For those of you who have never heard of an amniotic membrane, we're going to enlighten you today and let you know many of the great applications it has. An amniotic membrane is actually the innermost layer of the placenta, an organ which a woman's body makes naturally when carrying a child. No fetal tissue is harvested or disturbed while these membranes are collected and made, and most membranes come from women who had a planned cesarean section. This avascular membrane requires no tissue typing because it carries no Human Leukocyte Antigen (HLA), which is responsible for tissue typing in humans. This makes it easy to use in medicine, because there's no worry about graft failure or problems with a patient rejecting the membrane.

These membranes can be used in a few ways. First, they can act as grafts post surgery. And second, they can be used as bandages for a variety of different eye conditions. When used in this way, the actual tissue does not integrate with the host tissue but rather acts as a temporary cover while the eye heals.

Why are amniotic membranes so amazing? Amniotic membranes contain many anti-inflammatory and antimicrobial properties that make them super useful in eye care. They contain cytokines and growth factors that can be used to regenerate corneal and conjunctival cells in conditions like Stevens-Johnson syndrome, ocular cicatricial pemphigoid, persistent epithelial defects from recurrent corneal erosions (RCE) and epithelial basement membrane dystrophy (EBMD), neurotrophic ulcers, and even severe dry eye. 

Amniotic membranes are becoming more widely used in optometry and ophthalmology clinics nationwide, and they've become a fantastic option for those with the above conditions who may have tried everything else.

These membranes are available in a few different types, the details of which we'll cover later in the article. However, amniotic membranes must be either cryopreserved or dehydrated before use because using a fresh membrane can carry disease transmission risks. Cryopreservation involves slow freezing at –80°C using DMEM/glycerol to allow for slow-rate freezing without ice formation. This allows the tissue to maintain the natural quantity and quality of key biological components needed for healing, including hyaluronic acid. The tissue must be stored in a –80°C freezer and brought to room temperature as needed for use on a patient.

Freeze dried, dehydrated membranes are another option, and these are preserved using a vacuum with low temperature heat to retain devitalized cellular components. There are conflicting thoughts on whether or not these maintain all of their helpful, healing components throughout this process, but they are still healing for many conditions.  These are conveniently able to be kept at room temperature, but they must be rehydrated for use on a patient.

To cover the cost a bit, amniotic membranes (depending on the type) will cost your eye doctor anywhere from $300-1000 each. This means that the cost will be higher for you. However, insurance will often cover this service or at least relieve some of the financial burden. Your doctor will likely attempt to get prior approval from your insurance company, but they will still have you sign a financial statement, insurance preauthorization form, and informed consent.

As far as side effects go, they are minimal because most people tolerate them very well. The biggest side effect is going to be blurred vision, because the membrane is opaque (you can expect 20/200 vision, usually). The only membrane which will not interfere as much with vision is the ProKera Clear, which has a 6mm opening for optimal vision. Some people will also report irritation with the ProKera brand of membranes because they do contain a large ring holding the membrane in place.

ProKera makes the only cryopreserved amniotic membranes available for ocular use, and they are made using the proprietary CryoTek process to maintain the extracelluar matrix of the membrane and allow it to support the regenerative process.  They are FDA approved for reducing inflammation and promoting scarless healing of the eye. Contraindications include those who have a glaucoma filter and those with allergies to Ciprofloxacin or Amphotericin B (which the membrane is stored in).

The ProKera comes in ProKera Slim, which is thinner, more comfortable, and works well for a wide variety of conditions, the ProKera Plus for those with more severe issues, and the ProKera Clear, which has a 6mm opening for optimal vision during the treatment. The ProKera Clear may make the most sense for those with limbal stem cell deficiency or for those with dry eyes. Each ProKera does come with a ring surrounding the tissue, which is inserted and then removed once the membrane dissolves, usually in one week. 

ProKera membranes can cost your practitioner between $900-1000, so you can assume your charge per membrane placement will be higher. However, insurance may cover a significant portion of this cost if prior approval is granted.

While not your typical amniotic membrane bandage used in eye care, the AmnioGraft is a cryopreserved graft (made by the makers of ProKera) used during ocular surgical procedures. It does not contain a ring like the ProKera. A few conditions which may warrant a graft such as this are corneal ulcers, pterygia, conjunctivochalasis dry eye, and Stevens-Johnson syndrome. 

Side effects of the graft are minimal, and within 2-3 weeks, the patient can expect to see full healing. This is not to say that they will never need treatment again, but it is promising. 

Each AmbioDisk is cleaned, dehydrated, and sterilized before use on a patient. Most of the time, freeze dried or dehydrated amniotic membrane allografts are used along with a bandage contact lens to ensure that the membrane stays in place. This is great news for those who have issues with the comfort of membranes such as the ProKera. There is no large ring on the AmbioDisk, and it's as thin as tissue paper, so you'll notice it much less.

Just like the ProKera and other allografts, the AmbioDisk costs a significant amount for your doctor to purchase, and it's a specialized procedure as well. The process of placing and monitoring your amniotic membrane graft will not be cheap, but insurance will often cover some of the cost. 

These two are preserved by a controlled moisture HydraTek process, which preserves a viable extracellular matrix with biologic components needed to support tissue function, reduce scar formation, and modulate inflammation. Each membrane can be applied in either direction, forward or backward, with no orientation issues, making for super easy application for your clinician. No bandage contact lens is needed either, which is helpful and even more comfortable for the patient.

These are available in a thin, amnion-only or a thicker chorion-based variety for improved handling and optimal treatment coverage. These are significantly less expensive for your doctor to purchase and stock, so these will likely cost you less as well. However, insurance will cover some of the costs associated with the membrane and placement of it.

In conclusion, if you've got a compromised cornea, an amniotic membrane may be something for you to consider. These healing tissues are a branch of regenerative medicine because they are actually able to regenerate cells in your cornea, and we think this is pretty amazing!