Chapter 4
Eyelids

Anatomy and Physiology

Muscle and nerve supply

The facial nerve is motor to the orbicularis oculi muscle which closes the eyelids. The oculomotor nerve is motor to the levator muscle which raises the upper eyelid. The trigeminal nerve is sensory to the eyelids.

The terms palpebral, tarsal and blepharo all refer to eyelids.

Müller's muscle

Smooth muscle originating from inferior aspect of levator and inserting into and just below upper tarsal plate; often called Horner's muscle because it is affected in Horner's syndrome.

Glands of the eyelids

Meibomian glands (tarsal glands) - sebaceous glands.

Glands of Zeis - modified sebaceous glands connected with the follicles of the eyelashes.

Glands of Moll - sweat glands adjacent to the glands of Zeis.

Eyelashes (cilia)

Dog - present on upper eyelid.

Cat - no true eyelashes.

Horse, cattle, sheep and goat - many upper eyelid lashes, few lower.

Pig - present on upper eyelid.

Function of eyelids and blinking

Reforms the tear film.

Pumps tears into canalicular (drainage) system.

Protects intraorbital structures.

In the newborn pup, kitten, etc., the closed eyelids protect the cornea and conjunctiva from drying until sufficient tears are being secreted.

Nasolacrimal puncta

Located medially - for more information, see elsewhere.

Congenital Abnormalities

Eyelid agenesis

Congenital absence of part or all the layers of an eyelid. Treatment is directed at reconstruction of the eyelid (Doherty; Roberts and Bistner). Occurs infrequently, but more often in cats than in any other species.

There sometimes are additional congenital ocular lesions. Cats may have associated abnormalities of the iris and lens.

If the eyelid has a cleft or fissure rather than diffuse maldevelopment, this is called a coloboma of the eyelid.

Dermoids

Dermoids are islands of skin displaced to an abnormal site; they are considered choristomas (masses of tissue that are normal histologically, but abnormal in their location).

Ocular dermoids most frequently involve the globe, but sometimes extend to involve the eyelid.

Dissect the dermoid from globe and remove affected portion of the eyelid. If extensive eyelid loss results, repair procedures will be needed (Gelatt; Gelatt and Blogg).

More information is provided in the conjunctiva chapter.

Eyelash diseases

Distichiasis

Second row of eyelashes (can be complete row or just a few cilia), often inside the line formed by the openings of the ducts of the Meibomian glands - these abnormal cilia tend to fall out and regrow so observe for several months to determine extent of eyelid involved. (Districhiasis indicates that there is more than one cilium growing out of a follicle - commonly seen with distichiasis.)

Can cause ocular irritation with epiphora and even severe corneal disease due to entropion, but most cases are just incidental and are not associated with problems.

Often need oblique illumination and magnification to diagnose.

Most common in dogs; especially cocker spaniels and poodles - heritable.

Treatment: Most cases require no treatment - be sure that the cilia are causing a problem before attempting treatment because complications associated with treatment may lead to problems more troublesome than the cilia.

1. Epilation with forceps - tend to regrow, but clients can sometimes do themselves.
2. Electroepilation - usually permanent, but may cause cicatricial deformation of eyelid; topical antibiotics and steroids post-op.; many units available (see instrumentation chapter).
3. Cryotherapy - apply the probe to the base of the Meibomian glands and freeze until the ice ball reaches the eyelid margin.
4. Eyelid-splitting or wedge resection - causes too much eyelid deformation to be of use.

Complications of treatment:

1. Regrowth of cilia. Incomplete removal of the affected follicle will be followed by a regrowth of a cilium that can cause more irritation than the original one.
2. Entropion. Post-surgical scar contraction can cause entropion which must be corrected surgically.
3. Notching or shortening of the eyelid.
4. Epiphora. Due to damage to lacrimal punctum. Keep the punctum visualized, or catheterize it with a nylon suture during surgery to assist in visualization.

Ectopic cilia

These usually are more serious than distichiae and most often arise from the palpebral conjunctiva and irritate the cornea - these may be very difficult to find - best to excise (do not need to suture if incision is small); topical antibiotics and steroids post-op.

Trichiasis

Normally placed hairs growing in abnormal direction causing conjunctival and corneal irritation and disease; may be due to prominent nasal folds (e.g., in Pekingese or Pugs), facial hairs (e.g., poodles, etc.) or eyelid hairs in entropion; treatment aimed at eliminating primary cause:

1. Removal of nasal folds.
2. Correction of entropion.
3. In patients who also are used for 'show,' surgery is not allowed unless the individual is in pain or in danger of losing vision - ointment (petroleum jelly) to paste down hairs can be alternative; trimming of offending hairs also can be done, but resulting short hairs can cause corneal damage if they contact it.

Ankyloblepharon

Ankyloblepharon is when the eyelids are adherent to each other.

Ruminants and horses have their eyes open at birth. Dogs and cats have congenital ankyloblepharon that persists into the second week of life. If the eyes have not spontaneously opened by 14-16 days, gentle traction on the eyelids generally will separate them. If not, slip a blade of a blunt scissors into the medial opening of the eyelid and gently force the scissors toward the lateral canthus to separate the eyelids along their border; do not cut with the blades.

Neonatal keratoconjunctivitis

Seen in puppies and kittens with ankyloblepharon; also called ophthalmia neonatorum or neonatal ophthalmia.

Keratoconjunctivitis can occur before the eyelids separate. The orbital area will be swollen due to accumulation of exudate; some mucopurulent discharge usually will be present at the medial canthus. Usually many in the litter will be involved.

Treatment: The eyelids should be opened as described above to allow drainage and treatment.

1. After opening the eyelids, treat with topical antibiotic ointments. Steroids should be avoided if corneal ulceration is present, but are desirable for non-ulcerative keratitis. Prompt therapy usually prevents considerable scarring.
2. If the eyelids are not opened, the cornea may ulcerate and perforate, resulting in secondary glaucoma or phthisis bulbi.

Opening the eyelids prematurely in these cases does not appear to disturb postnatal ocular development.

This infection is transmitted by the dam prenatally or at birth; the dam should be checked for genital infection.

Blepharophimosis

There is a small eyelid aperture or palpebral fissure.

The size of the eyelid opening often is related to the size of the eyeball. Microphthalmia may result in a small palpebral fissure and an enlarged eye may cause an enlargement of the palpebral fissure.

Primary underdevelopment of the eyelids is rare.

Treatment:

If secondary to small eye, treatment is not necessary.

If there is primary underdevelopment, a canthotomy is used to enlarge the palpebral fissure ; the skin is sutured to the conjunctiva on each side of the incision, creating a new eyelid margin.

Cryptophthalmos

Rare condition in which the eyelids do not develop a normal margin and the palpebral fissure fails to open properly . This results in a small opening through which the normal globe can be seen. This may be a genetic defect in the cockatiel (Buyukmihci, et al.). No treatment seems to help, but may not be necessary if the patient is able to see adequately.

Acquired Abnormalities

Inflammation (blepharitis)

Diffuse blepharitis

Numerous causes - often related to an overall dermal problem (Johnson and Campbell):

1. Ulcerative blepharitis - by Staphylococcus aureus; treat with sulfacetamide in polyvinyl alcohol base.
2. Seborrheic blepharitis - part of the endocrine/seborrheic complex; often complicated by ulcerative blepharitis; treatment aimed at controlling the systemic problem in uncomplicated cases; use sulfacetamide topically if ulcerative lesions present.
3. Allergic blepharitis - usually related to an overall allergy problem, such as reaction to drugs, and is handled as such.
4. Solar (actinic) blepharitis may be seen in cats, cattle, dogs and horses that lack melanin in the eyelids. Sunlight absorbing dyes or antibiotic-corticosteroid ointments are of temporary value. Tattooing usually is effective as a permanent treatment.
5. Parasitic blepharitis - frequently seen in young dogs (sarcoptic or demodectic mange); signs include alopecia, pruritis and hyperemia; diagnosed by skin scraping; treatment - rotenone ointment or anticholinesterase ointment. Do not get these medications in the eye.
6. Dermatomyositis in Shetland sheepdogs .

Focal lesions

Chalazion: Granuloma of the Meibomian gland - may mimic neoplasm and vice versa; usually firm and not painful.

Treatment - may try medical therapy (topical antibiotics and steroids), but usually need surgery: incision is made over the conjunctival side of the lesion and parallel with the Meibomian glands - the bulk of the mass is removed in one piece and the area is scraped (curettage) - the wound is left open to drain and heal by second intention; antibiotic and mild steroid topically during postoperative period.

All surgically excised lesions should be submitted for histologic examination - neoplasms may mimic chalazia.

Hordeolum (stye): Bacterial abscess of the eyelid glands.

External: abscess of glands of Moll or Zeis.

Internal: abscess of Meibomian glands .

Region of affected eyelid usually reddened and painful.

Treatment - see below.

Treatment for most blepharitis

Hot, moist compresses and good eyelid hygiene; topical antibiotics; can express purulent material manually, but if sebaceous material escapes confines of Meibomian ducts into eyelid stroma, may lead to chalazion.

Trauma (lacerations)

Regardless of cause, should be handled as any other skin wound - the sooner the defect is repaired, the better the chance of cosmetic and functional result .

Must examine globe thoroughly to insure its integrity - many lacerations that appear superficial may extend through eyelids and penetrate globe. The lacrimal puncta and canaliculi should be identified and preserved if possible. Check for fractures of bones of orbital rim or deeper. These need to be repaired at same time as skin lesions; consult an orthopedic text.

Surgical repair

Best accomplished under general anesthesia; minor lacerations in horse may be repaired using local anesthesia and akinesia (auriculopalpebral nerve block; remember, akinesia only) along with tranquilization.

Clip hair from area (clippers or curved scissors); thoroughly cleanse area - iodine based surgical scrub is good - rinse thoroughly - no alcohol or iodine for preparation; rinse orbit (conjunctiva and cornea) with sterile saline. Check for foreign bodies and determine if wound extends into globe. Debride the wound, but be conservative because you will need all the available tissue for reconstruction. If globe is involved, refer patient to specialist; do not assume it is minor involvement even if it appears that way.

Full thickness laceration requires closure in two layers : conjunctiva and skin separately; heals better if suture lines do not overlap (remove tissue from skin on one side and conjunctiva on other side) - if this produces a tight palpebral fissure then a lateral canthotomy can be done to relieve tension.

Eyelid surgery in general requires careful (atraumatic) handling of the tissue, careful attention to technique, and proper instruments.

After debridement, palpebral conjunctiva is closed with 6-0 absorbable suture (knots placed subconjunctivally) - suture should only go half-thickness; close dead space with same suture material.

Skin is apposed with 4-0 or 3-0 silk in a simple interrupted pattern - remove in 10-14 days.

Topical and systemic antibiotics post-op. Tetanus antitoxin or toxoid for horses and sheep.

An auriculopalpebral nerve block may be necessary after surgery if there is severe blepharospasm - can be done several times a day for several days.

Complications such as entropion may occur and can be corrected later.

Entropion

Rolling in of eyelid - congenital or acquired - usually leads to trichiasis which can cause severe corneal damage which in turn causes blepharospasm which aggravates the entropion, etc.

Types

Spastic entropion - due to painful lesion of the globe - e.g., keratitis, corneal ulcer; almost always a complication of entropion due to other causes.

Cicatricial entropion - following inflammation, trauma, or surgery of eyelids.

Anatomic entropion - usually congenital, but may become worse as postnatal development progresses; often heritable; seen in all species, but especially foals, lambs, and dogs (chow chow, Shar-Pei, English bulldog, and the breeds used for hunting). Dr. Roy W. Bellhorn (Emeritus, University of California, Davis), has shown that many of these animals have an abnormally long eyelid, particularly the lower. This leads to an abnormal relationship between the cornea (globe) and the eyelids.

Treatment

Always evaluate the problem after topical anesthesia to decrease the spastic component - surgical correction should only involve the anatomic or cicatricial component.

There are many methods of correction, but the simplest and usually most effective is the skin and muscle resection. However, many entropions are not simple (e.g., in the Shar-Pei or chow chow) and require moderately involved procedures to correct (Robertson and Roberts; Wyman). These patients should be referred to an ophthalmologist.

Skin and muscle resection : An elliptical piece of skin is removed 2-3 mm from eyelid margin - length of incision should correspond to length of defect and width of fragment of skin being removed should be such that when edges of incision are apposed, eyelid will roll out to normal position. You may find it easier to outline the area to be removed by incising with a scalpel rather than crimping the skin first as depicted in the illustration .

Corresponding pieces of muscle and subcutaneous tissue also are removed.

Incision is closed with closely placed, simple interrupted sutures of 3-0 or 4-0 silk; remove in 10-14 days.

Topical antibiotics are used postoperatively; also use a topical steroid if there is no corneal ulceration.

As an alternative to the above method, an entropion clamp or chalazion forceps could be used to stabilize the eyelid and provide a surface against which to cut; this also provides hemostasis until the clamp is released prior to suturing. Use sharp dissection rather than clamping with hemostats. Because sharp dissection can be used, healing will be facilitated.

Swelling after surgery may make it appear as if over corrected - wait at least a week before deciding.

If the cause of the entropion is excessive eyelid length, the treatment involves shortening the eyelid. You may choose to do a simple full-thickness wedge resection ; the resection should be within the lateral one-third of the eyelid. If there are any questions or concerns, you should seek the assistance of a specialist.

Concurrent corneal disease (e.g., ulcer from eyelid rubbing) also should be treated, but conservatively because entropion will be relieved.

In foals or dogs with neonatal or perinatal entropion, best to just temporarily put in large, vertical mattress sutures which will have the effect of everting the eyelid margin . Leave sutures in place for 1-3 weeks. Repeat if necessary. Although the entropion usually resolves spontaneously, the temporary treatment should prevent corneal damage.

With large flocks of affected lambs, it may be impractical to do surgery - in this case, 0.5-1.5 ml of 70% ethanol injected subcutaneously in the affected eyelid in the area of the entropion (about 0.5-1.0 cm below eyelid margin) will usually cure the entropion. Penicillin can be substituted for the ethanol. Because I have no experience with this type of treatment, I cannot endorse it. I suspect the use of ethanol may be associated with pain for the sheep.

Ectropion

Rolling out of eyelid - congenital or acquired; allows exposure of the globe and buildup of debris in ventral conjunctival cul-de-sac which lead to chronic keratitis or conjunctivitis (which gives eye a reddened appearance) .

Types

Cicatricial ectropion.

Senile ectropion - connective tissue loses elasticity as it ages.

Anatomic ectropion - usually congenital, but may intensify as animal ages - can be heritable in some breeds (e.g., English bulldog, cocker spaniel, others).

Treatment

If the ectropion is causing a problem, then surgery is the only recourse; there are numerous procedures available, but most of these are for minor cases of ectropion and include procedures such as V to Y, or trephine; if the ectropion is moderately extensive, a full-thickness wedge resection may be indicated; however, if the ectropion is severe and is complicated by notching or other malformation of the eyelid, considerable reconstructive surgery may be necessary and these patients should be referred to a specialist.

The full-thickness wedge removal technique involves taking a full-thickness triangular wedge out of lateral eyelid area. This procedure has a relatively high rate of dehiscence of the marginal portion of the incision. Close the conjunctiva first, using 6-0 absorbable suture and bury the knots under the conjunctiva; then close the skin with 4-0 or 5-0 silk; use a 'figure of 8' suture for the skin margin. May be wise to do a temporary tarsorrhaphy to minimize eyelid movement and stress on the incision site. Can use topical antibiotics and steroid afterwards, but probably unnecessary. Sutures removed in 10-14 days.

Lagophthalmos

Failure of the eyelids to meet when they are blinked.

Causes

Congenital - predisposition in brachycephalic dogs (e.g., Pekingese).

Facial nerve paralysis.

Secondary:

1. Exophthalmos, e.g., due to buphthalmia secondary to glaucoma.
2. Impaired lubrication from keratoconjunctivitis sicca.

Treatment

Facial nerve paralysis - keep eye moist while waiting to see if the paralysis is temporary.

Congenital predisposition - topical ointments with antibiotics and corticosteroids to reduce melanosis and secondary keratitis, or surgery (permanent partial tarsorrhaphy).

Secondary - keep cornea moist until initiating cause is corrected and eyelid function returns to normal. If eye cannot be kept moist with drugs, do tarsorrhaphy.

Tarsorrhaphy: - suturing together of the eyelids; can be partial or complete, temporary or permanent

Temporary - no cutting is done - non-absorbable suture (e.g., 000 braided suture; 6-0 braided suture in birds) starting several mm from the eyelid margin (go half-thickness; never full-thickness or else the eyeball will be traumatized) with the needle coming out through the midpoint of the eyelid margin; small lengths of polyethylene tubing or buttons may be used for support.

Permanent - apposing eyelid margins are removed (about 2-3 mm) and the conjunctival and skin edges are sutured separately using absorbable suture (5-0 or 6-0) for conjunctiva and non-absorbable suture (000 or 4-0 braided) for skin; pattern can be simple interrupted; place sutures several mm from edges; remove skin sutures in 10-14 days.

Complications with permanent tarsorrhaphy: tend to break down - put sutures close together to prevent.

Symblepharon

Eyelid (usually conjunctiva) adherent to eyeball.

Usually a complication of infections and superficial neoplasms.

Especially in kittens after herpesvirus conjunctivitis.

Treated by surgically breaking down the adhesion followed by topical antibiotics and steroids to prevent re-adhesion. Recurrence is frequent, therefore, may not elect treatment if no serious problems are present. Moreover, if there is major damage to the cornea, treatment will not be beneficial.

Retained spectacle in reptiles

Snakes and other reptiles undergo periodic shedding (ecdysis) of their skin in response to growth and other factors. The spectacle is the transparent membrane covering the cornea of the snake and some other reptiles; it is part of the external skin layer and normally is shed simultaneously. In some cases, the spectacle is not shed for various reasons such as improper humidity and temperature, insufficient objects on which to rub the skin off and improper diet; it then is termed retained. These cases can be divided into uncomplicated and complicated types and management is based upon which type is present.

Uncomplicated - no infection

Soak the spectacle for several minutes with cotton swab moistened with warm water. Then grasp the spectacle with forceps and gently pull away. Do not continue attempts if there is great resistance because it is possible to remove the cornea, too; may have to wait a few days or refer to someone who has experience working with reptiles.

Complicated - infected

These often have been retained for some time and have become infected or began as an infection. Treatment consists of soaking the area with warm water and then removing the spectacle with forceps. This is followed by a topical antibiotic-corticosteroid ointment several times a day for several days. If there is resistance or any question as to what should be done, refer to someone who has experience working with reptiles.

The prognosis is good to excellent if there has been no intraocular damage due to corneal perforation.

Eyelid neoplasia

Eyelid neoplasms are the most frequent form of ocular neoplasia. There is considerable variation between the species in the types observed. All growths removed from the eyelids should be examined histologically to confirm or deny the diagnosis.

Dog (Roberts, et al.)

Adenoma : Most common eyelid neoplasm in the dog. Generally arises from Meibomian gland (sebaceous adenoma). If the eyelid is everted, the diseased gland often clearly can be visualized beneath the mucous membranes.

Rate of growth fluctuates considerably and is different from case to case. Essentially always benign in behavior although rarely may appear malignant histologically. Cystic changes are not uncommon. Must be completely removed or it will recur. In older animal may elect just to observe and remove only if causing problems or enlarging rapidly. Signs seen may include keratitis or conjunctivitis due to physical irritation.

Papilloma: This is the second most common neoplasm. Remove if it is causing a problem.

Viral papilloma: Not common - also can occur on the conjunctiva and cornea of young dogs. It is a variation of oral viral papillomatosis and may be seen with or without oral lesions. Remove only if causing problems because it eventually will regress as the patient develops immunity.

Histiocytoma: Uncommon - may be part of generalized histiocytomatosis or localized to the eyelid.

These usually resolve spontaneously in 3-6 months. Surgery or medical therapy should be done only if the mass is causing major irritation.

Melanoma: Uncommon - often adenoma/adenocarcinoma is misdiagnosed as melanoma due to melanosis. Weimaraners and vizslas are predisposed. Most of these tumors are benign and are cured by local excision; if malignant histologically, watch closely for recurrence after surgical removal in which case wide excision should be done.

Cat (McLaughlin, et al.)

Eyelid neoplasms are relatively uncommon. Squamous cell carcinoma is seen most frequently, especially in non-melanotic eyelids. The nose and ears also may be involved. Treatment usually requires radiation or chemotherapy in addition to surgery.

Horse

Squamous cell carcinoma : Most frequent neoplasm in the horse, especially involving non-melanotic tissue. As with cattle, actinic irritation may be a co-factor. May initially appear as an area of inflammation and be mistaken for blepharitis; be sure you biopsy all 'inflammatory' lesions which do not respond as expected to conservative therapy. May metastasize late. Surgical treatment is indicated for small lesions; surgical and radiation therapy should be used for extensive lesions.

Sarcoid : Seen in the eyelid, but usually more in surrounding regions; these usually are singular, but also may be multiple. Treatment is surgical for small lesions, but may require radiation or chemical therapy for extensive or recurrent lesions.

Fibrosarcoma and neurofibrosarcoma: Often in young animals. Locally invasive, tend to recur.

Cattle

Squamous cell carcinoma: Very common in southwestern USA, less common elsewhere in the USA. More common in portions of eyelid lacking melanin. Actinic irritation is an important factor. Metastatic potential is low when the lesion is small. Surgical excision is okay for small lesions. Cryotherapy, radiation or radiofrequency hyperthermia can be used for any size lesion. More information on squamous cell carcinoma is provided in the chapter on conjunctiva.

Other neoplasms of the eyelids are uncommon.

Sheep, goat and pig

Eyelid neoplasia uncommon, but squamous cell carcinoma seen in sheep.

Treatment of eyelid neoplasms

Surgical aim of eyelid neoplasm removal is to prevent local recurrence and maintain function and appearance of the eyelids.

Radiation therapy can be used in conjunction with surgery for radiosensitive neoplasms.

Small neoplasm removal

If neoplasms are diagnosed early, cosmetic removal usually is easy. In general, extramarginal tumors should be removed using an incision which is parallel with the eyelid margin (in direction of orbicularis oculi muscle fibers).

Neoplasms at the eyelid margin are best removed by an eyelid splitting technique . The eyelid margin is split into conjunctival and skin portions to isolate the neoplasm to one or the other tissue. Then a wedge of tissue including neoplasm can be removed and only one suture line need be closed. If this creates a fold or bunching up of the opposite layer (e.g., skin, if conjunctiva is excised), the eyelid splitting can be extended the same distance to one side and a wedge of tissue removed. This prevents the two incisions from being in line with each other. A modified Kuhnt-Szymanowski procedure also can be used (see Bistner, et al.).

In patients with excess eyelid length, a full-thickness wedge of eyelid can be removed (as much as 1/3 of the eyelid length in some cases) without seriously narrowing the palpebral fissure (Brightman and Helper). This is done similarly to that described for ectropion and has its attendant risk of wound dehiscence.

Removal of large neoplasms

If the lesion is extramarginal, use incision perpendicular to eyelid margin to minimize possibility of post-surgical entropion.

With some large marginal neoplasms it is not possible to do an eyelid splitting procedure and other procedures must be employed. Of course, it would be better not to let a neoplasm reach proportions that require major surgical procedures for removal, but if you are faced with one, a sliding procedure may be helpful .

Extensive neoplastic involvement

Some of these are beyond surgical repair. These must be treated by removal of the eyelid and the globe even if the globe itself is functional. It is unfortunate (to put it mildly) that someone would allow this to happen, but it does. Radiation therapy may be an alternative, but depends on the type of neoplasm and the availability of this type of therapy.