The red eye continues to be a common emergency department complaint and can be difficult for new and experienced learners alike due to the large differential. We have recently covered conjunctivitis, scleritis/episcleritis, and corneal abrasions. In this post, we will discuss another common cause of the red eye: uveitis.
Uveitis accounts for 10% of blindness in people of working age in the western world (1). Uveitis describes a group of intraocular inflammatory disorders that involve the uvea (iris, ciliary body, choroid) but confusingly can also involve other tissues in the eye (retina, vitreous, optic nerve). It is often associated with systemic diseases (sarcoidosis, juvenile idiopathic arthritis, Behcets disease) but can also be infectious.
Lets quickly review some anatomy to better understand where exactly this pathology is taking place. The uvea comprises the iris, ciliary body, and the choroid. The iris is the muscular structure that controls the size of the pupil. It is also responsible for eye color. The ciliary body is made up of the ciliary muscle and the ciliary epithelium. The ciliary muscle controls the shape of the lens while the ciliary epithelium produces aqueous humor. Aqueous humor is the fluid present in the anterior and posterior chambers of the eye. It is important to recognize that this is different that vitreous humor which is gel-like and located in the vitreous chamber (area between lens and retina). Finally, the choroid is a layer of the eye between the sclera and the retina. It contains vascular and connective tissue.
In uveitis, any of these structures can become inflamed/infected. As mentioned above, other structures can also be involved such as the retina (uveoretinitis), vitreous (vitritis), or optic nerve (papillitis). The nomenclature of uveitis is classified based on location, onset, duration, and time course. These definitions were agreed upon by the Standardization of Uveitis Nomenclature Working Group (2):
- Anterior: primary site of inflammation is anterior chamber (iris and ciliary body)
- Intermediate: primary site of inflammation is the vitreous
- Posterior: primary site of inflammation is the retina or choroid
- Panuveitis: inflammation in the anterior chamber, vitreous, and retina or choroid
- Sudden or insidious
- Limited (≤ 3 months) or persistent (> 3 months)
- Acute: sudden onset and limited duration
- Recurrent: repeated episodes separated by periods of inactivity without treatment for ≥ 3 months duration
- Chronic: persistent uveitis with relapse in < 3 months after discontinuing treatment
It is important to note that the term anterior uveitis has replaced the terms iritis (inflamation of the iris) and iridocyclitis (inflammation of the iris and ciliary body).
The presentation of uveitis is variable based on the location of the pathology. Patients with more anterior symptoms will have a more impressive exam while patients with predominantly posterior symptoms may only present with vision loss.
The classic symptoms of anterior uveitis include:
- Painful eye, conjunctival injection, photophobia, blurred vision
- Conjunctival injection more intense around the edge of the cornea (circumcorneal)
- Tearing present but a sticky/mucoid discharge is uncommon
- Pupil may appear smaller or irregular (see figure 2) due to spasm of the iris sphincter or posterior synechiae (adherence of iris to lens)
As mentioned above, posterior uveitis is more difficult to identify as there are few external features. These patients may not have any conjunctival injection, pain, or photophobia. These patients may present only with floaters or vision loss without any other symptoms.
Uveitis is typically broken up into infectious and non-infectious etiologies. Within the category of non-infectious causes, uveitis may be autoimmune, drug-induced, traumatic, or associated with malignancy. Almost half of cases are idiopathic and presumed autoimmune (1). It is important to recognize that many cases are associated with a systemic process, below are some of the common causes:
As in all presentations, history is pivotal to making the diagnosis. If clinical suspicion is high based on the history, it is important to determine what the underlying cause of the uveitis is as this will change management. Asking about infectious signs or symptoms, immunosuppression, history of HIV can all help in determining infection risk. In addition, looks for signs and symptoms of the systemic disorders that can manifest as uveitis.
In addition to a good history, perform a thorough eye exam. This includes visual acuity, intraocular pressure, a slit lamp exam, and a fluorescein exam. Findings concerning for uveitis include circumcorneal injection, cell and flare, and hypopyon. Keratic precipitates (inflammatory cells deposited on corneal epithelium) can also be seen (see figure 3). Evaluation of the posterior structures requires dilation and cannot be easily performed in the ED.
Cell and flare is a classic sign of inflammation in the anterior chamber. The "cell" is individual inflammatory cells floating in the anterior chamber. The "flare" is a foggy appearance of the aqueous humor due to leaked protein from inflamed blood vessels. This post has a great video on visualizing cell and flare.
The goal of treatment is resolution of ocular inflammation with restoration of vision. The treatment depends on the cause of uveitis. Infectious causes are treated specifically based on the causative virus/bacteria. This includes oral acyclovir/valacyclovir for HSV/VZV, oral valganciclovir for CMV, doxycycline for Lyme Disease, penicillin for syphilis, and appropriate antibiotics for TB. Topical steroids are also often prescribed to help decrease inflammation, but this should be done in consultation with an ophthalmologist.
Non-infectious causes are typically treated by treating the underlying disease. In addition, topical steroids are given to decrease inflammation (in conjunction with an ophthalmologist) and mydriatic eye drops can be prescribed to help with pain. Systemic immunosuppressants may be used in chronic uveitis but are outside the scope of this post.
Most patients diagnosed with uveitis need urgent ophthalmology follow up. However, appropriate treatment can and should be initiated in the ED.
- Uveitis is inflammation/infection involving the uvea (iris, ciliary body, choroid)
- Causes include infectious (HSV, VZV, Syphilis, TB) or non-infectious (autoimmune, traumatic, malignancy, drug-induced)
- Treatment focuses on treating infection if present and decreasing inflammation (topical steroids)
- Most cases require urgent referral to ophthalmology