Anatomy
Knowledge of anatomy is required in order to evaluate the eye and related structures (refer to Figure 16.1).
The eye is protected by the lids and surrounding orbital bones. The most anterior part of the eye is the tear film layer covering the cornea (clear front portion of the eye). The corneal margin, where the cornea meets the sclera, is referred to as the limbus. The conjunctiva is a thin membrane covering both the white sclera (bulbar conjunctiva), and the inside of the lids (palpebral conjunctiva). Because the bulbar and palpebral conjunctivae join in the superior and inferior fornix (the area where they join is known also as a “cul-de-sac”), objects such as foreign bodies and contact lenses cannot slip behind the eye and be lost.
Behind the cornea is the anterior chamber, which is approximately 2–4 mm in depth and is filled with clear fluid, known as aqueous humor. The aqueous circulation begins in the ciliary body located behind the iris and flows through the pupil and out through the trabecular meshwork located in the angle between the iris and the peripheral cornea.
The iris contains a circular constrictor muscle and radial dilator muscles, each controlling the circular pupil.
Behind the iris plane is the crystalline lens, which functions as the focusing mechanism of the eye. It is kept in place and controlled by fine suspensory ligaments (zonules), which form an attachment from the lens to the ciliary body.
The inner volume of the eye is filled with a clear gel, the vitreous body. Lining the inner sclera is the retina, a fine network of blood vessels and photosensitive nerve cells which are the first receptors of the visual pathway.
The bony orbit surrounds, supports, and protects the globe. In addition to the globe, the contents of the orbit include connective tissue, blood vessels, fat, and the six extraocular muscles that control eye movement.
Evaluation
Except for chemical injury, when immediate flushing is indicated, the first part of an eye examination is the evaluation and recording of visual acuity. While parts of the following eye examination can be omitted when appropriate, always assess visual acuity.
The standard Snellen chart at 20 feet is best, but other distances may be used as long as that distance is noted. The numerator of the Snellen Fraction denotes the distance from the chart and the denominator is a number given to each line. A smaller denominator refers to a smaller letter (optotype) – i.e., a letter on the “20” line is half the size of a letter on the “40” line, and ten times smaller than a letter on the “200” line. Thus, 20/200 means that a letter on the “200” line was correctly identified at 20 feet and 4/40 (its equivalent) means that the “40” line letter (five times smaller) was correctly identified at four feet (five times closer).
Charts using other symbols have been constructed for preliterate children but other methods can be used if a chart is not available, such as counting fingers at a specified distance, hand motions at a specified distance, observed eye closure when a light is directed in the eye (light rejection), or reading a newspaper headline at some distance. It is important to check each eye separately. Use a sterile gauze pad to occlude the non-tested eye without pressing on the globe. For children who wear corrective glasses, test visual acuity with and without the glasses. Test the “good” eye first in order to reduce anxiety. For infants and preverbal children, test visual acuity by assessing whether the child can fix on and follow an object.
Assuming that there are no other life-threatening or organ-threatening injuries, evaluate the eyes in a systematic manner, starting from the most anterior aspect of the eye to the most posterior. Look first at the lids and surrounding structures, palpate the bony orbital rim, assess the tears, look at the anterior aspect of the eye including the conjunctiva, cornea, and sclera, and assess ocular mobility by having the patient follow a finger (not a bright light, which may cause photophobia) moving in all positions of gaze (up, down, left, right). Note the depth and clarity of the anterior chamber, and observe pupillary reactivity to light. In a semi-darkened room, at a distance of 1–2 feet, dial the ophthalmoscope to sharply define iris markings (usually black or plus 1 or 2) and assess the clarity and symmetrical color of the pupils. Use the ophthalmoscope to evaluate the retina, which should be uniformly red, and note any hemorrhages or deposits. Look for the foveal reflex of the macula, which is temporal to the optic nerve and appears darker than the surrounding retina. If the macula is white or cherry-red, suspect blunt trauma, ischemia, or metabolic abnormalities. Finally, palpate the globes gently with your two index fingers if a ruptured globe is not suspected. If one eye is firmer than the other, suspect elevated intraocular pressure.
Decreased Vision
Decreased vision can be caused by life-threatening intraocular or intracranial tumors, eye-threatening diseases (trauma, iridocyclitis, idiopathic intracranial hypertension, glaucoma, retinal detachment), or minor conditions (corneal foreign body, conjunctivitis, tearing). In addition, decreased vision may be a functional complaint.
Clinical Presentation
The most common cause of an acute decrease in vision is ocular trauma, particularly a corneal abrasion. The priority is to rule-out a life-threatening or eye-threatening condition.
Diagnosis
Unless there is an obvious ruptured globe or chemical injury, the evaluation of the eyes (pp. 550–551) starts with a determination of visual acuity, preferably Snellen activity or the equlvalent.
For infants and preverbal children, first note the vision in both eyes, then in each eye separately. The sleeping infant reacts to bright light directed into each eye with further eyelid closure (“light rejection”) if the eye and vision sense are intact. Absence of light rejection or asymmetric light rejection suggests vision loss in one or both eyes. The preverbal child follows objects of interest, such as toys (avoid shining a bright light in the awake child’s eyes), by fixing centrally on the object and following it. Test each eye separately, using the examiner’s or parent’s thumb as an occluder. For an older child, use a Snellen chart that has been calibrated at 20 feet (p. 551). Testing can be done at a distance of 5–10 feet, although using shorter testing distances may miss subtle differences between the eyes. In the absence of a Snellen chart, ask the patient to count fingers held a few feet away or check the ability to read a newspaper headline at a set distance. The testing distance must be noted.
ED Management
Treat the chief complaint or primary illness. Indications for immediate ophthalmologic evaluation include a sleeping infant who does not reject light, an awake infant who does not follow with either or both eyes, and asymmetric vision, particularly if there has been ocular trauma.
Bibliography
Excessive Tearing
Tears are produced immediately after birth, but the volume increases after the sixth week. Excess tearing is very common and is secondary to either excess production or insufficient drainage. Excess production is usually due to irritation, infection, foreign body, trauma, iritis, or glaucoma. Insufficient drainage is caused by a stenotic or blocked lacrimal system, usually at the level of the nasolacrimal duct, which conducts tears from the lacrimal sac into the nose.
Clinical Presentation
Excess Production
Tearing due to excess production is often accompanied by conjunctival injection in older children, but injection is usually absent in the newborn. Lid swelling and nasal discharge are common.
Congenital Glaucoma (Elevated Intraocular Pressure)
Congenital glaucoma is accompanied by excess growth of the eye (buphthalmos), photophobia, loss of vision, and tearing, with discharge at the nares. The clarity of the cornea may be reduced with obscuration of the iris markings. It may be unilateral or bilateral, and there may be a positive family history.
Insufficient Drainage
Dacryostenosis (Nasolacrimal Duct Obstruction)
Dacryostenosis is the most common ophthalmologic cause of excess tearing in infancy, usually presenting in the first three months of life. A persistent mucoid or mucopurulent discharge is usually present, in addition to recurrent conjunctivitis. Nasolacrimal duct obstruction may be accompanied by dermatitis of the lids due to the chronic tearing, but there is no nasal discharge or photophobia (to distinguish dacryostenosis from congenital glaucoma).
Hydrops (Amniotocele)
Hydrops of the nasolacrimal sac is usually present at or shortly after birth and is secondary to blockage of the proximal and distal portions of the nasolacrimal sac. It presents as a bluish discoloration medially at the location of the lacrimal sac and can be confused with a meningocele. Secondary infection is common.
Diagnosis
The priority is to rule-out excessive tear production as the cause of excessive tearing before diagnosing nasolacrimal duct obstruction. Photophobia, eyelid closure (blepharospasm), ciliary flush, pain, and nasal discharge suggest excessive production. See Table 16.1 for the differential diagnosis of excessive tearing.
| Diagnosis | Differentiating features |
|---|---|
| Congenital glaucoma | Buphthalmos, corneal clouding, photophobia |
| Nasal discharge | |
| Corneal foreign body or abrasion | Sudden onset of tearing |
| Blepharospasm, pain | |
| Iritis | Ciliary flush, miosis, photophobia |
| May have a history of trauma | |
| Nasolacrimal duct obstruction | Onset in second or third month of life |
| Discharge, recurrent conjunctivitis | |
| Dermatitis of lids |
Consider a foreign body or corneal abrasion if the tearing started suddenly, especially if it is accompanied by pain and blepharospasm. The diagnosis of glaucoma is confirmed by evaluation of the intraocular pressure. Consider iritis after trauma which should result in pain in the affected eye when light is shone in the contralateral unaffected eye (due to consensual pupillary reflex).
The diagnosis of nasolacrimal duct obstruction is suggested by constant tearing beginning in the second or third month of life, associated with concurrent eye discharge. There may be swelling of the lacrimal sac with reflux of material from the punctum when digital pressure is applied to the side of the nose overlying the lacrimal sac. Dacryocystitis is likely if there is erythematous swelling of the lacrimal sac accompanied by tenderness.
ED Management
The management of excessive tearing secondary to a foreign body (p. 552) or conjunctivitis (pp. 555–557) is detailed elsewhere. Glaucoma and iritis require immediate ophthalmologic consultation.
Dacryostenosis
In most cases, dacryostenosis clears spontaneously by 6–12 months of age. Prescribe a topical ophthalmic antibiotic (erythromycin ointment, bacitracin ointment, or polymyxin-trimethoprim drops) tid to suppress infection. Refer the patient to an ophthalmologist for evaluation if the condition does not clear by the sixth month, especially if there have been frequent infections or significant dermatitis.
Dacryocystitis
Culture any material in the palpebral fissure and treat with oral and topical antibiotics. Use amoxicillin-clavulanate (875/125 formulation; 45 mg/kg/day div bid) or cephalexin (25–50 mg/kg/day div tid). If there is a significant prevalence of MRSA in the community, treat with clindamycin (20 mg/kg/day divided q 6–8h). Topical ophthalmic antibiotics (bacitracin, erythromycin, or moxifloxacin) qid and warm compresses qid are useful adjunctive therapies. Urgent referral to an ophthalmologist is indicated, as probing of the nasolacrimal duct may be necessary in order to avoid recurrence.
Indications for Admission
Bibliography
Eyelid Inflammation
The eyelids can be affected by dermatologic conditions that also involve other areas of the skin, although the unique structures of the eyelids make them prone to particular and characteristic diseases. The protective function of the eyelids, their constant movement, and their prominent location make abnormalities particularly noticeable and troubling.
Clinical Presentation and Diagnosis
Hordeolum
A hordeolum, or stye, is an infection (Staphylococcus most commonly) of a sebaceous or sweat gland of the lid (gland of Zeis or Moll). It usually presents as a localized erythematous swelling of the lid margin, although the entire lid may be affected. The area is tender, and the abscess may point at the base of a lash. Several styes may be present simultaneously.
Chalazion
A chalazion is a granulomatous swelling of the other sebaceous gland of the lid (Meibomian gland). It begins as a firm, painless, circular swelling within the lid itself. There may be multiple chalazia. Secondary infection leads to increased swelling and pain, with the abscess pointing onto the skin surface or the conjunctival side of the lid.
Blepharitis
Blepharitis is inflammation of the margin of the lid, usually secondary to Staphylococcus aureus infection. Blepharitis is often chronic and may contribute to the development of hordeola and chalazia. Typically, the lid margins are erythematous, crusted, and swollen. There may be an associated conjunctivitis. Pruritus, burning, foreign body sensation, tearing, blurry vision, and loss of lashes are common complaints.
Seborrheic Dermatitis
Seborrheic dermatitis is an erythematous, scaly, or crusting eruption with overlying yellowish greasy scale. The eyelids can be affected, in addition to the scalp, postauricular areas, ears, and neck. Conjunctivitis is uncommon.
Herpes Simplex
Herpes simplex (pp. 124–126) presents with grouped vesicles on an erythematous base. Eyelid involvement may be the sole finding or may be part of a more generalized herpetic infection. The surrounding skin and lips may also be affected. There may be associated conjunctivitis, keratitis, iritis, and preauricular lymphadenopathy. Recurrences are common.
Varicella
The characteristic maculopapular, vesicular, and crusting rash of varicella may affect the eyelids and surrounding skin. Conjunctivitis can be present, particularly if the lid margin is affected. Photophobia, iritis, pupillary abnormalities (irregular or sluggishly reacting), and loss of vision occur rarely. Zoster causes pain in the affected area, followed by swelling of the eyelids. Several days later, the characteristic vesicles develop.
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