Eyelids and orbit

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Eyelids and orbit C.E. Plummer

The feline eye exhibits a variety of diseases that are not seen or are uncommon in other species. There are a few specific indications for surgical procedures of the periocular structures and orbit and this chapter will focus on these. For further details of intraorbital and corneal surgery the reader is referred to specific ophthalmology texts and the current literature as these techniques often require specialized equipment and training.

The eyelids are innervated by branches of the facial nerve (sympathetic fibers and motor function) and by branches of the trigeminal nerve (sensory function). The majority of the vascular supply to the eyelids originates at the lateral and medial canthi from branches of the superficial temporal, the external ethmoidal, and infraorbital arteries. Lymphatic drainage from the eyelids is primarily to the parotid and mandibular lymph nodes.1,4

Orbit SURGICAL ANATOMY Eyelids Eyelids are composed of several different tissue types. The outer layer of haired skin covers a tarsal plate and musculature, which control the movement and positions of the eyelids. The inner layer adjacent to the globe is the palpebral conjunctiva, a thin, vascular tissue resembling a mucous membrane. The eyelids function to protect and support the globe. This is achieved by three methods: (1) they act as an initial defense against external dangers due to the presence of an active blink reflex; (2) they remove dirt and debris from the surface of the eye; and (3) they contribute portions of the tear fluid and distribute it across the ocular surface.1–5 The skin of the eyelids is thinner and more pliable than in other parts of the integument to allow for ease of movement. The thin subcutaneous tissue attaches the skin to the deeper orbicularis oculi muscle, which controls eyelid closure. Additional subcutaneous muscles allow for elevation of the upper eyelid (corrugators supercilii medialis medially and frontoauricularis laterally and the Müller muscle) and elongation of the palpebral fissure (retractor anguli oculi lateralis).1,3,4 Meibomian (or tarsal) glands are present along the margins of both the upper and lower eyelids and are responsible for producing the lipid fraction of the pre-ocular tear fluid. Their oily product exits through a series of openings that appear as little grey dots along the lid margin. Cilia, or eyelashes, are not normally present in the cat, although occasionally distichiasis, i.e., lashes that exit through the meibomian gland openings, are noted. Conjunctival goblet cells produce mucin, which is also a component of the tear fluid. © 2014 Elsevier Ltd DOI: 10.1016/B978-0-7020-4336-9.00057-3

The feline orbit is relatively deep and, although it is not completely formed of bone, it provides considerable coverage and protection for the globe. The bones that compose the orbital walls in the cat include the sphenoid, maxillary, lacrimal, zygomatic, and frontal bones. The orbit is incomplete caudoventrally and laterally; the lateral aspect of the orbital rim is completed by the thick, fibrous orbital ligament, and the caudoventral and lateral walls of the orbit, which do not consist of bone, are bordered by the temporal, masseter, and pterygoid muscles. The small bony portion of the orbital floor in the cat consists of a thin shelf of maxillary bone, which holds the last molar teeth. A thick layer of fascial endorbita (periorbita) lines the inner bony and soft tissue margins of the orbit. The contents of the orbit include the globe with its muscular attachments, which originate at the orbit’s apex and traverse the orbit to insert on the globe, anterior to its equator. These muscles consist of four bellies of the retractor bulbi muscle, which envelop the optic nerve along its path from the optic foramen to the posterior aspect of the globe, four rectus muscles, and two oblique muscles. The ventral oblique muscle is unique in that its origin is the medial orbital wall. An extensive vascular supply is present in the orbit, most of which consists of various branches of the maxillary artery and their respective venous vessels which pass through the rostral alar foramen, the most ventrally situated foramen. The internal ophthalmic artery enters the orbit through the optic foramen with the optic nerve. The third, fourth, branches of the fifth, and the sixth cranial nerves, along with some autonomic fibers, enter the orbit through the orbital foramen and provide both sensory and motor innervation. The zygomatic salivary gland is small and lies close to the maxillary nerve near the ventral floor of the orbit. The nictitating membrane, or third eyelid,

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inserts in the ventromedial orbit. Adipose tissue fills the remaining space of the orbit and acts as a cushion to support the globe.1–3

GENERAL CONSIDERATIONS When evaluating a cat for eyelid or periorbital conditions the signalment, in particular the age and breed of the cat, is relevant. A full history should be obtained from the owner in relation to how long the problem has been present, vaccination history, and history of concurrent disease such as rhinitis, history of trauma, etc. A full investigation of eye problems should include an intraocular examination and evaluation of vision.3,5

Eyelid evaluation Evaluation of the eyelids should begin with an appreciation of symmetry between the two eyes. Is the abnormality unilateral or does it affect both eyelids? Is the patient able to perform a complete blink when tactilely stimulated to do so (palpebral reflex)? Are swellings or ulcerations present? Mass lesions are often obvious, but many neoplastic lesions in cats will be tissue destructive rather than proliferative; squamous cell carcinoma is the classic example. Has the globe position deviated resulting in passive eyelid instability, as occurs with enophthalmos and secondary entropion? Secondary blepharospasm is common with painful disorders of the eyelids and this spastic trigeminal–facial nerve reflex may worsen the appearance of an eyelid defect. Prior to and as part of the planning for surgical approaches to eyelid abnormalities, a topical anesthetic should be applied to the eye in the conscious animal (prior to general anesthesia and sedation) in order to allow determination of the extent of the underlying structural problem. If the surgical plan is made without taking into account the aggravating effects of blepharospasm, an inappropriate repair may result. The eyelids in the cat are tightly apposed to the globe and allow very little visualization of structures posterior to the corneoscleral limbus. Compared to the dog, there is little redundancy of eyelid tissue and facial skin, which makes blepharoplastic procedures more challenging. For inflammatory and potentially neoplastic conditions, skin scrapings, fine needle aspirates or biopsies for histopathologic examination and microbiologic evaluation are usually indicated. If there is suspicion of systemic disease then virology or hematologic and biochemical analysis of blood may be necessary. If a neoplastic condition is determined to be present, staging with thoracic and abdominal imaging and lymph node aspirates (see Chapter 14) may be indicated, depending upon the expected biologic behavior of the tumor.

Orbit evaluation Evaluation of the orbit should begin with an external examination assessing globe position, symmetry, and globe mobility, followed by palpation of the orbital margins and retropulsion of the globe. If there is resistance to digital palpation and retropulsion, or the cat is unable to retract the globe, a retrobulbar space-occupying lesion is likely and imaging should be pursued to determine the character and the extent of the disease process. Inflammatory diseases of the orbit are often accompanied by pain when the extraocular muscles and globe are retracted, when the globe is retropulsed, or upon opening of the mouth. With cystic and neoplastic lesions, the retropulse reflex is impaired, but usually elicits no significant discomfort.

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Diagnostic imaging If surgical intervention in the orbit is anticipated, additional diagnostic procedures are recommended. B-scan ultrasonography of the orbit may provide useful information about the impact of the orbital disease on the globe and will often provide guidance for sampling of a lesion, but computed tomography (CT) and magnetic resonance imaging (MRI) are better options to delineate the extent and borders of the disease.6,7 A study in a cat that compared orbital echography, skull radiography, CT, and MRI to assess a mass involving the orbit showed that MRI was the only technique that delineated the entire border of the tumor.8

Histopathology Prior to surgical intervention, histopathologic evaluation of a biopsy specimen is advised to facilitate surgical and postoperative treatment planning. Depending upon the exact location of the lesion within the orbit, sampling may be performed posterior to the bony orbital rim or via the oral cavity. Since the ventral orbital floor is bordered only partially by bone, the soft tissue posterior to the last molar may be incised in order to access the ventral orbit. A scalpel blade is used to incise the mucosa and a hemostat is gently and bluntly introduced through the incision, through the pterygoid musculature and the periorbita into the orbit for blind sampling. Expansive lesions may extend into the oral cavity and may be grossly appreciable upon examination of the mouth. Care must be taken to avoid damaging the maxillary artery as it courses along the orbital floor.1,2 If a diagnosis of a malignant process in the orbit is determined, the patient should have thoracic and abdominal imaging and potentially aspirates of the regional lymph nodes performed for staging purposes (see Chapter 14).

SURGICAL DISEASES OF THE FELINE EYELIDS Most eyelid disorders in cats will be the result of either congenital and developmental abnormalities or neoplastic diseases. Inflammatory conditions occur uncommonly and may be associated with infectious agents (Demodex, dermatophytoses, myiasis, FHV-1), autoimmune disorders (pemphigus, lupus, eosinophilic complex disease), or trauma and exposure to irritating compounds (drug reactions).3

Ankyloblepharon Ankyloblepharon is fusion of the eyelids to one another. It is physiologic in the kitten until postnatal days 10–14.4 If the eyelids remain closed beyond this time, this indicates either incomplete development of the eyelids and periocular structures or more likely viral conjunctivitis (infection acquired from the queen either during parturition or during the first few days following birth) that has resulted in conjunctival adhesions or symblepharon. When an infection is introduced to the conjunctival space beneath the fused eyelids, neonatal ophthalmia results, which requires manual (premature) opening of the palpebral fissure. Often these kittens will have gross swelling of their orbits and eyelids and may have purulent discharge exiting through a small rent in the palpebral fissure. If the lids are left apposed when such an infection is present, the ocular surface will be irreparably damaged and vision will be significantly impaired if not lost completely. To open the lids, first topical anesthesia should be applied to the lid margins and then one side of a small scissor or a mosquito hemostat is placed through the rent in the fissure and gently advanced and

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Figure 57-2  Lower lid lateral canthal entropion in an eight-month-old domestic short-haired cat. Figure 57-1  Eyelid agenesis in a nine-month-old domestic short-haired cat. The dorsotemporal eyelid margin is absent and trichasis is present. There is also keratitis, evidenced by corneal vascularization.

or the commissure of the lip. Various surgical techniques have been employed.1,10–14

Entropion elevated along the fused lid margins to break the adhesion. It is not recommended to cut the fissure since it is very easy to miss the line of fusion and cut the tiny lids themselves. Once the palpebral fissure is open, copious flushing should be performed to remove as much debris and infectious material as possible. Topical antibiotics and lubricants should be applied frequently thereafter (every four hours) because the blink reflex and tear production are usually underdeveloped at this young age. If there are corneal ulcerations present when the lids are opened, treatment with a topical antiviral medication, such as idoxuridine or cidofivir, should be started.

Eyelid agenesis The incomplete formation of a portion of the eyelid is known as eyelid agenesis or coloboma (Fig. 57-1). It is usually associated with an absent eyelid margin.3 The severity of this condition varies dramatically among affected individuals.9 The majority of cases have absent lid tissue and margin along the temporal portion of the dorsal eyelid. Severe cases may have most of the upper lid missing, including the lateral canthus and portions of the lower eyelid as well. Mild cases may be managed medically with regular lubrication if minimal ocular irritation is present. Most cases, however, benefit from surgical reconstruction of the abnormal lids in order to provide greater coverage for the globe and to minimize discomfort from exposure and scarring that can impair vision. In many cases, ocular irritation will occur not only due to absent tissue and an impaired blink mechanism, but also as the result of trichiasis, in which hair from the face is deviated toward the cornea. Cats with eyelid agenesis often will have other ocular abnormalities including microphthalmia, cataract, retinal dysplasia, and keratoconjunctivitis sicca.9 A thorough ophthalmic examination should be performed to determine the extent of this congenital disorder. The surgical approach to this condition will vary depending upon the severity. In some cases, simple apposition of the normal margins will suffice; other cases will require sliding advancement grafts (see Boxes 57-4 and 57-5) or grafts of tissue from either the lower eyelid

Most cases of eyelid malposition in cats are because of entropion, i.e., the inversion of the eyelid margin rolling toward the globe.3,15,16 Medial canthal entropion is almost universal in brachycephalic cats and is one of the causes of tear overflow and staining at the medial corners.1,3 In these cases, if irritation is minimal and the face can be kept sufficiently clean, surgical repair is not always necessary. In cats that develop full lid or lateral entropion, surgical correction is indicated.1,3,4,15 Most cats with entropion are only affected along the lower eyelid and occasionally at the lateral canthus (Fig. 57-2). Careful evaluation of the eyelid anatomy in affected cats is warranted since many cases have not only entropion, but also excessive length to their lower eyelid. In these cases shortening of the lower eyelid with a wedge resection may augment the repair.16 Ectropion, or eversion of the eyelid, is exceedingly rare in cats, and typically only results from cicatrix formation.

Eyelid neoplasia Since eyelid neoplasms in cats are usually malignant, it is fortunate that they are relatively uncommon, occurring with significantly less frequency than cutaneous neoplasms elsewhere on the body.17,18 The prevalence of eyelid neoplasia increases with age in cats, but has not been found to correlate with breed or gender. The most common eyelid neoplasm in cats is squamous cell carcinoma. Other reported tumors include mastocytomas (Fig. 57-3), hemangiosarcomas and hemangiomas, fibrosarcomas, various neoplasms of glandular origin (adenomas, adenocarcinomas), basal cell carcinomas (Fig. 57-4), peripheral nerve sheath tumors, lymphomas, and others.3,17,18 Squamous cell carcinomas usually appear as ulcerated lesions along the eyelid margin with a crusting surface (Fig. 57-5). White cats seem to have a predilection for the development of this tumor.19 There is evidence for the role of actinic damage in the pathogenesis of this tumor. Squamous cell carcinomas are amenable to various forms of treatment and wide surgical excision is often curative, although grafting procedures are usually necessary to fill the resultant defect of excision. Most other types of feline eyelid neoplasm are also amenable to

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The Head and Neck surgical excision, with variable recurrence rates.1,3,17 Mast cell tumors of the eyelids in cats generally respond favorably to surgical excision. A recent retrospective study described results in 33 cats with periocular mast cell tumors, and reported that recurrences were rare and affected cats had a median survival time of 945 days.20 Plesiotherapy with strontium-90 is another treatment option, either as a sole modality or in combination with surgical excision, that has excellent success rates.20,21 However, extensive lesions or disseminated disease may be best approached with systemic chemotherapy rather than excision or local radiation in cats.20 Cystic structures at the medial canthus that are benign and resemble apocrine hidrocystomas are occasionally noted in brachycephalic cats.18,22 Recurrence is common following local excision of these lesions, according to the authors’ experience and that of other veterinary ophthalmologists.18

SURGICAL DISEASES OF THE FELINE ORBIT Figure 57-3  An 11-year-old domestic short-haired cat with an eyelid mast cell tumor.

In the normal state, the feline eye rarely develops traumatic corneal ulcerations, exposure keratitis, and many of the other ocular conditions frequently diagnosed in other species. However, the feline orbit is relatively small, so when disease states occur, there is very little room for expansion or swelling. Early deviation (exophthalmos, strabismus, protrusion of the nictitans membrane) of the eye and the orbital contents is frequently accompanied by exposure keratitis, conjunctivitis, and chemosis. Brachycephalic individuals tend to have more shallow orbits and prominent globes, which may predispose them to even earlier exposure issues.

Orbital neoplasia

Figure 57-4  A 12-year-old domestic short-haired cat with an eyelid myxosarcoma.

The most common disorders of the feline orbit are neoplastic proliferations. They tend to be malignant (90%) and usually of epithelial origin.3 Squamous cell carcinomas are the most frequently reported orbital tumors in cats, followed by lymphoma (Fig. 57-6), fibro­ sarcoma and various bone tumors (Fig. 57-7).23 At least fifteen different tumor types have been reported within the feline orbit.23,24 Treatment strategies for each vary upon the extent of the lesion and the known or supposed biologic behavior of that type of tumor. Conservative surgical approaches to orbital neoplasms, which attempt to maintain the globe and vision, are usually associated with unacceptably high rates of tumor recurrence. Hence, the treatment of choice for orbital neoplasia is usually exenteration (see Box 57-7), which involves removal of the entire contents of the orbit including the globe. Orbitotomy techniques that spare the globe and seek to remove focal abnormalities within the orbit are rarely indicated in the cat and should be considered only in the case of small, well-defined lesions (preferably non-neoplastic or at least nonmalignant). Advanced imaging of the head in cases of orbital neoplasia is strongly recommended because the incidence of concurrent orbital, nasal and sinus disease is high due to the close proximity of these spaces in cats.

Proptosis

Figure 57-5  A nine-year-old domestic short-haired cat with an eyelid squamous cell carcinoma.

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Unfortunately, because of the rigid nature of the orbital support, when a traumatic insult is sustained and the globe suffers injury, the great amount of force necessary to affect the globe usually results in significant damage, which may be vision or globe threatening. Proptosis, or the capture of the eyelid margins behind the equator of the globe (Fig. 57-8), usually with anterior displacement of the globe, is often associated with significant facial and orbital trauma and fractures of the

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Figure 57-6  (A) A 12-year-old Siamese-cross with orbital lymphoma. (B) A bulging mass lesion and hemorrhage was noted posterior to the last upper maxillary molar upon oral examination of the cat.

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Figure 57-7  Osteosarcoma in a 14-year-old cat. (A) There is exophthalmos, dorsolateral strabismus and elevation of the third eyelid. (B) Viewed from above the anterior deviation of the globe can be better appreciated. (C) Radiograph shows extensive bony lysis of the orbit.

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PREPARATION FOR EYELID AND ORBITAL SURGERY

Figure 57-8  Traumatic proptosis in a kitten.

skull and mandible.25 In most cases of traumatic proptosis in the cat, the affected globes are rendered non-visual and are so severely damaged that they require enucleation.1 The contralateral eye may also be blinded by damage to the optic chiasm from the stretching forces placed upon the affected globe.3 These cats are usually seriously injured and collapsed and should be triaged and treated first for shock, head-trauma, and concussive brain injury. If the globe can be salvaged, it should be kept well lubricated until the cat is stable enough to undergo anesthesia and a temporary tarsorrhaphy performed to provide for its protection.

Orbital inflammatory disorders Orbital inflammatory disorders are fortunately uncommon in the cat. Orbital cellulitis and abscessation may be associated with trauma, foreign bodies, dental disease, extension of inflammatory nasal or sinus disease (especially if infectious), and rarely, immune-mediated inflammation.3,26 Most of these conditions respond appropriately to medical therapy when the underlying etiology is recognized and treated. Surgical therapy is usually only indicated if it is necessary to establish drainage in the orbit (see above for details on accessing the retrobulbar space for diagnostics), to protect the globe if the function of the eyelids is impaired and the proper distribution of the tear film is not possible (temporary tarsorrhaphy), or to remove the eye if it has been irreparably damaged (enucleation). Most inflammatory orbital conditions that result in exophthalmos are associated with orbital, ocular, and oral pain and most patients have an inflammatory leukogram and may be febrile. The exception is the condition known as idiopathic sclerosing orbital disease or orbital pseudotumor.26–28 This disorder has been diagnosed with increasing frequency of late and usually has an insidious onset. Clinical signs include exophthalmos, progressively decreasing ocular mobility, and exposure keratitis. The orbital tissues and eyelids become fixed in place by fibrous tissue. It begins in one eye but eventually progresses to involve both. Response to therapy (immunosuppressive therapy and radiation) is generally poor and enucleation is often necessary when the exposure keratitis progresses to ulceration and perforation.

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Due to the proximity of the lids to the sensitive ocular structures, preparation of the surgical site must differ somewhat from other sites on the body. Rather than cleaning and rinsing the eyelids with alcohol, chlorhexidine and other traditional sterilizing agents, which can be incredibly irritating and damaging to the corneal and conjunctival epithelia, it is recommended that a dilute (1 : 50) solution of povidine-iodine (solution, not scrub) be used to cleanse the site.29 At least three scrubs of the skin with swabbing of the conjunctival fornices are recommended, followed by liberal rinsing of the site with normal saline.1 Routine perioperative antibiotics (such as intravenous cefazolin) are useful to limit the incidence of peri- and postoperative infection. Regional anesthesia is not a necessary adjunct to general anesthesia for eyelid procedures. And, in fact, the infusion of lidocaine or other injectable anesthetic agents may distort the anatomy of the eyelid and alter the results of the procedure. Once the surgical site has been prepared, care must be taken to ensure that the globe remains lubricated throughout the duration of the procedure. Artificial tear or broad-spectrum antibiotic (triple antibiotic combination) ointments can be applied sparingly. If these interfere with the surgical procedure, sterile saline may be used to repeatedly and frequently moisten the eye. If an orbital procedure such as enucleation or exenteration is to be performed, a retrobulbar block may be considered. These blocks are more difficult to perform in cats than in other species due to limited retrobulbar space in the feline orbit. It can be difficult to achieve proper placement of the injection. There are several approaches to this block, but no matter which procedure is chosen, it is critical that the dose of local anesthetic be calculated carefully to avoid toxicity.1,30,31 A 1.5–2.5 inch 22 gauge needle that has been bent to the approximate curve of the orbit wall can be inserted ventrolateral or dorsal to the globe through either the conjunctiva (for subconjunctival enucleations) or through the eyelid skin after cleaning and preparation (for transpalpebral enucleations) and advanced past the globe in a ventromedial direction towards the opposite temporomandibular joint until the base of the orbit is encountered. Regional retrobulbar and peribulbar anesthesia runs the risk of hemorrhage, globe perforation, intravascular or subarachnoid injection, and vagal reactions, but can significantly decrease the depth of general anesthesia necessary and decrease postoperative pain.1,30,31

SURGICAL TECHNIQUES AND MANAGEMENT OF EYELID DISEASE Initial management of a developmental or neoplastic eyelid problem is in most cases surgical, with adjunctive medical support.1 If a surgical procedure for the feline eyelid is to be performed, the surgeon should primarily consider the requisite functions of the eyelid and aim to restore or improve that function, not just the cosmetic appearance of the eye.

Tarsorrhaphy A temporary tarsorrhaphy (Box 57-1) is the requisite surgical procedure for proptosed eyes that are salvageable and is also indicated when an orbital condition has resulted in exophthalmos and corneal exposure or if a facial paralysis has developed which impairs the animal’s

Eyelids and orbit

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ability to blink and protect its globe.1,2,25 The tarsorrhaphy should be left in place until the blink reflex returns and the orbital swelling has resolved; in most cases this will be a matter of two to four weeks. It is preferable to remove one tarsorrhapy suture at a time, rather than all at once, so that at least partial support for the globe is maintained for an extended time.

Modified Hotz–Celsus

Simple lid mass resection

Combination Hotz-Celsus with lateral wedge resection

If a lesion to be removed involves less than one-third of the margin of the eyelid, simple full thickness resections are typically indicated (Box 57-2).

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The most commonly employed approach to entropion in the cat is to perform a modified Hotz–Celsus procedure (Box 57-3). The length and shape of the skin-orbicularis oculi incisions vary depending upon the amount and area of the entropion correction necessary (Fig. 57-11).

If lower lid entropion is accompanied by excessive lid length, the modified Hotz-Celsus procedure may be combined with a lid

Box 57-1  Tarsorraphy The cat is positioned in sternal recumbency and the eye aseptically prepared for surgery. If the eyelid margins are caught behind the equator of the globe (e.g., with a proptosed eye), a lateral canthotomy will be necessary to release them. With blunt-tipped tenotomy, strabismus or Metzenbaum scissors, a 5–10 mm full thickness lateral canthotomy incision is made (perpendicular to the lateral canthus, as if extending the palpebral fissure laterally). The lids are then lifted from their inverted posture and repositioned in their normal anatomic position. The canthotomy incision is then closed with 4/0 or 5/0 non-absorbable suture with a figure-of-eight suture (Fig. 57-9A) at the margin of the lateral canthus, followed by interrupted sutures of the same material to close the remainder of the incision. Next, two or three horizontal mattress sutures are preplaced along and across the palpebral fissure with 4/0 nonabsorbable suture material. These sutures should be placed only partial thickness through the eyelid; care should be taken not to go through the palpebral conjunctiva so that the suture does not contact the cornea when the fissure is closed. When there is tension on the lids, as in the case of a proptosis or extensive orbital swelling, stents should be employed to minimize damage to the eyelid skin and the potential for pull-through (Fig. 57-9B). Portions of sterilized rubber bands or intravenous tubing are useful for this purpose. The horizontal mattress sutures should be tightened slowly and the lids lifted over the exposed globe rather than the globe being pushed back into the orbit.

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Figure 57-9  Temporary tarsorrhaphy. The lid fissure is closed with two or three horizontal mattress sutures, prevented from cutting into the skin by stents (e.g., infusion tubing). (A) If a canthotomy has been performed, it is closed with a figure-of eight suture at the margin and simple interrupted sutures for the length of the incision. (B) These sutures should be placed only partial thickness through the eyelid. Using 4/0 or 5/0 non-absorbable suture on a cutting or micropoint needle. (In the diagram the suture is shown loose and untied so the placement of the suture is clear. In the cat the suture will appose the eyelids – no suture should contact the cornea.)

Box 57-2  Eyelid mass resection The cat is positioned in lateral recumbency and prepared for aseptic surgery. There are two options to consider.

Triangular wedge resection1,4 An incision is made with tenotomy scissors through the full thickness of the eyelid on either side of the defect or neoplasm so that the incisions intersect away from the lid margin (Fig. 57-10A).

The four-sided or ‘house’ technique32 Two parallel incisions are made on either side of the defect to be repaired or removed. These incisions should be perpendicular to the eyelid margin and palpebral fissure. Two additional incisions are then made to connect the initial cuts in an intersecting manner (as with the wedge). This procedure provides a larger surface area to distribute tension associated with wound apposition (Fig. 57-10B).

Closure For either technique described above, the defect is then closed in two layers. The first a deep tarso-conjunctival layer with a simple continuous pattern of 5/0 to 6/0 absorbable suture. Care must be taken to ensure that the suture does not penetrate through the palpebral conjunctiva as corneal abrasions and ulcerations can result. The external layer is apposed with 5/0 non-absorbable suture in an interrupted pattern. The first suture placed in this repair is at the eyelid. This suture is the most critical for ensuring proper alignment and should be a figure-of-eight suture (Fig. 57-10C; a modification of the cruciate mattress suture). The remainder of the skin layer can be closed routinely with simple interrupted sutures (Fig. 57-10D,E).

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Box 57-2  Continued

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Figure 57-10  Simple lid resection. (A) A full-thickness wedge of tissue is removed. (B) A four-sided excision may decrease tension along the repaired incision line. (C) The first suture should be placed to appose the eyelid margin. A figure-of-eight suture, which is essentially a modified cruciate mattress suture, will accomplish this nicely. (D) The deep layer should not penetrate through the palpebral conjunctiva. (E) Final appearance.

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Figure 57-11  (A) Bilateral lower eyelid entropion in an un-neutered male cat. (B) Trichiasis has occurred as a result of the lid inversion. (C) Immediate postoperative appearance after correction of the entropion with Hotz–Celsus. (D) Postoperative appearance at suture removal.

shortening procedure.16 The excessive length of the lower lid is estimated or measured with Jameson calipers. If the patient is only unilaterally affected with entropion, it can be helpful to measure the length of the lower lid of the non-affected eye for comparison. When the surgeon has determined how much to shorten the eyelid length, a full-thickness wedge resection is performed (see Box 57-2) in the lateral lower eyelid. The eyelid margin is then apposed with a

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figure-of-eight suture of 5/0 non-absorbable material. The modified Hotz-Celsus (see Box 57-3) is then performed as usual.

Sliding skin graft The sliding skin graft, or H-plasty, is employed when a traumatic or surgical defect involves greater than one-third of the eyelid margin

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Box 57-3  Modified Hotz–Celsus (Fig. 57-12) simple interrupted pattern. Closure of the incision should begin in its center and split the distance between sutures until it is completely closed and sutures are 1–2 mm apart. The suture knots should be directed away from the globe or the near tags cut short and the far tags left longer to facilitate removal. As the incision heals, wound contraction will result in an additional 0.5–1 mm eversion. The Hotz–Celsus procedure can be modified further for medial entropion (Fig. 57-12D), such as is common in brachycephalic animals. A triangular incision is made at the medial canthus in the lower eyelid wherein the tip of the triangle is opposite the lower lacrimal punctum. This incision should not be deeper than the orbicularis muscle or damage to the nasolacrimal puncta and canaliculus can occur. Closure is routine with a simple interrupted 5/0 non-absorbable repair.

The cat is placed in lateral recumbency and prepared for aseptic surgery. A lid plate is placed behind the eyelid to prevent full thickness incisions through the eyelid and damage to the globe. The initial incision is made 1–2 mm from the eyelid margin (usually where the skin pigmentation stops and the skin hair begins) through the skin into the orbicularis oculi muscle. The length of this incision will depend upon the length of the lid that is affected by inversion. A second elliptical incision that joins to the ends of the first incision is made ventral (or proximal) to the first; the width is dependent upon the amount of tissue that needs to be removed to evert the eyelid into its normal position. The delineated segment of skin with a small amount of underlying muscle is removed with tenotomy scissors. The orbicularis muscle in cats may be difficult to discern; as long as the skin is excised fully, a sufficient amount of adjacent muscle should accompany it. The resultant defect is then closed with 5/0 non-absorbable suture in a

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D

Figure 57-12  Modified Hotz–Celsus. (A) An elliptical incision delineates the tissue to be removed. (B) The skin and a small portion of the underlying orbicularis oculi muscle is excised. One suture is initially placed in the center of the surgical eyelid wound and then the subsequent sutures placed. (C) Final appearance of Hotz-Celsus repaired with simple interrupted sutures. (D) Modification of the Hotz-Celsus for focal medial canthal entropion.

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Figure 57-13  (A) Squamous cell carcinoma affecting the eyelid at the lateral canthus. (B) Immediate postoperative appearance after excision of the neoplasm and repair of the resultant defect with two sliding skin advancement grafts, one in the upper lid and one in the lower lid. (C) Postoperative appearance. The palpebral fissure is shortened, but the lids are functional and there was complete excision of the tumor.

(Box 57-4).1,4 This procedure is appropriate for both upper and lower eyelid repairs (Fig. 57-13).

Roberts–Bistner procedure and modifications Although there are innumerable surgical approaches to the correction of eyelid agenesis in the cat, the most common is the Roberts–Bistner procedure (Box 57-5), or a modification thereof. This procedure involves transplanting a myocutaneous pedicle from the lower eyelid beneath the margin into the upper lid defect (Fig. 57-15).11 The donor area on the nictitans is left to heal by second intention. The base of the conjunctival pedicle is transected three to four weeks following the initial surgery. This can usually be accomplished with topical

anesthesia alone, negating the need for a second episode of general anesthesia.

Lip-to-lid resection The lip-to-lid procedure (Box 57-6) is useful for grafting of large defects in the lower eyelid following resection of neoplastic lesions33,34 (Fig. 57-17).

ORBITAL SURGERY Because there is limited peribulbar space in the feline orbit, surgical procedures are more difficult to perform than in other species.1,3

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Box 57-4  The sliding skin graft After full thickness excision of the lesion, two slightly diverging incisions are made with a scalpel blade in the eyelid, that are approximately twice as long as the height of the defect (Fig. 57-14A). Two equal sized triangles of skin are removed at the proximal tips of both incisions to accommodate the shifting of the graft into the defect. After liberal dissection to separate the skin graft from its underlying subcutaneous attachments, the graft is advanced into the defect, which will collapse the triangles (Fig. 57-14B). The graft should be advanced 0.5–1 mm beyond the normal margin of the

eyelid to compensate for postoperative shrinkage and secured with 5/0 non-absorbable simple interrupted sutures (Fig. 57-14C). The sliding skin graft should be lined on its underside with mucosa, either adjacent conjunctiva that can be recruited or free grafts of conjunctiva from elsewhere or free grafts of buccal mucosa. This lining should be attached to the posterior aspect of the skin flap with 6/0 absorbable suture in a simple continuous pattern so that the knots are either buried or exposed on the skin side. A temporary tarsorrhaphy is helpful if there is tension on the advancement graft. Figure 57-14  Sliding advancement graft. (A) The margins of the graft to be advanced are determined by the size of the lesion. (B) Two triangular pieces of skin are removed at either side of the graft’s base to prevent dog-ears. (C) Once advanced, the graft is sutured in place and the triangles closed.

A

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Figure 57-15  (A) Eyelid agenesis in the cat. Note the trichiasis and the extensive corneal vascularization. (B) Intraoperative appearance of eye during harvesting of myocutaneous graft during Roberts-Bistner repair of eyelid agenesis. (C) Immediate postoperative appearance.

Box 57-5  The Robert–Bistner procedure musculature. It is then rotated into the upper lid defect and sutured in place with 5/0 simple interrupted non-absorbable sutures (Fig. 57-16C). The donor bed is reapposed similarly. If there is sufficient conjunctiva separated from the recipient bed during preparation of the site, it should be used to cover the posterior aspect of the graft and sutured to the new lid margin with 6/0 absorbable suture in a simple continuous pattern with the knots either buried or exposed on the skin surface.

The recipient bed is first prepared by dividing the lid skin that is present from the palpebral conjunctiva with either a scalpel blade or a pair of Westcott scissors (Fig. 57-16A). A scalpel blade is then used to make an initial incision in the skin 2–3 mm ventral to the lower eyelid margin that is slightly longer than the length of the upper lid defect (Fig. 57-16B). A second parallel incision should provide a pedicle that is 1.0 mm wider than the height of the upper lid defect. This pedicle is elevated with scissors and should include skin and orbicularis oculi

A

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D

Figure 57-16  Myocutaneous graft repair of eyelid agenesis. (A) The recipient bed is prepared by dissecting the underlying conjunctiva away from the eyelid skin. (B) A pedicle of skin and orbicularis oculi muscle is harvested from the lower eyelid. (C) The skin graft is sutured in place in the recipient bed. (D) The Dziezyc–Millichamp modification harvests a pedicle of conjunctiva from the anterior face of the third eyelid to line the posterior surface of the skin graft. The conjunctival pedicle is left attached at its base laterally. The conjunctival defect on the third eyelid will be left to heal by second intention.

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Box 57-5  Continued

Modifications Modification of this technique utilizes conjunctiva from other sources if there is not enough available from the recipient bed. The Dziezyc– Millichamp modification proceeds as above, but the conjunctiva used to line the posterior surface of the skin graft is recruited from the

A

B

anterior face of the nictitating membrane (Fig. 57-16D).20 A pedicle graft of conjunctiva with its base at the lateral aspect of the nictitans is prepared with scissors then rotated 180° and apposed to the posterior surface of the skin graft and secured in place with 6/0 to 7/0 absorbable suture in a simple continuous pattern.

C

Figure 57-17  (A) Basal cell carcinoma of the lower eyelid. (B) Immediate postoperative appearance following excision of the neoplasm and repair of the resultant defect with a lip-to-lid graft. (C) Postoperative appearance of eyelid margin following lip-to-lid repair. Mild ectropion is present.

Box 57-6  Lip-to-lid (Fig. 57-18) For this procedure it is helpful to draw the proposed incisions with a marking pen before committing to the cuts. The lesion to be removed should be excised from the lower lid full thickness in its entirety with tenotomy or Metzenbaum scissors. Two parallel incisions are made through the lip at a 45° angle to the commissure of the lip beneath the lower eyelid. Once enough oral mucosa has been exposed and elevated with the lip graft so that when placed into the recipient bed the missing conjunctiva is replaced, the oral mucosa should be carefully split so that it remains within the oral cavity while the skin graft from above continues to be harvested for transfer. The rostral aspect of the lip graft incision is continued so that it connects with the medial aspect of the eyelid defect. The graft is

A

B

carefully undermined and rotated into the position of the former eyelid margin. The oral mucosal defect is apposed with 4/0 absorbable suture in a simple continuous pattern. The graft is initially sutured in place by apposing its oral mucosa to the remaining conjunctival edges with 6/0 buried simple interrupted absorbable sutures. The cutaneous surface of the graft is sutured in a simple interrupted pattern with 5/0 non-absorbable material. The cutaneous donor bed is closed similarly to repair the defect in the lip. A modification of this technique that places the lateral commissure of the lip in place of the lateral canthus to correct eyelid agenesis has been described.14

C

Figure 57-18  Lip-to-lid resection. (A) The tissues to be excised and transposed are delineated. (B) A section of lip with oral mucosa is elevated. The oral mucosa is split, when enough has been harvested with the skin graft, to replace the conjunctival defect to be created with the lid excision. Once the eyelid defect has been created, the incisions between the lip and the lid defects are connected. (C) The lid graft is rotated into position and sutured in place. The remaining oral mucosa is reapposed.

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Enucleation

Box 57-7  Indications for enucleation

Enucleation or removal of the globe, the eyelid margins, and the nictitating membrane and its associated gland, is indicated in many different situations (Box 57-7). There are two main approaches to removal of the globe, the subconjunctival technique and the transpalpebral technique1 (Box 57-8). The transpalpebral technique is recommended in cases of ocular neoplasia or intraocular or ocular surface infections in order to decrease the chances of extension of disease into adjacent tissues.35 In all other instances, the choice of which procedure to perform is surgeon preference, although the subconjunctival technique is reported by most surgeons to be more rapid and associated with less intra and postoperative hemorrhage.1 Also, the subconjunctival technique may be preferable in cats as a matter of course since tissues are often easier to identify with this approach.36 In cases of refractory glaucoma wherein the globe has become enlarged, limiting the already limited space in the orbit, it may be helpful to place a small gauge needle (30 or 25 gauge) into the anterior chamber at the corneoscleral limbus to remove a small amount of aqueous humor to make the globe smaller and facilitate manipulation of the globe within the orbit. If this is done, the globe may become somewhat flaccid which can make

• Intraocular tumors are present that are not amenable to local excision and are still confined within the globe, especially if they have resulted in secondary glaucoma • Intraocular infections have destroyed the globe and are potential sources of systemic infection • Proptosis of the globe has occurred with extensive damage to the globe, rupture of multiple extraocular muscles or severing of the optic nerve • Intraocular inflammation has destroyed the globe, resulted in blindness and pain • Glaucoma is uncontrolled with medical therapy, especially if buphthalmos is causing problems with corneal exposure • Extensive trauma to the globe or corneal defects that do not have the possibility of successful repair • Congenital defects, such as microphthalmia when sight is not present, result in chronic problems like conjunctivitis and keratitis

Box 57-8  Enucleation The cat is positioned in lateral recumbency and prepared for aseptic surgery.

Subconjunctival enucleation (Figs 57-19A,B,C) With blunt-tipped tenotomy, strabismus or Metzenbaum scissors, a 5–10 mm full thickness lateral canthotomy incision is made (perpendicular to the lateral canthus, as if extending the palpebral fissure laterally). This will facilitate exposure of the globe. The nictitating membrane may be removed at this time or following removal of the globe. The nictitating membrane is grasped and retracted with forceps to allow visualization of its deep extent. Two small hemostats are clamped at its base from either side and then it, along with the gland at its base, is excised with Mayo scissors. Next the bulbar conjunctiva in incised 3–5 mm posterior to the limbus with curved tenotomy, strabismus or blunt-tipped Metzenbaum scissors. This incision is extended 360° around the globe. Blunt dissection is then performed underneath the bulbar conjunctiva posterior to this incision until the insertions of the extraocular muscles are identified. The transection of these muscles is facilitated by introduction of a small muscle hook to elevate the muscle from the sclera. The tendinous insertions of all four rectus muscles are cut, followed by transection of the oblique and retractor bulbi muscle insertions. The globe should at this time be mobile and may displace forward slightly. There should be sufficient room to maneuver a small curved hemostat behind the globe to clamp the optic nerve and its adjacent vasculature. With curved Metzenbaum or enucleation scissors, the optic nerve is severed anterior to the hemostat. If there is not enough room for both instruments behind the globe, which is often the case in cats, then the nerve should be clamped for a moment, then the hemostat removed followed by transection of the nerve with the scissor. In most cases, it is not necessary to place a ligature on the stump of the nerve and blood vessels. The globe is removed and the orbit inspected. Bleeding vessels that can be identified may be addressed with ligatures or point cautery. Direct pressure with a surgical sponge may stop or slow diffuse oozing. Next, 4–6 mm of the eyelid margins, including the lateral and medial canthi are removed with scissors and any remaining conjunctiva within the orbit is removed at this time.

702

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D

Figure 57-19  Subconjunctival enucleation. (A) A lateral canthotomy is performed to facilitate exposure. (B) A 360° incision in the conjunctiva is made. Blunt dissection underneath the conjunctiva will expose the insertions of the extraocular muscles which are transected. (C) Once the muscular attachments of the globe have been severed, the optic nerve is clamped, then transected and the globe is removed. (D) The margins of the eyelids are removed prior to a two-layer closure.

Transpalpebral enucleation The palpebral fissure is sutured closed with 4/0 to 5/0 non-absorbable suture in a simple continuous pattern (Fig. 57-20A). If the tags of suture are left long on either side of the fissure, they can be grasped with hemostats to facilitate exposure of the surgical site. The eyelid skin is then incised circumferentially with a scalpel blade approximately 4–6 mm from the margins (to avoid the base of the glands in the lid margin). Care must be taken to incise the skin

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Box 57-8  Continued and subcutaneous tissues alone, without penetrating through the palpebral conjunctiva. Once the submucosa of the conjunctiva is reached and identified, blunt dissection with curved tenotomy, strabismus or Metzenbaum scissors will continue posteriorly above the conjunctiva until the fornices are passed and the sclera can be visualized. The extraocular muscles are identified and transected (Fig. 57-20B). Once all the extraocular muscles are transected, the optic nerve is clamped, transected and the globe is removed (Fig. 57-20C).

B

Enucleation closure (Figs 57-19D and 57-20D) If a silicone implant (see Chapter 10) is to be placed within the empty orbit, it should be prepared by soaking in betadine solution followed by roughening or scarification by several incisions with a scalpel blade to roughen its surface and improve its orbital retention. The implant will then be placed within the orbit and a mesh of suture placed across the orbit from the dorsal to ventral orbital rims to facilitate its positioning. A simple continuous pattern of 3/0 to 4/0 absorbable suture will span the orbit over the implant with bites taken along the orbital rims through the periorbita. If no implant is to be placed, this meshwork may still be placed in an attempt to minimize the depression of skin into the empty orbit that results from loss of orbital contents. A standard two-layer closure of the remaining subcutaneous tissue and skin over the orbit is then performed. The subcutaneous tissues should be apposed with 4/0 to 5/0 absorbable suture in a simple continuous pattern. The skin may then be apposed with either 4/0 to 5/0 non-absorbable interrupted sutures or 4/0 to 5/0 absorbable suture in an intradermal pattern. If skin sutures are to be removed, they should remain in place for at least 10-14 days following surgery.

A

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D Figure 57-20  Transpalpebral enucleation. (A) The eyelids are sutured closed prior to the initial incision and an elliptical incision is made around the closed palpebral fissure. (B) Blunt dissection of the subcutaneous layers is performed until the insertions of the extraocular muscles are identified and transected at their origins. Care must be taken to avoid entering the conjunctival space surrounding the ocular surface when performing this dissection. (C) Once all the extraocular muscles are transected the optic nerve is clamped, then transected and the globe is removed. (D) Closure is in two layers.

Box 57-9  Exenteration The cat is positioned in lateral recumbency for surgery and prepared aseptically. The palpebral fissure is sutured closed with 4/0 to 5/0 non-absorbable suture in a simple continuous pattern. If the tags of suture are left long on either side of the fissure, they can be grasped with hemostats to facilitate exposure of the surgical site. The eyelid skin is then incised circumferentially with a scalpel blade approximately 4–6 mm from the margins (to avoid the base of the glands in the lid margin). Care must be taken to incise the skin and subcutaneous tissues alone, without penetrating through the palpebral conjunctiva. Once the submucosa of the conjunctiva is reached and identified, blunt dissection with curved tenotomy, strabismus or Metzenbaum scissors

will continue posteriorly above the conjunctiva until the fornices are passed and the sclera can be visualized. The initial incision is extended caudally through the orbicularis oculi muscles of the eyelids and the orbital fascia toward the orbital rim. The extraocular muscles are incised as close to their origins as possible and the optic nerve is clamped and severed as in a routine enucleation. A periosteal elevator may be used to remove the periorbita from the orbital bones and the orbital lacrimal gland from the dorsal orbit. Once the globe and its associated tissues are removed, remaining connective tissue and fat within the orbit may be excised if necessary. Closure is as in a routine enucleation.

delineation of its margins more difficult during the procedure, so care should be taken not to unwittingly damage the globe during its dissection. It is imperative to avoid excessive traction on the globe during enucleation in the cat. The retrobulbar optic nerve (from the posterior globe to the optic chiasm) is relatively short and traction on the diseased globe during its removal may damage the optic chiasm and the opposite optic nerve, rendering the patient blind.1,3

require removal of more skin that the eyelid margins alone and there is insufficient skin left to close the orbital defect, a caudal-auricular axial pattern flap may be used (see Chapter 19).37

Exenteration

Eyelid surgery

Exenteration (Box 57-9) involves the removal of not only the globe, but also the extraocular muscles and periorbita. This technique is usually indicated when there is orbital neoplasia (Fig. 57-21). The orbital depression that results from exenteration is more marked that that following enucleation alone. In cases of exenteration which

The most important part of the postoperative care of patients that have undergone some form of blepharoplasty is diligent attention to preventing self-trauma and dehiscence of the suture line. The importance of this for the success of the procedure should be stringently stressed to the caretaker. Rigid Elizabethan collars are the most common

POSTOPERATIVE CARE

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Figure 57-21  (A) A 12-year-old domestic short-haired cat with exophthalmos, chemosis and conjunctival hyperemia resultant from an undifferentiated orbital sarcoma. Note the dilated pupil which suggests damage to the optic nerve and the dull, lackluster appearance of the cornea, an indication that the ability to blink has been compromised. (B) Computed tomographic scan shows a mass in the ventral orbit causing exophthalmos. (C) Postoperative appearance two weeks following exenteration.

means to limit the patient’s ability to disturb the surgical site. Topical lubricants and broad-spectrum antibiotics are usually employed to minimize the likelihood of irritation to the ocular surface and infection of the surgical site. Systemic antibiotics following surgery are not usually necessary if appropriate perioperative antibiotics are used unless an infectious process is present at the time surgery is performed. If the patient is systemically able to tolerate non-steroidal anti-inflammatory agents, such as meloxicam, these are helpful to minimize pain and tissue swelling. Skin sutures should be left in place for at least ten to 14 days, preferably longer, as premature removal of sutures can result in dehiscence and lid defects and may necessitate additional surgery.

Orbital surgery If proper sterile and careful surgical technique is employed in orbital procedures, the postoperative recovery of the patient is usually un­ eventful. If preoperative retrobulbar anesthesia is administered (see Chapter 2), the requisite postoperative analgesia will be minimized. If they are not contraindicated by a systemic condition, non-steroidal anti-inflammatory agents administered systemically usually significantly improve patients’ postoperative comfort. Systemically administered antibiotics are usually unnecessary if perioperative antibiotics are given, unless there is concern because an infectious process necessitated the orbital surgery or removal of the globe. Postoperative

swelling may be decreased with prompt and repeated (as long as it is tolerated) application of a cold compress to the surgical site.

COMPLICATIONS AND PROGNOSIS Eyelids Complications of eyelid surgery may include suture dehiscence, infection, recurrence of the original problem, trichiasis, corneal ulceration, swelling, and discomfort. Cats latently infected with FHV-1 may suffer from recrudescent disease (conjunctivitis, corneal ulcers, upper respiratory signs) initiated by the stress of general anesthesia, hospitalization, and treatment.

Orbit The most common complications following enucleation and exenteration are hemorrhage and infection.1,2,35,36 In globe sparing procedures, damage to the globe, persistent displacement or deviation of the globe, exposure keratitis, corneal ulcerations that may progress or be slow to heal, keratoconjunctivitis, blindness, and recurrence or progression of the primary disease process (tumor recurrence, recrudescence of infection, etc.) are possible. Prognosis is highly dependent upon the etiology of the disorder.

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