from Tar, animal fat, gold wire Paint Polymethyl methacrylateThe nearly 5,000-year journey from the periodic table to the perfect prosthetic eye, or even plexiglass, is a journey through time. It’s also a story of art.
in July 1937 Popular Science He described the technique of making the artificial eyes using glassblowing techniques that date back to 16th-century Venetian glassmakers. The glass used in 1937 was a special stock imported from Germany. Its unusual properties derived from the work of dollmakers in the early 19th century, who had learned to infuse glass with oxygen to make lifelike eyes. CryoliteCryolite is a milky white mineral composed of sodium, aluminum and fluoride that was first discovered in Greenland. However, with the start of World War II, German exports of cryolite glass came to a screeching halt, forcing artificial eye makers to look for new sources of glass and new materials.
Enter polymethyl methacrylate (PMMA), the first acrylic used in dentistry. Since the 1940s, PMMA has been the most widely used material for prosthetic eyes, but prosthetic eye technology continues to advance. New materials, parts, tools, processes, and more recently, 3D printing, improve appearance, comfort, function, cost, and more.
Becoming an ophthalmologist
Tar, clay, wood, metal, stone, glass, acrylic… what is it that binds the makers of prosthetic eyes? OphthalmologistThat artistry, passed down for thousands of years, is an essential element in creating a prosthetic eye. Regardless of the material, creating a prosthetic eye requires a lot of practice and the ability to mold, sculpt, and paint.
“It’s truly an intergenerational profession,” says Lindsay Pronk, an ophthalmologist at the University of Iowa Hospitals and Clinics. “There’s a family history; my father-in-law taught me,” she says. “I have a friend in New Jersey who’s the third generation, working with her father, and her father’s cousin is training his son on the West Coast, so he’s the fifth generation.” Pronk explains that while you don’t need a college degree to become an ophthalmologist, it takes “a five-year apprenticeship — three years on the job and two years making eyes,” totaling about 10,000 hours. Many universities offer certified ophthalmic technician training programs for students who want to assist ophthalmologists, but none are specifically for ophthalmologists. American Association of Ophthalmologists However, it runs its own ophthalmology college and, like other professional organizations, offers a board certification that requires passing a written and practical exam. Pronk is a Board Certified Ophthalmologist (BCO). As of 2022, There were about 170 BCOs. Practicing in the US.
Evolutionary trajectory
The oldest known artificial eye is a 4,800-year-old sphere with a dark circle in the middle connected with gold thread, discovered in 2006. Iranian ruinsThe ancient Romans and Egyptians created eye patch prosthetics. Painted clay and leather strapsIn 16th-century Europe, wood and ivory were the first materials used to make socketed prosthetic eyes, followed later by enameled gold and silver, but it was Venetian glassblowers who took prosthetic eyes to a level of lifelikeness, sparking centuries of innovation in glass eyes that improved appearance and comfort.
Given how important eye contact is as a form of human communication, the demand for realistic prosthetic eyes is not surprising. Research Presentation PLoS One 2016French and Swiss researchers have found that making direct eye contact with someone triggers a series of brain activities that make you aware of that person’s presence. Research to be published in 2024The researchers: Other Recent Studies Researchers report that eye contact is one of the main signals that evoke romantic feelings and intimacy. As for prosthetic eyes, even if they cannot restore vision, they can directly impact the quality of social relationships. So mobility is just as important as appearance. Even the most realistic prosthetic eye will be noticeable if it doesn’t move or isn’t synchronized with the functional eye.
Improving movement with implants
Today we take anesthesia for granted, but up until the late 19th century, surgery was often performed without it, especially in the case of eye surgery, which can be brutal and painful. Extraction (removal of the entire eye) or Evisceration Surgery (removing the contents of the eyeball but leaving the sclera intact) was performed as a last resort. A glass eyeball is a hollow scleral shell that is usually slid under the eyelid and placed over the existing non-functioning eyeball. But because it was not fixed in place, movement was limited.
In 1885 Philip Henry MulesBritish ophthalmologist Mules performed the first known intraocular cavity enucleation with an orbital implant, a marble-sized glass sphere inserted into the eye socket or orbit, restoring the overall shape and volume of the eye. A glass artificial shell was placed over the implant, not the eye. Mules’ implant was not attached to the orbital muscles (non-integrated), but still rotated slightly with the soft tissues of the orbit. Orbital implant surgery marked the beginning of a new chapter in artificial eyes.
Article published in life December 1948 The doctor vividly described a procedure developed by Boston researchers to place a spherical, pegged intraocular implant into the eye socket. The pegged implant is attached to the orbital muscle, allowing the ball to rotate in tandem with the functioning eye. A removable prosthetic eye clicks into the pegged implant and can be replaced if necessary. However, the implant’s acrylic and metal mesh material (also known as an inert material) used in the procedure proved unstable as the muscle would dislodge. The peg also left the socket vulnerable to infection.
Such integrated implants were first developed in the 1980s. Bio-integrated MaterialsHydroxyapatite extracted from marine coral replaced acrylic and saw a resurgence in this treatment. The porous properties of marine coral stimulated soft tissue growth, promoting implant integration and increasing stability. However, marine coral was a bit rough, so similar porous materials such as porous polyethylene and aluminum oxide followed.
Pronk says most implants now use porous acrylic to make them completely integrated. “We attach four muscles to the ball of the implant and sew tissue over it,” she explains. “Then all that tissue grows into the implant and it becomes completely integrated.” About six weeks after the orbital implant surgery, Pronk steps in. Using the same material dentists use, a mold of the eye is made to create a custom prosthetic eye. In the U.S., all prosthetic eyes are made from PMMA, and Pronk claims it has been that way for quite some time. “I don’t think there’s anybody doing glassblowing in the U.S.”
In addition to hand-painting the iris to match the real eye (a task that takes about six hours), Pronk also spends time adjusting the curvature of the prosthetic eye to make it identical. Comfort is key, as is “getting as much movement as possible.”
Less demand is a good thing
According to the U.S. Eye Injury Registry: Hasn’t been maintained for over 10 yearsIn the 1960s, it was estimated that 2.5 million people in the United States suffered eye damage each year, and 50,000 lost some or all of their vision permanently. Although such data is no longer collected directly, organizations such as the American Academy of Ophthalmology still cite these figures: These statistics As an indicator of demand for certain eye care services, especially ophthalmologists who fabricate custom prosthetic eyes.
But Pronk believes that in his 18 years as an ophthalmologist, the demand for artificial eyes is declining. A systematic review of global blindness trendsShe cites improvements in workplace safety laws and advances in surgery to save eyes after injury or trauma.
Although the process of making a prosthetic eye (taking an impression, casting with acrylic, hand painting the iris, and polishing) has remained largely unchanged for decades, that doesn’t mean the technology has stopped innovating. Digital photography to capture images of the irisThe technology will be printed on special adhesive paper and embedded into the prosthesis. First person to wear custom 3D printed eyesIn a study published in . Nature Communication in 2024Researchers from Germany and the UK evaluated an automated process for scanning, fitting and printing 3D prosthetic eyes in 10 patients. Patients rated the quality of the printed eyes highly, but the skills of an ophthalmologist were still required for final adjustments and shaping of the prosthetic eye. Even with automation, it turns out that skill is still required to create a realistic prosthetic eye.
Pronk believes digital imaging could help with creating prosthetic eyes, but he doesn’t think 3D printing, which starts with scanning the eye socket, is a significant improvement over the traditional process. Plus, the equipment is expensive. And he doesn’t think that either 2D or 3D printing can match the intricacy of a hand-drawn iris.
As for art, Pronk confesses she’s not very good at drawing, but she loves painting irises, paying close attention to detail and building up the layers to “give the illusion of more depth.”
As for future technological advances, Pronk doesn’t foresee much change in how prosthetic eyes are made, but he is encouraged by the advances being made in artificial vision by companies like: Elon Musk’s NeuralinkBut she thinks an eye transplant may come first: “Just like a liver transplant,” she says. “At that point, I’ll be out of work, but that’s a good enough reason to be out of work.”
