Introduction

Entropion refers to an inward rolling of the eyelids or inversion toward the cornea, whereas ectropion refers to an outward or eversion of the eyelids away from the cornea. Entropion is one of the most common ocular problems encountered by general practitioners. Although entropion can occur in any breed, there are breeds that more commonly experience this condition and different causes of entropion. Determining why the patient has entropion is important to successful repair, so this chapter will discuss the most common reasons for entropion and how these causes are prevalent among certain breeds. There are numerous ways to correct entropion, but this chapter will focus on the Hotz‐Celsus technique and reduction in the size of the palpebral fissure when indicated, since this will correct most cases of entropion that are encountered in general practice.

Predisposed Breeds and Entropion Types

Entropion is much more common in dogs than in cats at a ratio of 7.12–1, so most of this discussion will pertain to the canine species.¹ As mentioned, entropion can occur in any breed, but it is most commonly found in breeds including the Shar Pei, Chow Chow, Rottweiler, Labrador, Bulldog, Great Dane, St. Bernard, Mastiff, Shih Tzu, Pekinese, and Pug. In our feline species, Maine Coons and Persians appear to be most commonly affected.¹

There are several causes of entropion, which include primary (also called developmental), spastic, conformational changes secondary to age or disease, and cicatricial. Primary, also called developmental entropion, is the most common cause of entropion encountered in dogs. Developmental entropion appears to be hereditary, but the exact mechanism appears to be quite complex. It is often associated with factors that affect the length of the eyelid opening, the skull conformation, the orbital anatomy, gender, and how extensive and heavy the folds are in the periocular region.² The age of onset varies by breed, with the Shar Pei and Chow Chow breeds often being affected as early as two to six weeks of age. Other breeds are often affected at four to seven months of age.² The Shar Pei and Chow Chow breeds typically need eyelid tacking performed early and may require multiple eyelid tacking procedures performed before they are old enough to consider surgical correction. These two breeds commonly have all four eyelids affected by entropion. Brachycephalic breeds, such as the Pug, Shih Tzu, and Pekinese, often have medial lower eyelid entropion. Giant breeds, such as the Great Dane, St. Bernard, and Mastiff, as well as the English and American Bulldogs, commonly have an exceptionally large eyelid opening called a macropalpebral fissure. This often results in a “diamond eye” shape, causing entropion of the medial and lateral portions of the eyelids and ectropion of the central portion of the eyelids. Shortening of the palpebral fissure along with a Hotz‐Celsus procedure is often required for successful correction. In breeds with excessive numbers of wrinkles or heavy brows, a brow sling procedure may need to be considered. However, since this chapter focuses on the most common cases encountered in general practice, this procedure will not be discussed, since it is rarely required for successful entropion correction.

Spastic entropion is the second most common type of entropion encountered in canines, while it is the most common cause of entropion encountered in our feline patients.¹ Spastic entropion refers to entropion that occurs when an animal retracts the globe secondary to pain. Most commonly, this is due to ulcerative keratitis, distichiasis, and conjunctivitis.³ Using proparacaine temporarily relieves this type of entropion, and the entropion typically resolves once the source of the pain resolves, at least in dogs. In cats, spastic entropion is more likely to require surgical correction, as it is a vicious cycle of ongoing ocular surface irritation and entropion.¹

Age‐related changes, disease, trauma, or surgery are also causes of entropion. For example, loss of lid support, atrophy of the retrobulbar fat pad, phthisis bulbi, and atrophy of periocular muscles due to age or diseases, such as myositis, can result in entropion.² Age‐related changes are the second most common cause of entropion in felines.¹ Cicatricial entropion refers to entropion that occurs from scarring following trauma, surgery, or eyelid disease. Any of these additional causes of entropion can necessitate the need for surgical intervention.

Clinical Signs

There are several clinical signs associated with entropion. Typically, patients will present with blepharospasm, conjunctival hyperemia, increased lacrimation, mucoid discharge, and a moist appearance to the entropic portion of the eyelid(s). The portion of the cornea that is irritated by the hairs adjacent to the eyelids often has edema, vascularization, pigmentation, granulation tissue, and/or corneal ulceration. Cats may also develop a corneal sequestrum, which is an area of corneal stromal necrosis that presents light brown in color to a dense black scab on the corneal surface. In most cases, the corneal changes can be drastically improved with correction of the entropion, but they cannot always be completely resolved. A corneal sequestrum is best treated with a keratectomy, so referral to a veterinary ophthalmologist is recommended in these cases. To try to prevent long‐standing changes from entropion, early intervention is the best practice.

Diagnosis

Diagnosing entropion is typically straightforward, but some cases are difficult, especially when the entropion is mild. Examination of the patient at a distance with no distortion of the face from an assistant holding should first be performed before moving in for an up‐close look. When examining up close, be sure the assistant is not restraining too tightly around the neck, since this can place too much traction on the skin and distort the appearance of the eyelids.² Looking closely for corneal changes in the suspected or the obviously entropic area can help the clinician decide when intervention is warranted. Applying proparacaine to relieve any spastic component after the initial examination also can be an especially useful diagnostic tool. Another useful tool can be to gently pinch the skin adjacent to the eyelid starting about 10 mm below the eyelid margin, apply gentle traction to force the eyelid to roll inward against the cornea, then release the pinched portion of the skin. The eyelid should correct itself into a normal position with one blink. If it remains entropic, the patient suffers from habitual entropion² (Video 4.1). This technique can be especially useful if there is a question as to whether a patient has entropion. If it is still not clear if entropion is the cause of the presenting ocular abnormalities, temporary eyelid tacking can be a useful diagnostic tool to monitor for improvement of corneal changes, squinting, conjunctival hyperemia, and ocular discharge, which often accompany entropion with varying severity. These signs should improve within a few weeks if the entropion is temporarily relieved by the tacking.

The normal palpebral fissure opening, when measured in a stretched horizontal position from the medial to the lateral canthus, is about 33 mm in medium to large‐breed dogs. However, in dogs with a macropalpebral fissure, the palpebral fissure is often 39 mm or more in length when measured horizontally in the same stretched position.² The horizontal length of the palpebral fissure can be measured with a pair of calipers, but in some patients, this can be difficult. There are a few things the author has found to help determine if the patient would benefit from a reduction in the size of the palpebral fissure. First, if the patient has a diamond eye shape or the eyelids obviously do not fit closely to the normal corneal curvature or are ectropic in places, they will likely benefit from eyelid shorting. Also, in the entropic patient, if an outward notch of the eyelid appears in the lateral portion of the eyelid when it is tensed and stretched in a lateral direction, the eyelid will benefit from shortening (Figure 4.1).

Treatment

If the entropion is mild, corneal lubrication may provide adequate protection. However, if corneal changes are present, intervention is recommended sooner than later to try to prevent chronic corneal changes, ulceration, and even corneal rupture. Ideally, permanent correction should be delayed until the patient is fully grown, which is 1.5–2 years of age. However, in many patients, this is not possible due to the severity and persistence of the entropion, so typically, the author’s goal is to get them as close to one year of age as possible. The author always discusses with the owners that waiting until the patient is fully grown is ideal because the amount of correction can change, and some cases will resolve or at least significantly improve as they reach maturity, which can affect the surgical plan and the outcome. However, if the entropion is severe or requires multiple eyelid tackings, most owners are anxious to get them in for surgical correction as soon as possible.

Temporary eyelid tacking is performed with 4‐0 or 5‐0 nonabsorbable suture material. Interrupted sutures are placed by taking two, roughly 5 mm “bites” of skin perpendicular to and starting about 2 mm from the eyelid margin while directing the needle away from the eye. Each interrupted suture should evert the eyelid margin away from the eye to prevent inversion. The number of sutures placed varies by the amount of the eyelid that is needed to be everted, but typically three to five sutures are needed if just one eyelid is affected (Figure 4.2). Sutures are typically left in place for two to six weeks, depending on the reason for the suture placement. For developmental entropion, the author recommends leaving the sutures in place until they are no longer holding the tissue, the patient develops a suture reaction, or they fall out on their own. For suspected spastic entropion, the tacking sutures are left in place for one to two weeks beyond the resolution of the painful stimulus.

There are numerous techniques used for the surgical repair of entropion, but the Hotz‐Celsus is the most used and is appropriate in most situations and will be the technique focused upon in this chapter. If the patient has a macropalpebral fissure and would benefit from a reduction in the size of the eyelid opening, this should either be performed first with a plan to perform a Hotz‐Celsus if additional correction is needed, or it can be combined with a Hotz‐Celsus to save time if the surgeon is sure both procedures will be needed for a successful repair. It is important not to overcorrect because this could result in iatrogenic ectropion and the need for additional surgery. Remember, Bulldogs and many giant breeds often need a combo procedure.

If it has been determined that the patient needs correction, the surgeon must decide how much tissue needs to be removed. There are multiple ways to decide, but this chapter will focus on the technique that seems the most straightforward. First, decide which eyelid is most affected (superior or inferior) and which portion(s) of the eyelids are affected. Sometimes, it is the entire eyelid, while other times, it is just the nasal (i.e., medial) or temporal (i.e., lateral) portion of the eyelid that is entropic. The most common area affected is the inferior temporal portion of the eyelid. With the eyelid in its entropic state, starting about 2–2.5 mm from the eyelid margin, forceps are used to pinch the amount of skin adjacent to the eyelid margin that is needed to evert the eyelid into a normal position. Toothed forceps work best for this and will leave two marks on the skin, indicating the placement of the dorsal and ventral aspects of the incision (Figure 4.3). Next, an eyelid plate is used to stabilize the eyelid margin, and calipers can be used to measure the width between the teeth marks of the forceps, and the calipers should be locked in place. A #15 Bard‐Parker surgical blade is used to make the first incision parallel to the eyelid margin starting 2–2.5 mm from the eyelid margin (at the junction of the haired and nonhaired portion of the eyelids) and is extended 1 mm beyond the medial and lateral extent of the entropion.² With a little bit of blood from the incision on the dorsal blade of the caliper, invert it and run it across the skin where the second parallel incision will be made (Figure 4.4). The surgical blade is then used to create the second partial‐thickness parallel incision that has been outlined with the blood from the dorsal incision. The ventral incision is typically tapered toward the first incision at the temporal and nasal aspects until the dorsal and ventral parallel incisions meet (Figure 4.5). The author prefers a #15 Bard‐Parker surgery blade, but the use of a #69 or #64 Beaver blade for small patients is also acceptable if preferred. The skin between the two parallel incisions is removed using tenotomy or Metzenbaum scissors.

Some ophthalmologists advocate for the removal of a thin strip of the exposed orbicularis oculi muscle while others do not, as it causes more bleeding.^2,4,5 Many ophthalmologists do not feel this makes a difference in the surgical outcome. Hemostasis is controlled with pressure, cautery, or clamping small bleeders with mosquito forceps, but typically bleeding is minimal and easily controlled with intermittent pressure. The skin is then closed in a single layer with interrupted sutures with proper alignment being crucial. The author prefers to place the first suture in the middle of the incised area, followed by sutures placed to split the medial and lateral aspects in half again. The remaining incision is closed using the law of bisection by splitting the distance needing to be closed in half until a suture is placed every two to three millimeters. Suture‐sized 4‐0 to 6‐0 with 10–16 mm, 3/8–1/2 circle, extra sharp‐pointed round, micropoint, or extra‐fine‐cutting needles are used.⁶ The author prefers absorbable sutures, even though the sutures are typically removed at 14 days to reduce the risk of skin irritation or a suture reaction. However, sometimes a suture gets missed or the patient is too aggressive to allow suture removal, so the author likes having the flexibility that absorbable suture allows. After the first few sutures are placed, evaluate if the eyelid eversion is sufficient. If additional correction is needed, a little bit more skin from the Hotz‐Celsus can be removed. Figure 4.6 shows a severe case of entropion in a Shar Pei. As severely as this patient was affected, just performing a Hotz‐Celsus was enough to properly evert the eyelid margins and provide relief for this patient.

There are certain breeds that almost always need to have their eyelids shortened, such as Bulldogs and giant breeds (Figure 4.7), but the eyelid length should be evaluated for each patient individually because there are exceptions to every rule. If the eyelids have a diamond shape, such as in most Bulldogs and many giant breeds, shortening is recommended because if just a Hotz‐Celsus is performed, the excessively long eyelid will still be prone to entropion. Reduction in the size of the palpebral fissure can be performed alone or in combination with the Hotz‐Celsus procedure. The amount the eyelid needs to be shortened can be estimated at the time of surgery by retracting the eyelid laterally and looking for a notch in the eyelid to form (as shown in Figure 4.1).

Using the toothed forceps, pinch the excess eyelid margin to mark the area of the eyelid margin that needs to be shortened. Next, stabilize the eyelid margin with the lid plate, and using your surgical blade, create a V‐shaped partial‐thickness wedge through the skin. The wedge of eyelid margin and associated periocular skin to be removed should be twice as high as it is wide (see Chapter 2 for more details on this). The author prefers to reduce the size of the palpebral fissure by removing the “V‐shaped” piece of eyelid margin where it is ectropic or the loosest, which is typically centrally for dogs with the diamond eye conformation or temporally in most other patients. The partial thickness Hotz‐Celsus is then made as previously directed to help evert the entropic portion of the eyelid. The skin between the parallel cuts of the Hotz‐Celsus is removed first, followed by full‐thickness excision of the incised outline of the eyelid wedge. In dogs with the diamond eye configuration with central ectropion and medial and lateral entropion, the Hotz‐Celsus can be narrowed centrally and then widened temporally and medially to remove an appropriate amount of eyelid. Alternatively, an elliptical‐shaped wedge of skin can be removed medially and laterally and not connected along the central portion of the eyelid. Hemostasis is controlled with pressure, cautery, or clamping small bleeders with mosquito forceps. The eyelid margin is closed first with a figure‐of‐8 suture pattern, leaving the suture tails long to trap the suture tails away from the eye to prevent them from rubbing the cornea as discussed in Chapter 2 of this book on eyelid mass removal.

If correction of only one eyelid on an eye is planned, the author recommends that the opposite eyelid be evaluated during surgery to be sure it still appears to be in a normal position, as sometimes the eyelid position changes when the opposite eyelid is surgically altered.

Postoperative Care

A hard, plastic Elizabethan collar is needed for at least 10–14 days until the sutures are removed, but the author often recommends that the patient continues to wear it for a few days following suture removal due to residual mild skin irritation. A topical antibiotic ointment is sent home and applied TID to QID to the corneal surface. This provides a topical antibiotic source to help prevent infection. It also helps prevent corneal irritation if a suture should shift and start to rub the cornea during healing. The author prescribes systemic antibiotics due to the numerous sutures present and the tendency for pre‐existing or post‐surgical moist dermatitis. Topical Optixcare is great for sending home with owners to aid in soaking discharge that accumulates on the skin sutures. This can be applied liberally over the discharge, left to soak for a few minutes, and then gently removed with a moist cotton ball. Oral anti‐inflammatory and pain medications are also dispensed.

Complications

Complications are typically minimal with swelling, moist dermatitis, and suture reaction being the most common potential complications. There is a risk of corneal ulceration if a suture should shift and start rubbing the cornea, so the author advises owners to contact the clinic right away if a sudden increase in squinting is noticed. The author always warns owners that additional correction may be required either shortly after surgery or at some point in the future, since it is ultimately not known what the animal will look like until they are fully healed. Also, aging, trauma, myositis, and corneal pain can result in additional changes in eyelid conformation that warrant additional correction.