Acute corneal injuries respond to amniotic membrane treatment
Cryopreserved amniotic membrane can reduce or reverse the effects of vision-threatening conjunctival scarring, dry eye disease and stem cell dysfunction.
Corneal chemical injuries and ocular surface burns, whether acidic or alkaline, can result in vision-threatening conjunctival scarring, dry eye disease and stem cell dysfunction. Conventional treatment methods, such as irrigation, antibiotics, steroids and even stem cell and corneal transplants, have limitations and risks. Timely use of sutured or self-retained cryopreserved amniotic membrane provides a safe and effective means of returning acutely damaged corneal tissue to its original state.
When patients incur a corneal chemical injury, they should immediately flush the affected eye with sterile saline solution, if available. If it is not available, fresh water is acceptable. Although not ideal, flushing with fresh water is better than worsening a chemical burn. Next, they should head to an emergency department or their eye care provider where the pH is immediately checked and the affected eye is irrigated with 1 L to 2 L of sterile saline solution. After 30 minutes of irrigation, litmus paper should be used to recheck the pH in the conjunctival fornix. Once the pH is returned to 7.0, an eye exam can be performed and treatment can be implemented.
Acidic chemical injuries tend to do damage to the ocular surface, whereas alkaline injuries can saponify the cornea, doing damage to the anterior segment of the eye as well as the ocular surface. With either of these injuries, patients can sustain conjunctival scarring, stem cell dysfunction/damage and dry eye disease.
Stem cell dysfunction is one of the main causes of chemical injury-associated vision loss. Stem cells form a barrier between the cornea and the conjunctiva. When that barrier is disrupted, this can lead to corneal scarring, conjunctivalization of the cornea and poor healing of the epithelium. In turn, compromised healing can result in corneal melting, infection and loss of corneal sensation. Conjunctival scarring causes goblet cell loss and scarring of the lacrimal gland ductules, and can introduce lid malposition and poor lid closure, all causing dry eye disease. If the scarring causes the lashes to touch the eye, the cornea can become irritated, leading to serious ocular surface damage.
In the acute phase of a chemical injury, the first step is to flush the eye to neutralize the pH and then to provide a course of antibiotics to prevent infection. After the acute phase, lubrication and treatment with Restasis (cyclosporine ophthalmic emulsion 0.05%, Allergan), Xiidra (lifitegrast ophthalmic solution 5%, Novartis) or Cequa (cyclosporine ophthalmic solution 0.09%, Sun Pharmaceutical Industries) can be prescribed to treat the dry eye disease and rehabilitate the ocular surface. At this point, if there is scarring, surgical treatment of the affected eyelid may be necessary.
Either self-retained cryopreserved amniotic membrane (CAM) (Prokera, Bio-Tissue) or sutured CAM (AmnioGraft, Bio-Tissue) can be used to successfully treat acute corneal conditions and injuries. Both CAM forms contain a cryopreserved amniotic complex: heavy chain-hyaluronic acid (HC-HA) and pentraxin 3 (PTX3). The components in this complex are present separately in adults but can only be found together in fetal tissue. HC-HA/PTX3 is preserved only in the cryopreservation process; dehydration does not preserve this complex. This cryopreserved amniotic complex is responsible for CAM’s anti-inflammatory, anti-angiogenic and anti-scarring properties, as well as its regenerative property, which allows treated corneal tissue to revert to its original state.
The cryopreservation process preserves AM’s biological properties, which are essential for its anti-inflammatory and anti-scarring effects. Dehydration, on the other hand, alters the structural and biological integrity of AM tissue, breaking down HC-HA/PTX3 to pro-inflammatory, low molecular weight hyaluronic acid. Thus, CAM may be a better choice for treatment of acute vision-threatening conditions and injuries.
Self-retained or sutured?
Self-retained CAM is the best choice in cases of acute chemical injury or for patients in burn units as a result of severe thermal burns because Prokera’s ring acts as a symblepharon ring to prevent symblepharon formation and helps to maintain its placement. These patients often cannot be transferred to the operating room to have fresh amniotic tissue sutured in, and self-retained CAM is easy to insert in the intensive care unit. In the more chronic phase of an acute injury, after the eye has scarred, sutured CAM is an excellent choice to act as a substrate to help heal the fornix.
CAM is effective in the acute phase of vision-threatening injuries for anywhere from 6 days to 2 weeks and is equally useful long term for reconstruction of the eye. Whether in the case of a stem cell transplant or reconstructing the fornix, it is a powerful adjunct that has no risk for increasing infection, and it is equipped with properties that encourage corneal healing and tissue regeneration.
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- For more information:
- Mark Milner, MD, associate clinical professor at Yale University Medical School, Department of Ophthalmology, and partner and director of cornea, GoldmanEye, can be reached at GoldmanEye, 3502 Kyoto Gardens Drive, Suite B, Palm Beach Gardens, FL 33410; email: firstname.lastname@example.org.
Disclosure: Milner reports he receives consulting fees or is on the advisory boards of Allergan, Novartis, Bausch + Lomb, Sun, Omeros, Avedro, Ocular Science, Kala, Valeant, Dompe, Bio-Tissue and Eyevance; receives honoraria from promotional, advertising or non-CME services from Allergan, Novartis, Bausch + Lomb, Sun, Avedro, Dompe, TearScience, Ocular Science, Valeant, Bio-Tissue and Eyevance; does contracted research for Kala, EyeGate, Icare, Biotherapeutics and Aldeyra; and has ownership interest in Eyevance, Percept Technologies and RPS.