Amniotic membrane heals cornea, stimulates re-epithelialization
The device, which can be applied without sutures, is indicated for a wide range of corneal conditions.
A new treatment alternative for healing corneal wounds is now available in the form of Prokera, a biologically active amniotic tissue for topical ocular use.
“Prokera provides mechanical protection for ocular surface disease similar to a bandage contact lens, with additional properties that promote faster healing of the cornea,” private practitioner Kim Castleberry, OD, told Primary Care Optometry News in an interview. “It can also be used in conditions where bandage contact lenses are contraindicated, such as with herpes keratitis and corneal ulcers.”
According to literature from the manufacturer, Bio-Tissue Inc., Prokera, which is placed into a self-retaining device on the ocular surface, is indicated for the treatment of neurotrophic persistent epithelial corneal defect, infectious keratitis, filamentary keratitis, dry eye syndrome, exposure keratopathy and recurrent corneal erosion.
“If a dry eye patient has a damaged or eroded cornea and cannot heal, Prokera is a great way to jumpstart the healing process,” Allan Panzer, OD, told PCON.
The amniotic bandage tissue is also indicated for use before and after cataract and refractive surgeries, with Salzmann’s nodular degeneration, post-Descemet’s stripping endothelial keratoplasty and bullous keratopathy.
“As with a bandage contact lens, Prokera would be a short-term solution for those awaiting or not a candidate for surgery,” Castleberry said.
According to Bio-Tissue, the 16-mm device conforms to the ocular surface and inhibits angiogenic processes and inflammation, which provides scarless healing and stimulates healthy re-epithelialization of the cornea in moderate to severe ocular surface conditions. It also provides pain relief and reduces haze, resulting in improved visual acuity for patients.
The application procedure is fairly simple, Castleberry said.
The patient is seated in the exam chair with his or her head against the backrest. The optometrist removes the Prokera from the packaging and has the patient look down. The optometrist inserts the device into the upper fornix while holding the upper lid, then pulls the lower lid out and pushes the lower ring into the lower fornix, he said.
“Technique varies occasionally,” Castleberry added. “Sometimes the Prokera placement needs to be done in a minor surgery room with the patient in a supine position.”
The patient should be seen daily until the cornea is healed, and the retaining ring should be removed once the tissue dissolves or the patient exhibits an intolerance for it, he said.
Panzer and Castleberry both said they may use antibiotic drops in conjunction with the device to prevent any secondary infection.
Panzer usually sees the patient at 1 week.
“The membrane is usually gone by then,” he said, so he removes the retention ring.
Panzer added that when removal of the membrane is necessary, it is usually facilitated by the use of latex gloves.
“This helps you get friction on the lens,” he said.
Prokera undergoes a cryopreservation process that preserves the active extracellular matrix of the amniotic membrane. Extracellular matrix components found in cryopreserved amniotic membranes regulate and promote regenerative healing processes and tissue remodeling, whereas when an amniotic membrane is dehydrated, the extracellular matrix components are destroyed, leaving only its structural elements, according to Bio-Tissue.
Image: Tseng SCG
Prokera bears therapeutic advantages over bandage contact lenses (BCLs) because BCLs are not made from amniotic membrane and, as a result, have no anti-inflammatory or pro-healing properties inherent as in placental tissue, Castleberry said.
“Moreover the ring that holds the tissue in place fits looser than a contact lens, keeping lens adhesion from irritating the tissue. BCLs fit tighter and can cause mechanical irritation, or they can further inflame ulcers or herpes lesions, worsening the ocular conditions,” he said.
Prokera also has an advantage over other membrane bandage alternatives due to the fact it comes in the form of a contact lens, according to Panzer.
“Others come as just a piece of membrane, and the problem with that is you have to cut them and lay them on, sew them on or put a contact lens over top of them. That doesn’t work for your typical optometrist,” Panzer said.
“Optometrists are particularly suited to performing this procedure because of specific training and expertise in placing contact lenses and other medical devices on the surface of the cornea,” Castleberry added. “The amniotic tissue is delicate, and the ring is awkward to handle initially, but it is a simple procedure, similar to handling scleral and hybrid contact lenses.”
Patients may sometimes not prefer this treatment option, however, Panzer said.
“It’s a semi-opaque membrane, so we’re essentially asking the patient to lose their vision in one eye for 5 to 7 days,” he said. “They’re never too happy with that.”
Additionally, patients will be less comfortable with Prokera than with a BCL due to the size and thickness of the ring, according to Castleberry.
“However, because many conditions that necessitate Prokera use have associated pain, the Prokera will provide relief, and that will be attractive to the patient,” he said.
“In any event, the faster healing associated with Prokera will resolve most conditions in 2 or 3 days,” Castleberry added.
Prokera is reimbursable, but acquiring the reimbursement for the procedure can be tricky, Panzer said.
“It usually involves prior authorization and careful follow-up with the insurer,” he said.
According to Castleberry, his previous carrier paid optometrists for using Prokera, but his new carrier has not yet approved optometrists as providers for Prokera.
“There have been some insurance denials, but we’ve been successful in appealing all cases and we have received notification from the medical director that we are being added to the list of provider types to allow payment,” Castleberry said. – by Daniel R. Morgan