How can amniotic membrane benefit patients with acute ocular chemical injuries?
Ocular surface chemical burns can be presented to ophthalmologists in a range of severities and may involve damage to various structures of the eye. The most common cause of chemical injury is exposure to alkali or acid from occupational exposure in industry and agriculture, domestic accidents, and assault. In the UK alone, there has been a 90% increase in the number of acid attack violence in the last 10 years, meaning the incidence of these injuries are increasing. Healthcare professionals aim to provide a rapid treatment to tackle inflammation and drive the wound healing of the eye, but also prevent formation of symblepharon and provide pain relief.
Amniotic membrane (amnion) beneficial properties
Amnion is the innermost layer of the placental sac and its use in ophthalmic specialities has been popular since in the 1990’s. Amnion can provide a range of natural healing benefits due to natural structural barrier composition that allow for the tissue to provide an environment for the wound to reach healthy stability and quiescence.
One of the methods in which amniotic membrane can be applied to the ocular surface is as an onlay-graft (patch) transplant. Orientated epithelial-side-down towards the injured ocular surface, an amnion patch acts as a temporary biological bandage that protects the ocular surface from further insult; prevents the formation of symblepharon or ankyloblepharon and allows wound healing to take place. There is an emphasis on treating the eye within the acute phase of injury, to promote the best long-term outcomes for the patient.
Amniotic Membrane Transplantation
Traditionally, amnion transplantation requires sutures or glue and is therefore dependent on a surgical setting. Studies have shown that transplantation is most successful at promoting wound healing in patients that have moderate, rather than severe burns, most likely linked with limbal stem cell survival. These patients have been shown to have the best re-epithelisation rate.
Advances in amnion technologies means there are now ways in which amnion can be applied to the ocular surface without the need for sutures. This may be through the application of amnion using a bespoke contact lens (such as OmniLenz® from www.nu-vision.co.uk) or amnion placed around two rings (such as PROKERA® from www.biotissue.com). Alternatively, a larger piece of amnion can be used to cover burns to the ocular or entire mucosal surface, which is held in place with a symblepharon ring or IV tube.
When used in conjunction with medical management suture free acute application of amnion could offer a therapy that could drive patients towards and stable and healthy ocular surface.