David J. Maggs, BVSc (Hons), DACVO
Professor, Veterinary Ophthalmology, University of California - Davis, Davis, CA, USA
Surgical correction of eyelid problems can be one of the most satisfying surgeries in general practice. However, attention to the smallest of details is essential if good results are to be attained. Important considerations include:
1. Adequate instrumentation and a source of magnification. Although instruments used for general surgery can also be used for some eyelid procedures, instruments intended specifically for ophthalmic surgery will reduce surgeon frustration and length of procedure, and improve surgical outcome and client satisfaction. Magnification is best provided by binocular head loupes.
2. Patient positioning and preparation. Maximizing surgeon comfort and manual control is best if the surgeon is seated with forearms or wrists comfortably stabilized on the patient or operating table. The patient is usually best positioned so that the surface to be operated upon is parallel with the table surface. In most cases, lateral recumbency with the nose raised provides adequate positioning for eyelid surgery. Ventral or dorsal recumbency provides the opportunity to view both eyes, which can be advantageous if a symmetrical surgical result is required. The minimum amount of periocular hair should be carefully trimmed. My preference for antiseptic is povidone iodine (Betadine®) solution diluted 1:50 in saline. Preoperative treatment with ophthalmic ointments should be avoided, since these will create a greasy operating surface and because the vehicle can lead to granulomatous inflammation.
3. Clinically relevant anatomy and physiology. The primary functions of the eyelids are to protect the eye (and especially the cornea) and to retain and disperse the tear film. This is achieved by perfect anatomic relationships between the many tissues that comprise the eyelid, and by adequate neurological and muscular function. The surgeon must be very conscious of these relationships and functions; in particular the specialized eyelid margin which acts like a "squeegee" that retains and spreads the tears over the cornea, and is critical for corneal health, comfort, and vision. There are two landmarks that are useful for eyelid surgery: the meibomian gland orifices (a line of small whitish-tan circles running along the eyelid margin) and the haired-nonhaired border (junction between haired periocular skin and non-haired eyelid margin).
Specific Surgical Treatments for the Eyelids
Eyelid Tumors - Resect or Freeze?
Eyelid neoplasia of dogs is common. The vast majority are benign. The most common neoplastic condition is a benign meibomian adenoma. Treatment involves debulking the tumor followed by cryotherapy and can often be done with only sedation. A Desmarres chalazion clamp provides superb stabilization of the eyelid margin and hemostasis. Any section of the lesion that protrudes beyond the eyelid margin can then be carefully debulked (without incising the margin itself) and the tissue submitted for histopathological confirmation. The palpebral conjunctiva is then incised perpendicular to the eyelid margin and overlying the length of the swelling. Frequently, little firm glandular material is present in these lesions and instead inspissated mebum and granulomatous debris is curetted from the subcutaneous/subconjunctival space using a Meyerhoefer chalazion curette. If there is neoplastic tissue at this site, it may be debulked using a small blade or tenotomy scissors and Bishop-Harmon tissue forceps. Two cycles of cryosurgery is a useful adjunct therapy to reduce the chance of lesion recurrence. See the following sites for reasonable methods of cryotherapy for your practice - Verruca-Freeze (www.cryosurgeryinc.com) or Brymill (www.brymill.com). Wedge resection, which was once recommended universally for these masses, is now used only if debulking and cryotherapy are unlikely to be successful (due to tumor size), or when tumors other than meibomian adenomas may require wider surgical margins. In these cases, grafting procedures may also be necessary.
Because clinically significant entropion is always associated with some degree of trichiasis, spastic entropion is a component of all cases of entropion. Therefore thorough assessment of entropion includes determination of the cause and relative contribution of blepharospasm and must include examination of the patient before and after the application of a topical anesthetic.
Although a large number of procedures are described for entropion, mastering the Hotz-Celsus procedure will allow correction of the majority of the simpler cases of entropion. More complex cases may best be referred to an ophthalmologist. In all cases, surgery should be deferred until facial maturity is achieved. In larger breeds, this can be as late as 1 year old. Until then, the owner should be encouraged to consider temporary "tacking" procedures. I like to use surgical staples for this.
The majority of cases of simple conformational entropion can be addressed using a Hotz-Celsus procedure. Most practitioners are already familiar with this technique. The purpose of this description is to highlight some helpful hints to improve success rates.
1. The incisions:
a. Where? The initial incision should be made parallel to the eyelid margin at the haired-nonhaired border. (A common error is to place this incision too far from the eyelid margin leading to under-correction).
b. How long? The length of this first incision is dictated by the length of inverted eyelid. The tapered ends of the resected tissue mean that the everting effects are minimal at both wound ends; therefore I tend to make this longer than the inverted tissue.
c. How wide? The amount of tissue to be resected is always an estimate. I use clues like applying gentle pressure with my thumb on the lower lid at the point of entropion until the eyelid margin (meibomian gland orifices) can be seen along the whole eyelid length. Other clues are provided by the pale discoloration, blepharedema, and alopecia that all occur secondary to maceration of eyelid skin due to constant exposure to the tear film. With this incision, it is generally better to err on the side of under-treatment as a subsequent entropion surgery can always be performed. Use of calipers or some other simple method of measurement may assist in symmetrical resection of the contralateral eyelid if that is required.
d. How deep? Although some texts recommend resection of the orbicularis muscle, removal of the dermis is sufficient. Following an initial skin incision with a #15 Bard-Parker scalpel blade, eyelid tissue is best resected with a small pair of tenotomy scissors in a "V"- or "boat keel"-type of pattern. This maximizes eversion of the lid and ensures excellent wound apposition when the incision is sutured.
a. Multiple, small, closely-spaced, sutures should be placed perpendicular to the wound margin using the "rule of bisection". This special technique aids wound alignment although the wound margins are of unequal length, and minimizes tissue redundancy at the end of the wound. Sutures are placed so that each bisects the distance between two previously placed sutures.
The Arrowhead Procedure for Lateral Entropion
Dogs such as the Rottweiler, Retrievers, Great Danes, etc. with broad heads have a peculiarly laterally placed entropion that may be subtle and less responsive to Hotz-Celsus procedures. These dogs often have entropion of the lateral aspect of their lower (and sometimes upper) eyelids as well as marked inversion of the lateral canthus. The lateral canthal ligament in these breeds is directed in such a way that it causes an inversion of the lateral canthus and nearby eyelids. Additionally, many have weak or absent tarsal plates at the lateral canthus. The arrowhead procedure with lateral canthal tendonotomy was developed to correct these anatomic variations.
Briefly, I begin with the lateral canthal tendonectomy. The lid margins are firmly grasped with tissue forceps at the lateral canthus and the canthus is elevated away from the globe and in a slightly lateral direction. Blunt-tipped tenotomy scissors are then used in a closed position to "strum" the lateral canthal tendon through the conjunctiva. A small conjunctival incision is then made over this tendon using scissors. The tendon is then further localized with the same strumming motion and cut blindly. A gradual relaxation will be appreciated in the tension with which the lateral canthus is attached to the lateral orbit as all of the fibers of the lateral canthal tendon are slowly cut. I do not recommend removal of a small section of the ligament.
The second part of the surgery uses identical basic principles to those described for the Hotz-Celsus. The initial skin incision along the haired-nonhaired border includes upper and lower eyelids and lateral canthus. Sufficient tissue to evert the entropic lateral regions of the upper and lower eyelids is resected as for the Hotz-Celsus. The outer curvilinear incisions are joined at a point sufficiently lateral to the lateral canthus to evert the inverted canthal tissue. The incisions are closed using the rule of bisection, beginning with a suture placed at the (new) apex of the lateral canthus. Postoperative management is as for simpler Hotz-Celsus procedures.
I acknowledge Elsevier for provision of surgical figures used in today's lecture. They can be found in Slatter's Fundamentals of Veterinary Ophthalmology, 4th Edition, Maggs, Miller and Ofri.