Iritis (anterior uveitis) is inflammation of the iris and ciliary body — the most common form of uveitis, accounting for 41%–60% of all cases. It predominantly affects adults aged 20–50 years and can cause vision-threatening complications (posterior synechiae, glaucoma, cataracts, macular edema) if untreated. [1] The following is a structured clinical summary for emergency medicine and primary care.
The JAMA 2025 review provides a useful diagnostic algorithm for initial assessment:
1. History
- Onset and laterality: Acute vs. insidious; unilateral (more common) vs. bilateral (raises concern for systemic disease) [1]
- Pain quality: Sharp, deep aching pain worsened by bright light, reading, or accommodation [1]
- Photophobia: Ask specifically about consensual photophobia (pain in the affected eye when light is shone in the contralateral eye) — a pathognomonic clue [2]
- Vision changes: Blurred vision present in up to 50% of anterior uveitis cases [1]
- Prior episodes: Recurrent iritis is common and a strong diagnostic clue; ask about frequency and prior workup [2]
- Associated symptoms: Joint pain/stiffness (spondyloarthritis), oral/genital ulcers (Behçet), skin rash, cough/dyspnea (sarcoidosis), recent STI exposure (syphilis), vesicular rash (herpetic) [1]
- Trauma history: Recent blunt ocular trauma can cause traumatic iridocyclitis [3]
- Medication history: Immune checkpoint inhibitors, bisphosphonates, rifabutin, fluoroquinolones, sulfonamides, topiramate can all cause drug-induced uveitis [1]
2. Alarm Features
- Significant vision loss or distortion — requires urgent same-day ophthalmology referral [1]
- Hypopyon (layered white/yellow material in the anterior chamber) — visible without slit lamp in severe cases; suggests severe inflammation or endophthalmitis [4]
- Fever, hypotension, or systemic illness with eye pain — consider endophthalmitis and sepsis; refer to ED immediately [1]
- Bilateral presentation — higher likelihood of systemic autoimmune or infectious etiology [1]
- Posterior segment involvement (floaters, visual distortion, fundoscopic abnormalities) — suggests intermediate/posterior uveitis or panuveitis with higher complication risk [1]
- Herpetic vesicles on the face/eyelid — avoid corticosteroids until antiviral coverage is initiated [2]
- Recent ocular surgery or penetrating injury — exogenous endophthalmitis must be excluded [1]
3. Medications
Causative medications to screen for
- Immune checkpoint inhibitors (nivolumab, pembrolizumab)
- Bisphosphonates (pamidronate, alendronate)
- Rifabutin
- Fluoroquinolones (moxifloxacin)
- Sulfonamides, topiramate, latanoprost [1]
Treatment medications (see Treatment Plan below)
- Prednisolone acetate 1% — first-line topical corticosteroid [1]
- Difluprednate 0.05% — alternative; noninferior to prednisolone acetate 1% at 4× daily vs. 8× daily dosing, but higher IOP risk [5-6]
- Cycloplegics (cyclopentolate 1%, homatropine 5%, or atropine 1%) — for pain relief and synechiae prevention [2]
- Avoid topical steroids if herpetic etiology is suspected without antiviral coverage [2]
Contraindicated/caution
- Topical steroids without ophthalmology follow-up (risk of steroid-induced glaucoma and cataracts)
- Cycloplegics if concern for elevated IOP or narrow angle [2]
4. Diet
- No specific dietary triggers or recommendations for acute iritis
- Adequate hydration and general anti-inflammatory nutrition may be supportive in chronic/recurrent autoimmune-associated uveitis
- Patients on chronic systemic corticosteroids should follow calcium/vitamin D supplementation guidelines
5. Review of Systems
- MSK: Low back pain/morning stiffness (ankylosing spondylitis), joint swelling (reactive arthritis, psoriatic arthritis, IBD-associated arthritis) [1]
- Derm: Psoriatic plaques, erythema nodosum, oral/genital ulcers (Behçet), vesicular rash (HSV/VZV), vitiligo/poliosis (Vogt-Koyanagi-Harada) [1]
- Pulmonary: Cough, dyspnea (sarcoidosis, TB) [7]
- GI: Chronic diarrhea, bloody stools (IBD) [1]
- Neuro: Headache, tinnitus, hearing loss (VKH), numbness/weakness (MS) [1]
- GU: Urethritis, dysuria (reactive arthritis); recent STI (syphilis) [8]
- Constitutional: Fevers, night sweats, weight loss (TB, lymphoma, sarcoidosis)
6. Collateral History and Family History
- Family history of autoimmune disease: ankylosing spondylitis, psoriasis, IBD, sarcoidosis, Behçet disease
- HLA-B27 prevalence in family — HLA-B27–associated uveitis is more common in men (male:female ratio up to 1.5:1) [1]
- Social/sexual history: MSM status (rising ocular syphilis rates), IV drug use (endogenous endophthalmitis), TB exposure, travel to endemic areas [8]
- Immunocompromised status: HIV, immunosuppressive medications (CMV retinitis risk)
7. Risk Factors
- HLA-B27 positivity — strongest genetic risk factor for acute anterior uveitis; associated with axial spondyloarthritis (15%–50% of anterior uveitis cases) [1]
- Age 20–50 years (60%–80% of cases) [1]
- Autoimmune comorbidities: Spondyloarthritis, psoriatic arthritis, IBD, sarcoidosis, Behçet disease, MS [1]
- Infections: HSV/VZV (5%–15%), TB (1%–13%), syphilis (1%–4%), toxoplasmosis (5%–7%) [1]
- Environmental: Air pollution, tobacco smoking [1]
- Prior episodes of uveitis — recurrence is common
- Geographic: Behçet disease more common along Silk Road regions; TB-associated uveitis more common in low/middle-income countries [1]
8. Differential Diagnosis
Cannot-miss diagnoses
- Acute angle-closure glaucoma — severe pain, halos, mid-dilated fixed pupil, rock-hard globe, nausea/vomiting (pupil is mid-dilated vs. constricted in iritis) [9]
- Endophthalmitis — post-surgical or endogenous; hypopyon, severe vision loss, systemic sepsis signs [1]
- Keratitis (bacterial, herpetic) — corneal opacity, fluorescein uptake positive [2][9]
- Ocular lymphoma (masquerade syndrome) — consider in patients >50 with chronic uveitis refractory to treatment [10]
Common mimics and distinguishing features
- Conjunctivitis — diffuse injection, discharge (purulent or watery), no photophobia, no vision loss, pain relieved by topical anesthetic [2][9]
- Episcleritis/scleritis — sectoral redness; scleritis has severe boring pain, scleral edema; no anterior chamber cells [9]
- Corneal abrasion — fluorescein positive, foreign body sensation, history of trauma [9]
- Subconjunctival hemorrhage — painless, no vision change [9]
Key distinguishing feature of iritis: Pain is NOT relieved by topical anesthetic drops, and fluorescein staining is negative. [2]
9. Past Medical History
- Prior episodes of iritis/uveitis (number, laterality, treatments used)
- Ankylosing spondylitis, psoriatic arthritis, reactive arthritis, IBD [1]
- Sarcoidosis, Behçet disease, MS, JIA (in younger patients) [1]
- HIV status, TB exposure, syphilis history [8]
- Prior ocular surgery or trauma
- History of herpes simplex or zoster keratitis
- Chronic steroid use (risk of steroid-induced glaucoma/cataracts)
10. Physical Exam
- Visual acuity: Decreased in up to 50% of anterior uveitis cases [1]
- Pupil: Constricted (miotic) and sluggishly reactive; may be irregular from posterior synechiae [4]
- Injection pattern: Circumcorneal (perilimbal) injection — redness concentrated around the limbus, distinct from the diffuse injection of conjunctivitis [1][4]
- Consensual photophobia: Pathognomonic — pain in the affected eye when light is shone in the unaffected eye (tests ciliary spasm) [2]
- Anterior chamber: Cells and flare on slit lamp; hypopyon visible without magnification if severe [4]
- Keratic precipitates: Cell deposits on posterior cornea (slit lamp finding) [1]
- Posterior synechiae: Irregular pupil from iris-lens adhesions — can be seen without slit lamp [1]
- IOP: May be elevated or decreased; check with tonometry
- Fluorescein staining: Should be negative (positive suggests corneal pathology) [2]
- Topical anesthetic test: Pain does NOT resolve (resolves in conjunctivitis) [2]
- Fundoscopy: Assess for optic disc swelling, retinitis, choroiditis (suggests posterior involvement) [1]
11. Lab Studies
First episode, unilateral, uncomplicated anterior uveitis: No labs required [1]
Recurrent, bilateral, or atypical presentations — order
- RPR/VDRL + FTA-ABS (syphilis) — recommended in all forms of uveitis [11]
- HLA-B27 — most contributive test in acute anterior non-granulomatous uveitis (positive in 56% of tested cases in the ULISSE study) [12]
- ACE level (sarcoidosis) [11-12]
- CBC, ESR, CRP — nonspecific but helpful for systemic inflammation [12]
- QuantiFERON-TB Gold / tuberculin skin test — most contributive first-step investigation (17.1% diagnostic yield) [12]
- Chest X-ray — screening for sarcoidosis and TB (8.4% diagnostic yield) [12]
- Urinalysis — tubulointerstitial nephritis and uveitis (TINU) syndrome
If infection suspected
- Aqueous humor tap for PCR and culture (organisms identified in only 22%–32% of cases) [1]
- HIV testing in at-risk populations [8]
12. Imaging
- Chest X-ray: First-line screening for sarcoidosis (hilar lymphadenopathy) and TB [10][12]
- Chest CT: Higher sensitivity for sarcoidosis; recommended in chronic or recurrent uveitis when CXR is negative [7][11]
- Sacroiliac MRI: If spondyloarthritis is suspected (chronic low back pain + HLA-B27+) — 46.4% diagnostic yield when clinically indicated [12]
- Brain MRI: Consider in intermediate/posterior uveitis in patients >40 years to evaluate for MS or primary CNS lymphoma [11]
- 18F-FDG PET/CT: Emerging role in identifying occult sarcoidosis [7]
- Imaging is unnecessary for a first episode of uncomplicated unilateral anterior uveitis without systemic symptoms [1]
13. Special Tests
- Slit-lamp biomicroscopy: Gold standard for diagnosis — identifies anterior chamber cells, flare, keratic precipitates, and synechiae [1]
- Tonometry: IOP measurement (may be elevated or low)
- Fluorescein staining: To rule out corneal pathology
- Consensual photophobia test: Penlight in unaffected eye → pain in affected eye [2]
- Topical anesthetic test: Pain persists (unlike conjunctivitis) [2]
- Standardized Uveitis Nomenclature (SUN) grading: Anterior chamber cell grading (0 to 4+) and flare grading used to quantify severity and monitor response [1]
14. ECG
- Not routinely indicated for iritis
- Consider ECG if sarcoidosis is suspected (cardiac sarcoidosis can cause conduction abnormalities, arrhythmias)
- Consider if starting hydroxychloroquine for associated rheumatologic disease (QTc monitoring)
15. Assessment
Anterior uveitis is the most common and generally most benign form of uveitis, but untreated disease can lead to cataracts, glaucoma, macular edema, posterior synechiae, and permanent vision loss. [1] Key clinical pearls:
- Most cases are idiopathic (27%–51%) or HLA-B27–associated [1][12]
- A first episode of unilateral, non-granulomatous anterior uveitis in a young adult without systemic symptoms is the most common presentation and does not require extensive workup [1]
- Recurrent, bilateral, granulomatous, or treatment-refractory cases warrant systemic investigation for sarcoidosis, spondyloarthritis, syphilis, TB, and other etiologies [1][11]
- Infectious etiologies (HSV, VZV, syphilis, TB) must be excluded before initiating corticosteroids, as steroids can worsen infection [2][8]
- Masquerade syndromes (lymphoma, retinoblastoma) account for 1%–5% of cases and should be considered in atypical or refractory presentations [1]
16. Treatment Plan
Initial stabilization (ED/urgent care)
Medications
- Prednisolone acetate 1%: 1 drop every 1 hour while awake (severe) or every 4 hours (mild) in the affected eye [1-2]
- Difluprednate 0.05%: Alternative — 1 drop 4× daily (noninferior to prednisolone 8× daily) [5-6]
- Cycloplegic agent: Cyclopentolate 1% 1 drop TID, or homatropine 5% 1 drop TID, or atropine 1% 1 drop BID — relieves ciliary spasm (pain) and prevents posterior synechiae [2]
- Oral prednisone 40–60 mg daily: If topical drops unavailable or disease worsening despite topical therapy [2]
- Topical NSAID (e.g., ketorolac): If herpetic etiology suspected and steroids must be withheld [2]
Taper (ophthalmology-directed)
Infectious uveitis
Refractory/chronic disease
- Sub-Tenon or intravitreal corticosteroid injections [1]
- Systemic immunosuppression (methotrexate, mycophenolate, adalimumab) for posterior/panuveitis or steroid-dependent disease [1]
17. Disposition
Discharge with urgent ophthalmology follow-up (24–48 hours):
Same-day ophthalmology referral
- Vision loss or distortion with eye pain and redness [1]
- Hypopyon [4]
- Suspected posterior segment involvement
- Recurrent or bilateral disease
ED referral / admission
- Visual symptoms with systemic illness (fever, hypotension) — concern for endophthalmitis/sepsis [1]
- Suspected endogenous endophthalmitis requiring IV antibiotics and possible vitrectomy
Ophthalmology consultation triggers
- All cases of iritis/uveitis should ultimately be evaluated by ophthalmology [1][13]
- Recurrent cases need systemic workup coordination with rheumatology/internal medicine [14]
18. Follow Up / Return Precautions
Follow-up timing
- 24–48 hours with ophthalmology for slit-lamp reassessment after initiating treatment [1][13]
- 1 week for steroid taper adjustment
- Recurrent cases: ongoing ophthalmology monitoring every 1–3 months depending on severity
Return precautions — instruct patients to return immediately for:
- Worsening eye pain or new-onset severe headache
- Decreasing vision or new visual distortion
- Increasing redness despite treatment
- Fever or systemic illness developing
- Symptoms in the contralateral eye
Patient counseling
- Do NOT stop steroid drops abruptly — must be tapered to prevent rebound inflammation [1]
- Shake prednisolone acetate bottle well before each use (suspension)
- Sunglasses may help with photophobia
- Iritis can recur — educate on recognizing early symptoms for prompt retreatment
- Expected recovery: most episodes of acute anterior uveitis resolve within 4–6 weeks with appropriate treatment, though recurrence rates are significant [1]
References
1. Uveitis in Adults. — Maghsoudlou P, Epps SJ, Guly CM, Dick AD. The Journal of the American Medical Association. 2025.
2. Wilderness Medical Society Clinical Practice Guidelines for Treatment of Eye Injuries and Illnesses in the Wilderness: 2024 Update. — Paterson R, Drake B, Tabin G, Cushing T. Wilderness & Environmental Medicine. 2024.
3. Topical Mydriatics as Adjunctive Therapy for Traumatic Iridocyclitis. — Hom J, Sarwar S, Kaleem MA, et al. The Cochrane Database of Systematic Reviews. 2020.
4. The Red Eye. — Leibowitz HM. The New England Journal of Medicine. 2000.
5. FDA Drug Label. — Updated date: 2025-07-23. Food and Drug Administration.
6. Difluprednate 0.05% Versus Prednisolone Acetate 1% for Endogenous Anterior Uveitis: A Phase III, Multicenter, Randomized Study. — Sheppard JD, Toyos MM, Kempen JH, Kaur P, Foster CS. Investigative Ophthalmology & Visual Science. 2014.
7. Uveitis as an Open Window to Systemic Inflammatory Diseases. — El Jammal T, Loria O, Jamilloux Y, et al. Journal of Clinical Medicine. 2021.
8. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.
9. Conjunctivitis: Diagnosis and Management. — Winters S, Frazier W, Winters J. American Family Physician. 2024.
10. Uveitis: The Collaborative Diagnostic Evaluation. — Harman LE, Margo CE, Roetzheim RG. American Family Physician. 2014.
11. Uveitis: Diagnostic Work-Up. A Literature Review and Recommendations From an Expert Committee. — Sève P, Cacoub P, Bodaghi B, et al. Autoimmunity Reviews. 2017.
12. Contribution of Diagnostic Tests for the Etiological Assessment of Uveitis, Data From the ULISSE Study (Uveitis: Clinical and Medicoeconomic Evaluation of a Standardized Strategy of the Etiological Diagnosis). — Grumet P, Kodjikian L, de Parisot A, et al. Autoimmunity Reviews. 2018.
13. What Is Uveitis?. — Angulo MI, Barajas M, Vela M. The Journal of the American Medical Association. 2025.
14. Uveitis for the Non-Ophthalmologist. — Burkholder BM, Jabs DA. BMJ. 2021.