Episcleritis and Scleritis

Episcleritis

Background

  • Inflammation of the episclera (thin fibroelastic structure that lies between the conjunctiva and sclera)
  • Usually mild and self-limiting

Pathophysiology and aetiology

  • Most cases are idiopathic
    • Up to a third of patients have an underlying systemic conditions e.g. rheumatoid arthritis, inflammatory bowel disease, SLE, vasculitic disease, dermatological disease etc
  • There are two forms of episcleritis
    • Simple episcleritis
      • intermittent bouts of mod-severe inflammation that often recur at 1-3 month intervals.  Usually last 7-10 days
    • Nodular episcleritis (more commonly associated with systemic disease)
      • Often more severe and prolonged attacks
      • Characterised by a discrete, elevated area of inflamed episcleral tissue

Presentation

  • General
    • Diffuse or localised, bright red/pink bulbar injection (cf scleritis which is darker/violet)
    • Usually unilateral
    • Some may report other symptoms such as discomfort, photophobia or tenderness
      • Severe pain and discharge are not common
  • Simple
    • Often acute redness, occasionally associated with pain (mild-moderate)
      • Usually peaks around 12 hours then slowly resolves over 2-3 days
      • Tends to recur in same or both eyes at the same time
        • With time, attacks become less frequent and can disappear completely
  • Nodular
    • Gradual onset redness, noted particularly upon wakening in the morning
    • Worsens over several days, causing discomfort and takes on a nodular appearance
    • Also self-limiting but tends to last longer
    • nodular episcleritis

Management

  • Supportive management i.e. reassurance is all that is required in most cases
    • NSAIDs may be helpful (ibuprofen tablets), moreso in nodular episcleritis than simple episcleritis

Scleritis

Background

  • In contrast with episcleritis, scleritis is potentially blinding and usually requires referral to ophthalmology
  • Inflammation of the sclera

Aetiology

  • There is a strong link between autoimmunity and scleritis.  In particular, patients with rheumatoid arthritis are at a much higher risk than the general population.
  • Also more common in women.

Disease class

  • There are two main forms of scleritis which can be further classified as such:
    • Anterior scleritis: inflammation anterior to the extraocular recti muscles
      • Diffuse: anterior scleral oedema is present with dilation of the deep episcleral vessels.  This may be diffuse or localised
      • Nodular: a distinct nodule of scleral oedema is present (can be single or multiple).  They are often tender.
      • Necrotising: most severe form.  Severe pain and scleral tenderness.  Severe vasculitis as well as infarction and necrosis with exposure of the choroid may result.
        • Rarely, necrotising scleritis can occur without inflammation (scleromalacia perforans).  The sclera become very pale, avascular and thin.
    • Posterior scleritis: rare but potentially more serious.  Characterised by flattening of the posterior globe, thickening of the posterior coats of the eye (choroid and sclera) and retrobulbar oedema
      • Can manifest as serious retinal detachment, choroidal folds or both
      • There can also be loss of vision as well as pain on eye movement

Pathophysiology

  • Common pathological features include scleral oedema and inflammation, often with a zonal granulomatous (can also necrose) reaction that may be localised or diffuse.  Often mediated by  type III and subsequent type IV autoimmune reactions involving a variety of cell types (T cells, macrophages, B cells, plasma cells etc)

Presentation

  • History
    • Redness
      • Gradually increases over several days
      • characteristic violet/blue tinge
    • Pain
      • Most describe severe boring/piercing eye pain over several days
        • may radiate to surrounding facial areas
        • may awaken the patient in the night (cf episcleritis)
        • Tender on movement and palpation
        • Usually not helped by analgesia
    • Tearing may occur secondary to discomfort but discharge is uncommon.
    • PMHx
      • Remember to ask about any autoimmune/ophthalmological conditions 
  • Examination
    • Blue hue is best observed under natural light
    • On slit-lamp, inflamed scleral vessels are congested and often have criss-cross pattern and (under green light) there may be areas of capillary non-perfusion and granulation
    • Phenylephrine (constrictor) will only constrict the superficial conjunctival/episclera vessels but the florid appearance of scleritis should remain.

Management

  • Main aim is to minimise inflammation and reduce any damage
    • Topical NSAIDs and corticosteroids may be used.  However, ultimately, treatment of any underlying cause may require systemic NSAID/steroid use or even immunomodulatory agents
    • Severe (necrotising) disease will require systemic treatment in any case

 

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