Modern intraocular lenses (IOLs) are now a routine part of cataract surgery, but their invention represents one of the most important turning points in the history of eye care. For patients, this innovation is the main reason cataract surgery can restore clear vision without the very thick glasses or contact lenses that used to be necessary.[1][2][3][4]

Early cataract surgery: before lens implants

For centuries, cataract surgery involved either displacing the cloudy natural lens deeper into the eye (“couching”) or removing it altogether without replacing it. Although this could improve vision, patients were left extremely long-sighted and dependent on heavy, thick spectacles to see clearly, particularly for near tasks. In the first half of the 20th century, cataract extraction had become safer and more precise, but there was still no way to put a new lens inside the eye, so the optical limitations remained.[2][5]

Sir Harold Ridley’s observation

The modern intraocular lens arose from the clinical observations of a British ophthalmologist, Sir Harold Ridley, during and after the Second World War. While treating Royal Air Force pilots with eye injuries, Ridley noticed that small fragments of cockpit canopy plastic (polymethyl methacrylate, or PMMA) lodged in the eye often remained inert and did not provoke the severe inflammatory reaction seen with glass. This biocompatibility suggested that a carefully shaped piece of the same plastic might be used as a permanent artificial lens inside the eye.[4][6][1][2]

Ridley developed the idea further with the help of engineers and industry partners, having lens blanks manufactured from high‑grade PMMA. At the time, the concept of leaving an artificial object inside the eye after surgery was highly controversial, and many colleagues were sceptical or openly hostile. Nonetheless, Ridley persisted, convinced that restoring a focusing lens inside the eye would give far better visual results than relying on strong external spectacles.[7][8][1][4]

The first intraocular lens implantation

On 29 November 1949, at St Thomas’ Hospital in London, Ridley implanted the first intraocular lens into the eye of a 45‑year‑old woman undergoing cataract surgery. The lens was made of PMMA and placed in the posterior chamber after removal of the cloudy natural lens, in an era before modern small‑incision techniques. The early implants lacked the fine supporting structures (“haptics”) used today and were relatively crude by modern standards, but the principle was proven: a transparent artificial lens could be tolerated long‑term inside the eye and provide useful focusing power.[8][1][4][7]

Ridley presented his results in the early 1950s, but initial reaction from the medical community was largely critical, with concerns about complications such as lens dislocation, inflammation, and glaucoma. Despite this, he continued to refine his technique and lenses, and a small number of surgeons in the UK and abroad began to adopt and adapt the idea.[1][4][7][8]

Refinement and wider adoption

Through the 1950s and 1960s, lens designs evolved from early Ridley lenses to anterior chamber lenses and iris‑supported designs, as surgeons experimented with different locations and fixation methods to improve stability and safety. At the same time, cataract surgery techniques improved, with better microscopes, sutures, and instruments making intraocular procedures more predictable. These developments gradually reduced complication rates and improved visual outcomes, helping the concept of IOL implantation gain broader acceptance.[5][9]

A major leap came with the development of phacoemulsification in the 1960s and 1970s, which used ultrasound to break up the lens so it could be removed through a much smaller incision. This paved the way for foldable intraocular lenses in the 1980s, allowing the lens to be inserted through tiny corneal incisions that often require no stitches. Over subsequent decades, IOLs diversified into monofocal, toric (astigmatism‑correcting), multifocal, and accommodating designs, giving surgeons and patients more options to tailor vision after cataract surgery.[3][9][5]

Impact on patients and modern practice

The invention of the intraocular lens has transformed cataract surgery from a restorative but visually limiting procedure into a highly effective refractive operation that can correct vision and reduce dependence on glasses. For most patients today, an IOL is chosen to match the eye’s measurements and visual needs, offering clear distance vision and, in some cases, improved focus at multiple distances or reduction of pre‑existing astigmatism. The operation is usually performed as a day‑case through a very small incision, with rapid recovery and high levels of patient satisfaction.[9][3][5]

From a historical perspective, Ridley’s insight that the eye could tolerate a plastic lens, and his decision to implant the first IOL in 1949, fundamentally changed ophthalmology and the outlook for people with cataract worldwide. For patients reading about cataract surgery today, the routine use of intraocular lenses is the direct legacy of that work, and underpins the excellent visual results that modern cataract surgery can now reliably provide.[4][5][7][9][1]

Sources
[1] Harold Ridley and the invention of the intraocular lens - PubMed https://pubmed.ncbi.nlm.nih.gov/8658339/
[2] Cataract Surgery: History and Intraocular Lens Implants - Indiana Eye Clinic https://indianaeyeclinic.com/blog/cataract-surgery-history-and-intraocular-lens-implants/
[3] The Evolution of Cataract Surgery: A Brief History https://www.reevewoods.com/blog/the-evolution-of-cataract-surgery-a-brief-history.html
[4] Sir Harold Ridley as the Pioneer of Intraocular Lenses https://pmc.ncbi.nlm.nih.gov/articles/PMC11453175/
[5] Cataract surgery: historical devices, modern innovations, ... https://www.tandfonline.com/doi/full/10.1080/17434440.2024.2419477
[6] Sir Harold Ridley 1906 - 2001 -pioneer of cataracts https://www.stjohnswoodmemories.org.uk/content/new-contributions/sir-harold-ridley-1906-2001-pioneer-of-cataracts
[7] Harold Ridley and the Invention of the Intraocular Lens https://rayner.com/wp-content/uploads/sites/5/2021/12/Invention_of_the_IOL.pdf
[8] Casanova and the Spitfire pilots (The Story of the Development of the Intraocular Lens) https://pmc.ncbi.nlm.nih.gov/articles/PMC1860162/
[9] The Evolution of Cataract Surgery https://spacecoastophthalmology.com/the-evolution-of-cataract-surgery/
[10] Harold Ridley (ophthalmologist) - Wikipedia https://en.wikipedia.org/wiki/Harold_Ridley_(ophthalmologist)