Scleritis and Episcleritis

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Emergency physicians will see many patients presenting with a "red eye" throughout their career.  They will need to determine which patients have a benign source, and which are suffering from a life or sight threatening pathology.  Episcleritis and scleritis are two causes of red eye that can have similar presentations, but require an astute clinician to distinguish them.  The following post will cover a brief overview of these pathologies as well as a few pearls to guide diagnosis and treatment.

Scleritis

Scleritis is a rare but emergent cause of a red eye.  It is thought to be caused by an autoimmune response that can be idiopathic, triggered by infection or trauma, or secondary to underlying autoimmune dysregulation.  In fact, it is estimated that up to half of all cases of scleritis have an underlying autoimmune disorder such as IBD, SLE, granulomatosis with polyangiitis (Wegener's granulomatosis), or scleroderma.  There are two main types of scleritis: anterior and posterior.

  • Anterior scleritis: involvement of the sclera anterior to the extraocular muscle insertion.  There are three variants: Diffuse (most common and most treatable), nodular (presents with tender nodules), and necrotizing (most severe and destructive).
  • Posterior scleritis: involvement of the sclera posterior to the extraocular muscle insertion.  This is rarer than anterior scleritis and difficult to detect due to its more posterior location.  It is associated with retinal detachment, angle closure glaucoma, and vision loss.  

Figure 1.  Scleritis.  Courtesy of Wikimedia Commons (6). 

Patients suffering from scleritis may complain of severe pain in the affected eye which sometime radiates to the adjacent face.  They also may have blurry vision and photophobia.  Clues on physical exam to detect scleritis include severe tenderness of the globe, pain with eye movement, a criss-crossed pattern of fixed scleral vessels, a violet hue to the sclera, and objective vision loss.  

If a provider has suspicion for scleritis, he or she should consider whether the patient exhibits any other concerning items on history that should prompt further autoimmune work-up.  Treatment for these patients typically includes systemic steroids, NSAIDs, and possible topical antibiotics.  Ophthalmology should also be consulted to help direct management as some may require surgery for scleral repair in severe cases.

Episcleritis

Episcleritis is more common than scleritis.  It involves only the superficial episcleral vessels, sparing the deeper scleral vasculature.  These superficial vessels are located just beneath the bulbar (ocular) conjunctiva.  There are two main types of episcleritis: diffuse and nodular.  Diffuse episcleritis is typically idiopathic while nodular episcleritis may be associated with an underlying systemic autoimmune disorder in up to one third of cases.  

Figure 2.  Episcleritis.  Courtesy of Wikimedia Commons (7).

Patients with either variant often present with acute onset of mild eye discomfort and redness.  On exam, patients will have a reddish hue to the sclera with a more radial pattern of vasculature emanating from the limbus.  Unlike the deep, fixed, inflamed vessels of scleritis, vessels in episcleritis are more superficial and are able to be easily moved with a cotton swab.   When in doubt, providers may choose to use phenylephrine ophthalmic drops.  These will blanch inflamed episcleral vessels, but have no effect on deeper scleral vessels. 

Episcleritis is usually self-limited over the course of 1-2 weeks and does not require treatment.  In severe or persistent cases, providers may consider topical therapies including corticosteroids and NSAIDs.  

Scleritis vs Episcleritis

Table 1. Scleritis vs Episcleritis

Pearls

  • Scleritis is characterized by significant pain, pain with eye movement, vision loss, and vessels that do not blanch with phenylephrine.  
  • Episcleritis is typically less painful with no vision loss.  Vessels blanch with phenylephrine drops and can be moved by a cotton swab. 
  • Management of scleritis involves ophthalmology consultation and steroids +/- topical antibiotics.  Episcleritis is typically self-limited and does not require acute treatment.

Authored by Jimmy Summers, MD

Posted by Tim Murphy, MD