Amniotic membrane (AM) is nothing new in the world of ophthalmology. It’s been around in clinical use for some 80 years, and clocks in at more than two million transplants per year. People use it because it works: It has known healing benefits, and is a solid anti-inflammatory, anti-fibrotic and anti-angiogenic agent.
But every once in a while, people discover that the way things have been done for a long time can be done significantly better. That’s the gist of a presentation at the recently held Swiss Academy of Ophthalmology (SAoO) 2021 annual congress. Dr. Andrew Hopkinson, founder and CSO of NuVision Biotherapies and a principal research fellow at the University of Nottingham, led the presentation. And the lesson? The potentials of Omnigen🄬 and Omnilenz🄬 (NuVision Therapies, Nottingham, U.K.) are omni-obvious, given the results shown. Dr. Hopkinson was backed up with a study presented by Dr. Mohamed Elalfy, a consultant ophthalmic surgeon at Queen Victoria Hospital.
This particular presentation should be a head-turner, because the findings inside make such sense it almost seems silly nobody came up with them decades ago.
We’ve Been Drying It All Wrong
The chief takeaway from Dr. Hopkinson’s presentation is this: Our historical methods of preserving AM can and have been improved upon, and he can prove it. The 20-year-old technologies of preservation have simply had their time, and it’s time for better tech to take over.
For the past two decades, AM has been frozen, freeze-dried or heat-dried to preserve it for later use. This had led to some limitations on the benefits one stands to gain from AM. As Dr. Hopkinson points out, it’s difficult to store, ship and use. It’s restricted to surgical situations, and isn’t available for in-office use.
And perhaps most crucially, the tissue is damaged in the process. If you’ve ever frozen a piece of meat, you know that the texture when thawed isn’t exactly the same as when it’s fresh.
That’s because ice crystals form inside the tissue if frozen or the tissue is otherwise damaged by heat or cold. Now, if you’re freezing a bit of chicken or sausage for later consumption — oh well, it’ll be fine. If you’re freezing a piece of delicate AM to be used in a medical context, however, being more careful with it seems like a sound idea.
Microscopic images shared by Dr. Hopkinson confirm just that, with fresh AM looking structurally very different from frozen. The look is far from the most important part, however. Previous storage methods lead to a significant loss of soluble regenerative compounds within the AM. Growth factors, proteases, cytokines and more all experience double digit percentage drops, reaching as high as 90% in cryopreserved amniotic membrane (CPAM).
What this means is that cryopreserved AM relies heavily on the physical mechanism for healing, and isn’t being used to its best ability. Simply put, we can do better.
New Processes, Better Healing
This is where NuVision really starts hitting its stride. The company has created a new method of preserving AM that radically improves the tissue’s retention of its healing compounds.
The process begins with what the company calls the Tereo method. There are three things that make it unique. First, the process removes all of the spongy layer. We’ll explain why that’s important later on. Second, it uses a protective washing step with raffinose sugar. Third, and perhaps most crucially, the tissue is dehydrated using low temperature vacuum evaporation.
That process solves a lot of problems that troubled previous preservation methods. When observed under a microscope, the vacuum dried amniotic membrane (VDAM) doesn’t even look substantially different from fresh AM. Any untrained eye could quickly spot the difference between CPAM and VDAM.
One major difference between CPAM and VDAM is permeability. Dr. Hopkinson pointed out that CPAM is quite permeable, with 33% of tissue samples being completely permeable. VDAM, on the other hand, is simply not permeable. This means the tissue is more intact.
That’s not all, though. Epithelial growth factor (EGF) remains significantly higher in VDAM than CPAM. Tack another point on the board for VDAM.
And, yet further, Dr. Hopkinson showed that CPAM actually increased corneal epithelial cell (CEC) death, while VDAM encouraged its growth. This may be attributed to the lack of a spongy layer.
In a rabbit model following chemical burns, both CPAM and VDAM showed improved healing versus a control group. Of course, CPAM isn’t a bad thing — it still helps. But a significant difference was that VDAM encouraged regeneration of damaged cells rather than the proliferation of new cells.
Highly Practical Uses
One of the greatest selling points of VDAM is its variability in use. It can be stored at room temperature, can be applied in a clinic as well as in surgery, and can be taken directly from the packet and applied right to the damaged area of the eye. Its size can be custom tailored to the eye and it’s easy to manipulate. What’s not to like?
We promise, we’re not salesmen here. We’re just impressed.
Another method of delivering VDAM developed by the company is Omnilenz🄬. This technique relies on a bespoke contact lens containing VDAM as an alternative way to deliver an AM transplant.
It’s a very quick procedure, taking no longer than four to six minutes. Currently, it relies on a 16mm lens with a 12mm piece of AM inside, though the company will soon be releasing a larger, 18mm version.
Dr. Hopkinson noted the Omnilenz can be used as a preventive or quick response measure rather than a reactive measure to handle all sorts of superficial conditions. Typical usage times for the lens are between 7-14 days, and it can be used repeatedly if necessary.
There are a few contraindications and precautions to note, of course. Doctors should look out for keratoconus patients or those with irregular topography as well as those with abnormal eyelids or antibiotic sensitivity. Children and heavy eye rubbers should be warned to, well, not rub their eyes so much. Dr. Hopkinson suggested an eye shield for children.
The Elalfy Alley-Oop
Dr. Mohamed Elalfy, a consultant ophthalmic surgeon at Queen Victoria Hospital followed up Dr. Hopkinson with some valuable statistics and a potential novel approach with the Omnilenz.
Dr. Elalfy and his colleagues conducted a study on 81 patients with 93 persistent corneal epithelial defects treated with Omnilenz. Just so we don’t get overwhelmed with numbers, here’s the key takeaway: Omnilenz was an overwhelming success, with the vast majority (89%) of patients needing one application of the Omnilenz. Just 8% needed two. The average treatment length was between 22-25 days, according to Dr. Elalfy.
An interesting note is that among these patients, the majority (59%) also showed improved best corrected visual acuity (BCVA). Of the rest, 27% were stable and only 14% worsened.
Interestingly, Dr. Elalfy noted that the Omnilenz could be cut and applied as a ring to help it stay in place. Otherwise, the Omnilenz still allowed enough transparency to make ophthalmic examination easy.
In general, we’re pretty darn impressed with this new technology, and can’t wait to see how it will positively impact the world of eyes. Kudos to the team.
Editor’s Note: The Swiss Academy of Ophthalmology 5th Annual Congress took place from March 3-5, 2021. Reporting for this story took place during the event.
