What is a Cataract?

A cataract is a loss of transparency or clouding of the lens of the eye. The lens is the part of the eye that helps focus light on the retina and is located inside the eye behind the iris. It is responsible for 33% of the focusing power of the eye and the cornea, a clear structure at the front of the eye, provides the remaining 67%.

Cataracts cause a progressive and painless deterioration in vision, ranging from mild blurriness initially to severe loss of vision, where no shapes or movements are seen, only light and dark. Other symptoms include glare sensitivity, poor night vision, faded colours, and yellowing of images.

Globally, cataract is one of the leading causes of vision impairment with over 65 million people affected by it (WHO World Report on Vision 2019).

Image 01: To show what someone with blindness can see, the International Agency for the Prevention of Blindness created the image below.

What causes Cataracts?

Aging causes the lens to become compact and cloudy (a cataract), reducing the quality of vision and eventually interfering with daily activities and impacting a person’s independence. Cataracts are inevitable with age and will affect everyone eventually as they grow older, but they can also affect other age groups too. Some children are born with a cataract (congenital cataract) and early detection and treatment is vital to prevent permanent visual loss.

Other causes of cataracts include eye injuries and inflammation, underlying conditions like diabetes, certain medications such as steroids, tobacco use, exposure to sunlight (UV), and genetic disorders.

Image 02: A patient with cataract on his left eye. 

What is the Treatment?

Currently no eye drops are available to prevent or cure cataracts, instead a cataract is treated by relatively straightforward surgery. In cataract surgery, the cloudy natural lens is removed and replaced with an implant called an intra-ocular lens (IOL), restoring sight with the person able to see clearly within a few hours after surgery. Medication and care is needed for a few weeks after the surgery until the eye is completely healed.

Without treatment, cataracts eventually lead to blindness. Severe vision loss from cataracts disproportionately affects individuals in developing countries as they typically have reduced access to this sight-restoring surgery. The impact of cataracts extends beyond vision loss, affecting work, education, and family life. This keeps people in the poverty cycle and can lead to premature death.

Cataract surgery is one of the most successful and cost-effective surgical procedures of all time.

-The World Bank

Image 03: A cataract surgery

History of Cataract Surgery

The term “cataract” stems from the Greek word “katarrhaktēs,” meaning “waterfall,” possibly alluding to the opaque appearance resembling rushing water. Cataract is as old as human civilization, and cataract surgery may actually be one of the first medical conditions people attempted to treat surgically.

The earliest recorded attempt at surgery was in the 5th century BC using the “couching” technique. This involved inserting a needle into the eye and moving it around to dislodge the cloudy lens away from the visual axis, instantly improving vision temporarily although with very blurry results due to the lack of lens focusing power. While the cataract was no longer blocking light, it remained inside the eye and the retained lens and lack of proper hygiene led to severe complications and blindness shortly after the procedure. Unfortunately, despite its risks and barbaric nature, couching is still practiced in some developing countries today due to a lack of access to eyecare services.

Cataract surgery improved in 1747 when the French Ophthalmologist Jacques Daviel successfully removed the cataract from the eye rather than merely dislodging the lens. However, there was no implant available to replace the lens and people required very strong prescription spectacles after surgery, meaning very thick glasses!

The Impressionist painter, Claude Monet, developed cataracts in his mid-fifties impacting his vision and ability to see colours, evident in the increasingly yellowed colour palette of his artwork at the time. Eventually he underwent cataract surgery on one eye in 1923, and combined with thick glasses, his vision significantly improved allowing him to return to his earlier artistic style with paintings appearing much more similar to his pre-cataract work.

The next big improvement was in the 1940s with the development of an implant to replace the cataractous lens using polymethylmethacrylate (PMMA). The English Ophthalmologist Sir Harold Ridley noticed that British Royal Air Force Flight Crew with eye injuries from shattered airplane windshields tolerated the small pieces of PMMA (Perspex) in their eyes. He concluded that Perspex would be the ideal material to make an artificial lens (IOL) and the first successful IOL surgery was performed in London in 1949.

Today sophisticated foldable IOLs are used worldwide, and surgical technique continues to improve.

Image 04: A cataract couching by Indian doctors


Disclaimer: the information on this page is provided for general informational purposes only and is not intended to be medical advice. For medical advice, please contact your healthcare professional.