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Of all the organs of the body, the eye is most accessible to direct examination. Visual function can be quantified by simple subjective testing. The external anatomy of the eye is visible to inspection with the unaided eye and with fairly simple instruments. Even the interior of the eye is visible through the clear cornea. The eye is the only part of the body where blood vessels and central nervous system tissue (retina and optic nerve) can be viewed directly. Important systemic effects of infectious, autoimmune, neoplastic, and vascular diseases may be visible from the internal eye examination.

The purpose of sections I and II of this chapter is to provide an overview of the ocular history and basic complete eye examination as performed by an ophthalmologist. In section III, more specialized examination techniques will be presented.

I. OCULAR HISTORY

The chief complaint is characterized according to its duration, frequency, intermittency, and rapidity of onset. The location, the severity, and the circumstances surrounding onset are important as well as any associated symptoms. Current eye medications being used and all other current and past ocular disorders are recorded, and a review of other pertinent ocular symptoms is performed.

The past medical history centers on the patient's general state of health and principal systemic illnesses if any. Vascular disorders commonly associated with ocular manifestations-such as diabetes and hypertension-should be asked about specifically. Just as a medical history should include ocular medications being used, the eye history should list the patient's systemic medications. This provides a general indication of health status and may include medications that affect ocular health, such as corticosteroids. Finally, any drug allergies should be recorded.

The family history is pertinent for ocular disorders such as strabismus, amblyopia, glaucoma, cataracts, and retinal problems, such as retinal detachment or macular degeneration. Medical diseases such as diabetes may be relevant as well.

COMMON OCULAR SYMPTOMS

A basic understanding of ocular symptomatology is necessary for performing a proper ophthalmic examination. Ocular symptoms can be divided into three basic categories: abnormalities of vision, abnormalities of ocular appearance, and abnormalities of ocular sensation-pain and discomfort.

Symptoms and complaints should always be fully characterized. Was the onset gradual, rapid, or asymptomatic? (For example, was blurred vision in one eye not discovered until the opposite eye was inadvertently covered?) Was the duration brief, or has the symptom continued until the present visit? If the symptom was intermittent, what was the frequency? Is the location focal or diffuse, and is involvement unilateral or bilateral? Finally, is the degree characterized by the patient as mild, moderate, or severe?

One should also determine what therapeutic measures have been tried and to what extent they have helped. Has the patient identified circumstances that trigger or worsen the symptom? Have similar instances occurred before, and are there any other associated symptoms?

The following is a brief overview of ocular complaints. Representative examples of some causes are given here and discussed more fully elsewhere in this book.

ABNORMALITIES OF VISION

Visual Loss

Loss of visual acuity may be due to abnormalities anywhere along the optical and neurologic visual pathway. One must therefore consider refractive (focusing) error, lid ptosis, clouding or interference from the ocular media (eg, corneal edema, cataract, or hemorrhage in the vitreous or aqueous space), and malfunction of the retina (macula), optic nerve, or intracranial visual pathway.

A distinction should be made between decreased central acuity and peripheral vision. The latter may be focal, such as a scotoma, or more expansive as with hemianopia. Abnormalities of the intracranial visual pathway usually disturb the visual field more than central visual acuity.

Transient loss of central or peripheral vision is frequently due to circulatory changes anywhere along the neurologic visual pathway from the retina to the occipital cortex. Examples would be amaurosis fugax or migrainous scotoma.

The degree of visual impairment may vary under different circumstances. For example, uncorrected nearsighted refractive error may seem worse in dark environments. This is because pupillary dilation allows more misfocused rays to reach the retina, increasing the blur. A central focal cataract may seem worse in sunlight. In this case, pupillary constriction prevents more rays from entering and passing around the lens opacity. Blurred vision from corneal edema may improve as the day progresses owing to corneal dehydration from surface evaporation.

Visual Aberrations

Glare or haloes may result from uncorrected refractive error, scratches on spectacle lenses, excessive pupillary dilation, and hazy ocular media, such as corneal edema or cataract. Visual distortion (apart from blurring) may be manifested as an irregular pattern of dimness, wavy or jagged lines, and image magnification or minification. Causes may include the aura of migraine, optical distortion from strong corrective lenses, or lesions involving the macula and optic nerve. Flashing or flickering lights may indicate retinal traction (if instantaneous) or migrainous scintillations that last for several seconds or minutes. Floating spots may represent normal vitreous strands due to vitreous "syneresis" or separation (see Chapter 9), or the pathologic presence of pigment, blood, or inflammatory cells. Oscillopsia is a shaking field of vision due to ocular instability.

It must be determined whether double vision is monocular or binocular (ie, disappears if one eye is covered). Monocular diplopia is often a split shadow or ghost image. Causes include uncorrected refractive error, such as astigmatism, or focal media abnormalities such as cataracts or corneal irregularities (eg, scars, keratoconus). Binocular diplopia (see Chapters 12 and 14) can be vertical, horizontal, diagonal, or torsional. If the deviation occurs or increases in one gaze direction as opposed to others, it is called "incomitant." Neuromuscular dysfunction or mechanical restriction of globe rotation is suspected. "Comitant" deviation is one that remains constant regardless of the direction of gaze. It is usually due to childhood or long-standing strabismus.

ABNORMALITIES OF APPEARANCE

Complaints of "red eye" call for differentiation between redness of the lids and periocular area versus redness of the globe. The latter can be caused by subconjunctival hemorrhage or by vascular congestion of the conjunctiva, sclera, or episclera (connective tissue between the sclera and conjunctiva). Causes of such congestion may be either external surface inflammation, such as conjunctivitis and keratitis, or intraocular inflammation such as iritis and acute glaucoma. Color abnormalities other than redness may include jaundice and hyperpigmented spots on the iris or outer ocular surface.

Other changes in appearance of the globe that may be noticeable to the patient include focal lesions of the ocular surface, such as a pterygium, and asymmetry of pupil size, called "anisocoria." The lids and periocular tissues may be the source of visible signs such as edema, redness, focal growths and lesions, and abnormal position or contour, such as ptosis. Finally, the patient may notice bulging or displacement of the globe, as with exophthalmos.

PAIN & DISCOMFORT

"Eye pain" may be periocular, ocular, retrobulbar (behind the globe), or poorly localized. Examples of periocular pain may be tenderness of the lid, tear sac, sinuses, or temporal artery. Retrobulbar pain can be due to orbital inflammation of any kind. Certain locations of inflammation, such as optic neuritis or orbital myositis, may produce pain on eye movement. Many nonspecific complaints such as "eyestrain," "pull-ing," "pressure," "fullness," and certain kinds of "headaches" are poorly localized. Causes may include fatigue from ocular accommodation or binocular fusion, or referred discomfort from nonocular muscle tension or fatigue.

Ocular pain itself may seem to emanate from the surface or from deeper within the globe. Corneal epithelial damage typically produces a superficial sharp pain or foreign body sensation exacerbated by blinking. Topical anesthesia will immediately relieve this pain. Deeper internal aching pain occurs with acute glaucoma, iritis, endophthalmitis, and scleritis. The globe is often tender to palpation in these situations. Reflex spasm of the ciliary muscle and iris sphincter can occur with iritis or keratitis, producing brow ache and painful "photophobia" (light sensitivity). This discomfort is markedly improved by instillation of cycloplegic dilating drops (see Chapter 3).

Eye Irritation

Superficial ocular discomfort usually results from surface abnormalities. Itching, as a primary symptom, is often a sign of allergic sensitivity. Symptoms of dryness, burning, grittiness, and mild foreign body sensation can occur with dry eyes or other types of mild corneal irritation. Tearing may be of two general types. Sudden reflex tearing is usually due to irritation of the ocular surface. In contrast, chronic watering and "epiphora" (tears rolling down the cheek) may indicate abnormal lacrimal drainage (see Chapter 4).

Ocular secretions are often diagnostically nonspecific. Severe amounts of discharge that cause the lids to be glued shut upon awakening usually indicate viral or bacterial conjunctivitis. More scant amounts of mucoid discharge can also be seen with allergic and noninfectious irritations. Dried matter and crusts on the lashes may occur acutely with conjunctivitis or chronically with blepharitis (lid margin inflammation).

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