Improving of postoperative appearance after enucleation and exenteration in dogs
Eye enucleation and exenteration is a commonly performed procedure to treat and diagnose serious ocular disease. Several types of orbital prostheses have been described for use mainly in dogs and horses after enuclation or exenteration, and several techniques have been used to improve the cosmesis of the face and orbit following enucleation. The implantation of an intraocular prosthesis, or placement of non – absorbable sutures in the orbital rim are currently used as an alternative to enucleation of a blind eye. In this article we describe using of prosthetic material – polyethylene – dimethyl mesh for improving of postoperative appearance after enucleation and exenteration.
In enucleation, the globe and its contents are excides. The indications for enucleation include ocular congenital defect, such as microphthalmia, that results in chronic problems such as conjunctivitis and keratitis; intraocular infection that have destroyed the globe, and are potential sources of systemic infection; intraocular tumors not amenable to local excision or laser therapy and still confined to the globe; proptosis of the globe with several of the extraocular muscles and/or the optic nerve severed; intraocular inflammation that has destroyed the intraocular tissue and resulted in blindness; and extensive trauma to the globe with the loss of intraocular tissue and without the possibility of successful repair.
Blind glaucomatous and enlarged globes may be also treated by enucleation, however, the evisceration procedure followed by insertion of an intraocular prosthesis has largely replaced the enucleation procedure because of superior cosmetic results.
For all orbital surgeries, the periorbital skin and eyelids are clipped, shaved, and prepared for aseptic surgery in a routine manner. The ocular surface and conjunctival sac are flushed with sterile saline solution, or 0, 5% povidone iodine solution.
In the enucleation procedure in small animals, the eye, eyelid margins, nictitating membrane, and lacrimal gland are excised. The most commonly used surgical technique in small animals is the subconjunctival approach through the bulbar conjunctiva. Another techniques for enucleation are transpalpebral (´en bloc ´) enucleation, and lateral enucleation.
Exenteration involves removal of the conjunctiva, periorbita, extraocular muscles, and globe. In case of an orbital tumor, exenteration may be extended to involve all orbital contents. For exenteration is usually used transpalpebral approach, in which the eyelids are sutured together in a continuous pattern. After exenteration is the orbital depression more marked than following enucleation.
Evisceration with intraocular prosthesis in small animals is an attractive alternative to the enucleation procedure. This procedure, like the enucleation technique, treats blind and painful eyes, removes the need for topical and systemic medications, but provides improved cosmetics.
In the evisceration procedure, the entire intraocular contents are removed through a scleral or limbal incision, leaving only the fibrous tunics of the cornea and sclera. Into this corneoscleral shell is inserted a sterile silicone sphere, and the scleral or limbal wound apposed. The primary indication for evisceration is end – stage of primary glaucoma, which has become medically non – responsive, with enlarged and painful globes. Globes with secondary glaucoma associated with septic panophthalmitis and intraocular neoplasms are not indicated for evisceration, and should be treated by the enucleation procedure.
Several techniques have been used to improve the cosmetics of the face and orbit following enucleation and evisceration as intraocular silicone prosthesis, intrascleral silicone implants, Darcon mesh, prolene, intrascleral silicone prosthesis after evisceration, corneoscleral conformer, scleral cosmetic shell, and corneoscleral prosthesis.
An intraorbital silicone prosthesis may be inserted to prevent sunken appearance of the orbit after removal of the entire globe in the subconjunctival enucleation procedure. The size of the prosthesis is selected to fill the orbit and approximate the size of the contralateral globe.
Material and methods
The medical records of all 12 dogs requiring an enucleation or exenteration at the University of Veterinary Medicine and Pharmacy in Košice, Slovakia, between January 2010, and December 2011, were reviewed. The age, sex, breed, history, previous treatment of the eye, clinical findings, medical treatment, outcome of the enucleation/ exenteration, and post – operative appearance were recorded.
Anesthesia consisted from premedication with atropine (0,015 mg/kg IM) to prevent cardiac reflex; butorphanol (0,2 mg/kg IM) for analgesia, propofol for induction, and isoflurane with oxygen for maitenance. Retrobulbar injection with inferior – temporal techniques was used for administration of anesthetic agents in all enucleation/ exenteration surgeries (expect patient with orbital neoplasia). To perform a peribulbar block, the conjunctiva was gently lifted with forceps, and approximately 2 mm from the limbus at the 12,3,6, and 9 o´ clock position around the globe 0,2 ml of 2 % lidocaine was administrated. After them 1 ml of 2 % lidocaine was applied into the eyelid margin.
Enucleation was performed in 10 dogs by subconjunctival technique. The globe was excised from surrounding Tenon ´s capsule with the majority of the surgical dissection limited to the sub – Tenon´s space. After transection of the extraocular muscles and incision of the retractor muscle and oblique muscle insertion, the globe was displaced forward and carefully removed (Fig 2,3)
Exenteration with complete removing of the all orbital tissue, including the globe, nictitating membrane, conjunctivae, lacrimal gland, zygomatic salivary gland, and extraocular muscles was performed in 2 dogs with intraocular neoplasia occupying retrobulbar space.
In all – 12 dogs the parietal reinforcement implant mesh (Cousin Biotech, Biomesh France) was used. Appropriative size of mesh was sutured to the periorbital rim by using of no absorbable suture material Suprolene 2 – 0 USP (Resorba, Germany). The eyelid – subcutaneous layer was apposed with 3 – 0 to 4 – 0 absorbable material, and the eyelid skin was apposed with the same material, by using of simple interrupted, horizontal mattress or intradermal sutures (Fig. 4,5,6).
Results and discussion
Twelve dogs of different breed, gender, with untreatable ocular disorders were included in this study. The average age at presentation was 6, 5 years (range from 5 month to 13 years). Five dogs were diagnosed with traumatized eye – proptosis (Fig. 1), severe eyeglobe laceration, severe eyeglobe trauma, three dogs with panophthalmitis, two dogs with chronic glaucoma, and two dogs with intraocular neoplasia extending to the retrobulbar space.
The dogs have a history of eye trauma with or without corneal or scleral perforation and intraocular contents prolapse; on the treatment irresponsible intraocular inflammation and glaucoma, and slowly progressive exophthalmos, with pain upon opening the mouth.
The duration of clinical signs ranged from one day to 14 month (2 cases with chronic glaucoma).
The clinical signs was depending on the pathological changes on the eye, and frequently included following: acute pain, purulent ocular discharge, blepharospazm, in cases of eye trauma and scleral perforation sudden painful blepharospazm, and sudden voluminous watery discharge; chemosis, circumcorneal ciliary injection, corneal edema, hypopyon or hyphema, anterior or posterior synechiae, vitreous opacity, retinal edema, exudate or detachment and lowered or elevated intraocular pressure.
In this study, the main alterations were ocular trauma. In two patient with intraocular neoplasia extending to the retrobulbar space, compression of the third eyelid against the orbit by an orbital mass caused occluding of venous drainage, creating protrusion of the its gland and chemosis. Strabismus can be explained by displacement of the orbital neoplasia. Exposure keratitis occurs when the eyelids cannot cover the surface of globe, or if trigeminal or/and facial nerves involvement has occurred. Glaucoma and retinal detachments result of tissue compression by neoplasia.
The usage of different materials for improving of postoperative appearance after enucleation and exenteration have been reported. Lower cost, practicality and infrequent adverse effect have been indicated as the main justification. In the postoperative period in none of our patients were observed some complications and cosmetical effect was satisfying (Fig 7, 8).
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