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Dr. Ofri is a professor of comparative ophthalmology at the Koret School of Veterinary Medicine at Hebrew University of Jerusalem in Rehovot, Israel.
Conditions in which the eyelid rubs against the eyeball, as well as drooping eyelids, can only be corrected surgically. Here’s a look at the appropriate procedures for various conditions.
Proper eyelid anatomy is essential for protecting the globe, as well as for distributing the tear film on the ocular surface. However, many dog breeds suffer from inherited eyelid abnormalities that affect their function. This article discusses surgical correction of some of the more common disorders of this critical organ.
Entropion, or inward rolling of the eyelid margin, causes eyelashes and facial hair to contact the conjunctiva and cornea (Figure 1), leading to conjunctivitis, keratitis, and possible ulceration. There are 3 types of entropion: conformational (caused by anatomic abnormalities of the eyelids themselves) spastic (caused by marked contraction of the orbicularis oculi muscle), and cicatricial (caused by scarring from an injury or previous surgery).
Conformational entropion is by far the most common presentation. It usually affects both eyes, and more commonly the lower eyelid. Severe cases may involve the entire lid, but typically just a portion of the margin is affected. In brachycephalic dogs, conformational entropion is more notable at the medial lower eyelid, whereas in large, broad-skulled dogs it often affects the lateral part of the lower eyelid and the lateral canthus. Upper eyelid involvement is usually seen in dogs with very heavy brows, such as bloodhounds, Shar-Peis (Figure 2), and chow chows. Conformational entropion is believed to be inherited in a large number of dog breeds, including the chow chow, English bulldog, Irish setter, Labrador and golden retrievers, Saint Bernard, Shar-Pei, Rottweiler, Great Dane, and Chesapeake Bay retriever.
Although conformational entropion may manifest soon after eye opening, it often does not become clinically evident until later in life as the skull and associated facial skin gain their adult conformation. Conversely, maturation may also be associated with reduction or sometimes even resolution of entropion. For these reasons, surgeons should use temporary tacking and postpone definitive surgery until facial maturity is achieved, although such a delay is not advisable in severe cases.
The surgical method chosen to correct entropion depends on the patient’s breed and facial maturity, mechanism and severity of the condition, and position of the eyelid abnormality. Of these, mechanism is perhaps the most important, as the entropion may be caused by excessively long or short eyelids, excessive facial skin, an overly tight or misdirected canthal ligament, or a painful process causing spastic entropion. Regardless of the technique chosen, accurately assess the extent of skin resection before sedation, premedication, or anesthesia induction. Consider use of a dermatologic marker pen. Always apply topical anesthesia to eliminate other causes of spastic entropion before deciding on the extent of surgical resection. Keep in mind that the goal is to correct for the conformational or anatomic component only, not the spastic component. Correction of the conformational component will also alleviate the spastic component.
The majority of simple, breed-related entropion cases can be addressed using the Hotz-Celsus procedure. For this technique, make the initial incision parallel to the eyelid margin at the haired-nonhaired junction while protecting the ocular surface with a lid plate (Figure 3). Avoid placing this incision too far from the eyelid margin. This is a common error that causes a significant loss of “mechanical advantage” and achieves less eversion. The length of this first incision is dictated by the length (extent) of inverted eyelid. First, apply gentle pressure with the thumb at the point of entropion to roll out the eyelid until the eyelid margin (meibomian gland orifices) can be seen along the whole length; this will assist with outlining the full lateral and medial extent of entropion. Other clues are provided by the pale discoloration, blepharedema, and alopecia that occur secondary to rubbing of eyelid skin against the cornea.
Next, make a curvilinear incision joining the 2 ends of this first incision. The real art of entropion surgery is in deciding on the amount of tissue to resect (ie, the distance between the first and second incisions). This was predetermined during the examination of the awake patient (using topical anesthetic) and can be confirmed during surgery by applying the same clues used to determine the length of the first incision. The most important point is to ensure that the widest tissue resection is planned for the most inverted section of the eyelid, even if this creates an asymmetric area of resected tissue.
A number of patients will benefit from some form of temporary relief of entropion until permanent blepharoplasty is performed. This has traditionally been achieved with a series of temporary tacking sutures placed so as to evert the eyelid (Figure 4). Temporary tacking procedures may be considered to treat entropion in the following patients:
Surgical staples have been used recently in place of sutures for temporary tacking because they are quicker, less traumatic, less irritating, persist in the tissue longer than sutures, and can usually be applied without general anesthesia. Animals may be sedated, but do not infuse local anesthetic into the eyelids. This disrupts the eyelid anatomy and hinders corrective tacking. Place as many staples as necessary to evert the affected eyelid margin (and canthus in some patients). Each staple should be perpendicular to the eyelid margin. Leave the staples or sutures in place for as long as necessary. In some animals, tacking may have to be repeated several times until facial maturity is reached and permanent corrective surgery can be performed.
Upper eyelid entropion is seen most commonly in dogs with excessive brow tissue, such as chow chows, Shar-Peis, basset hounds, and bloodhounds. In these patients it is usually the upper eyelashes that irritate the cornea because of ptosis of the heavy upper eyelid and the consequent “flat” angle at which these lashes approach the cornea. As such, standard entropion procedures such as the Hotz-Celsus technique may not alleviate the problem. Rather, these dogs usually require correction using the Stades technique.
To start the Stades technique, resect a large, approximately semicircular or crescent-shaped piece of tissue from the dermal side of the upper eyelid (including the cilia themselves, avoiding the Meibomian glands). Then, bring down the dorsal wound border toward (but not meeting) the wound nearer the eyelid margin. Suture to leave an exposed strip of subcutis about 3- to 4-mm wide. This tissue is left to heal by second intention such that the contraction and cicatrization during this process further everts the upper eyelid and forms a relatively hair-free margin. Severe cases may benefit from highly involved stellate rhytidectomy procedures (skin fold resections from the top of the head) to alleviate the heavy skin that contributes to the upper eyelid ptosis.
Like entropion, ectropion (eversion of the eyelid) almost always affects the lower lid only. Clinically significant ectropion is less common than entropion. The most common type is conformational or breed-related ectropion. The condition is seen in dogs with loose facial skin, such as retrievers, Saint Bernards, bloodhounds, and cocker spaniels. It can cause secondary lagophthalmos, keratitis, or conjunctivitis.
Depending on the severity of the ectropion, it can be resolved using one of two techniques: wedge resection or V-to-Y blepharoplasty.
When ectropion is secondary to mild euryblepharon (elongated eyelids), shorten the lower eyelid by resecting a full-thickness wedge from the lateral end of the lower eyelid (Figure 5). Then, use a standard 2-layer closure to perfectly appose the sides of the eyelid margin.
The V-to-Y (or Wharton-Jones) blepharoplasty procedure is used in moderate and severe cases of ectropion, and for cicatricial ectropion (Figure 6). Begin by outlining a triangular piece of skin with the base being parallel to the eyelid margin and sufficiently wide to encompass the section of everted eyelid. Do not make any incision at the base of the triangle. Rather, incise the skin along the two sides of the triangle, and elevate a V-shaped flap of skin between them toward the base. Excise all scar tissue beneath and surrounding this flap. Then, suture the incision beginning at the apex farthest from the eyelid margin; use simple interrupted sutures of 3-0 to 5-0 braided nylon or silk to form a vertical line perpendicular to the eyelid margin. This vertical portion forces the triangle and eyelid margin toward the globe. The length of the vertical portion depends on how much elevation or inversion of the eyelid margin is required to return it to its normal position. To allow for subsequent wound contraction, it should be about 2- to 3-mm longer than required. Finally, suture the remaining parts of the 2 incisions to the free edges of the flap so that the sutured skin forms a Y.
A syndrome of eyelid, conjunctival, and corneal lesions is seen commonly in brachycephalic dogs. This so-called brachycephalic ocular syndrome consists of any combination of the following features:
Brachycephalic ocular syndrome is sometimes exacerbated by distichiasis and decreased tear production or quality. Medial canthoplasty neatly corrects many of the signs associated with this syndrome. It reduces the palpebral fissure size, removes the medial caruncle, and everts the lower medial entropion, thereby reducing corneal exposure, frictional irritation from trichiasis, and functional nasolacrimal apparatus obstruction.
Medial canthoplasty is recommended for dogs with this combination of signs, especially when the signs are associated with progressive corneal melanosis. It is also suitable for patients with shallow orbits, exposure, or strabismus following proptosis, especially when these are associated with secondary corneal lesions. When performing this procedure, be sure to avoid the lacrimal puncta, meticulously remove all hair follicles from the medial caruncle, carefully incise the eyelids, realign the eyelid margins perfectly, and provide appropriate postoperative management as for other eyelid procedures.
Full-thickness wedge resection is used to remove small eyelid tumors (Figure 7) or (as previously discussed) to shorten the eyelids from their lateral end when ectropion is due to euryblepharon. Always avoid the medial canthal area and nasolacrimal apparatus. Tumors larger than 25% of the eyelid length in cats and in mesaticephalic and dolichocephalic dogs, or more than 33% in brachycephalic dogs, should be removed using alternative surgical techniques. When performing a wedge resection, the height of the triangle should be approximately twice its base.Make the skin incision with a No. 15 Bard-Parker scalpel while supporting the eyelid with a Jaeger eyelid plate (see Figure 3).Cut the subcutis and conjunctiva with straight Mayo or Stevens tenotomy scissors, so that the tissue wedge is resected completely. Appose the lid margin using the 2-layered closure.
Ron Ofri, DVM, PhD, DECVO, is a professor of comparative ophthalmology at the Koret School of Veterinary Medicine at Hebrew University of Jerusalem in Rehovot, Israel.