Basic Ophthalmic Surgical Procedures

Chapter 124

Basic Ophthalmic Surgical Procedures

Ophthalmic surgery is indicated for a vast number of diseases and encompasses many types of surgical techniques. Although some procedures use standard operating protocol, most use techniques and instruments specific to ophthalmic surgery. Because of this, a strong knowledge of ophthalmic anatomy, physiology, diseases, and pharmacology is imperative when considering almost any type of ophthalmic surgery.

The purpose of this chapter and Chapter 125 is to describe the most common adnexal and extraocular procedures done on dogs and cats. Although some clinical diseases are described, ophthalmic texts should be referenced if additional information is needed to become familiar with the disease processes. Intraocular procedures are not described here except for some information in the emergency procedure chapter (Chapter 125) because advanced training is required to master those techniques.

Perioperative Considerations


General anesthesia is required for all but the most minor surgical procedures. Modern anesthetic protocols are acceptable for general anesthesia for patients undergoing ophthalmic procedures. Just as with all other patients requiring general anesthesia, a blood cell count, serum chemistry panel, and thorough general physical examination should be obtained. Thoracic radiographs, urinalysis, and other diagnostics may also be indicated. For most ophthalmic procedures, a quiet induction and smooth recovery are tremendously important to prevent ocular trauma. Paralysis with neuromuscular blocking agents such as atracurium can render optimal eye position for corneal and intraocular surgery, prevent increases in intraocular pressure from extraocular muscle contraction, and aid in prevention of the oculocardiac reflex.19 Ocular lubrication is a necessity during general anesthesia. When the cornea is exposed and artificial tear ointment cannot be used, an ophthalmic balanced salt solution should be dripped on the cornea every 5 to 10 seconds to maintain corneal moisture and prevent corneal desiccation and ulceration. Sedatives and analgesics should be on hand during the postoperative period in case there are signs of a rough recovery.

Retrobulbar blockade is used by some; however, studies on its clinical effectiveness are rare. Two studies evaluated retrobulbar blocks for the purpose of negating the use of neuromuscular blocking agents in dogs undergoing phacoemulsification; both found the procedure to be safe and to provide good globe position.1,51 More frequently, blocks are used with enucleation to provide additional analgesia and slightly exteriorize the globe. Retrobulbar blocks are usually unnecessary and may result in complications such as retrobulbar hemorrhage, globe rupture, intravenous injection, and optic nerve injection and damage. Retrobulbar blocks should not be performed when local infection or neoplasia is present or when anesthetic monitoring is insufficient.

Oculocardiac Reflex

Although not a common problem in veterinary ophthalmology, the oculocardiac reflex may result in decrease in heart rate with pressure or traction on the globe. A satisfactorily deep plane of anesthesia is important for preventing this reflex. Administration of an anticholinergic, such as glycopyrrolate or atropine, during premedication is recommended to reduce the likelihood of reflex occurrence. Although both drugs inhibit the reflex equally well, glycopyrrolate may do so without associated tachycardia and dysrhythmias. Neuromuscular blockade prevents the oculocardiac reflex but also requires significant additional monitoring and ventilation. If the oculocardiac reflex is elicited, the surgeon should stop ocular manipulations until the reflex resolves. Intraoperative administration of atropine (0.02 mg/kg IV) may be required if the reflex does not resolve immediately.

Presurgical Preparation

After anesthetic induction, the periocular area is carefully clipped. Abrasion of the eyelid skin is avoided to prevent postoperative irritation, which can lead to self-trauma. The cilia are trimmed with scissors. Sterile lubricating jelly is placed on the globe before clipping to prevent clipped hairs from entering the conjunctival sac. This is especially important if the globe is perforated. The lubricating jelly is then rinsed away with the adherent hairs. The periocular area is then gently scrubbed using sterile 4 × 4 gauze sponges soaked with povidone–iodine solution diluted with saline (1 : 50, 0.2% solution), alternating with sterile saline. Povidone-iodine scrub contains detergents harmful to the cornea and should not be used. The conjunctiva, including both sides of the nictitating membrane, is then cleansed with the same solutions using sterile cotton-tipped applicators to remove mucus and debris. Finally, povidone–iodine solution and saline are used to irrigate the cornea and conjunctiva. The nonoperated eye should be lubricated with artificial tear ointment or taped closed.

Perioperative intravenous antibiotics are administered during corneal, intraocular, orbital, and some adnexal procedures. Administration of postoperative antibiotics is determined on an individual case basis as determined by invasiveness of the procedure and presence of other conditions such as diabetes, pyoderma, blepharitis, or otitis externa.

Instrumentation and Hemostasis

Instruments used in ophthalmic surgery vary tremendously depending on the surgical procedure. Although some general surgical instruments are used with adnexal and orbital surgeries, additional finer instruments are also necessary. To perform many of the procedures described in this chapter, the surgeon should have one pack that includes a Barraquer eyelid speculum, Jaeger eyelid plate, fine-toothed Bishop-Harmon forceps, curved Steven’s tenotomy scissors, and small Derf needle holders (Figure 124-1). Additional instruments are mentioned in the text as needed.

Hemorrhage is usually minor with simple adnexal procedures. Generally, direct pressure with a cotton-tipped applicator will suffice for hemostasis. Wedge-shaped cellulose sponges are used for intraocular procedures and for hemostasis when the globe is perforated because, unlike cotton, they do not shed fibers. Small hand-held cautery units or direct pressure with 4 × 4 gauze sponges can be helpful in more involved adnexal procedures. Care should be exercised to prevent iatrogenic corneal ulceration from contact of a 4 × 4 sponge with the cornea. Irrigation with topical ophthalmic phenylephrine or 1 : 10,000 epinephrine is also useful for hemostasis.

Globe Exposure

Globe position while under general anesthesia can be problematic with entropion repair, corneal surgery, and intraocular surgery. With general anesthesia, the globe passively retracts into the orbit, accentuating entropion and allowing for nictitating membrane protrusion. Additionally, the globe rolls ventrally, creating visualization problems for corneal surgery. Several kinds of eyelid specula are available to assist in eyelid retraction and visualization. The most lightweight is the Barraquer wire speculum, which is available in several sizes. A self-retaining Castroviejo eyelid speculum can also be used with larger eyes. When properly placed, both will retract the third eyelid.

Lateral canthotomies that extend through the lateral canthus and terminate anterior to the lateral canthal ligament can be used to increase globe exposure (Figure 124-2). Hemorrhage is minimal if the incision is made while the eyelid speculum is in place. Alternatively, a small mosquito forceps can be used to gently crush the tissue before incision. The incision can be closed in a single (usual method) or double layer. If the deep tarsoconjunctival layer is closed, 5-0 or 6-0 simple interrupted absorbable sutures are placed, taking care to ensure that the suture does not contact the corneal surface. The eyelid skin and eyelid margin are closed in a simple interrupted pattern with nonabsorbable or absorbable 4-0 to 6-0 sutures. Occasionally, a figure of eight suture will be placed. Suture tags from the margin suture can be incorporated into the skin sutures.

Neuromuscular blocking agents result in optimal centralized eye position; because of increased monitoring and potential complications, however, they are not always used. Scleral fixation sutures help rotate the globe to a workable position. When they are needed, they must be placed partially through the sclera. Generally, 5-0 or 6-0 suture is used with the bites taken 1 to 2 mm from the limbus and in different locations as required. Care is taken to avoid full-thickness sclera penetration. The suture can be tagged with small hemostats to facilitate manipulation. When removed, one arm of the suture is cut short to reduce trauma during extraction.


The primary function of the eyelids is to protect the ocular surface. Eyelids provide a mechanical barrier, secrete the lipid portion of tear film, sweep away foreign bodies, and spread tear film over the corneal surface and direct it toward the lacrimal puncta. The latter is accomplished effectively through perfect and close apposition of eyelid margins as they glide over the corneal surface. In dogs and cats, the superior eyelid is more mobile and more important than the inferior in maintaining the ocular surface. Anything that disturbs motion or apposition of the eyelids over the corneal surface can result in pathology.

Anatomy and Physiology

The typical arrangement of the muscles, cilia, and glands and location of the lacrimal puncta within the canine eyelid is depicted in Figure 124-3. In dogs, the tarsus, a fibrous tissue thickening surrounding the tarsal glands, is poorly developed or absent. The eyelids are therefore unstable and need to be in contact with the ocular surface to maintain conformation. The superior eyelid is elevated by the levator anguli oculi medialis, levator palpebrae superioris, Müllers, and frontalis muscles. The inferior eyelid is lowered by the malaris muscle. The superior and inferior eyelids are brought toward each other by the sphincter-like orbicularis oculi muscle. All eyelid muscles are innervated by the branches of the facial nerve except for the levator palpebrae superioris (oculomotor nerve) and Müllers (sympathetic) muscles (Figure 124-4). Sensation to the eyelids and corneal surface is provided by branches of the trigeminal nerve, which constitutes the afferent branch of the blink reflex.34,89

Medial and lateral canthal ligaments stabilize the eyelid commissures and prevent the palpebral fissure from becoming circular. The medial ligament is a distinct fibrous band originating from the frontal bone near the nasomaxillary suture. The medial ligament serves as the origin and insertion of the orbicularis oculi muscle. The lateral ligament is a poorly developed thickening of the orbital septum that originates from the zygomatic arch and ventral orbital ligament and terminates by blending into the fibers of the upper and lower tarsi. Function of the lateral palpebral ligament is supplemented by the retractor anguli lateralis muscle, which lies anterior to the ligament.34,89

Special Surgical Considerations

Eyelids are extremely vascular, and hemorrhage from incisions may be profuse and a nuisance. However, because excessive scarring can lead to conformational changes of the eyelid, cautery should not be used for most eyelid procedures. Because of copious blood supply, suture choices that would be considered anathema at other locations are routinely used on eyelids. For example, polyglactin can and is routinely used for skin apposition around the eyelids. The suture’s excellent knot security and handling, along with the fact that it becomes soft when wet, make it a good choice, especially for apposition of the eyelid margin. Additionally, because they are absorbable, polyglactin sutures do not need to be removed, a feature that becomes very desirable when faced with the unpredictable behavior of some of the breeds that commonly develop entropion.

Postoperative care for all eyelid surgeries should include a protective Elizabethan collar to minimize self-trauma and a topical broad-spectrum topical ophthalmic antibiotic ointment to lubricate and prevent secondary infection of incisions. Surgical procedures that typically result in dramatic inflammation of the eyelids (e.g., cryotherapy) or that have an inflammatory cause (e.g., chalazion) should also be treated with a topical corticosteroid ointment as long as there are no contraindications. General principles of perioperative intravenous antibiotic usage apply to the eyelids.

Developmental or Congenital Defects


Delayed opening of the eyelids (>14 days) may be associated with infection in dogs (Staphylococcus spp.) and cats (herpesvirus, Chlamydophila felis, Staphylococcus spp.). The typical presentation is mucoid ocular discharge. Conservative management with warm compresses can be attempted for 24 hours in the expectation that opening will occur on its own. If opening does not occur with conservative treatment, eyelid separation using firm digital pressure should be attempted immediately after treatment with a warm compress. If that is unsuccessful, tips of small mosquito hemostats can be inserted through the palpebral fissure at the medial canthus (where there is typically a small separation) and then opened to pry open the eyelids. To avoid trauma, hemostats should not be closed while within the palpebral fissure. After the eyelids are opened, the ocular surface should be flushed with physiologic saline or dilute povidone-iodine solution (1 : 50). The cornea should be stained with fluorescein to rule out corneal ulceration, and a topical antibiotic effective against the suspected infectious organism should be applied three to four times daily for 7 to 10 days. Fused eyelid margins should not be sharply incised because this may result in irreversible damage to the eyelid margins or meibomian glands, which could result in lifelong keratitis.

Eyelid Agenesis

Congenital absence of a portion of the eyelid margin is most common in cats and usually involves absence of a portion of the lateral superior eyelid. In dogs, the defect more commonly affects the lateral or central inferior eyelid. Small defects may be treated medically with topical petroleum-based lubricants. Defects that result in keratitis should be treated surgically. This condition can be associated with lacrimal gland agenesis, keratoconjunctivitis sicca, persistent pupillary membranes, cataract, retinal dysplasia, and optic nerve coloboma in cats.7

Defects smaller than one third of the eyelid margin may be treated by removing the edges of the defect; the edges of the resulting wedge defect are apposed with a simple two-layer closure (see section on simple two-layer closure below). Larger defects require more extensive reconstructive procedures and are typically repaired using the procedure first described by Roberts and Bistner108 and then modified by Dziezyc and Millichamp.27 Many other reconstructive techniques have been adapted to correct this defect;11,29,131 the technique used is therefore based on surgeon preference and the characteristics of the defect.


Inward rolling of the eyelid margin can be conformational, cicatricial, involutional, or spastic. In the first three, a defect in the anatomic relationship between the ocular surface and the eyelid promotes inward curling of the eyelid margin. In spastic entropion, a painful stimulus results in spasm of the orbicularis oculi muscle and retraction of the globe, resulting in inward rolling of the margin. If the painful stimulus is removed, spastic entropion will resolve; therefore, topical anesthetic should be applied to the ocular surface before surgical correction of entropion is considered. Moreover, because trichiasis from entropion is inherently painful, there is a spastic component to every case of entropion. If this spastic component is not identified, surgical correction may result in ectropion. Surgical correction should only be pursued after all possible inciting causes have been ruled out with a Schirmer tear test, fluorescein staining to detect corneal ulcers, examination with magnification to detect cilia disorders, and assessment of intraocular pressure and aqueous flare. Additionally, entropion should be confirmed to be conformational by examination of the patient before and after topical anesthesia.

All entropion-correcting procedures rely on accurate estimation of the amount and location of inward rolling of the eyelid. This can only be done while the patient is awake and unsedated and after topical anesthesia has been applied and other causes of spastic entropion have been eliminated. A simple way to estimate the amount of rolling in is to visually, or with a dermal marker, mark the highest point (on the lower eyelid) or the lowest point (on the upper eyelid) on the entropic eyelid. The distance between the mark and eyelid margin corresponds to the amount of correction needed. Alternatively, a finger can be placed on the skin just distal to the rolled-over portion of the eyelid. Gentle traction away from the eye is then used to evert the eyelid to its correct conformation. The distance between the beginning and ending finger positions corresponds to the amount of correction needed.

Temporary Correction.: Temporary correction may be pursued in very young dogs if there is significant keratitis and skull development is not complete. Ideally, permanent correction should be postponed until skull conformation has reached adult size. In some breeds, such as Shar-Peis and Chow Chows, temporary correction is all that is needed because entropion resolves when facial maturity is attained. Temporary correction is achieved by placing vertical mattress sutures perpendicular to the eyelid margin in the area of the entropion. The first bite is placed 2 to 3 mm from the eyelid margin. The distance between the inner aspects of the first and second bites should correspond to the estimated amount of correction. Bites extend through the skin only and not through the conjunctiva because this would cause corneal irritation. The sutures are tied and knots positioned as far away from the eyelid margin as possible (Figure 124-5). A 3-0 to 5-0 nonabsorbable monofilament is typically recommended. Alternatively, polyglactin may be used. Inflammation associated with breakdown of absorbable suture may sometimes result in mild scarring that prevents entropion recurrence. An alternative to skin sutures that is quick, effective, and lasts longer is the use of skin staples. Staples are placed so a furrow forms within the staple, everting the eyelid.

Permanent Correction.: Permanent correction is most commonly accomplished by removal of a crescent-shaped section of skin from the entropic region of the eyelid (Hotz-Celsus procedure). The eyelid is supported by a Jaeger eyelid plate or Desmarres entropion forceps. A skin incision parallel to and 2 mm from the eyelid margin, extending just beyond (2 to 3 mm) the rolled-in portion of the eyelid, is made with a #15 Bard-Parker or a 6400 Beaver blade. A second skin incision that arches away from the eye, beginning at one end of the first incision and ending at the other, is made. The distance between the first and second incisions, at its widest point, should correspond to the previously estimated correction amount. The crescent-shaped section of skin is sharply excised with tenotomy scissors; it is not necessary to remove any of the underlying orbicularis oculi muscle. If there is medial and lateral entropion but the central margin is normal, two crescents should be excised, one medially and one laterally. The defect is closed with simple interrupted 4-0 or 5-0 nylon or polyglactin sutures. The first suture should join the center of the first and second incisions. The second and third sutures should be placed so they bisect the remaining defects and so on until there are sutures every 3 to 4 mm. Sutures should be tightened only to the point where there is perfect apposition of skin margins (Figure 124-6). Suture tags should be cut short enough to ensure that they will not contact the cornea.

This basic technique can be modified for use in special situations such as medial entropion with epiphora of miniature and brachycephalic breed dogs and lateral upper and lower entropion of large-breed dogs. The goal for miniature-breed dogs is to slightly evert the eyelid at the medial canthus, changing the position of the inferior lacrimal puncta, to promote tear uptake and drainage via the nasolacrimal duct. An isosceles triangle–shaped incision, with the base parallel and 2 mm from the margin, through just the skin is made and the skin excised. The base of the triangle is usually 5 to 12 mm wide, and the distance between the base and the vertex is usually 5 mm. A simple interrupted suture is placed from the center of the base of the triangle to its apex. The remaining incision is closed by bisecting the remaining edges until there are sutures every 3 to 4 mm.

In large-breed dogs that have concurrent upper and lower eyelid entropion laterally, an arrowhead-shaped section of skin is removed (Figure 124-7). Transection of the lateral canthal ligament improves the success of this procedure in breeds with large, broad skulls (e.g., Rottweilers, retrievers, and great Danes) in which the lateral canthal ligament causes inversion of the lateral canthus.109 Transection of the ligament is accomplished by grasping the lateral canthus and pulling it anteriorly and nasally so as to tighten the ligament. The ligament is localized by gently “strumming” across the conjunctival surface. An incision through the conjunctiva just over the ligament is made with tenotomy scissors. The ligament is relocalized by strumming and is then blindly transected with scissors. The conjunctival incision is not sutured.

The eyelids, because of the poorly formed tarsus, are unable to maintain their conformation without resting on the corneal surface. When enophthalmos from orbital fat pad shrinkage (secondary to inflammation or cachexia) or an increase in orbital volume (e.g., chronic masticatory myositis) occurs, the eyelids tend to roll inward, resulting in involutional entropion. Correction of this type of entropion is difficult; the procedures outlined above are not ideal for its treatment because they do not address the position of the globe within the orbit. The eyelids will continue to roll in unless the corneal surface can be brought anteriorly to support the eyelids. Although poorly described in the veterinary literature, ideally, the enophthalmos should be corrected. Temporary success has been achieved in sighted humans with an intraconal injection of stabilized hyaluronic acid gel.70,124


Ectropion, or eversion of the eyelid, can be caused by an excessively long palpebral fissure, by contraction of scar tissue from a previous laceration, or by overcorrection during entropion surgery. The first is corrected by shortening the eyelid and the latter two by a V-to-Y blepharoplasty. Ectropion need only be surgically corrected if it results in clinically relevant pathology such as keratitis or excessive accumulation of debris within the ectropic pocket, especially because a degree of ectropion is part of the breed standard for many breeds.

There are many procedures designed to correct ectropion, and they are discussed extensively elsewhere.34,79,119

Wedge Resection.: The majority of cases of simple ectropion from an excessively long palpebral fissure can be corrected with a wedge resection or Munger and Carter modification of the Kuhnt-Szymanowski procedure.87 The wedge of tissue to be removed can be positioned anywhere along the eyelid margin. In cases with uniform eversion all along the eyelid margin, it may be wisest to excise the wedge close to the lateral canthus to diminish the consequences of notching that may occur if margin apposition is not perfect. In some breeds, such as mastiffs and Saint Bernards, there is a crease in the central portion of the eyelid; positioning the wedge to remove the creased portion of the eyelid can be advantageous. The length of eyelid margin that is removed should be slightly shorter than the amount of correction needed because fibrosis and wound contraction provide an additional 0.5 to 1.0 mm of correction (see section on wedge and pentagonal resection below). The wedge is closed using a simple two-layer closure (see section on simple-two layer closure below).

Margin-Sparing Techniques.: The modified Kuhnt-Szymanowski procedure avoids splitting the eyelid as described in the original Kuhnt-Szymanowski procedure. An incision through the skin and orbicularis muscle, 3 mm from and parallel to the margin, starting at the lateral boundary of the medial third of the eyelid and ending 1 cm lateral to the lateral canthus is made. A second skin–orbicularis incision is continued ventrally from the lateral end of the first incision for approximately 1.5 cm. The skin and muscle flap is undermined with small tenotomy scissors. Two wedges with the same base width—one from the lateral extent of the skin muscle flap and one from the medial extent of the tarso-conjunctival flap—are removed. The wedges should be slightly smaller than the needed correction. The tarsoconjunctival margins are apposed with 4-0 or 5-0 simple interrupted absorbable sutures, taking care to not penetrate through conjunctiva, which could leave suture rubbing against the cornea. The eyelid margin is apposed with a figure of eight suture. The skin is apposed with simple interrupted sutures, with the first suture placed at the junction of the horizontal and vertical skin incisions and subsequent sutures bisecting the remaining incisions (Figure 124-8).

The VY-plasty begins with two converging skin incisions on each side of the scarred tissue or ectropic margin. The V-shaped skin flap is elevated and underlying scar tissue resected, if present. The incisions are closed in the shape of a Y with simple interrupted 4-0 or 5-0 sutures. The length of the base of the Y should be about 2 to 3 mm longer than the amount of correction needed (Figure 124-9).


Euryblepharon refers to a symmetric enlargement of the palpebral aperture secondary to longer than normal eyelids (macroblepharon). In brachycephalic breeds, this condition may be associated with medial canthal trichiasis and lagophthalmos, leading to chronic keratitis and progressive pigmentary infiltration (with or without corneal ulceration). Temporary relief can be achieved with topical lubricant ointments; however, definitive correction involves surgical reduction of the palpebral fissure. This is best accomplished by a permanent medial canthoplasty. Although several different procedures have been described, the pocket technique provides the greatest closure stability. In large-breed dogs such as Neapolitan mastiffs, bloodhounds, Newfoundlands, and Clumber spaniels, the exaggerated palpebral fissure and conformational enophthalmia may result in combined central ectropion with lateral entropion. A combination of a wedge resection to shorten the fissure and a Hotz-Celsus procedure to evert the entropic areas may be enough in some cases. However, when there is marked canthal instability, a procedure such as described by Bigelbach may be more appropriate.9

Pocket Technique for Permanent Medial Canthoplasty.: The lower lacrimal punctum is cannulated with 0-0 to 2-0 nonabsorbable monofilament suture. The upper and lower eyelids are split with a 6400 Beaver blade and small tenotomy scissors to a depth of about 10 mm, starting 2 to 3 mm medial to the upper and lower puncta. The eyelid margin is freshened by removing a small strip of eyelid margin in the area of the pocket. An incision in the conjunctiva, perpendicular to the eyelid margin, at the lateral aspect of the pocket in the upper eyelid is made to create a triangular flap; this sacrifices the upper lacrimal punctum. If there is extensive medial aberrant dermis or caruncular trichiasis, the offending tissue is sharply excised at this point. A horizontal mattress of 4-0 nonabsorbable suture is used to secure the tip of the conjunctival flap to skin at the bottom of the pocket of the lower eyelid. The new canthus is apposed with a figure of eight suture with 5-0 polyglactin, and the skin is closed in a simple interrupted pattern with the same material (Figure 124-10). If the lower nasolacrimal duct is inadvertently damaged during the procedure, the monofilament suture should be left within the duct and secured so that it remains in place for 3 to 4 weeks as the duct reepithelializes. The nonabsorbable mattress suture should be removed in 10 to 14 days. Placing a temporary tarsorrhaphy temporal to the surgical closure for 10 to 14 days helps to prevent stretching of the surgical site.


Cilia that exit the meibomian gland openings are called distichia. They can be an incidental finding in many breeds (cocker spaniels, miniature poodles) while causing significant pathology in others (American bulldogs, Shih-Tzus). Distichia should be treated only if they are causing significant discomfort or keratitis. Distichia as the cause of discomfort can be confirmed by manual epilation with fine forceps. This should result in improvement of clinical signs until the hair regrows in 3 to 4 weeks.

Although many strictly surgical techniques have been described for permanent treatment of distichia,6,34 noninvasive techniques such as cryo- and electroepilation have the advantage of preserving the eyelid margin and usually do not result in scarring, which distorts and adversely affects eyelid function.127 All techniques aim to destroy the meibomian gland, thereby preventing hair regrowth. Destruction of a large percentage of the meibomian glands may result in qualitative tear deficiencies because of a lack of the lipid portion of the tear film. This can be treated medically by applying a topical petrolatum-based artificial tear ointment three or four times a day.

Cryoepilation.: Because cryodestruction is best accomplished with a rapid freeze and slow thaw, a chalazion clamp is placed to decrease blood flow to the area. Cryoepilation is accomplished by placing a 4-mm cryoprobe over the base of the meibomian gland from the conjunctival side. When the ice ball reaches the eyelid margin, freezing should be stopped and the eyelid margin allowed to thaw. The process is repeated for a total of two freeze–thaw cycles (Figure 124-11). Nitrous oxide and liquid nitrogen probes are equally effective; because liquid nitrogen probes become much colder, however, excessive freezing is more likely with this medium. Immediately after treatment, there is usually severe eyelid and conjunctival swelling, which resolves in 48 to 72 hours. Marginal eyelid depigmentation is an expected sequela to freezing and usually resolves completely in 6 months.129 Overzealous freezing (tissue temperatures below −30° C) has been associated with eyelid scarring, necrosis, and permanent pigment loss. Thermocouples can be used to monitor and avoid excessively low tissue temperature; in practice, close observation of the ice ball and stopping freezing when it reaches the eyelid margin accomplishes the same objective.

Electroepilation.: Electroepilation can be accomplished with a direct current electrocautery unit equipped with a fine cilia-epilating needle or specialized electroepilation unit. The goal is to thread the needle down into the meibomian gland and deliver enough energy to destroy the gland but not so much as to damage the rest of the eyelid. Because specialized electroepilation units are designed specifically for this purpose, they are preferable. Delivery of energy to the gland is done best by guiding the needle alongside the hair shaft down to a depth of 3 to 4 mm. Positioning of the needle and energy delivery is confirmed by meibum bubbling out of the meibomian gland orifice (Figure 124-12). Destruction of the gland is confirmed when the cilia can be manually epilated as if no attachment remains. Treatment should be repeated or the power setting increased until easy manual epilation is possible. A starting setting of 0.5 is recommended for electrocautery units.79 Complications are uncommon and recurrence rates are low when a specialized electrolysis unit is used.95

Ectopic Cilia

Hairs, usually originating from the meibomian glands, that break through and exit the palpebral conjunctiva are termed ectopic cilia. They abrade the cornea directly and predictably cause severe pain and keratitis. Ectopic cilia are most commonly seen in young adult dogs. The treatment of choice is to remove the offending cilia and the meibomian gland from which they originate. This is most easily accomplished by placement of a chalazion clamp and excision en bloc of an approximately 1- to 2-mm2 section of tissue (down to the muscular layer) surrounding the cilia. This can be done “freehand” with a #11 Bard-Parker blade or a 6500 Beaver blade or by centering an appropriately sized dermal biopsy punch over the cilia.24 The resulting defect is not sutured. Postoperative bleeding is minimal and can be decreased by the application of 2% phenylephrine.

Acquired Disorders

Eyelid Neoplasia

In dogs, meibomian gland tumors, squamous papillomas, melanomas, and histiocytomas make up more than 80% of all eyelid tumors. Of these, the most common is meibomian gland adenoma. Most eyelid tumors (73%) in dogs are benign.61 In cats, the most common eyelid tumor is squamous cell carcinoma. Even though some tumors have distinctive clinical characteristics, definitive diagnosis should be reached by microscopic evaluation in all cases.

Meibomian gland tumors have a characteristic exophytic, pedunculated, cauliflower surface appearance and are based at the meibomian gland opening or over the meibomian gland itself. Because meibomian gland tumors are so common and almost universally benign in dogs, an eyelid mass with these characteristics is typically resected with minimal margins (1 mm) and submitted for histopathology. If histology of the mass reveals a malignant, incompletely resected mass, a second more extensive resection should be performed.

If an eyelid mass does not clinically resemble a meibomian gland tumor, a fine-needle aspirate can be attempted to obtain a cytologic diagnosis. In some cases, if the mass is large enough, a small punch biopsy of the mass can be obtained without damaging the eyelid margin. Resection of the mass should then be performed with margins based on current recommendations for that tumor type (see the section on wedge and pentagonal resection below). Eyelid reconstruction techniques are discussed below; however, because of the nature and extent of some types of neoplasia, reconstruction of the eyelids in a way that would protect the ocular surface is not always possible, and enucleation of the globe may be necessary.


A chalazion is an enlargement of the meibomian gland from intraglandular accumulation of meibum secondary to duct obstruction. It appears as a yellow-white swelling visible through the palpebral conjunctiva when the eyelid is turned outward. It is typically painless; however, rupture of the gland and infiltration of the eyelid stroma with meibum results in substantial inflammation. Although the condition itself is not neoplastic, the cause of the blockage may be. In fact, most meibomian gland tumors have some degree of chalazion histologically. Therefore, it may be advantageous to treat meibomian gland tumors with topical corticosteroids for 1 week before resection because the size of the mass may decrease substantially after the inflammation is controlled. This may allow for substantially smaller resection of the eyelid margin.

Chalazia are treated by surgical removal of inspissated material. A Francis chalazion clamp is placed. The conjunctival surface over the chalazion is incised with a #11 Bard-Parker blade or a 6500 Beaver blade, and all contents are removed with a chalazion curette (Figure 124-13). Alternatively, the contents are gently expressed through the incision. The wound is left to heal by second intention; conjunctival sutures should not be placed to avoid corneal abrasion. Some advocate performing two freeze–thaw cryotherapy cycles over the affected gland because the obstruction may be caused by formation of microscopic neoplasia occluding the gland. Topical corticosteroid ointment should be applied postoperatively for 5 to 7 days.

Eyelid Reconstruction

Wedge and Pentagonal Resection

If reconstruction of the eyelid margin is to be carried out using a simple two-layer closure or a semicircular flap, a wedge or pentagonal resection of the mass should be performed. A pentagonal resection is one in which the base is formed by the eyelid margin; the parallel sides are perpendicular to the margin, and the last two sides are made of incisions that connect the ends of the parallel segments to a point distal to the eyelid margin. Ensuring that the sides of the wedge or pentagon are of equal length and the plane of section through the eyelid is perpendicular to the eyelid margin will also help to establish perfect apposition.

A Jaeger eyelid plate is used to stabilize the eyelid margin and protect the cornea. A #15 Bard-Parker or 6400 Beaver blade is used to make an incision through the skin, orbicularis oculi, and tarsus, and the conjunctiva is incised with tenotomy or strabismus scissors. Making the entire incision solely with scissors creates uneven cut margins that hinder perfect apposition. Apposition is improved and eyelid distortion diminished by making the height of the wedge or pentagon at least twice its width.

Simple Two-Layer Closure

When the length of the excised margin is less than one third of the length of the eyelid margin, the defect can be closed by apposition of the cut edges. Resection should be performed in the form of a wedge or a pentagon. Then, the tarsus and orbicularis muscle layer is apposed with a horizontal mattress suture such that the plane of the bites is parallel to the eyelid margin, the knot is away from the margin, and neither the knot nor the suture is exposed through the palpebral conjunctiva. This step can be skipped with very small (i.e., 1 to 2 mm) resections and may even hinder perfect apposition in these situations. Next, the eyelid margin is apposed with a figure of eight suture. Suture tags are left long and pulled away from the eye by incorporating them into the simple interrupted sutures that are used to appose the skin distal to the eyelid margin (Figure 124-14). This technique should also be used to appose lacerations that involve the eyelid margin.

Sliding Pedicle Advancement Flap

Defects that involve more than one third of the eyelid margin can be reconstructed using this technique. If this technique is to be used, a rectangular excision should be performed. If the tumor does not involve the conjunctiva, the conjunctiva should not be excised so that it can be used to line the bulbar aspect of the graft. After excising the affected tissue, two slightly diverging skin incisions, two times the height of the excised defect, are made, starting at the base of the defect. Two identical triangles of skin (Burrow’s triangles), with bases approximately 20% longer than the height of the defect, are removed to accommodate shifting of the skin into the defect. The skin flap and skin surrounding the Burrow’s triangles are liberally dissected from the underlying muscle. Undermining should continue until the graft lies tensionless within the defect. A simple interrupted 5-0 or 6-0 suture is placed to join the distal corner with the proximal corner of each triangle. The flap is then positioned with a simple interrupted suture so that its leading edge sits 0.5 to 1 mm beyond the normal eyelid margin. The remaining skin incisions are apposed with simple interrupted sutures every 3 mm (Figure 124-15). The bulbar aspect of the graft can be lined with the conjunctiva from the adjacent eyelid, conjunctiva from the anterior surface of the third eyelid, a free conjunctival graft from opposite eyelid, or a free buccal mucosa graft after it has been mobilized avoid placing tension on the graft. The mucosal graft should be sutured with 6-0 to 8-0 absorbable material so sutures do not contact the cornea. This can be accomplished by beveling the leading edge of the skin graft so that the conjunctiva, when sutured to the border of the cut margin, is pulled away from the cornea (Figure 124-16).

Some advocate letting conjunctival cells spontaneously line the posterior aspect of the graft, arguing that spontaneous conjunctival healing is very rapid and may be less likely to result in traction bands in the grafted area and donor areas that could result in leading-edge entropion.119

Myocutaneous Pedicle Graft

This technique is ideal for reconstruction of defects of the upper eyelid that involve large portions of the eyelid margin and are of limited height (e.g., eyelid agenesis or squamous cell carcinoma affecting the eyelid margin). In this manner, the entire margin can be reconstructed if necessary. To create a recipient bed in cases of eyelid agenesis, an incision at the junction between the skin and the conjunctiva is made to create a fresh wound margin. A laterally based single-pedicle conjunctival flap is harvested from the palpebral surface of the third eyelid. It is rotated 180 degrees, positioned within the defect so that the underside faces outward, and sutured to the incised conjunctival edge with 7-0 or 8-0 polyglactin in a simple continuous pattern. A rectangular pedicle of skin, hinging at the lateral canthus and slightly (1 mm) larger than the recipient bed, is created by making incisions through skin and orbicularis muscles of the lower eyelid. The incision closest to the lower eyelid margin should be parallel to and about 5 mm from the margin. A lateral canthal incision is then made to allow the pedicle to be rotated into place. The leading edge of the pedicle is sutured to the edge of the normal eyelid margin with a figure of eight suture. The rest of the pedicle is then apposed routinely with simple interrupted 5-0 or 6-0 sutures. To decrease the likelihood of trichiasis from the transposed pedicle (because the hairs will now point toward the eye), the edge of the graft that will constitute the new eyelid margin can be beveled so that the conjunctiva is pulled around the edge of the new eyelid margin to reach the edge of the cut margin (see Figure 124-16). The transposed conjunctiva and skin graft are then apposed with 7-0 or 8-0 simple interrupted or continuous polyglactin sutures (Figure 124-17). If there is significant trichiasis after the site has healed, offending hairs can be removed with cryotherapy or electroepilation, as for distichiasis.129


Figure 124-17 Myocutaneous pedicle graft as described by Dziezyc and Millichamp27 for the repair of eyelid agenesis. The conjunctiva can be harvested from the anterior surface of the third eyelid as depicted or the graft can be lined with mucosa from a different site, buccal mucosa, or not lined at all. (From Moore CP, Constantinescu GM: Surgery of the adnexa. Vet Clin North Am Small Anim Pract 27:1011, 1997.)

An alternative to harvesting the skin pedicle from below the lower eyelid is to harvest it from skin above the upper eyelid.75 By doing this, trichiasis should be less of a problem. Because skin from this location does not contain a section of the orbicularis muscle, mobility may be decreased after repair of large defects. Some surgeons note successful outcomes with myocutaneous flaps without concurrent conjunctival transposition.75

Semicircular Flap

This technique is suitable for large upper or lower eyelid defects, regardless of their height.99 The lesion is excised in the shape of a pentagon. The skin is incised in a semicircle with a radius equal to or slightly larger than the eyelid, arching in the opposite direction of the eyelid to be repaired. A Burrow’s triangle, with base length equal to the eyelid margin defect, is removed so that the apex of the triangle points in the same direction as the arch of the incision. The skin flap is liberally undermined and transposed to cover the defect. The eyelid margin is apposed with a two-layer closure. The skin is apposed with simple interrupted sutures (Figure 124-18). The transposed skin that makes up the new eyelid margin can be lined with conjunctiva harvested from the adjacent eyelid.

Lip-to-Lid Flap

A lip-to-lid flap uses a portion of the upper lip for the reconstruction of large defects of the lower eyelid, providing a mucocutaneous junction that approximates the eyelid margin. Its successful use has been described in dogs98 and in cats54 as a sole procedure or as one step in the multistep reconstruction of the upper eyelid.29 An appropriate width flap to repair the defect is created so the angle of the flap is at 45 to 50 degrees to the line between the medial and lateral canthi. The incisions defining the flap should be slightly divergent to provide a wider base. The buccal mucosa is incised at least 5 mm proximal and parallel to the lip margin. The flap is then elevated so as to include the platysma muscle. Dissection should be cautious to avoid damage to the parotid salivary gland duct, facial vein, or buccal nerve.

The buccal mucosal defect is apposed with 3-0 or 4-0 absorbable monofilament with buried knots. A bridging incision is then made from the rostral edge of the flap base to the eyelid defect. The flap is turned into the defect, and the mucosal surfaces are apposed with 6-0 or 7-0 polyglactin. The two margins of the transposed lip margin are apposed to the recipient eyelid margins with a simple two-layer closure (Figure 124-19). Puckers or dog ears in the skin are not removed until approximately 6 weeks after surgery, when the flap has healed completely. A right angle or T-shaped extension of the mucocutaneous lip junction can be created for repair of lateral portions of the upper eyelid in addition to the lower eyelid.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Basic Ophthalmic Surgical Procedures

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