The Eyes

Figure 20.1

Normal Eye, Gross

A sagittal section through the orbit (♦) in the left panel shows the relationship of the eyeball to the eyelid apparatus. The orbit in which the eyeball is located contains yellow adipose tissue (∗). In the right panel is a closer sagittal view of the upper eyelid. The outer squamous epithelial covering of skin (◄) is on the right. Beneath this are connective tissue and the palpebral part of the orbicularis oculi muscle. There is a dense plate of connective tissue called the tarsus (□), beneath which to the left are the meibomian glands (►), which secrete fluids forming the tear film. Eyelashes (▲) are seen at the lower right margin of the eyelid.

Figure 20.2

Normal eyes and orbits, MRI

Normal axial MR images (T1 in the left panel, with fat having the brightest attenuation, and T2 in the right panel, with fluid the brightest) show the temporal lobe (▪) and occipital lobe (□), basilar artery (▼), internal carotid artery (▲), basis pontis (♦), aqueduct of Sylvius (►), cerebellar vermis (+), ethmoid sinus (†), pituitary (◄), globe of eye (∗), and lens of eye (×).

Figure 20.3

Normal eye, CT image

Normal sinus CT scan shows structures in the orbit, including optic nerve (+), superior rectus muscle (▼), superior oblique muscle (♦), medial rectus muscle (►), inferior rectus and inferior oblique muscles (▲), and lateral rectus muscle (◄) in the anterior skull. Within the cranial cavity above are the right and left frontal lobes divided by the falx cerebri (×).

Figure 20.4

Idiopathic orbital inflammation, CT image

The orbital mass (►) with bright attenuation posterior to the globe is an inflammatory pseudotumor. This idiopathic condition may be unilateral or bilateral. Tissues involved include lacrimal gland, extraocular muscles, or the fascial layer around the eye. There is a mixed inflammatory infiltrate with fibrosis. Some cases arise in conjunction with IgG4-related disease.

Figure 20.5

Cyclopia, gross

This infant with trisomy 13 (Patau syndrome) has cyclopia (single midline eye) with a proboscis (the projecting tissue just above the eye). The “eye” often consists of nothing more than a slit like space without a globe. Other ocular anomalies with trisomy 13 when a globe is present include colobomas, cataracts, persistent hyperplastic primary vitreous, and retinal dysplasia.

Figure 20.6

Trisomy 21, gross

This is a prominent epicanthal fold (♦) covering the medial aspect of the eye. Also present is a Brushfield spot (▼). Other ocular findings that can be present with trisomy 21 (Down syndrome) include hypertelorism, keratoconus, and oblique palpebral fissures. Such a subtle finding by itself early in life may have no significance, but if present with a spectrum of other findings suggests an underlying syndrome.

Figure 20.7

Arcus senilis, gross

The circumferential thin white ring (▲) at the periphery of the cornea seen here is a condition known as arcus senilis, or arcus lipoides . This finding results from deposition of lipid (cholesterol, phospholipids and triglycerides) and when seen with aging often has no pathologic significance. Past age 80 virtually everyone has some amount of corneal arcus. In younger persons it may result from abnormalities in lipid metabolism with hyperlipidemia.

Figure 20.8

Pterygium, gross

This submucosal proliferation is composed of fibrovascular connective tissue encroaching (▼) onto the cornea, which can interfere with vision, but does not cause blindness because the process does not cross the midline. In contrast, a pinguecula would be found only on the conjunctiva. The appearance of this raised, whitish yellow lesion is associated with advancing age and is thought to be the result of environmental or solar exposure with solar elastosis over a lifetime. Inflammation induced within a pinguecula by a foreign body in the eye can produce an actinic granuloma.

Figure 20.9

Normal conjunctiva and pterygium, microscopic

The appearance of normal conjunctival epithelium is shown in the left panel . The conjunctiva forms the mucous membrane of the eyelid, extending posteriorly to the tarsal plate and around the fornix to form the bulbar conjunctiva that extends to the cornea. Note the scattered goblet cells (▼) in this stratified epithelium. At the right is a pterygium. Beneath the thinned conjunctival epithelium is an area of elastosis (∗) with basophilic degeneration of the substantia propria collagen.

Figure 20.10

Trachoma, microscopic

This conjunctival scraping from the eye, with Giemsa stain, reveals an intracytoplasmic elementary body of Chlamydia trachomatis (←) . This is a chronic, progressive infection of the upper tarsal plate that produces scarring of the conjunctiva and cornea through inversion of the upper eyelid to direct the eyelashes inward (trichiasis) This process may eventually lead to partial or complete blindness. In contrast, chlamydial infection acquired by passage through the birth canal can produce a purulent conjunctivitis known as inclusion blennorrhea . In children and adults, inclusion conjunctivitis results from limited conjunctival inflammation with C. trachomatis .

Figure 20.11

Chalazion, gross

This localized swelling (◄) involves the upper eyelid. A chalazion forms with plugging of a duct from eyelid glands. Involvement of a tarsal meibomian gland causes a deep chalazion, and of a Zeis gland a superficial chalazion. There can be chronic lipogranulomatous inflammation. This is usually a slowly enlarging, non-tender, annoying, but benign process. More acute inflammation with a tender nodule would be termed a hordeolum. A recurrent chalazion should undergo biopsy to rule out the possibility of a sebaceous carcinoma.

Figure 20.12

Basal cell carcinoma, gross

There is a small nodule (▲) with central ulceration at the edge of the lower eyelid. This is the most common malignant neoplasm of the eyelid, and it arises in the setting of sun damage from chronic ultraviolet light exposure. The nodule has a central rounded ulceration and raised pink margins. A basal cell carcinoma is slow growing, but in this location, it presents a problem in removal because adequate margins are needed to prevent recurrence, whereas enough eyelid must be preserved to be functional.

Figure 20.13

Herpetic keratitis, gross

Fluorescein dye placed onto the surface of the eye yields the appearance of the cornea seen by slit-lamp examination under fluorescent light. The dye is collecting at the top and bottom conjunctival margins, but also in the lesion seen, a dendritic ulceration (◄) of the corneal epithelium, which is a coalescence of smaller punctate ulcerations. Such a dendritic ulcer is characteristic of infection with herpes simplex virus. Herpetic keratitis is a serious infection because it can be recurrent and can penetrate through the cornea to involve the stroma.

Figure 20.14

Cataract, gross

An opacification (∗) of the crystalline lens results from a series of events starting in the lens cortex with rarefaction, then liquefaction, of cortical cells. This leads to fragmentation of lens fibers and extracellular globule formation. In the lens nucleus, there is a progressive increase in the amount of insoluble proteins, which leads to hardening (sclerosis) and brownish discoloration (brunescence). Cataracts are more common in the elderly and in persons with diabetes mellitus. Cataracts can be removed and replaced by an artificial lens.

Figure 20.15

Normal retina, funduscopy

The normal funduscopic appearance of the retina is shown. Note the arteries (brighter red) emanating from the central optic disc (►). The larger caliber and darker retinal veins extend back to the optic disc. These vessels are evenly distributed. The margins of the optic disc are sharp and clear. The normal posterior chamber vitreous is avascular. With aging, liquefaction and collapse of the posterior chamber vitreous can lead to perceived “floaters” in the field of vision anterior to the retina.

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Dec 29, 2020 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on The Eyes
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