What is the most likely diagnosis for a patient with a painful eye after trauma, presenting with normal ocular movements, anisocoria (unequal pupil size), and circumcorneal hyperemia (redness around the cornea), with visual acuity of 20/25 in the affected eye?

Traumatic Iritis (Anterior Uveitis)

The most likely diagnosis is traumatic iritis (traumatic anterior uveitis), which presents classically with the triad of eye pain, circumcorneal hyperemia (ciliary flush), and a smaller pupil in the affected eye due to ciliary muscle spasm following blunt ocular trauma. 1, 2

Clinical Reasoning

The presentation is pathognomonic for traumatic iritis:

• Circumcorneal hyperemia (ciliary flush) is a vision-threatening sign that distinguishes anterior segment inflammation from benign conjunctivitis 2
• Miosis (smaller pupil) in the affected right eye results from ciliary muscle and iris sphincter spasm, a hallmark of anterior uveitis 1
• Preserved visual acuity (20/25) is typical in traumatic iritis, with mean initial visual acuity of 20/40 in affected eyes 1
• Normal ocular movements help exclude orbital fracture with muscle entrapment 3
• Blunt trauma mechanism (volleyball to eye) is consistent with sports-related injury, the most common mechanism of traumatic iritis (18.6% of cases) 1

Essential Immediate Examination

The initial assessment must include 3, 4:

• Slit-lamp examination to identify anterior chamber cells and flare (diagnostic of iritis)
• Intraocular pressure measurement to exclude traumatic glaucoma or hypotony from cyclodialysis cleft 5
• Pupillary examination for relative afferent pupillary defect (RAPD), which would suggest more serious pathology like optic nerve injury or retinal detachment 3
• Dilated fundus examination (if safe) to rule out posterior segment injury including vitreous hemorrhage, retinal tears, or commotio retinae 3

Critical Differential Diagnoses to Exclude

While traumatic iritis is most likely, vision-threatening conditions must be ruled out 3, 6:

• Hyphema (blood in anterior chamber) - requires immediate identification 5
• Globe rupture - any suspicion mandates rigid eye shield and immediate ophthalmology consultation 6
• Traumatic cyclodialysis cleft - presents with hypotony and may require ultrasound biomicroscopy 5
• Orbital fracture with entrapment - excluded by normal ocular movements, but bradycardia, nausea, or vomiting would indicate oculocardiac reflex requiring urgent surgical intervention 3, 7

Imaging Considerations

Imaging is NOT routinely indicated for isolated traumatic iritis with normal examination findings 3. However, non-contrast thin-section orbital CT with multiplanar reconstructions should be obtained if 3, 4:

• Concern for orbital fracture (enophthalmos, restricted motility, periorbital emphysema)
• Suspicion of intraocular foreign body (sensitivity 94.9% for metallic foreign bodies) 4
• Never order MRI if metallic foreign body is suspected - this is an absolute contraindication 3, 4

Treatment Approach

Standard management for traumatic iritis includes 1, 8:

• Topical corticosteroids (prednisolone acetate 1% every 1-2 hours initially, then taper based on response) 8
• Cycloplegic agents (atropine 1% or cyclopentolate 1%) to relieve ciliary spasm, reduce pain, and prevent posterior synechiae 8
• Median follow-up duration is 11 days with mean of 2.1 visits for traumatic iritis 1
• Expected visual recovery to 20/30 or better in most cases 1

Common Pitfalls

• Missing hyphema or microhyphema - requires slit-lamp examination, not just penlight inspection 5
• Failing to measure intraocular pressure - both elevated (traumatic glaucoma) and low (cyclodialysis, globe rupture) pressures indicate serious pathology 3, 5
• Overlooking RAPD - a large RAPD (>0.3 log units) suggests optic nerve injury or retinal pathology, not simple iritis 3
• Dismissing the ciliary flush - circumcorneal injection is a vision-threatening sign requiring urgent evaluation, unlike diffuse conjunctival injection 2