Enucleation in Cats

Enucleation is the surgical removal of the eye. Enucleation surgery is the irreversible and permanent solution for various eye disorders. Enucleation in cats is performed when all other medical options have proven ineffective in order to alleviate pain and give the feline a better quality of life. Enucleation surgery is performed by a veterinary ophthalmologist. 

The veterinary ophthalmologist can approach enucleation surgery in two ways; transconjunctival or transpalpebral. The transconjunctival approach to enucleation has the advantage of reducing orbital tissue loss, subsequent orbital sinking, less hemorrhaging and a faster procedure time overall. In a transconjunctival surgery, the veterinarian ophthalmologist will only remove a portion of the eye’s orbit. WIth the transpalpebral approach, the entire eye globe is removed including the elements within the conjunctival sac (nictitating membrane, conjunctiva, eyelids). The veterinary eye specialist may choose to take the transpalpebral approach if the eye is unsalvageable. 

The patient’s vital signs are taken before induction of pre-anesthetic drugs are administered. General anesthesia is started after sedation is achieved through injectable tablet induction. The fur surrounding the affected eye is shaved to the midline. The upper eyelashes are trimmed with fine scissors and douched with ointment to prevent lashes from falling into the eye’s orbit. Tape is applied directly to the skin to remove fine hairs. 

1. The periocular skin, corneal surface and the conjunctival fornix is prepared with a 1:50 povidone-iodine solution. 
2. The patient’s head is placed in lateral or semi dorsal recumbency with the palpebral fissures aligned parallel to the floor. 
3. The endotracheal tube is reinforced to avoid anesthetic complications. 
4. The eyelids may be sutured shut if the globe is infected. Any suture material may be used, as the sutures begin from one corner of the eyelid to the other, close to the meibomian glands. 
5. A No. 5 scalpel blade is used to cut around the eye. 5 mm thick elliptical incisions will be made away from the eyelid margins, joining the incisions at the lateral and medial canthus. 
6. An Allis tissue forceps or towel clamp will be used to grasp the incised eyelid margins. 
7. Blunt dissections will be made using a Metzenbaum scissor, alternating from side to side until approaching the sclera. 
8. Using a No.15 scalpel blade, the medial and lateral canthal ligaments are transected.   
9. Hemorrhaging is controlled and the orbital rim is identified.
10. The posterior ciliary arteries and optic nerve are clamped, or ligated. These structures are severed through use of a curved Metzenbaum scissor. 
11.  A plane of dissection is made using Metzenbaum scissors to release the globe from the orbital tissues that remain in the orbital rim. 
12. The dissected globe is removed and handed off to a veterinary technician to prepare for histological laboratory submission. (Important for detecting life-threatening disease).
13. The veterinary ophthalmologist will return to the orbital opening, dissecting the periocular tissue from the sclera. 

14. The eye socket will be packed with gauze, applying light pressure for 5+ minutes to encourage a clot to form. Excessive bleeding may be ligated and synthetic hemostasis products may be applied to halt unsourced bleeding. 

15. A sterile silicone orbital prosthesis will be placed in the orbit. The veterinarian will trim the prosthetic to size. (only used in non-neoplastic or infectious conditions) 
16. Using 3-0 or 4-0 monofilament polyglyconate synthetic, absorbent sutures, the orbit will be closed with a minimum of three layers. The last layers of sutures will be using a 3-0 absorbable braided or monofilament type.