in the Blink of an Eye
by Jill Spotz
ransplants and implants are becoming increasingly important in eye surgery, especially when trauma destroys tiny eye structures critical for vision. Take the case of the young man who sought the help of UMDNJ-New Jersey Medical School (NJMS) ophthalmologists when hot cement burned the entire surface of his eye. Or the child whose eye orbit was fractured during a baseball game and was rushed to UMDNJ-University Hospital’s Level I trauma center. Response to severe trauma always demands incredible skill, experience, and speed to stop the cascade of damage to the body. For ocular trauma, performing repairs in small, intricate spaces with the latest technology is the reason NJMS ophthalmologists are sought after in times of crisis.
One new procedure to save damaged eyes is called DSEK or Descement Stripping Endothelial Keratoplasty. A suture-less surgery that replaces only the back portion of a damaged cornea, it has a far shorter recovery period than its counterpart — full cornea transplants. As David Chu, MD, assistant professor in the Institute of Ophthalmology and Visual Science at NJMS explains, in cases where the endothelial layer of the cornea is diseased or has sustained trauma, it can be replaced with donor tissue from an eye bank. Chu performed his first DSEK procedure in 2005 and has helped dozens of patients regain their eyesight so far. “DSEK takes less than an hour and is completed on an outpatient basis,” he says. “The benefit of this type of surgery over traditional cornea transplants is that the patient’s vision returns to normal in about one month as opposed to one year.” Why the fast recovery time? “Because the wound is much smaller and there are no sutures to keep the graft in place,” he says.
According to the National Science Foundation and Research to Prevent Blindness, more than 11 million people in the U.S. suffer from cornea disorders. Many have experienced irreversible cornea damage and are in need of corrective surgery. Full cornea transplants have been the surgical solution offered to patients with corneal diseases like Fuchs’ corneal dystrophy or herpes keratitis and ocular trauma. In addition to the long recuperation period, complications include poorly predictable glasses or contact lens requirement following the surgery, risk of a ruptured wound, and for patients who require the procedure in both eyes, the first one must be healed before surgery can begin on the second.
Comparatively, DSEK is a technically more challenging procedure, but the results are more predictable. During the surgery, the patient is given a numbing medication and is fully awake, if the patient chooses local anesthesia. Small incisions are made to the cornea and the unhealthy endothelial cells are removed. This is what is known as Descemet stripping. These old and damaged cells are replaced with healthy donor cells. In order to help the new cells adhere to the back of the cornea, an air bubble is used to press the tissues together. The risk of both intra-operative as well as post-operative complications is significantly less compared to full thickness corneal transplants. However, there are still risks, including dislocation of the graft, which may require a return trip to reposition the donor cells. Chu also adds, “Only patients with endothelial cell issues are candidates for this type of procedure. Patients who have corneal scarring or other conditions would still require a full cornea transplant.”
Another surgeon who like Chu is well equipped to handle even the most difficult cases is Paul Langer, MD, assistant professor of Ophthalmology at the Institute of Ophthalmology and Visual Science at NJMS. For individuals suffering blunt trauma to the face, resulting in the buckling or breaking of bones around the eye, he’s the one to call. Langer sees about 150 patients with orbital fractures each year, making him particularly experienced in this arena. Orbital fractures are complex injuries caused by anything from car accidents, falls, violence, even accidentally getting hit with a baseball bat. As Langer explains, “The orbit comprises seven facial bones, with the orbital floor (the part under your eye) being the thinnest and weakest.”
Langer replaces the fractured bone with an implant made of a porous material that actually becomes part of the body. The implant is a polyethylene plate, surrounding a thin sheet of titanium, making it pliable and easy to work with. “The benefits of this type of implant are numerous,” says Langer. “The implant is stronger than one made of just polyethylene, but unlike pure titanium which has to be screwed into position, this implant has plastic on the surface, so we can glue it in place. Because it is porous, the orbital tissues grow into it and the implant becomes incorporated into the body.”
Langer accesses the fracture by making an incision inside the eyelid, avoiding a visible external scar. When orbital bones are ruptured, oftentimes a hole develops allowing tissue to fall inside the sinus cavity and beneath the orbit, compromising movement of the eye. “We pull the tissue out of the cavity and then place the implant under the eye to cover the hole in the bone,” he explains.
In ophthalmology, treatment of difficult trauma cases may call upon the most unlikely of materials. Chu treats difficult ocular surface injuries with one of these unlikely tissues — amniotic membrane. Originally used to treat skin burns, amniotic membrane is the perfect material to implant in the eye because it is so delicate. The membrane, which is the innermost layer of the placenta that protects the fetus, has been shown to reduce healing time, assist in cell regeneration, decrease inflammation and serve as an anti-microbial barrier. Amniotic membranes are collected from consenting maternal donors during elective caesarian sections. The membranes are frozen and stored for up to one year in banks, or dried, to be stored on the shelf. Up to 70 pieces of stamp size amnion can be harvested from one placenta, to be used for a variety of ophthalmic applications.
Chu explains that when the ocular surface sustains chemical or thermal injury, the stem cells of the corneal and conjunctival epithelium may be severely damaged. “Amniotic membrane transplants can promote the healing of this severely damaged tissue and protect the eye.” Chu is currently reviewing the long-term outcomes of these cases and he intends to present his findings at an international scientific meeting this fall. He still remembers one of his first patients. “Hot cement fell into his eye. It burned the whole surface so it was not just a chemical injury but a heat injury as well. We replaced the ocular surface with amniotic membrane and within the first month we performed two more amniotic membrane surgeries. Subsequently, he also required a corneal stem cell transplant, corneal transplant, and cataract extraction. When the referring physician sent him to University Hospital he said it was likely he would lose that eye — six years later our patient has 20/40 vision.”
As Chu and Langer have demonstrated, new technology and materials are offering ophthalmologists better ways to repair orbital fractures, replace ocular structures, restore injured surfaces and ultimately save those baby blues.