What is the difference between iritis and uveitis?

Difference Between Iritis and Uveitis

Iritis is a specific type of anterior uveitis that affects only the iris, while uveitis is the broader term for inflammation of the uveal tract which can involve the iris, ciliary body, and/or choroid. 1

Anatomical Classification

Uveitis is classified according to the anatomical location of inflammation:

• Anterior uveitis (iritis/iridocyclitis): Inflammation of the iris alone (iritis) or iris and ciliary body (iridocyclitis)
• Intermediate uveitis: Inflammation primarily of the vitreous
• Posterior uveitis: Inflammation of the choroid, retina, or optic nerve
• Panuveitis: Inflammation throughout all layers of the uvea 1

Clinical Presentation

Iritis (Anterior Uveitis)

• Typically presents with:
  • Eye pain
  • Photophobia
  • Blurred vision
  • Redness (ciliary flush)
  • Miosis (pupillary constriction) 2
  • Cells and flare in anterior chamber
  • May be acute or chronic

Other Forms of Uveitis

• Intermediate uveitis: Often asymptomatic or with floaters and blurred vision
• Posterior uveitis: Visual disturbances, floaters, and visual field defects
• Panuveitis: Combination of symptoms from all forms 1, 3

Etiology

• Iritis/Anterior uveitis: Often associated with HLA-B27-related conditions (ankylosing spondylitis, reactive arthritis), JIA, or may be idiopathic 1
• Intermediate uveitis: May be idiopathic or associated with multiple sclerosis, sarcoidosis
• Posterior uveitis: Often infectious (toxoplasmosis, herpes viruses) or associated with systemic inflammatory diseases 4

Clinical Course

• Acute anterior uveitis (including iritis): Sudden onset, often unilateral, episodic, characterized by erythema, pain, and photophobia 1
• Chronic anterior uveitis: Often asymptomatic until complications develop, may be bilateral, insidious in onset, and long-lasting 1

Diagnostic Approach

• Iritis is diagnosed through slit-lamp examination showing cells and flare in the anterior chamber
• More extensive uveitis requires comprehensive ophthalmologic evaluation including:
  • Dilated fundus examination
  • Optical coherence tomography
  • Fluorescein angiography when posterior segment involvement is suspected 1, 5

Treatment

Iritis/Anterior Uveitis

• Topical corticosteroids (prednisolone acetate) as first-line treatment 6
• Cycloplegic/mydriatic agents to:
  • Prevent synechiae formation
  • Relieve ciliary spasm
  • Reduce pain 2

Other Forms of Uveitis

• Anterior uveitis: Responds to topical therapies
• Intermediate, posterior, or panuveitis: Often require systemic treatments:
  • Oral corticosteroids
  • Immunosuppressive agents (methotrexate)
  • Biologic agents (TNF inhibitors like adalimumab and infliximab) 1, 7

Complications

• Untreated or poorly controlled uveitis (including iritis) can lead to:
  • Synechiae (adhesions between iris and lens)
  • Cataracts
  • Glaucoma
  • Band keratopathy
  • Vision loss 1

Key Differences Summary

1. Scope: Iritis specifically refers to inflammation of the iris, while uveitis encompasses inflammation of any part of the uveal tract
2. Anatomical location: Iritis affects only the anterior segment, while uveitis can affect anterior, intermediate, or posterior segments, or all (panuveitis)
3. Treatment approach: Iritis/anterior uveitis may respond to topical treatments alone, while other forms of uveitis often require systemic therapy 7

Clinical Pearl

Early detection through regular ophthalmology screening and timely treatment is crucial, especially in asymptomatic cases like chronic anterior uveitis in children with JIA, to prevent vision-threatening complications 1.