Rare diseases · Sign or symptom

Cataract

Clouding of the lens of the eye

HP:0000518

What it means

A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule.

Note that some ophthalmologists call any opacity in the lens a cataract, while others restrict the term to lens opacities that impair vision. We use the term to refer to the first meaning (any lens opacity).

In everyday care

Most people with this sign do not have a rare disease — it appears in common conditions far more often. These general reference pages cover the same topic:

Rare diseases that can present with this318

Very common80–99%

55

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 2 diseases where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Cataracts · Cloudy lens · Lens opacities · Lens opacity

Cataract

Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.

Start free with Eleplan

This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.