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How does a cataract interfere with vision?

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How lenses and mirrors affect light and vision — lens Explanation of the refraction of light through different lenses.

A cataract interferes with vision by causing an opacity in the crystalline lens of the eye, which is normally a transparent structure responsible for focusing light onto the retina.12

When the internal lens fibers become disorganized or undergo changes—such as hardening, yellowing, or browning—they lose their ability to transmit light effectively. This obstruction results in several visual symptoms, including:13

Cloudy or blurred vision: The primary effect of the reduced transparency.13
Glare: Increased sensitivity to light.1
Color vision problems: Difficulty with color discrimination.13
Refractive changes: Frequent shifts in eyeglass prescriptions.13
Double vision: Occurring rarely in the affected eye.1

The severity of these symptoms depends on the type and location of the opacity within the lens. While early stages may be managed with corrective lenses, progressive deterioration often requires surgical removal of the clouded lens and replacement with an artificial intraocular lens.13