Cataract surgery is one of the oldest surgical procedures known, first documented in the fifth century BC. In ancient times, cataracts were treated with a technique called couching, which could only be performed when the lens had become completely opaque, rigid, and heavy to the point that the supporting zonules had become fragile. The eye would then be struck with a blunt object with sufficient force to cause the zonules to break so that the lens would dislocate into the vitreous cavity, restoring limited but completely unfocused vision.
Centuries later, the technique was modified so that a sharp fine instrument was inserted into the eye to break the zonules to cause the dislocation. The first reported surgical removal of a cataract from the eye occurred in Paris in 1748. The advent of topical anesthesia made this procedure more practical.
The early techniques involved removing the entire opaque lens in one piece using an incision that went halfway around the circumference of the cornea. It was critical that the lens remained intact as it was being removed, so surgery was restricted to so-called ripe lenses: cataracts so hardened that they would not break into pieces as they were being removed. This limited the surgery to only the most advanced cataracts.
Since fine sutures did not exist at that time, patients were kept immobilized with sandbags around their head while the wound healed. Consequently, the early literature reporting cataract surgery routinely documented the mortality rate (secondary to pulmonary emboli). The improvements in cataract surgery and the corresponding results over the past few decades have been nothing short of astounding.
The first major advance was the development of techniques allowing the removal of the lens while leaving the lens capsule behind. The intact capsule acted as a barrier preventing lens material from falling into the vitreous cavity. This allowed less advanced cataracts to be removed since any residual fragments could be removed at the time of surgery with aspiration and would not be retained in the vitreous, where they would incite inflammation.
This change also resulted in the reduction of the wound down to approximately a quarter of a corneal circumference. The introduction of fine sutures around this time greatly enhanced the safety and quality of results.
The most significant change marked by the modern era was the introduction of phacoemulsification surgery in 1967 by Dr. Charles Kelman. In this technique, ultrasonography is used to break the lens into minute fragments that can be aspirated. A combined ultrasonographic, irrigation, and aspiration hand piece allows the removal of any lens through a small incision. This revolutionized the performance of surgery, leading to smaller and smaller wounds. Today, routine wounds are <3 mm long, and 1 mm wounds are on the horizon.
As the evolution of surgical techniques progressed, the advancement in lens replacement technology was equally dramatic. Originally, no intraocular lens implants were used following cataract surgery, and patients had to rely on “Coke bottle”-thick hyperopic glasses. These were associated with a variety of unpopular optical aberrations.
Intraocular lenses evolved secondary to the pioneering work of Howard Ridley, a British ophthalmologist. He recognized that the penetration of shattered fragments from airplane windshields into the eyes of World War II fighter pilots when their planes had been hit did not always lead to damage. He created the first artificial lens from this material, leading to the creation of an entire industry. The evolution of smaller surgical incisions was matched by the development of new lens implants created out of different materials (such as acrylic and silicone) that could be folded to allow the lens to be inserted through a tiny wound.
At the present time, commercially available lenses can be inserted through wounds a little over 2 mm. Lenses are manufactured in a variety of different optical powers. Prior to surgery, patients undergo a series of measurements determining the optical length of their eye and the focusing power of their cornea to determine what will be the optimal intraocular lens power for them. The majority of the lenses currently implanted in North America are monofocal with a power chosen to restore good distance vision. This usually still leaves the patient dependent on glasses for reading.
When someone with a cataract makes the decision to undergo modern cataract surgery, there is yet one more decision that must be made: what type of intraocular lens (IOL) to have placed in the eye.
Dr. Swedberg and the surgical coordinator will discuss the various options available. These may include monofocal, toric, multifocal, pseudo-accommodating, and extended depth of focus (EDOF) IOLs. Such a broad range of choices can be a bit overwhelming. It was not always so.
As recently as the turn of the millennia patients were not given a choice as to what type of IOL to have implanted as there was no choice to be made. Only one type of IOL, “monofocal” was used. A half century prior even that option was not available.
That all changed with the pioneering work of Sir Harold Ridley, who first implanted an IOL in 1949. Although he is now considered a hero in the field of ophthalmology, he was initially demonized by many of his contemporary surgeons for placing a foreign object into the eye. Sir Harold Ridley’s early critics, however, had reason to be concerned.
At that time it was simply not known what would happen to a foreign material implanted in the eye. Today an intraocular lens (IOL) is almost always placed in the eye at the time of surgery. They are generally considered to be both safe and effective as all IOLs implanted in the USA undergo a rigorous process of evaluation by the FDA.
Nonetheless, modern eye surgeons know that not all material choices have proven to be long-lasting. There is a remote possibility for the IOL material to degrade after it has been implanted in the eye.
The implant is a synthetic lens designed to provide focus for your vision. They’re not donated from other humans and they’re not from animals. The common materials that are used here in the U.S. are acrylic, silicon and polymer.
The reason these materials are used is because they’re clear, they’re bio-compatible so the body doesn’t reject them and they’re flexible. The flexibility is important because the incision that’s created at the time of cataract surgery tends to be about two to three millimeters.
In addition to different materials being used there are actually different types or functions of intraocular lens – also known as IOLs. The lens implant is designed to be placed in the eye’s capsule, which has no nerve fibers, making it so that you cannot feel the implant.
However, when the implant is new to your eye, about 10% of people get undesired visual symptoms such as flickering or seeing a dark crescent from the edge of the implant. Over time, these undesired visual symptoms tend to lessen as your brain adjusts to the lens implant.