Eyelid function is important in maintaining the health of the cornea and globe. Eyelids distribute tears over the corneal surface, remove foreign bodies from the surface of the eye, control the amount of light entering the eye and protect the globe from trauma.
Eyelid function is important in maintaining the health of the cornea and globe. Eyelids distribute tears over the corneal surface, remove foreign bodies from the surface of the eye, control the amount of light entering the eye and protect the globe from trauma. The outer eyelid is haired skin and the inner surface is palpebral conjunctiva. The upper lid is more mobile than the lower. The orbicularis oculi muscle (innervated by a branch of the facial nerve) encircles the eyelids and enables closing of the eyelids; closure occurs laterally to medially. The levator palpebrae muscle (innervated by the oculomotor nerve) is the main muscle responsible for opening the upper lid and the malaris muscle opens the lower lid. The eyelid margin is a mucocutaneous junction. The meibomian gland openings are positioned at the eyelid margin; these play a role in maintaining the tear film and produce the outer lipid component of the tear film (meibum) that prevents evaporation.
There are few congenital abnormalities that require surgical correction. Ankyloblepharon is delayed opening of the eyelids and should be differentiated from neonatal ophthalmia. True anklyloblepharon is infrequent and requires surgical separation of the eyelids. Neonatal ophthalmia results from infection, either intrauterine or at parturition. In these case bulging of purulent material behind the eyelids is usually evident. Careful massaging apart of the eyelids, sometimes using a mosquito hemostat will achieve normal eyelid separation. Culture and cytology of the material should be performed and topical antibiotics dispensed.
Cats may have abnormal/incomplete development of the upper lateral eyelid. Usually the medial quarter to third is normal and the condition is bilateral. The eyelid margin is absent laterally resulting in trichiasis and the palpebral conjunctiva may be absent as well. This results in an adhesion-like situation between the eyelid and the bulbar conjunctiva. Multiple techniques have been described to address this defect; the severity of the agenesis determines the correction that I use. The most simple repair utilizes a strip of haired skin harvested from below the lower eyelid; the lateral aspect of the graft is left attached and the graft is rotated to create the upper lid. This usually results in trichiasis so a graft of mucosa or conjunctiva, if available may be performed at the same time. Alternatively, a second procedure utilizing cryotherapy to address the trichiasis may be planned.
Eyelids that are too long, too short, or otherwise incongruent create problems for the ocular surface. Surgical correction is indicated in these patients. Although many of these cases present while still immature, temporary corrective techniques are important until the eyelids finish growing. Too early correction may lead to further problems that require another surgery or to permanent deformity of the eyelids. For patients with entropion, or rolling in of the eyelids and the haired skin is in contact with the globe, temporary eversion of the eyelids is performed until growth is finished. Suture, staples, or glue may be used to create a fold to shorten the eyelid so the normal margin is in apposition to the cornea. As the patient grows the everting material may need to be replaced so that the appropriate amount of tissue is folded into the temporary eversion.
Once the patient is grown the need for a permanent surgery may be assessed. Sometimes, with maturity the eyelid grows to fit the globe and no surgery is indicated. In many instances the incongruity remains and tissue must be removed permanently to create normal eyelid:globe apposition. Permanent eyelid surgery should not be performed if dermatitis is present. The Hotz-Celsus procedure is the most commonly utilized; a new moon or banana shaped piece of tissue is removed. The incision starts 1-2 mm from the eyelid margin. The appropriate width of tissue is removed so that when the incisions are sutured together the eyelid margin is appropriately situated. Measurement is performed when the patient is awake with normal muscle tone; measurement after anesthesia is induced may lead to removal of too much tissue. If uncertainty is present about how much tissue to remove, for instance in a dog that squints when the eye is approached, it is better to be conservative. More tissue may always be removed, but if too much is resected long term complications may occur. Suturing of the incision proceeds with simple interrupted non-absorbable suture material using the law of halves; 4-0 to 6-0 suture is used.
Eyelid laxity may also be present with entropion. This is corrected by performing a wedge resection at the lateral canthus, either before or after the entropion surgery. In breeds with loose eyelids the primary entropion is often a factor of the long eyelids. Failure to shorten the eyelid, even when the entropion is corrected may predispose to problems over the long term. Although the easiest technique is the associated wedge resection many procedures have been described to accomplish this. Reference to an ophthalmology text is recommended for other techniques.
Correction of ectropion or rolling out of the eyelids is usually accomplished using a wedge resection. This addresses irritation from chronic exposure of the conjunctiva. Again measurement should be performed on the awake patient to ensure that appropriate tissue is removed. Suturing of the eyelid margin using 6-0 absorbable suture material and a figure of 8 suture is performed first to assure perfect margin apposition. Subcutaneous sutures of the 6-0 material are then placed. The skin is sutured last using 4-0 to 6-0 nonabsorbable suture in a simple interrupted pattern. Cicatrical ectropion results from burns, from inappropriate surgery, or from other trauma. A V to Y-plasty is performed for correction; if significant scarring and fibrosis are present this may be a difficult surgery due to inelasticity of the fibrotic tissue.
Exposure issues from lagophthalmos may lead to recurrent corneal ulcers, corneal pigmentation and scarring, inappropriate tear film, and increased risk of physical trauma. The brachycephalic breeds are predisposed. The canthoplasty procedure, medial and/or lateral is performed to correct this. A simple canthoplasty may be performed utilizing a 2-layer closure for more fibrosis and to decrease stretching after healing. Alternatively, a pocket canthoplasty may provide more stability to the repair, however the upper lacrimal punctum must be sacrificed in this procedure. The lid margins are resected as for a standard canthoplasty. The upper lid is split to create a pocket, then a flap of conjunctiva is pulled up into the pocket of the split upper lid and sutured. Subcutaneous sutures of 6-0 vicryl are placed and skin is closed with 4-0 or 5-0 nonabsorbable suture. One to two temporary tarsorrhaphy sutures are placed adjacent to the sutures to decrease tension on the eyelid and incision during healing. Transplanting the conjunctival flap into the pocket strengthens the surgery site and creates more stability. Mild medioventral entropion is often present in these breeds so a concurrent, minor Hotz-Celsus procedure may be performed for the lower medial eyelid at the same time. The canthoplasty will address the exposure issue and any caruncular trichiasis leading to hair floating on the cornea. The Hotz-Celsus will address irritation from the hair in contact with the cornea secondary to medioventral entropion. These patients do well and are able to maintain a normal tear film after surgery; often an issue due to the eyelid conformation beforehand.
Trichiasis results from normal hair that is misdirected. The misdirected hair may cause conjunctival irritation and corneal ulceration or scarring; in the worst case scenario the ulcer may progress to a rupture. Brachycephalic breeds may be especially predisposed due to the presence of a nasal fold. In some breeds and older dogs, tone of the upper eyelid is not enough to prevent downward drooping of the eyelashes. Removing the irritating hair may be accomplished in multiple ways. Often a minor Hotz-Celsus procedure will evert the skin and hair that is touching the cornea; because entropion is not associated with true trichiasis care must be taken to avoid creating ectropion. Other modalities include cryosurgery, CO2 laser ablation, and excision with second intention healing, similar to a Stades procedure. More radical correction of nasal fold trichiasis involves removal of the nasal fold. Upper lid trichiasis may require a large resection of skin right above the lash line; this is left to heal by second intention creating fibrosis and pulling the lash line away from the cornea; this is a true Stades procedure and will leave a scar.
Distichiasis or the presence of eyelashes that originate from the Meibomian gland openings and thus contact the cornea may be treated in many ways. If they are few, fine, and the patient has a good tear film nothing needs to be done. If they are irritating as evidenced by blepharospasm and epiphora, removal is recommended. Cryosurgery is the most common approach for my patients but other methods including electrolysis for many distichia are also utilized. Surgical resection of the tarsal plate and CO2 laser ablation are possibilities also. Inflammation develops post-operatively which usually resolves in a few days. Adjunctive use of oral steroids will facilitate a decrease in the swelling. Other medications that should be dispensed are oral and topical antibiotics and pain medication. Some patients may develop permanent depigmentation at the site of the resection so owners need to be educated about this, especially when cryosurgery is used. In young dogs more distichiae may erupt over time and a second procedure may be required; if the patient presents after the age of 4-5 years I am not as concerned about needing to perform a second procedure.
Ectopic cilia are also eyelashes that erupted abnormally. Instead of growing out through the eyelid margin they grow downward and project through the palpebral conjunctiva of the eyelid. This creates contact with the cornea at right angles and may be very painful. Corneal ulceration is often present at the contact area. Patients are generally placed under the operating microscope. The whole hair follicle is resected and I like to use a biopsy punch (usually 2 mm) to incise around the follicle. The skin and follicle are removed and the area is treated with a double freeze/thaw cycle of cryotherapy to kill associated tissue around the follicle. As soon as the offending hair is removed the patient is more comfortable and any corneal ulceration heals. Post-operative swelling may be addressed with oral steroids; oral and topical antibiotics as well as pain medication should be dispensed. Healing time is generally 2 weeks.
Eyelid masses are another surgically addressed issue. 95% of eyelid masses in dogs are benign; cats have a much greater percentage of malignant masses. Regardless, biopsy is always recommended to achieve a definitive diagnosis and prognosis. Generally resection of the mass when it is small (less than 2-3mm) is recommended. At this size the mass may be addressed by a simple 4-sided excision; when the mass is greater than 25% of the length of the eyelid an adjunctive eyelid reconstructive procedure must be utilized or a technique other than a simple excision used. A 4-sided excision results in good apposition of the incisions without distortion and the tension is evenly divided along the incision. I place my 6-0 vicryl figure-of-eight suture at the eyelid margin first to be sure that excellent apposition is achieved, then subcutaneous sutures are placed to close the conjunctival aspect of the eyelid. Lastly, skin sutures of 4-0 or 5-0 nonabsorbable material are placed. If the mass is greater than 25% of the eyelid length then a H-plasty could be used to replace the resected tissue. This usually results in trichiasis, which if severe enough will need to be addressed by cryoepilation. Other techniques involve rotating or semicircular flaps to replace the resected tissue; an adequate blood supply must be present to ensure survival of the flap. Post-operative therapy includes topical and oral antibiotics, as well as pain medication. An Elizabethan collar should always be placed.
Other surgical techniques for addressing eyelid masses are laser ablation and cryosurgery. Recurrence rates are approximately the same for all techniques, however time to recurrence is shortest for cryosurgery (7 months), intermediate for laser (18 months) and longest for surgical resection (28 months). If the mass is extensive, only surgery will achieve complete resection (and associated reconstruction) without leaving a significant lid defect.
The development of a chalazion creates an appearance similar to a mass. The swelling is usually based on the palpebral aspect of the eyelid and is firm. A chalazion results from leakage of Meibomian gland secretions leading to a chronic granulomatous reaction; this predisposes to a Staph infection. A chalazion may be addressed by incising the palpebral aspect of the mass and curetting the granuloma to remove it. The incision should heal by second intention; topical and oral antibiotics as well as pain medication should be dispensed.
Eyelid lacerations are another category of surgical treatment and can be enjoyable to treat. If the wound is fresh minimal debridement may be necessary and simply apposing the edges with suture may achieve closure. Suturing the eyelid margin first is important so that a normal margin is recreated for normal eyelid function; this is more important for the upper lid than the lower. In general, the upper lid that is more mobile is more critical as far as appropriate reconstruction. I generally try to place a figure-of-eight suture at the margin. If significant tissue has been devitalized or is missing then advancement, semicircular, or rotational flaps may be needed. Eyelid tissue and especially conjunctiva contracts after incising it and is fairly fragile; harvesting slightly more tissue than measured is necessary for closure without excessive tension. Careful handling of eyelid tissue is important for a viable repair. Other concerns are viability of the upper lacrimal gland if the trauma affects that area of the lid. Monitoring of tear production over the long term or treatment with cyclosporine may be required.
1. Veterinary Ophthalmology, 4th ed., Gelatt KN, editor, Blackwell Publishing, Ames IA 2007.
2. Ophthalmic Disease in Veterinary Medicine, Martin CL, Manson Publishing, 2005.