Almost everyone will develop a cataract eventually. The only question is when. The surgery that treats it is the most performed operation in the world, with a success rate that is hard to match in medicine.

A cataract is simply a clouding of the natural lens inside the eye. The lens sits behind the pupil and is normally clear, bending light precisely onto the retina at the back of the eye. As a cataract develops, the lens gradually becomes cloudy, yellowed, or opaque. Light scatters rather than focusing cleanly. The result is vision that slowly becomes blurry, hazy, and increasingly difficult to work with. Cataracts are the leading cause of reversible visual impairment worldwide, and the treatment, when the time is right, restores vision reliably and quickly.

How Vision Changes With a Cataract

The changes happen so gradually that many people adapt without realising how much their vision has declined. You start needing more light to read. Oncoming headlights at night feel uncomfortably bright, or have halos around them. Colors look slightly washed out or yellowed. Then one day you realise that even with new glasses, things still aren’t quite right.

Typical symptoms

• Blurred or hazy vision that glasses cannot fully correct
• Increased sensitivity to bright light and glare, especially driving at night
• Colors appearing faded, yellowed, or less vivid than they used to be
• Needing a lot more light for reading or close work
• Frequent changes in glasses prescription
• A temporary improvement in near vision (called second sight) in some cataracts, followed by deterioration as it progresses
• Halos or starbursts around lights at night

Types of Cataract

Age-related cataract

The vast majority of cataracts are age-related. The lens proteins gradually break down and clump together over years or decades, clouding the lens. Most people over 65 have some degree of lens clouding, though not all are symptomatic enough to need surgery. Age-related cataracts can affect one or both eyes.

Nuclear, cortical, and posterior subcapsular cataracts

Age-related cataracts are classified by where the clouding occurs within the lens. Nuclear cataracts affect the central core and are the most common. Cortical cataracts develop in the outer layers, producing spoke-like opacities that cause significant glare. Posterior subcapsular cataracts form at the back surface of the lens and tend to progress more quickly, causing disproportionate glare and difficulty reading even when the cataract appears relatively small. This type is also associated with steroid use and diabetes.

Other types

Congenital cataracts are present from birth or develop in early infancy and require urgent treatment to prevent deprivation amblyopia. Traumatic cataracts can follow a direct eye injury. Secondary cataracts develop as a consequence of other eye conditions such as uveitis, or as a side effect of prolonged corticosteroid use. See our steroids in eye care page for more on this.

When Is Surgery Needed?

There is no medical urgency to operate on most cataracts. The right time is when the cataract is affecting your daily life in a way that matters to you: when driving has become unsafe, reading is genuinely difficult despite good lighting and glasses, or work and leisure activities are badly affected. That decision is yours, guided by your ophthalmologist’s assessment.

Waiting is not harmful in most cases. But there is no benefit to it either. The cataract won’t improve. It will slowly get worse. A more advanced cataract is technically more challenging to remove than an earlier one. And in the meantime, the vision loss affects quality of life, independence, and safety in ways that are easy to underestimate when the decline has been gradual.

Cataract Surgery

How the operation works

Modern cataract surgery uses phacoemulsification. Through a tiny self-sealing incision at the edge of the cornea, a fine ultrasound probe breaks up and removes the cloudy lens. The natural lens capsule, a thin membrane that surrounded the lens, is left in place. A foldable artificial intraocular lens (IOL) is inserted through the same small incision and unfolds inside the capsule. No sutures are needed. Fifteen to twenty minutes, local anaesthetic, awake but comfortable throughout, home the same day.

Choosing an Intraocular Lens

Standard monofocal lenses

The most commonly used IOLs are monofocal lenses set for one focal distance, usually distance vision. Most patients with monofocal lenses will still need reading glasses after surgery for near tasks. These lenses are highly reliable and are used in the majority of cataract operations worldwide.

Premium lenses

Extended depth of focus (EDOF) lenses provide a continuous range of vision from distance to intermediate with some near function. Multifocal lenses split incoming light to simultaneously focus near and far. Both types involve trade-offs, most commonly some degree of halos or glare around lights at night. Not every patient is a suitable candidate. The discussion with your surgeon about which lens fits your life is one of the most important conversations before the operation.

Toric lenses

For patients with significant astigmatism, toric IOLs correct both the cataract and the astigmatism simultaneously, producing sharper unaided distance vision than a standard lens would achieve in the same eye.

If you would like to learn more, the American Academy of Ophthalmology’s cataracts page offers a clear overview of cataracts, symptoms, diagnosis, and treatment.