed on the optic nerve.
How do you create your periosteal flap?
I undermine the periosteum and then suture the dorsal and ventral periosteal layer to each other in order to create a bridging flap over the orbital implant. I then close any muscle and subcuticular layer with 3-0 to 4-0 PDS.
The skin is usually closed in a subcuticular layer with 5-0 vicryl in a simple continuous buried pattern to avoid the need for suture removal in the future. The globe is always submitted for histopathological analysis.
What kind of pain management protocol do you suggest?
I typically perform a retrobulbar or peribulbar block with a combination of lidocaine and bupivacaine, which provides analgesia for several hours post-operatively. In addition, I prescribe an oral NSAID, as well as oral tramadol. We have been impressed with the lack of postoperative pain in our patients since we have started using this analgesic regime.
Any final words of wisdom?
General practitioners can perform an enucleation as long as they are comfortable with the anatomy of the eye, good surgical technique is followed, the globe is submitted for histopathology and pain relief is provided. When in doubt, refer to an ophthalmologist. l
Dr. Phil Zeltzman is a mobile, board-certified surgeon near Allentown, Pa. His website is DrPhilZeltzman.com.