A Critical Sense
The proverbial “in the blink of an eye” doesn’t always describe a tenth of a second, but when it does, it’s describing the fastest muscle in the human body: the orbicularis oculi.
Responsible for controlling the eyelid, the orbicularis oculi protects the complex inner workings of a crucial human sense. The cornea, the iris and the lens — to name a few of the essential pieces — work in tandem to extrapolate and define images from their surroundings. And while there are many steps along the way, vision begins with light — specifically the amount of light let into the eye. The iris, or the part of the eye that provides each person with their distinctive eye color, widens or narrows in an effort to let in more or less light as needed.
Without an iris, whether due to a congenital problem or a physical trauma, people are unable to dampen the light that enters the eye. And they are unable to see.
Karolinne Maia Rocha, M.D., Ph.D., the director of the Cornea & Refractive surgery division at MUSC Health, works with patients with aniridia — those who don’t have an iris or have injured their iris. She recently performed a rare iris transplant along with an intraocular lens implant procedure, which returned vision to her patient’s injured eye and ceased his photophobia, or light sensitivity.
“It’s an exciting surgery,” said Rocha. “You’re not just restoring the cosmetic side of things when you perform an iris implant, but you’re restoring the functional aspect as well. Patients can see better. They can begin driving at night, and they can play golf. They can have a normal life.”
Rocha was the first surgeon in the U.S. to perform an artificial iris implant after it was approved by the FDA, and she did so at the MUSC Health Storm Eye institute in 2018. And in 2021, she performed the hospital’s second.
Rocha’s recent patient experienced a trauma in 2013 that caused a ruptured globe. Since that time, he has been wearing a very thick contact lens, but he still lacked any light protection without an iris and so was unable to see properly. With Medicare’s recent expansion to cover iris implants, Rocha was able to perform the procedure for her patient. She hopes to perform more in the future now that it is more accessible.
HumanOptics used photos to design and handcraft an artificial iris that closely resembled the brown and gold hues of the patient’s corresponding, healthy iris. The replacement iris took about 8 weeks to create.
Prior to surgery, Rocha and her team photographed their patient’s eyes. HumanOptics, a medical device company based in Germany, then used these photos to design and handcraft an artificial iris that closely resembled the brown and gold hues of their 73-year-old patient’s other, healthy iris. The replacement iris took about 8 weeks to create and was sent with a second, extra iris in case anything was amiss during surgery.
This particular procedure consisted of three major steps — an anterior vitrectomy, a secondary intraocular implant and the artificial iris implant — all of which were performed through 3-millimeter incisions to protect the clear outer layer of the eye known as the cornea.
The lens and the retina are separated by a clear, gel-like liquid called vitreous humor. Made of 98% water, the vitreous also contains bundles of collagen fibers suspended in hyaluronic acid which give it a thicker and more elastic consistency. By removing any part of the vitreous that could cloud the lens or may have entered other parts of the eye through surgical incisions, Rocha ensured clearer vision for the patient after the iris replacement.
After clearing the vitreous humor and placing the intraocular lens using a scleral fixation technique and a one-piece intraocular lens, Rocha and clinical cornea fellow Ryan Mercer, M.D., moved on to the iris transplant portion of the procedure.
Rocha performs an iris replacement on a patient with a previous iris injury which rendered him unable to see.
To ensure the smoothest insertion of the iris, Rocha pre-sutured it and measured it again for accuracy. In order to keep the iris in place, it must be attached to the white portion of the eye, the sclera. Suturing the iris once it was already under the cornea would have required a larger incision, so Rocha and Mercer began the sutures prior to implanting. After measuring and trimming the iris transplant for size, they looped the thread around the edge of it. Next, Rocha folded it burrito-style into the injector. This tool allowed her to insert the iris under the cornea through smaller incisions and then unfold it in the correct position with sutures already in place for the final attachment.
If the patient has part of an iris remaining, as was the case with this patient, Rocha keeps it in the eye.
Rocha then inserted the new iris underneath the former iris, securing it to the sclera.
Past cases have shown Rocha that if the iris is not sutured into place and thus moves, patients can experience uveitis-glaucoma-hyphema syndrome (UGH syndrome), which leads to chafing in the eye.
“We prepared the sclera for pre-suturing by making small grooves or holes ahead of the iris placement,” said Rocha. After this preliminary step, she passed the sutures already in place on the iris through the sclera, securing it in place.
The iris implant can also come with or without fiber throughout. Rocha says that while there are benefits to both, she prefers the fiberless silicone transplant because it is easier to fold into the injector. Rocha also notes that while the silicone iris is fixed and cannot widen or narrow with light changes like a natural iris would, the implant is hardly noticeable to other people, and it controls enough light to allow the patient to see better.
In terms of recovery, some patients may expect a rise in intraocular pressure following surgery as well as an increase in inflammation and potential corneal folds. Rocha suggests next-day follow-ups to make sure the recovery is going smoothly. “Most patients are seeing well within a week, just like this one,” she said.
By performing surgery at a tertiary medical center like MUSC Health, Rocha is able to help her patients see again. And while MUSC is one of a handful of places performing this procedure, Rocha is looking forward to helping more patients in the future now that the surgery has become more accessible and affordable.
