Ординатура / Офтальмология / Английские материалы / Small Animal Ophthalmology Secrets_Riis_2002

25. Describe how to correct a diamondor pagoda-shaped palpebral fissure with significant lateral canthal entropion when shortening of the palpebral fissure is desired.

A rhomboid or diamond lateral canthoplasty may be used to concurrently evert the lateral canthus and shorten the palpebral fissure (Fig. 10). The lid margin to be removed is measured from the lateral canthus to the point on the margin appropriate to achieve the desired shortening of the palpebral fissure. Both the upper and lower lids are incised perpendicular to their margins and the incisions extended dorsolaterally (for the upper lid) and ventrolaterally (for the lower lid). The length of each incision is approximately 1-2 times the width of the margin to be excised depending on the desired degree of entropion correction. These two incisions form the medial arms of the rhombus or diamond. From the ends of these incisions, two more incisions are made perpendicular to the first to intersect in a right angle lateral to the lateral canthus. The incisions define the diamond-shaped area of skin and tarsoconjunctiva excised to create the typical rhomboid defect. The cut end of the upper and lower lid margins are then joined with a 5---D to 6---D nonabsorbable suture using a cruciate pattern to recreate the lateral canthus. The conjunctiva is next closed with a continuous pattern of 5---D to 6---D absorbable suture. The lateral canthus is then apposed to the lateral corner of the diamond with an interrupted subcutaneous absorbable suture. The subcutaneous tissue is closed with a continuous pattern of absorbable suture, and the skin is closed with interrupted nonabsorbable sutures. The result is a curved sutured incision that tenses the lateral canthus laterally, and the procedure has shortened the palpebral fissure.

(

A B

D

Figure 10. Rhomboid canthoplasty. A, Delineation of the tissue to be excised in the rhomboid canthoplasty. B. Initial closure of the lateral lid edges to reform the lateral canthus. C, Closure of the conjunctiva and subcutaneous tissues with continuous absorbable suture. D, Final curvilinear skin closure resulting in narrowed palpebral fissure and resolution of the lateral canthal entropion and ectropion.

26.What techniques can be used to deal with lagophthalmos?

Lagophthalmos associated with transient ocular or orbital swelling may be countered by a

temporary tarsorrhaphy using 1-3 nonabsorbable mattress sutures passed though the lid margins at the level of the gray line. When there is little tension on the lids, the sutures may be placed with-

Figure 12. Medial canthal closure protects the globe while narrowing the palpebral fissure and masking the medial sclera. Most brachycephalic breeds show more sclera medially resulting in an exotropic appearance. Medial canthal closure to narrow the palpebral fissure (extent indicated by the dashed line) not only protects the globe but also improves the cosmetic appearance.

28.Is there a simple way of dealing with medial canthal trichiasis?

The simplest and perhaps most effective way to resolve medial canthal trichiasis is to use

cryoablation of the offending hairs. The tissue from which the hairs arise can be frozen with a liquid nitrogen spray (being careful to ensure the adjacent structures are protected from freezing). The tissue should be frozen twice, separating each freeze by a slow thaw. In patients with lagophthalmos in which a partial medial tarsorrhaphy is contemplated, the lacrimal caruncle and other structures from which the hairs arise may be removed prior to closure.

29.When confronted with removal oflarge lid tumors, how much of the lid may be removed and still allow simple apposition and closure?

The rule of thumb is that up to one-fourth of the lid may be removed by a simple wedge resection without requiring more than simple closure. However, all rules have exceptions, and more lid may be removed in dogs with more expansive or elastic periocular skin and lids. Figure 13 presents a good example from a cocker spaniel with a large sebaceous adenoma on the upper lid. A pentagonal, full-thickness resection is used to remove the tumor, and because the upper lid is long, primary closure can be achieved. While the resultant upper lid shortening narrows the palpebral fissure, the elasticity of the tissue has allowed closure, and gradual stretching allows the palpebrae to assume a more normal and quite acceptable appearance by the time of suture removal. Further remodeling and reshaping will continue with time.

30.What is an H blepharoplasty and how is it performed?

H-plasty uses a sliding skin flap to move adjacent skin vertically into a lid defect. The tissue

removed at the lid margin represents the first section of the H, and the flap of skin to be mobilized represents the second. Once the full-thickness resection of the lid lesion has been performed, two slightly diverging incisions are extended away from the defect. These incisions should be twice the height of the lid defect, and two triangles of equal size (Burow's triangles) are removed from the skin adjacent to the distal extent of the sliding flap. The flap is then dissected free from the subcutaneous tissue and advanced, closing the triangles. The deep surface of the flap may be covered by adjacent palpebral and fornix conjunctiva, conjunctiva from the opposite lid, or a free graft from the buccal mucosal. The skin flap is advanced to 0.5-1.0 mm beyond the adjacent lid margins to compensate for postoperative contraction of the graft. The sides of the skin flap are apposed with 4--D to 6-0 simple interrupted nonabsorbable sutures. The conjunctiva or mucosal graft is attached to the flap with continuous 5-0 to 6-0 absorbable sutures using either a continuous pattern or interrupted sutures with knots carefully buried or positioned away from the edge of the flap to avoid contact with the cornea (Fig. 14).

31. Describe how larger upper eyelid defects (those that cannot be closed by primary apposition of the edges) can be repaired to preserve optimal lid function.

Because the upper lid covers the majority of the cornea during blinking, preservation of its function is extremely important for optimal lid function. Preservation of upper lid mobility and

Figure 13. Simple closure of a large eyelid defect. A. Preoperative appearance of large sebaceous adenoma. B, Pentagonal defect at time of resection. C, Checking apposition. D, Immediately after closure. E, Close-up appearance at II days postoperatively after suture removal. F, Comparison with fellow eye 11 days postoperatively.

Figure 14. H-plasty. A. Initial incisions for removal of mass and formation of sliding skin-muscle flap. B, Lid defect and Burow's triangles performed in preparation of sliding of the flap. C, Skin-muscle flap sliding into position with collapse of the Burow's triangles. D, Final closure with flap advanced 0.5-1.0 mm beyond lid margins to allow for postoperative contraction of the skin. (From Gelatt K (ed): Handbook of Small Animal Ophthalmic Surgery. TalTY town, NY, Elsevier, 1994, with permission.)

provision for a good lid margin are critical factors that cannot be achieved with advancement and rotational flaps. Munger and Gourley describe a cross lid flap that uses a lower lid flap to reconstruct the upper lid, thus providing for both a lid margin and mobility for the upper lid. The width of the flap from the lower lid is 3/4 of the width of the defect in the upper lid because the adjacent upper lid tissue can be stretched to fill l/4 of the defect. The pedicle of the flap must be at least 4 mm wide to preserve blood supply to the flap. The pedicle may be either medial or lat-

Figure 16. Repair of laceration of lacrimal canaliculus using a pigtail probe. A, Pigtail probe passed from the superior punctum into medial lower canaliculus. Note suture passed through eye of probe that will be retracted out through superior punctum. B, In the next stage, the probe is passed through the lower punctum and out through the lacerated canaliculus. The suture is then passed through the eye and retracted out through the lower punctum. Silastic tubing passed over the suture and clamped to the suture with a hemostat

(H) can then be pulled through the system. C, Silastic tubing in place. D, Closure complete with silastic tube tied in the medial canthus.

c

BIBLIOGRAPHY

I. Gelatt KN, Gelatt JP: Surgery of the eyelids. In Handbook of Small Animal Ophthalmic Surgery. Vol I: Extraocular Procedures. Tarrytown, Elsevier Science, 1994, pp 69-124.

2.Jensen JE: Canthus closure. Comp Cont Educ 1:735-741, 1979.

3.Munger RJ,Cater JD: A further modification of the Kuhnt-Szymanowski procedure for correction of atonic ectropion in dogs. J Am Anim Hosp Assoc 20:651-656,1984.

4.Munger RJ, Gourley 1M: Cross lid flap for repair of large upper eyelid defects. J Am Vet Med Assoc 178:45-48, 1981.

5.Wyman M: Lateral canthoplasty. JAm Anim Hosp Assoc 7:196-201,1971.

6.Wyman M: Ophthalmic surgery for the practitioner. Vet Clin North Am Small Anim Pract 9:311-348, 1979.

7.Wyman M, Wilkie DA: New surgical procedure for entropion correction: Tarsal pedicle technique. J Am Anim Hosp Assoc 24:345-349, 1988.