Iridociliary Cysts in Cats: Expert Vet Guide 🐱👁️ 2025

By Dr Duncan Houston BVSc, veterinarian & founder of Ask A Vet

Iridociliary cysts (also called iris or uveal cysts) are benign, fluid-filled sacs that originate from pigment epithelium on the back of the iris or ciliary body. While usually harmless, larger or multiple cysts can interfere with vision, cause glaucoma, or mimic serious eye conditions. This in-depth 2025 guide covers:

• 🔍 What iridociliary cysts are and how they form
• 🧬 Risk factors and causes
• 🚨 Clinical signs and differential diagnosis
• 🧪 Diagnostic steps including transillumination & tonometry
• 🛠 Treatment options: laser, aspiration, surgical referral
• 🛡️ When cysts require no treatment and monitoring tips
• 🤝 Ask A Vet telehealth support from diagnosis through recovery

🔍 What Are Iridociliary Cysts?

These benign cysts form when epithelial cells from the iris or ciliary body trap aqueous fluid, creating a smooth, round, often pigmented sac in the anterior chamber ^{:contentReference[oaicite:2]{index=2}}. They may float freely or attach to the pupillary margin, and most cats remain symptom-free. 🛎️

🧬 Causes & Risk Factors

• Idiopathic—spontaneous in otherwise healthy cats ^{:contentReference[oaicite:3]{index=3}}.
• Trauma or prior uveitis may trigger cyst formation ^{:contentReference[oaicite:4]{index=4}}.
• Genetic predisposition suspected, especially in some breeds (e.g., Siamese), though data is limited ^{:contentReference[oaicite:5]{index=5}}.
• Occasional iatrogenic or post-surgical origins when posterior tissues are disrupted.

🚨 Signs & Clinical Presentation

• Visible round masses in the eye—pigmented or translucent ^{:contentReference[oaicite:6]{index=6}}.
• Often incidentally found during routine eye exams.
• Possible vision interference if large or blocking the pupil—walking into things, reduced navigation.
• Rare complications include secondary glaucoma or uveitis.
• Can mimic iris tumors—transillumination and mobility help distinguish ^{:contentReference[oaicite:7]{index=7}}.

🧪 Diagnostic Approach

1. Ophthalmic exam: slit-lamp examination reveals round cysts, often attached at the pupillary margin; note size and number.
2. Transillumination test: shining light through the cyst causes it to glow—unlike melanoma ^{:contentReference[oaicite:8]{index=8}}.
3. Mobility test: floating cysts move with head position—suggests fluid-filled nature ^{:contentReference[oaicite:9]{index=9}}.
4. Tonometry: measure intraocular pressure to check for glaucoma if obstruction or large cysts are present.
5. Uveitis evaluation: assess anterior chamber inflammation, as uveitis may underlie cysts ^{:contentReference[oaicite:10]{index=10}}.

🛠 Treatment Options

1. No Treatment (Monitor Only)

• Small, asymptomatic cysts require monitoring only.
• Periodic checks for growth, vision changes, or pressure spikes.

2. Laser Ablation

• Diode laser disrupts the cyst wall, allowing fluid to reabsorb ^{:contentReference[oaicite:11]{index=11}}.
• Minimally invasive, surgically performed by a veterinary ophthalmologist.
• Effective for large cysts or those causing visual impairment.

3. Fine-Needle Aspiration

• Under sedation, fluid is aspirated directly—riskier but effective ^{:contentReference[oaicite:12]{index=12}}.
• Risks include hemorrhage or infection.

4. Surgical Referral

• If malignancy cannot be ruled out or if glaucoma develops, referral for biopsy or enucleation may be required.

5. Manage Complications

• Glaucoma: medication to reduce pressure such as dorzolamide or timolol.
• Uveitis: treated with topical NSAIDs or steroids after ruling out infection.

📆 Monitoring & Follow-Up

• Recheck every 3–6 months with slit-lamp and tonometry.
• Monitor for new cysts or intraocular pressure changes.
• Be alert to behavior changes signaling vision issues or discomfort.

🤝 Ask A Vet Telehealth Support

Our telehealth service assists by:

• 📸 Reviewing your eye photos to assess cyst size, location, and features.
• 💬 Guiding when to see a vet in person versus watchful waiting.
• 📆 Advising on pressure checks and medication timing at home.
• 🪛 Providing clarity on referral vs management decisions.
• 🚑 Recognizing signs of glaucoma, pain, or vision loss needing prompt attention.

✅ Key Takeaways

• Iridociliary cysts are benign but may affect vision or eye pressure if large or numerous.
• Diagnosis relies on appearance, mobility, and transillumination—helps distinguish from tumors.
• Treatment ranges from monitoring to laser or aspiration, depending on impact.
• Early detection and follow-up protect vision and prevent glaucoma.
• Ask A Vet telehealth helps you navigate every step—from spotting cysts to follow-up care.

📞 Final Thoughts

While most feline iridociliary cysts are harmless, they can mimic more serious eye conditions or cause secondary issues. With expert evaluation, monitoring, and available treatments, the majority of cats maintain clear vision and comfort. Ask A Vet’s telehealth support ensures you have expert advice when you need it. ❤️👁️

Have eye photos, pressure readings, or cyst concerns? Visit AskAVet.com and download the Ask A Vet app for personalized telehealth support anytime!