---
title: What causes secondary cataracts?
description: "'Secondary cataract' is a common term patients use for blurred vision that develops months or years after [cataract surgery](https://bluefinvision.com/cataract-surgery/). In most cases this refers to posterior capsule opacification rather than a new cataract. ## Posterior Capsule Opacification After surgery, the…"
url: "https://bluefinvision.com/knowledge-base/topics/conditions-diseases/what-causes-secondary-cataracts/"
updated: "2025-12-11"
category: "Conditions & Diseases"
---

# What causes secondary cataracts?

'Secondary cataract' is a common term patients use for blurred vision that develops months or years after [cataract surgery](https://bluefinvision.com/cataract-surgery/). In most cases this refers to posterior capsule opacification rather than a new cataract.

## Posterior Capsule Opacification

After surgery, the thin capsule that holds the lens implant is left in place. Residual lens cells can grow across this membrane, forming a cloudy layer that scatters light.

- Symptoms mimic the original cataract: blur, glare, and reduced contrast
- PCO is one of the most common late complications of surgery
- It does not mean the implant itself has failed

## Other Causes of Post-Surgical Blur

Macular oedema, dry eye, or unrelated retinal disease can also reduce vision after an initially good result. Careful examination distinguishes these from capsule changes.

## Treatment and Information

Most cases of PCO are treated with YAG laser capsulotomy to clear the visual axis. The Blue Fin Vision® blog article [blurred vision after cataract surgery](https://bluefinvision.com/blog/blurred-vision-2-years-after-cataract-surgery-causes-and-solutions/) explains these causes and treatments in more detail.