1 SURGICAL ANATOMY of EYE the Eyelids and Orbit House and Protect

Dr. Hussein Hadi Nahi Eye surgery 5th stage

SURGICAL ANATOMY OF EYE

The eyelids and orbit house and protect the eye. Eyelids are mobile folds of skin that block light and protect the cornea. The upper lid is slightly larger and more mobile than the lower lid. The upper and lower lids join at the medial and lateral commissures, which are stabilized by the medial and lateral palpebral ligaments. The width of the opening between the lids is controlled by opposing groups of muscles; the orbicularis oculi muscle closes the palpebral fissure while the fissure is widened by the levator palpebrae superioris, pars palpebralis of the sphincter colli profundus muscle, and smooth muscles of the periorbita.

The upper and lower lacrimal puncta, which drain tears, open onto the bulbar surfaces of the lid margins 2 to 5 mm from the medial commissure. The lacrimal caruncle is located near the medial commissure. It projects fine, small hairs; has sebaceous glands; and may be pigmented. Long hairs known as cilia project from the upper lid margin, while the lower lid is devoid of cilia. There is a tuft of long tactile hairs at the dorsal medial margin of the orbit, which corresponds to man's eyebrows.

Glands in the lid margins are similar to glands found elsewhere in skin. Sebaceous glands open into follicles of the cilia on the upper lid. Both upper and lower lids have specially modified sebaceous glands—the tarsal glands (meibomian glands). Duct openings of these glands are found in a shallow furrow immediately caudal to the mucocutaneous junction. The tarsal glands produce an oily tear film and are usually visible through the conjunctiva. Sometimes very fine hair originates from these glands. This condition is called distichiasis.

Ciliary glands (apocrine sweat glands) secrete into hair follicles, sebaceous glands, or directly onto the lid margin. superficial gland of the third eyelid, a mixed seromucous gland that contributes significantly to the tear film, surrounds the base of the cartilage

Dr. Hussein Hadi Nahi Eye surgery 5th stage

(FIG.1): Ocular and periocular anatomy.

(FIG.1): Intraocular anatomy

Dr. Hussein Hadi Nahi Eye surgery 5th stage

Eyelid laceration. A, Repair eyelid lacerations perpendicular to the lid margin by first placing a mattress suture in the tarsal plate (B and C) at the mucocutaneous junction to accurately align the eyelid margin and conjunctiva, and then appose the conjunctiva with a simple continuous suture pattern. D and E, Appose the skin beginning at the eyelid margin with a cruciate suture, keeping suture ends away from the cornea. Inset, If the nasolacrimal duct is damaged near the medial canthus, first stent it with monofilament suture to guide polypropylene or Silastic tubing through the duct, and then appose the conjunctiva and skin.

Corneal sutures: should penetrate 75% to 90% of the cornea, with sutures entering and emerging perpendicular to the surface and at a distance of 1 to 2 mm from the wound edge. A, Desired width and depth of corneal sutures. B, Insert the needle so it penetrates the cornea perpendicular to the surface; then it is tipped upward before entering the opposite corneal edge so it emerges from the cornea perpendicular and 1 to 2 mm from the wound edge.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

Temporary tarsorrhaphy. A, Temporary closure of the eyelid achieved by orienting horizontal mattress suture parallel or perpendicular to the eyelid margin (B). Sutures do not penetrate the full thickness of the eyelid.

Enucleation or Exenteration

Enucleation is the removal of the globe, the nictitating membrane, and the lid margins. Exenteration is removal of the globe, nictitating membrane, orbital contents, and lid margins. Enucleation is indicated after severe ocular trauma, intractable glaucoma, endophthalmitis, panophthalmitis, intraocular neoplasia, congenital defects, or intractable infections. Exenteration is indicated for intraorbital neoplasia or ocular neoplasia that has extended beyond the globe. Owners often are resistant to either procedure despite the predicted improvement for the animal.

Conjunctival flap. A, Prepare a thin sliding conjunctival flap by grasping the conjunctiva with ophthalmic forceps approximately 2 mm from the limbus; apply traction and incise with tenotomy scissors (B). C, Elevate the flap, and rotate to cover the corneal defect. Place two sutures from the flap through half the depth of the limbus, then place additional continuous sutures. D and E, A bipedicle flap can be created and transposed for large corneal defects in a similar manner.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

Third eyelid flap. A, Pass a cutting needle through the upper eyelid in the dorsolateral conjunctival fornix. Exteriorize and extend the third eyelid with forceps and direct the needle through the external surface of the third eyelid, around the cartilage crossbar but not through the third eyelid on the bulbar surface. B, Direct the suture through the dorsolateral conjunctival fornix and out the upper eyelid. C, Tie the suture over a stent with a bow to allow release and periodic corneal inspection.

Enucleation. A, Perform a lateral canthotomy, then grasp the conjunctiva at the limbus and make a 360° perilimbal incision. B, Separate the conjunctiva, Tenon's capsule, and extraocular muscles from the sclera, then sever the optic nerve. Attempts to ligate or visualize the optic nerve before severing results in excessive tension on the optic chiasm and may lead to blindness in the other eye. C, Excise 3 to 4 mm of the eyelid margins. D, Close the conjunctiva, Tenon's capsule, and orbital septum. E, Appose the subcutaneous tissue and skin of the eyelid margins.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

Entropion is inward rolling of the eyelid margin, which may be developmental, spastic, or cicatricial.

DIFFERENTIAL DIAGNOSIS Entropion must be differentiated from enophthalmus and phthisis bulbi, which may mimic entropion but are not associated with pain and epiphora. Distichiasis, trichiasis, ectopic cilia, imperforate lacrimal puncta, dacryocystitis, and corneal injuries are other causes of epiphora. Corneal ulceration, distichiasis, ectopic cilia, and severe uveitis are other causes of blepharospasm.

MEDICAL MANAGEMENT A nonsurgical method of treating entropion includes subcutaneous injection of an antibiotic such as procaine penicillin, which provides temporary eyelid margin eversion and relief from trichiasis and blepharospasm. The larger the volume injected, the greater the eyelid margin eversion. Surgical correction is generally required. Corneal ulcers and conjunctivitis are treated medically. Treatment of the underlying cause of spastic entropion sometimes relieves the spasm, although surgery is often necessary for correction.

SURGICAL TREATMENT Various methods of treating entropion have been described. Selection of technique is based on the species, severity, and position of the abnormality.

1. Entropion-eyelid tacking. Use Lembert sutures in the neonate to temporarily evert the eyelid margin. The first bite is 5 mm wide and begins 3 mm from the eyelid margin (inset). Position the second 5-mm- wide bite over the rim of the orbit, biting into the orbital fascia. Tie the suture, inverting a furrow of skin. A few drops of surgical glue placed within the created furrow minimize tension on the sutures and helps maintain their position if the patient rubs at the eyes.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

2. Hotz-Celsus procedure for entropion repair. A, Using thumb forceps, tent the skin in the area of the entropion to estimate the size of the ellipse to be removed. B, Stabilize the lid by placing a Jaeger eyelid plate into the conjunctival fornix. Incise along the length of the entropion beginning 3 mm from the lid margin and remove a crescent-shaped piece of skin. C, Begin closing the defect at the center of the wound with a simple interrupted split-thickness skin suture (inset). D and E, Place additional sutures 2 to 3 mm apart.

3. Y-to-V correction for cicatricial entropion. A, Make a Y-shaped incision with the arms of the Y extending just beyond the affected segment of eyelid. Apply traction to the skin flap until the margin of the eyelid is in normal position to determine the length of the Y-stem incision. B, Undermine the flap and remove scar tissue. C, Suture the point of the flap to the most distal aspect of the incision. D, Appose the remainder of the incision.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

4. Permanent lateral tarsorrhaphy. A, Excise upper and lower lid margins at the lateral canthus, removing a V-shaped segment of skin. B, Place intradermal or subcuticular sutures to realign the skin edges. C and D, Place skin sutures to precisely align the eyelid margins and appose the skin.

Ectropion is eversion of the lower eyelid.

DIFFERENTIAL DIAGNOSIS Ectropion must be differentiated from eyelid trauma. Other causes of epiphora include distichiasis, trichiasis, ectopic cilia, imperforate lacrimal puncta, dacryocystitis, and corneal injuries. Conjunctivitis may also be caused by microorganisms, parasites, allergens, foreign bodies, toxins, or precorneal film deficiency.

MEDICAL MANAGEMENT Treat corneal ulcers and conjunctivitis as described on (p. 6). SURGICAL TREATMENT Developmental ectropion and ectropion caused by scar tissue that causes conjunctival or corneal lesions may be corrected by a variety or combination of surgical techniques. Surgical correction of intermittent ectropion is contraindicated. The goal of surgery is to provide a relatively normal length to the lower eyelid; most procedures shorten and strengthen the lid. Selection of technique is based on the species, severity, and position of the abnormality. Most procedures involve the lateral one half of the lower eyelid and lateral canthus to avoid the nasolacrimal apparatus and nictitating membrane. Correction is required less frequently than with entropion, and only when it causes conjunctivitis, corneal vascularization or pigmentation, or exfoliative blepharitis from epiphora. 8

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1. Trephination for mild ectropion correction. A, Use a skin biopsy punch to remove several small circles of skin 3 to 4 mm from the eyelid margin. B, Place sutures to close the defect and realign the skin edges in a vertical direction.

2. Wedge resection for ectropion correction. A, Mark the width of resection by nicking or crushing the eyelid margin. B, Excise a triangle of skin with the base at the lid margin. For good apposition, the sides of the triangle should be twice the length of the base. C, Appose the conjunctiva using a simple continuous pattern. D, Align and accurately appose the lid margin with a simple interrupted skin suture, then place additional skin sutures.

Dr. Hussein Hadi Nahi Eye surgery 5th stage

3. V-to-Y ectropion correction. A, Make a V-shaped incision distal and slightly wider than the ectropion area. B, Undermine the flap to near the eyelid margin and remove scar tissue if present. C, Beginning at the most distal aspect of the V, begin placing sutures from medial to lateral, creating the stem of the Y. D, Close the arms of the Y when the desired position of the lid is obtained.

4. Lateral blepharoplasty for animals with combined entropion-ectropion. A, Excise an ellipse of skin from the upper and lower lids, which meets at the lateral canthus. Extend the incision laterally to the temporal bone. Dissect a corresponding strip of orbicularis oculi from both the upper and lower excision sites, which remains attached at the lateral canthus. B, Suture the muscle pedicles together, retract them laterally, and suture them to the periosteum over the temporal bone. C, Place appositional sutures to appose the skin.