A

B

FIGURE 8-19

A, Asymmetric signs in ophthalmic Graves’ disease, proptosis of the left eye. B, CT scan showing proptosis of the right eye. (A from Kanski JJ: Clinical ophthalmology: a systematic approach, ed 5, Oxford, UK, 2003, Butterworth-Heinemann; B courtesy. Weon Jun, O.D., Portland VA Medical Center, Portland, Ore.)

Clinical Comment: Exophthalmos

Protrusion of the globe is termed exophthalmos, or proptosis (Figure 8-19). It can be caused by a number of pathologic conditions, including inflammation, edema, tumors, and injuries.16 The most common type is thyroid ophthalmopathy (dysthyroid orbitopathy, Graves’ disease), which can cause hypertrophy of the extraocular muscles; in some patients the muscles become enlarged to eight times their normal size.3 Thyroid ophthalmopathy also causes proliferation of orbital fat and connective tissue, and lymphoid infiltration.3 Because the orbital tissue is encased in immovable bony walls, this increase in volume of the orbital contents produces protrusion of the globe and simulates eyelid retraction. At the first sign of proptosis, investigation is necessary to determine the causative factor.

AGING CHANGES IN THE ORBIT

In elderly adults the orbital septum often weakens, particularly in the medial inferior area, and herniation of fat and loose connective tissue can occur. The walls of the paranasal sinuses thin, and with age these walls may actually contain perforations that pass into the orbit.

REFERENCES

1.Warwick R: Eugene Wolff’s anatomy of the eye and orbit, ed 7, Philadelphia,­ 1976, Saunders, pp 1, 8, 15, 19.

2.Doxanas MT, Anderson RL: Clinical orbital anatomy, Baltimore, 1984, Williams & Wilkins, pp 20, 25, 117.

3.Kanski JJ: Clinical ophthalmology, ed 3, London, 1994, ButterworthHeinemann, pp 33, 52.

4.Forrest LA, Schuller DE, Strauss RH: Management of orbital blowout fractures, Am J Sports Med 17(2):217-220, 1989.

5.Taher AA: Diplopia caused by orbital floor blowout fracture, Oral Surg Oral Med Oral Pathol 75(4):433-435, 1993.

6.Koornneef L: Orbital connective tissue. In Jakobiec FA, editor:

Ocular anatomy, embryology, and teratology, Philadelphia, 1982, Harper & Row, p 835.

7.Rosenstein T, Talebzadeh N, Pogrel MA: Anatomy of the lateral canthal tendon, Oral Surg Oral Med Oral Pathol Oral Radiol Endod

89(1):24-28, 2000.

8.Reeh MJ, Wobig JL, Wirtschafter JD: Ophthalmic anatomy, San Francisco, 1981, American Academy of Ophthalmology, p 11.

9.Webster RC, Gaunt JM, Hamdan US, et al: Supraorbital and supratrochlear notches and foramina: anatomical variations and surgical relevance, Laryngoscope 96(3):311-315, 1986.

10.Sires BS, Gausas R, Cook BE Jr, et al: Orbit. In Kaufman PL, Alm A, editors: Adler’s physiology of the eye, St Louis, 2003, Mosby, p 11.

11.Goldberg RA, Hannai K, Toga AW: Microanatomy of the orbital apex.Computedtomographyandmicrocryoplaningofsoftandhard tissue, Ophthalmology 99(9):1447-1452, 1992.

12.Lang J, Kageyama I: The ophthalmic artery and its branches, measurements, and clinical importance, Surg Radiol Anat 12(2):83-90, 1990.

13.Blaylock WK, Moore CA, Linberg JV: Anterior ethmoid anatomy facilitates dacryocystorhinostomy, Arch Ophthalmol 108(12):17741777, 1990.

14.Bansberg SF, Harner SG, Forbes G: Relationship of the optic nerve to the paranasal sinuses as shown by computed tomography,

Otolaryngol­ Head Neck Surg 96(4):331-335, 1987.

15.Cheung DK, Attia EL, Kirkpatrick DA, et al: An anatomic and CT scan study of the lateral wall of the sphenoid sinus as related to the transnasal transethmoid endoscopic approach, J Otolaryngol 22(2):63-68, 1993.

16.Berkow R, editor: The Merck manual, ed 14, Rahway, NJ, 1982, Merck, p 1984.

17.Mills RP, Kartush JM: Orbital wall thickness and the spread of infection from the paranasal sinuses, Clin Otolaryngol 10(4):209-216, 1985.

18.Silver HS, Fucci MJ, Flanagan JC, et al: Severe orbital infection as a complication of orbital fracture, Arch Otolaryngol Head Neck Surg 118(8):845-848, 1992.

19.Tenon JR, Naus J, Blanken R: Anatomical observations on some parts of the eye and eyelids, Strabismus 11(1):63–68, 2003.

20.Eggers HM: Functional anatomy of the extraocular muscles. In Tasman W, Jaeger EA, editors: Duane’s foundations of clinical ophthalmology, vol 1, Philadelphia, 1994, Lippincott.

21.Rodríguez-Vázquez JF, Mérida-Velasco JR, Jiménez-Collado J: Orbital muscle of Müller: observations on human fetuses measuring 35-150 mm, Acta Anat (Basel) 139:300-303, 1990.

22.Dutton JJ: Clinical and surgical orbital anatomy, Ophthalmol Clin North Mm 9(4):527, 1996.

23.Wolfram-Gabel R, Kahn JL: Adipose body of the orbit, Clin Anat 15(3):186-192, 2002.

The ocular adnexa includes the structures situated in proximity to the globe. This chapter discusses the eyebrows, structures of the eyelids, the conjunctiva, and the lacrimal system, which consists of a secretory system, for tear production, and an excretory system, for tear drainage.

E Y E B R O W S

The eyebrows consist of thick skin covered by characteristic short, prominent hairs extending across the superior orbital margin, usually arching slightly but sometimes merely running horizontally. Generally, in men the brows run along the orbital margin, whereas in women the brows run above the margin.1 The first body hairs produced during embryologic development are those of the eyebrow.2

The muscles located in the forehead—the frontalis, procerus, corrugator superciliaris, and orbicularis oculi—produce eyebrow movements, an important element in facial expression (Figure 9-1). The frontalis muscle originates high on the scalp and inserts into connective tissue near the superior orbital rim. The fibers are oriented vertically and raise the eyebrow, causing a look of surprise or attention. The corrugator originates on the frontal bone and inserts into skin superior to the medial eyebrow. It is characterized as the muscle of trouble or concentration, and its fibers are oriented obliquely; it moves the brow medially, toward the nose, creating vertical furrows between the brows. The procerus, the muscle of menace or aggression, originates on the nasal bone and inserts into the medial side of the frontalis. It pulls the medial portion of the eyebrow inferiorly and produces horizontal furrows over the bridge of the nose.2,3 The orbicularis oculi (described later) lowers the entire brow. The fibers of these muscles blend with one another and are difficult to separate.2 All are innervated by the facial nerve—cranial nerve VII.

E Y E L I D S

The eyelids, or palpebrae, are folds of skin and tissue that, when closed, cover the globe. The eyelids have four major functions: (1) cover the globe for protection,

(2) move the tears toward drainage at the medial canthus on closure, (3) spread the tear film over the anterior surface of the eye on opening, and (4) contain structures that produce the tear film. On closure the upper eyelid moves down to cover the cornea, whereas the lower eyelid rises only slightly. When the eyes are closed gently, the eyelids should cover the entire globe.

Clinical Comment: Lagophthalmos

LAGOPHTHALMOS  refers to incomplete closure of the eyelids (Figure 9-2). Its cause may be physiologic,

mechanical­ (e.g., scarring), or paralytic. Lagophthalmos is most evident during sleep, when drying of the inferior cornea may result. Scratchy, irritated eyes are evident on awakening, and punctate keratitis can occur.4-6 Clinical­

assessment of the inferior cornea will show varying degrees of epithelial disruption, manifested as staining with ­fluorescein dye.

PALPEBRAL FISSURE

The palpebral fissure is the area between the open eyelids. Although numerous variations exist in the positional relationship of the lid margins to the limbus, generally the upper lid just covers the superior limbus when one’s eyes are open and looking straight ahead. The lower lid position is more variable, usually lying within 1 mm of the inferior limbus.7-9

The upper and lower eyelids meet at the corners of the palpebral fissure in the lateral and medial canthi. The lateral canthus is located approximately 5 to 7 mm medial to the bony orbital margin and lies directly on the globe.9 The medial canthus is at the medial orbital margin but is separated from the globe by a reservoir for the pooling of tears, the lacrimal lake. The floor of the lacrimal lake is the plica semilunaris (Figure 9-3). This narrow, crescent-shaped fold of conjunctiva, located in the medial canthus, allows for lateral movement of the eye without stretching the bulbar conjunctiva. The caruncle is a small, pink mass of modified skin located just medial to the plica. It is covered with epithelium that contains goblet cells and fine hairs and their associated sweat and sebaceous glands.

FIGURE 9-1

Forehead muscles that control the eyebrows. These are called the muscles of expression.

FIGURE 9-2

Lagophthalmos: inability to oppose the eyelids on attempted lid closure. In this patient, left seventh cranial nerve palsy caused a lower lid paralytic ectropion and lagophthalmos. (From Krachmer JH, Palay DA: Cornea color atlas, St Louis, 1995, Mosby.)

EYELID TOPOGRAPHY

The upper eyelid extends to the eyebrow and is divided into the tarsal and the orbital (or preseptal) parts. The tarsal portion lies closest to the lid margin, rests on the globe, and contains the tarsal plate. The skin is thin, and the underlying loose connective tissue is devoid of adipose tissue. The orbital portion extends from the tarsus to the eyebrow, and a furrow—the superior palpebral sulcus—separates the tarsal portion from the orbital portion (Figure 9-4). This sulcus separates the pretarsal skin, which is tightly adherent to the underlying tissue, from the preseptal skin, which is only loosely adherent to its underlying tissue, which contains a cushion of fat. In the eyelids of those of Eastern Asian descent, the orbital septum fuses with the levator aponeurosis below the upper tarsal border, allowing the fat to descend

Plica semilunaris

Caruncle

Lacrimal punctum

Pores of meibomian glands

Papilla

Cilia

FIGURE 9-3

Structures located in left medial canthus.

FIGURE 9-4

Surface anatomy of the right eyelid.

further into the lid10 and eliminating the superior palpebral sulcus.2,11-13

In the lower eyelid the inferior palpebral sulcus, which separates the lower lid into tarsal and orbital parts, is often not very distinct. The tarsal portion rests against the globe, and the orbital portion extends from the lower border of the tarsus onto the cheek, extending just past the inferior orbital margin to the nasojugal and malar sulci (see Figure 9-4). These furrows occur at the attachment of the skin to the underlying connective tissue and become more prominent with age.