Amniotic membrane is a unique biological material increasingly used in medicine, particularly in ophthalmology. This specialized tissue is derived from the innermost layer of the human placenta, typically obtained from healthy, consenting donors during elective cesarean sections. After careful screening for transmissible diseases and sterile processing, it is prepared for therapeutic use on the eye’s surface. The membrane functions as a therapeutic bandage, offering a protective and regenerative environment for damaged ocular tissues.
The Healing Properties of Amniotic Membranes
Amniotic membranes are effective in eye treatment due to their distinctive biological attributes. They serve as a physical barrier, shielding the delicate ocular surface from external irritants and reducing friction from eyelid movements as healing occurs. The membrane also contains a rich array of bioactive factors, including growth factors, cytokines, and matrix proteins, which actively promote the growth and migration of new, healthy epithelial cells on the cornea. This cellular support is facilitated by the membrane’s basement layer, which provides a scaffold for cell adhesion and differentiation.
Amniotic membranes possess anti-inflammatory properties, reducing swelling and discomfort by suppressing pro-inflammatory cytokines. They also inhibit fibroblast growth and reduce protease activity, preventing dense, vision-obstructing scar tissue. The tissue also prevents unwanted new blood vessel growth that can impair vision. Being naturally avascular, the amniotic membrane presents a low risk of immune rejection, making it a well-tolerated allogeneic dressing.
Ophthalmic Conditions Treated
Amniotic membranes treat various ocular conditions, primarily those affecting the cornea and conjunctiva where surface healing is compromised. They are applied for persistent corneal epithelial defects, which are wounds on the eye’s surface that struggle to heal. Patients with severe dry eye disease, especially with corneal damage like keratitis, may find relief as the membrane aids in repairing the ocular surface. This treatment is also beneficial for neurotrophic keratitis, a degenerative corneal condition resulting from nerve damage.
The membrane offers therapeutic benefits for acute injuries such as chemical or thermal burns to the eye, helping to mitigate further damage and promoting tissue regeneration. It also treats corneal ulcers, including those involving thinning or perforation, by providing a biological dressing that fills the cavity and supports healing. Following eye surgeries, such as pterygium removal, amniotic membrane transplantation can reconstruct the conjunctival surface and minimize scar tissue formation, aiding in a smoother recovery.
The Application Process on the Eye
Amniotic membrane application varies depending on the specific condition and severity. One common approach is the sutureless method, where the membrane is pre-mounted within a self-retaining ring or similar device, resembling a large contact lens. This device, such as PROKERA, is gently inserted onto the eye’s surface after topical anesthetic drops are administered. The ring holds the membrane in place, allowing it to continuously release healing factors while protecting the ocular surface. This in-office procedure is less invasive and often chosen for conditions that do not require surgical intervention.
For more severe or complex ocular surface diseases, a surgical graft method is used, typically performed in an operating room. In this procedure, the amniotic membrane is carefully placed directly onto the damaged eye surface and secured using fine sutures or a specialized tissue adhesive (fibrin glue). This ensures firm adherence of the membrane to the affected area, providing a stable scaffold for extensive tissue repair. The choice between the sutureless device and a surgical graft is determined by the specific needs of the patient and the nature of their ocular surface condition.
Patient Experience and Recovery
Patients undergoing amniotic membrane treatment may experience common sensations during the healing period. If a sutureless device, like a PROKERA lens, is used, it may cause a foreign body sensation, similar to having a large contact lens in the eye. This can lead to discomfort and potentially blurry vision while the membrane remains in place. Eye doctors often advise patients to avoid rubbing their eyes and may suggest a temporary tape tarsorrhaphy, where the eyelid is partially taped closed, to help the lens stay settled.
The membrane typically remains on the eye for several days, often two to seven days, though some types may dissolve naturally over about a week. For devices that do not dissolve, removal is a simple, quick procedure performed by the eye doctor during a follow-up visit. Post-treatment care involves using prescribed antibiotic or steroid eye drops to prevent infection and manage inflammation. Patients are advised to take it easy, avoid strenuous activities, and refrain from swimming for a period to promote optimal recovery.