---
title: What is cystoid macular oedema?
description: "Cystoid macular oedema (CMO) is swelling at the macula where fluid collects in small cyst-like spaces within the retina. It can occur after surgery, inflammation or vascular disease. ## How CMO affects sight People may experience blurred or distorted central…"
url: "https://bluefinvision.com/knowledge-base/topics/conditions-diseases/what-is-cystoid-macular-oedema/"
updated: "2025-12-11"
category: "Conditions & Diseases"
---

# What is cystoid macular oedema?

Cystoid macular oedema (CMO) is swelling at the macula where fluid collects in small cyst-like spaces within the retina. It can occur after surgery, inflammation or vascular disease.

## How CMO affects sight

People may experience blurred or distorted central vision, difficulty reading and changes in colour or contrast. The pattern of cysts is typically seen on OCT scanning.

- Common causes include cataract surgery, uveitis and retinal vein occlusion
- Treatment depends on the underlying trigger and may involve drops, injections or tablets
- Addressing inflammation or vascular leakage is crucial
- Regular imaging helps track response to therapy

## Further information

Assessment and treatment of CMO are part of the [medical retina](https://bluefinvision.com/medical-retina/) service at Blue Fin Vision®. Macular swelling and its management are described in [diabetic retinopathy treatment options](https://bluefinvision.com/blog/what-is-diabetic-retinopathy/).