Anterior Uveitis, Hypopyon, and Hyphema
Adria Simon
Anjum F. Koreishi
THE CLINICAL CHALLENGE
Anterior uveitis, hypopyon, and hyphema represent a spectrum of pathologies affecting the anterior segment of the eye. The anterior segment is the space between the iris and the cornea. Uveitis is a general term for inflammation within the eye. The uveal tract consists of the iris and ciliary body anteriorly and the choroid posteriorly. Anterior uveitis involves inflammation of the iris and/or ciliary body, encompassing terms like iritis and iridocyclitis,1 which are clinically essentially interchangeable. Hypopyon refers to a collection of white blood cells in the anterior chamber and is a clinical presentation of anterior uveitis. Hyphema is a collection of red blood cells in the anterior chamber. Whereas anterior uveitis can affect any age group or gender, hyphema most commonly results from blunt or penetrating trauma and is seen more often in children and young males.2
The etiology of anterior uveitis can be challenging to parse out in the emergency setting. This umbrella term represents a group of heterogeneous disorders unified by the presence of inflammation in the anterior uveal tract (iris and/or ciliary body). Anterior uveitis can be acute, subacute, or chronic, although it is typically acute in the emergency setting. It is typically immune mediated, but notable infectious etiologies must be ruled out.3 Trauma can also cause uveitis. Anterior uveitis shares many presenting symptoms with other common forms of ocular pathology, including redness, photophobia, tearing, pain, and blurry vision. Distinguishing between these conditions necessitates a comprehensive history and ocular examination. This variability in presentation and etiology causes a clinical challenge as workup, management, and prognosis vary in each case.
Most appreciable hyphemas can be easily diagnosed on visual inspection. Hyphema most often occurs in conjunction with ocular trauma, and severe pathology such as open globe must be excluded. Secondary hemorrhage can be difficult to predict in a patient without clear clinical risk factors and is associated with complications like corneal blood staining, elevated intraocular pressure, and formation of synechiae.2 Careful documentation and communication of the initial degree of hyphema between emergency providers and ophthalmologists at follow-up is necessary to determine appropriate treatment if secondary hemorrhage occurs.
PATHOPHYSIOLOGY
Anterior Uveitis and Hypopyon
Whether infectious, traumatic, or secondary to systemic infection, anterior uveitis results from an underlying inflammatory process with subsequent transudation of proteins and leukocytes from inflamed vessels. The hallmark clinical finding of anterior uveitis is cells, visible leukocytes in the anterior chamber, and flare, when the aqueous fluid is visible owing to protein leakage (Figure 38.1).
Inflammation of the iris ciliary muscles causes ciliary spasm and pain. Inflammation of the ciliary body may cause low intraocular pressure, such as in HLA-B27 related uveitis. Inflammation of the trabecular meshwork, which drains aqueous fluid from the eye, can cause elevated intraocular pressure, as in Herpesviridae-related uveitis.4
Inflammation of the iris ciliary muscles causes ciliary spasm and pain. Inflammation of the ciliary body may cause low intraocular pressure, such as in HLA-B27 related uveitis. Inflammation of the trabecular meshwork, which drains aqueous fluid from the eye, can cause elevated intraocular pressure, as in Herpesviridae-related uveitis.4
Figure 38.1: Slit lamp photo showing cells (small white specks between the light beam). These are not visible without a slit lamp. (Courtesy of Dr. Debra Goldstein.) |
Hypopyon can often be visualized with the naked eye (Figure 38.2). This finding does not occur in isolation; rather, hypopyon is a sequela of other underlying conditions such as severe uveitis, bacterial keratitis, or, most concerningly, endophthalmitis.5
Hyphema
Hyphema is most commonly the result of blunt or penetrating trauma to the eye. Rupture of vessels supplying the ciliary body and iris results in accumulation of blood in the anterior chamber (Figure 38.3). Pathophysiology of spontaneous hyphema is particular to the etiology, including retinal ischemia, typically because of retinal vein occlusion or diabetic retinopathy, ocular ischemia from carotid occlusion, or intraocular tumors. Rebleeding, which is recurrence of hyphema usually after 3 to 7 days, occurs in about 5% of cases owing to clot retraction.6 Elevated intraocular pressure can develop owing to trabecular meshwork obstruction in the setting of rebleeding or clot. Particular caution is warranted in patients with underlying sickle cell disease or trait. The relative hypoxia and acidic pH of the anterior chamber induces sickling of red blood cells in the trabecular meshwork, reducing outflow of aqueous and causing significant elevations in intraocular pressure.7
APPROACH/THE FOCUSED EXAM
Anterior Uveitis and Hypopyon
Anterior uveitis should be considered in patients presenting with pain, conjunctival injection, blurred vision, and photophobia. A careful history should include recent trauma/foreign body or ocular surgery, full review of systems relating to inflammatory or infectious conditions such as axial stiffness from ankylosing spondylitis and oral ulcers/skin lesions from Herpesviridae (specific concerns listed in Table 38.1). Examination should always include visual acuity and intraocular pressure. Ocular discharge should not be present and helps distinguish anterior uveitis from other etiologies of the painful red eye. Inspection of the eye may reveal perilimbal injection known as ciliary flush,8 although diffuse conjunctival injection may be present. A red eye that is significantly tender to palpation should raise concern for scleritis. Examination of the pupil can reveal a poorly reactive pupil secondary to ciliary spasm8 or an irregular pupil caused by posterior synechiae, scarring of the iris to the lens (Figure 38.4). Consensual photophobia, the presence of pain when illuminating the unaffected pupil, is suggestive of anterior uveitis.3 Fluorescein staining of the cornea can assess other causes of the acutely painful red eye such as keratitis or corneal abrasion. Hypopyon may be seen without the slit lamp as a white deposit in the inferior anterior chamber (Figure 38.2). Slit lamp examination, notably the presence of cells and flare (Figure 38.1), is the key to evaluation of anterior uveitis. Inflammatory deposits on the corneal endothelium, known as keratic precipitates, may be noted on slit lamp exam. Dilated examination is necessary to rule out posterior uveitis and to evaluate for optic disc or macular edema, which can be manifestations of anterior uveitis and are vision threatening. Table 38.2 highlights key ocular findings.
Hyphema
Patients most often present with blurred vision after trauma. Hyphema can occur with relatively insignificant mechanisms; any ocular trauma warrants evaluation for hyphema.2 The emergency provider should first evaluate for more significant traumatic injury such as globe rupture and retrobulbar hematoma. Fluorescein staining allows for evaluation of concurrent corneal abrasion or penetrating injury to the globe. Visual acuity, pupillary response, and intraocular pressure should be measured (unless there is concern for open globe). Layered hyphema can be visible without the slit lamp (Figure 38.3). Small hyphema, microhyphema (red blood cells in anterior chamber without layering), and corneal blood staining (blood deposited in the cornea) are evaluated with the slit lamp.