A cataract is a common condition where the typically clear, natural lens inside the eye becomes cloudy, causing vision to blur and fade over time. This clouding is caused by the breakdown and clumping of proteins within the lens structure, which prevents light from passing through clearly to the retina. While modern surgery provides a quick and highly successful solution, the earliest attempts to restore sight were rudimentary, dangerous, and practiced millennia ago.
The Ancient Practice of Lens Couching
The first surgical interventions for cataracts date back thousands of years, with evidence pointing to practices in ancient India and Egypt as early as 800 BCE. The earliest method was known as couching, which remained the standard approach for nearly two millennia. This technique was not designed to remove the cloudy lens, but rather to displace it from the central line of sight.
The procedure involved using a sharp, pointed instrument, often a needle, to pierce the eye and push the opaque lens downward and backward into the vitreous humor. Though successful in clearing the visual axis, the displaced lens often led to severe complications, including infection, inflammation, and glaucoma.
The technique was documented in texts like the Sushruta Samhita, an ancient Indian Sanskrit medical treatise from around 600 BCE. Even if successful, the patient was left with an eye that lacked its natural focusing lens, a condition called aphakia. This meant any restored vision was highly blurred and required thick spectacle lenses for useful focus.
The Shift to Surgical Lens Extraction
A fundamental change occurred in the mid-18th century, signaling a shift from merely displacing the lens to intentionally removing it from the eye. The French ophthalmologist Jacques Daviel is widely credited with performing the first planned extracapsular cataract extraction (ECCE) in 1747, marking the beginning of modern cataract surgery.
Daviel’s method involved making a large incision, often exceeding 10 millimeters, at the edge of the cornea. Through this opening, the surgeon would remove the hardened, cloudy core of the lens, leaving the outer layer, or capsule, in place. This intentional removal represented a significant technical advancement, leading to a much higher rate of success than previous methods.
This new extraction technique still carried considerable risks, including infection, hemorrhage, and poor wound healing. Following Daviel’s work, a variation known as intracapsular cataract extraction (ICCE) emerged, documented by Samuel Sharp in 1753. ICCE involved removing the entire lens, including its capsule, which often resulted in higher rates of complications like retinal detachment. For over a century, surgeons continued to refine these methods, but the problem of the eye being left without a lens persisted.
Defining the Modern Cataract Procedure
The 20th century introduced three major technological innovations that transformed the procedure into the precise, high-success surgery known today. The first was the invention of the intraocular lens (IOL) by Sir Harold Ridley, a British ophthalmologist, following World War II. Ridley observed that fragments of polymethyl methacrylate (PMMA) plastic from aircraft canopies, when lodged in the eyes of injured pilots, did not cause severe inflammation.
This observation led him to design a synthetic lens made of PMMA to replace the eye’s natural lens after extraction. Ridley implanted the first IOL in 1950, solving the problem of aphakia and eliminating the need for extremely thick glasses after surgery. Although initially met with skepticism, the IOL concept became the foundation for all modern lens replacement surgery.
The second major advancement was the development of phacoemulsification, or “phaco,” by American ophthalmologist Charles Kelman in the late 1960s. Kelman adapted ultrasonic dental technology to eye surgery. Phacoemulsification uses a small probe that emits high-frequency ultrasonic waves to break the hard lens nucleus into tiny fragments, which are then immediately suctioned out of the eye.
This technique allowed the entire procedure to be performed through a much smaller incision, typically 3 to 4 millimeters, drastically reducing recovery time and surgical complications. The combination of phacoemulsification, advanced operating microscopes, and foldable IOLs inserted through the small incision has made cataract surgery one of the safest and most frequently performed procedures globally.