Eyeworld

AUGUST 2019 | EYEWORLD | 53 C the membrane. For example, in Stevens-John- son syndrome, Prokera doesn't cover enough of the eyes to be fully effective on its own, he said. Prokera can be used to cover the cornea, but in cases where there is extensive conjunctival sloughing, he will cover those areas with a sheet of amniotic membrane fixated with sutures. Fibrin glue can be used to attach amniotic membrane, but it does not work as well if some of the membrane extends over areas of intact epithelium, as is often the case in Stevens-John- son syndrome. Another form sometimes used is amniotic fluid drops, which have benefits for patients who have a non-healing epithelial defect such as a neurotrophic ulcer. "I've had patients who have partial limbal stem cell deficiency and they have a hard time maintaining a healthy epithelial layer on the cornea," he said, adding that while he has only tried this in a handful of cases, it seems to have helped heal epithelial defects when other significant measures have not. Overall, in Dr. Hovanesian's view, if physi- cians treat ocular surface disease and pterygium, using amniotic membrane will advance the standard of care that they offer patients. clinicians usually say it's up to the physician which type of material they prefer handling and which is more comfortable for the patient." Dr. Holland doesn't think the dehydrated form works quite as well. "If it's a sight-threat- ening case and I want the best amnion, I use cryopreserved," Dr. Holland said. "But if it's a persistent epithelial defect and we're using it for a smaller corneal lesion, then I use the dehy- drated form because of its convenience." The self-retained cryopreserved form of amniotic membrane is known as Prokera (Bio-Tissue), and the dehydrated form is known as AmbioDisk (Katena). With Prokera, a plastic ring is attached to the amniotic membrane, which is stretched across it like a drumhead, Dr. Hovanesian noted. With AmbioDisk, dried amniotic membrane is paired with a soft contact lens. Dr. Hovanesian finds both work well but has concerns that more patients experience pain with Prokera because of the ring. "These eyes are almost always inflamed and when you put a foreign object on top of that, they often will react," he said. Dr. Gregory pointed out that while the self-retained amniotic membrane is quick and easy to apply, it's not always the best way to use Financial interests Gregory: None Holland: BioTissue Hovanesian: Katena Dehydrated amniotic membrane is trimmed with scissors to an appropriate size to use as a graft after pterygium removal. Source: John Hovanesian, MD Join the largest subspecialty society representing the fields of cornea and external disease. www.CorneaSociety.org

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