Everyday answers for common conditions of the eyelid/conjunctiva (Proceedings)

Distichia and Ectopic Cilia

Distichiae are aberrant hairs that arise from the meibomian glands and exit through the meibomian gland opening in the eyelid margin. Distichiasis occurs commonly in many breeds of dogs. In some breeds the hairs cause virtually no clinical signs (e.g., Cocker Spaniels), whereas in other breeds they can result in epiphora, corneal fibrosis and vascularization, and occasionally corneal ulceration. The presence or absence of clinical signs depends on the number of hairs, their length, their rigidity, and the eyelid conformation of the dog. Ectopic cilia hairs arise from the same location in the meibomian glands but they exit through the palpebral conjunctiva and are much more likely to cause corneal irritation and ulceration. A non-healing superficial ulcer in the dorsal cornea of a young dog is the classic clinical presentation for an ectopic cilia hair. Magnification is required to see many ectopic cilia. They can be highlighted by a surrounding area of pigmented conjunctiva. The application of fluorescein stain can help to highlight the cilia in some cases.

Distichiae can be manually epilated, but will normally grow back in three to four weeks and the regrowth can be more rigid and more irritating than the original hairs. The hairs can be electroepilated with a surgical cautery unit, but this requires high magnification and is tedious. Cryoepilation is the quickest procedure for treatment of large numbers of distichia. Either nitrous oxide or liquid nitrogen can be used. A chalazion forcep is applied to stabilize the lid and the lid is everted to expose the palpebral conjunctiva. The cryoprobe is placed at the base of the meibomian glands and applied until the iceball extends to the meibomian gland opening at the lid margin. The iceball is allowed to completely thaw, and freeze/thaw cycle is repeated if using nitrous oxide. If using a liquid nitrogen cryogun, only a single freeze/thaw cycle is necessary. Several sites can be frozen before moving the chalazion forcep to another location. Ectopic cilia are first surgically excised and then the area is treated with cryotherapy. Eyelid swelling and depigmentation of the eyelid margins are anticipated sequelae following cryoepilation. Clients should be advised of this, particularly if the patient is a show-dog. Swelling is transient and pigmentation often returns in a few months. Topical antibiotic/steroid ointment is recommended q 12 hours post-operatively unless an ulcer is present. Oral non-steroidal anti-inflammatories or corticosteroids can be used to control postoperative swelling and inflammation. The use of the CO2 laser to ablate ectopic cilia and distichia is not recommended. Ectopic cilia treated with the CO2 laser ablation have a high rate of recurrence. Treatment of multiple distichia with the laser can cause significant lid margin scarring and lid distortion.

Prolapsed Gland of the Third Eyelid and Its Replacement

Although it is much easier to excise a prolapsed gland of the third eyelid, the current standard of care is surgical replacement of the gland. The gland of the third eyelid is estimated to produce 30% of aqueous tear film and excision of the gland may predispose some animals to the development of dry eye. The correlation between gland excision and the development of dry eye is often not made because prolapse occurs in young animals, whereas dry eye usually develops in middle-aged or older dogs. In most dogs the pocket technique is sufficient to treat the prolapsed condition of the gland. In some breeds however, orbital or scleral tacking or even a dual procedure is required for successful treatment of the prolapsed gland. In the pocket technique, approximately 1 cm curvilinear incisions are made in the posterior third eyelid conjunctiva, above and below the gland. The conjunctival tissue is undermined to free the edges. Without excising any tissue, the incisions are re-apposed using 6-0 Vicryl in a continuous pattern in one direction and returning to the starting point with an inverting pattern. The suture line is begun and tied off on the palpebral aspect of the third eyelid to prevent corneal irritation by the suture. To prevent the formation of a lacrimal cyst, the medial and lateral extent of each incision should be left open creating an exit site for tears after surgery. Post-operative treatment is with triple antibiotic ointment with or without steroid q12 hours for 10-14 days.

Entropion

Entropion is a primary conformational defect that is found as a congenital/developmental in young dogs. Entropion can also be found secondary to injury, corneal pain or atrophy of retrobulbar fat. Spastic entropion, secondary to ocular pain can normally be differentiated from primary entropion by applying a topical anesthetic to the globe. Cases of primary entropion may also be complicated by a spastic component and this should be determined prior to making a surgical correction.

Eyelid Tacking

Eyelid tacking is indicated for the temporary repair of entropion in young dogs (< 6 months to a year of age) or in older dogs that have spastic entropion secondary to corneal pain. In many pups, the entropion can resolve with growth and facial development. These cases be effectively treated with a single tacking procedure. Additional eyelid tacking procedures are sometimes necessary until the dog reaches its adult facial conformation, at which time a permanent correction may be performed. Non-absorbable 3-0 or 4-0 suture is normally used, depending on the size of the dog. A vertical mattress suture pattern is used with the first bite is taken through the eyelid skin 2-3 mm from the lid margin. Each bite should engage about 4-5 mm of tissue. A second bite is taken in the facial skin overlying the orbital rim. The suture is tied with a surgeon's throw and followed by three additional throws, adjusting the tension to evert the eyelid margin. The eyelids should be slightly over-corrected for temporary repair, and the number of sutures required for eversion varies with the individual dog. Sutures are left in place for 2-4 weeks. Antibiotic ointment is applied to the eye BID-TID until sutures are removed.

Hotz-Celsus Procedure

The Hotz-Celsus procedure is the classic entropion repair and proves useful in a majority of canine cases of entropion. The affected eyelid is stabilized with a Jaeger lid plate and then incised 2-3 mm from the lid margin, just below the mucocutaneous junction, using a #15 Bard-Parker blade. The incision is extended parallel to the lid margin for the entire length of the affected area. The second incision is curvilinear and is made distal to the initial incision. The second incision should incorporate enough eyelid tissue to correct the entropion. The incised strip of skin is removed by sharp dissection. The defect is closed with 5-0 to 6-0 non-absorbable suture in a simple interrupted pattern starting at the centern of the wound and cutting the wound distance in half with each subsequent suture. Skin sutures are placed at 2-3 mm intervals. A useful rule-of-thumb to determine sufficient correction is that you should be able to easily see the eyelid margin after correction without digital manipulation of the eyelid. If corneal disease is present, an antibiotic ointment may be applied to the eye q 8 to q 12 hours until sutures are removed two weeks after surgery. Oral antibiotics and anti-inflammatories may also be administered for 5-7 days post-operatively. Use of an Elizabethan collar is non-negotiable.

Eyelid Mass Lesions

The differential diagnosis of eyelid neoplasms includes other mass lesions such as granuloma, meibomianitis, localized blepharitis, or congenital dermoid with eyelid involvement. Clinical diagnosis is usually not difficult. Histopathology, and less commonly cytologic evaluation of material obtained by fine needle aspiration can confirm the diagnosis. Complete surgical excision, CO2 laser ablation, or cryotherapy are recommended in most instances. The cure rates for these techniques appear similar. Following surgical excision of a very large neoplasm, the eyelid may need to be reconstructed using a blepharoplastic procedure. In some such cases cryosurgery can be a viable alternative and certainly an easier option. If the neoplasm involves a third or less of the eyelid margin, a simple wedge excision is normally adequate. Careful consideration should be given to the species and/or breed in question, as well as whether the mass is recurrent before removing eyelid margin. For instance, a collie dog that has an eyelid mass cannot tolerate excision of very much lid margin without compromising lid function, due to the tight lid/globe conformation typical of the breed. A four-sided excision can be performed to conserve eyelid margin length. Two full-thickness and parallel cuts are made perpendicular to the eyelid margin, 1-2 mm on either side of the mass. These incisions are extended to the most distal extent of the mass. The incisions are then extended towards eachother to converge at a point distal to the mass. Following full thickness lid mass removal the wound is closed in two layers. A continuous run of 5-0 to 6-0 absorbable suture material is used to close the tarsoconjunctival layer adjacent to the lid margin. Care must be taken not to penetrate palpebral conjunctiva to avoid suture irritation post-operatively. The cutaneous lid margin is best closed using a figure-8 suture. The meibomian gland openings are used as an anatomical landmark for accurate alignment of the lid margin; the suture is passed through the meibomian glands or just to the cutaneous side of them. A figure-8 suture of absorbable material (e.g., 5-0 or 6-0 Vicryl) is used to close the lid margin followed by simple interrupted suture pattern to close the remaining skin.

Many masses can easily be ablated with a CO2 laser. This procedure can be performed under general anesthesia, with sedation, or with local anesthesia dependent upon the compliance of the patient, experience of the restraining technician, and confidence of the surgeon. Proparicaine is applied to the globe and a local block of lidocaine is infused in and around the lesion. Tissue raised above the level of the lid or lid margin can be debulked with scissors. The laser is then used to ablate the remaining abnormal tissue. CO2 laser ablation of lid masses is an excellent option for senior or debilitated patients for whom general anesthesia is not possible or deisred.

Nasal Canthoplasty

• Most commonly utilized in the Pug, Bull Dog and the Boston Terrior, medial canthoplasty is indicated in brachycephalic breeds with lagophthalmos and exposure keratitis, progressive pigmentation of the cornea, or keratitis secondary to medial canthal entropion or nasal fold trichiasis. For this procedure, the medial eyelid margins are excised for the desired length of shortening. Care should be taken to avoid disruption of the inferior lacrimal puncta. The superior puncta can often be sacrificed without significant clinical impact. The lacrimal caruncle and additional hairs in the medial canthus should be carefully excised as well. The new canthus is initially apposed with 5-0 or 6-0 Vicryl. The cutaneous lid margin is then apposed with a figure-8 suture of the same, followed by interrupted sutures to close the remaining tissue. A temporary tarsorrhaphy is then placed just temporal to the incisional sutures to limit tension on the incision line as it heals. Temporary sutures can be removed in 2 weeks, but the incisional sutures should remain in place for 3-4 weeks as this is a high tension area and can be subject to dehiscence. Topical antibiotic/steroid combination ointment should be applied q 12 hours during this time.