By tar, animal fat and gold threads to paint polymethyl methacrylate, or plexiglass, the nearly 5,000-year journey to perfect prosthetic eyes has been an odyssey through the periodic table. It has also been an art story.
In July 1937, Popular science described the art of making artificial eyes using glassblowing techniques dating back to 16th-century Venetian glassblowers. The glass used in 1937 was special stock imported from Germany. Its unusual properties are derived from the work of early 19th century doll makers, who had learned to make realistic eyes by imbuing glass with cryolite, a milky white mineral of sodium, aluminum and fluoride that was first found in Greenland. However, when World War II broke out, German exports of cryolite glass came to a standstill, forcing prosthetic eye makers to look for new sources of glass and new materials.
Enter polymethyl methacrylate, or PMMA, an acrylic first used in dentistry. Although PMMA has been the most widely used ocular prosthetic material since the 1940s, artificial eye technology has not stood still. New materials, parts, tools and processes have improved appearance, comfort, functionality and costs, including, most recently, 3D printing.
About becoming an ophthalmologist
Whether they used tar, clay, wood, metal, stone, glass or acrylic, what has bound eye prosthetists, or ocularists, through the millennia is their artistry. Despite the medium, making artificial eyes requires a lot of practice and the ability to sculpt, sculpt and paint.
“It really is a generational career,” said Lindsay Pronk, an ophthalmologist at the University of Iowa Hospitals and Clinics. “You have family lines. My stepfather taught me,” she says. “I have a friend in New Jersey, she is third generation and still works with her father, whose cousin on the West Coast is training his son, who will be fifth generation.” Pronk explains that becoming an ophthalmologist does not require a college degree, but rather “a five-year internship – three years of on-the-job training and two years of eye-making,” for a total of about 10,000 hours. Many universities offer accredited ophthalmologist training programs for students who want to assist ophthalmologists, but there is no specific program for ophthalmologists. The American Association of Ocularists however, operates its own College of Ocularistry and, along with other professional organizations, offers board certification, which requires passing a written and practical exam. Pronk is a certified ophthalmologist (BCO). From 2022 there were approximately 170 BCOs practicing in the United States.
Following evolution
The oldest known artificial eye – a 4,800-year-old sphere with a dark central circle interspersed with gold threads – was discovered in 2006 at a archaeological site in Iran. The ancient Romans and Egyptians used it to make prosthetics in the form of an eye patch painted clay and leather straps. In 16th-century Europe, wood and ivory may have been the first materials used for socketed artificial eyes, followed by enamel-covered gold and silver. But it was Venetian glassblowers who took prosthetic eyes to a realistic level, leading to centuries of glass eye innovation that improved appearance and comfort.
Given how important eye contact is as a form of human communication, the search for realistic eye prostheses is not surprising. In a study published in PLoS One in 2016Researchers from France and Switzerland have found that direct eye contact with someone triggers a series of brain activities that attune us to the other person's presence. And in one study published in 2024researchers confirmed something other recent studies have reported – that eye contact is one of the most important cues associated with romantic attraction and a sense of connection. When it comes to prosthetics, artificial eyes can directly influence the quality of social relationships, even if they cannot restore vision. That is why, apart from appearance, dexterity is so important. Even the most realistic artificial eye will be noticeable if it is motionless or out of sync with the working eye.
Improving movement through implants
Today we take anesthesia for granted, but until the end of the 19th century, operations were performed without anesthesia. That meant eye surgery, which was particularly gruesome and painful enucleation (removal of the entire eyeball) or lash out (removal of the ocular contents, leaving the sclera intact) were performed as a last resort. Glass eyes were usually hollow eyecups that slipped under the eyelids and rested on the existing, non-functional eye. But his freedom of movement was limited because he was not restrained.
That was in 1885 Philip Henry Mules, an English ophthalmologist, performed the first known panceration, followed by an orbital implant, a marble-sized glass ball placed in the eye socket or clerical cavity to restore the eye's overall shape and volume. The glass prosthetic shell then rested on the implant instead of the eye. Although the Mules implant was not attached to the orbital muscles (non-integrated), it still rotated somewhat with the soft tissue of the socket. The orbital implant procedure heralded a new chapter in artificial eyes.
A story published in TO LIVE December 1948 provided vivid images of a procedure, developed by researchers in Boston, to place a spherical, pinned ocular implant into the eye socket. Attaching the pinned implant to the orbital muscles allowed the ball to rotate together with the working eye. A removable prosthetic eye clicked into place on the pinned implant and could be replaced if necessary. But the implant's acrylic and metal mesh materials – also called inert materials – used in the procedure proved unstable because the muscles would loosen; and with the pin the socket was susceptible to infection.
Such integrated implants were largely abandoned until a new one came along in the 1980s bio-integrated materialhydroxyapatite, derived from ocean coral, replaced acrylic, breathing new life into the procedure. It was the porous properties of ocean coral that stimulated soft tissue growth, improving implant integration and making it more stable. But ocean coral was a bit rough, so other similar porous materials followed, such as porous polyethylene and aluminum oxide.
According to Pronk, most implants are now fully integrated using porous acrylic. “They still attach the four muscles to the ball of that implant,” she explains, “and then sew the tissue over it. All that tissue then grows into the implant, making it fully integrated.” About six weeks after the orbital implant surgery, Pronk intervenes. Using the same material that dentists use, she makes a mold of the eye to create a custom prosthesis. In the US, Pronk claims that all artificial eyes have been made of PMMA for some time. “I don't think there's anyone in the U.S. who does glass blowing.”
In addition to hand-painting the iris to match the working eye, which takes about six hours, Pronk spends time adjusting the curvature of the prosthesis to ensure it is similar. Comfort is key, as is “making sure we get as much exercise out of it as we can.”
Declining demand is a good thing
According to the United States Eye Injury Registry, which has not been maintained for more than ten yearsThere were an estimated 2.5 million eye injuries in the US each year and 50,000 people permanently lost all or part of their vision. Such data is not directly collected today, but organizations such as the American Academy of Ophthalmology still cite it those statistics as a measure of demand for certain eye care services, including those ophthalmologists who make custom prosthetic eyes.
However, Pronk believes that the demand for prosthetic eyes has decreased during her 18 years as an ophthalmologist, which is in line with systematic reviews of global blindness trends. She cites improvements in workplace safety laws and advances in surgical procedures to save eyes that have suffered injury or trauma.
Even though the process of making prosthetic eyes – mold making, acrylic casting, hand-painting the iris and polishing – has remained largely the same for decades, technological innovation has not stood still. Some ophthalmologists are turning to digital photography to capture images of the iris, which is printed on special adhesive paper and embedded in the prosthesis. And in 2021 there was a British patient at University College London the first to be equipped with a custom 3D printed eye. In a study published in Nature communication in 2024researchers from Germany and Great Britain evaluated an automated process of scanning, fitting and printing 3D prosthetic eyes in 10 patients. Although patients gave high ratings for the quality of the printed eyes, the process still required the skills of an ocularist to make final adjustments and sometimes even shape the artificial eye. It turns out that even with automation, there is still an art to creating realistic artificial eyes.
Although Pronk thinks there is a role for digital imaging in creating prosthetic eyes, she is not convinced that the technology in 3D printing, which starts with scanning the eye socket, offers much improvement over traditional process. Moreover, the equipment is expensive. She's also not convinced that printing – 2D or 3D – can match the complexity of hand-painted irises.
When it comes to art, Pronk confesses that she cannot draw to save her life. But she loves painting irises, which requires her to pay attention to the smallest details and build them up layer by layer to “give a better illusion of depth.”
As for future technological developments, Pronk doesn't expect any significant changes in the way prosthetic eyes are made, but she is encouraged by some of the advances in artificial vision by companies like Elon Musk's Neuralink. But she wonders if eye transplants might come first. “Just like they do a liver transplant,” she says. “At that point, you know, I don't have a job anymore. But it is a good reason to be unemployed.”
