Can Iritis Cause a Misshapen Pupil?
Yes, iritis can cause a misshapen pupil through the formation of posterior synechiae, which are adhesions between the iris and the lens that develop as a complication of the inflammatory process.
Mechanism of Pupil Deformity in Iritis
The pupil becomes misshapen in iritis through a specific pathological process:
- Posterior synechiae formation occurs when inflammatory cells and proteins cause the iris to adhere to the anterior lens capsule, pulling the pupil into an irregular shape 1
- These adhesions develop during active inflammation and can become permanent if the condition is not promptly treated 2, 3
- The American Academy of Ophthalmology guidelines specifically identify posterior synechiae as a recognized complication of iritis that requires preventive management 1
Clinical Implications and Prevention
The key to preventing permanent pupil deformity is aggressive early treatment with mydriatic agents:
- Mydriatic and cycloplegic agents are essential in iritis management specifically to prevent posterior synechiae formation by keeping the pupil dilated and mobile 2, 3
- Topical corticosteroids address the underlying inflammation, while mydriatics mechanically prevent iris-lens adhesions 2, 3
- The ophthalmology guidelines emphasize dilating the pupil during follow-up care to decrease the risk of posterior synechiae formation 1
Additional Pupillary Complications
Beyond posterior synechiae, iritis can cause other pupillary abnormalities:
- Post-inflammatory fixed dilated pupils can occur as a permanent sequela, particularly in severe or inadequately treated cases 4
- One case report documented fixed dilated pupils following cidofovir-induced iritis, demonstrating that severe inflammation can cause permanent pupillary dysfunction 4
Critical Clinical Pitfall
Do not confuse iritis-related pupil irregularity with other causes of misshapen pupils:
- Trauma with sphincter rupture causes iris transillumination defects and sectoral irregularity 1
- Acute angle-closure presents with a mid-dilated pupil (not irregular) along with corneal edema and elevated intraocular pressure 1
- The presence of photophobia, pain, and cells in the anterior chamber on slit-lamp examination distinguishes iritis from these other conditions 2, 3
Treatment Approach
When iritis is diagnosed, immediate intervention is required:
- Start topical corticosteroids immediately to control inflammation 2, 3
- Add mydriatic/cycloplegic agents concurrently to prevent synechiae formation and break any early adhesions 2, 3
- Close monitoring is essential because steroid overuse has serious side effects, while undertreatment leads to complications including permanent pupil deformity and glaucoma 2, 3
- In cases with established posterior synechiae causing steroid dependency or other complications, systemic immunosuppression may be necessary 5