The European Approach to Dry Eye

Christophe Baudouin is Professor of Ophthalmology at Versailles Saint-Quentin en Yvelines University, Versailles, France, and a chairman of Quinze-Vingts National Ophthalmology Hospital, Paris. He is also a founder and President of the European Dry Eye Society (EuDES). Here, he outlines the need for a non-linear approach to treating dry eye.

Why did you establish a dry eye society in Europe?
 

There was already an Asia Dry Eye Society – founded by my friend, Kazuo Tsubota, in Japan – and based in the US there is TFOS (the Tear Film & Ocular Surface Society). But there was nothing in Europe. With respect to those organizations, the Asian approach and the American approach are slightly different. Some of the dry eye experts in Europe were already working together, writing papers on inflammation, on the vicious cycle of dry eye, the mechanism of dry eye, and so on, so it was logical that we create a society around the  European approach. And it has been very successful – we now have more than 3,000 members and we’re planning our fourth congress in Madrid in June 2024, after successful events in Paris and Munich.

I was also inspired to create EuDES by the European Glaucoma Society (EGS). I’m also a glaucoma specialist; I wanted EuDES to do for dry eye what EGS does for glaucoma. There’s also EuCornea for corneal disease, which includes but is not dedicated to dry eye; and the European Society of Cataract and Refractive Surgeons (ESCRS), which of course is focused on refractive and cataract surgery.

In terms of the other dry societies, particularly TFOS, how do their definitions and classifications differ from those of EuDES?
 

TFOS has done a great job and produced some really useful work; I was a member of this society myself. Their definition of dry eye – and their way of understanding it – is absolutely correct. But they advocate a linear approach; in other words, mild, moderate, more severe, and very severe dry eye follows a line. So, the recommended treatment is also linear. But I would say that patients are not exactly like that. There are discrepancies between signs and symptoms; it’s not linear. Twenty years ago, I devised a concept I called the dry eye vicious cycle. In my view, the vicious cycle is a way to understand the non-linear mechanism of dry eye, which means that, at some point, patients have a disease that is self-stimulated. Hyposecretory or evaporative dry eye – or whatever causes abnormalities of osmolality – stimulates the nerves, stimulates the inflammation, and results in additional loss of tears. It is a vicious cycle. There are also plenty of other causes of dry eye – the menopause, the environment, refractive surgery, contact lenses, glaucoma, preservative-containing eye drops, and cataract surgery. It’s a mix of different causes. But if we understand that they are not independent causes but simply different entry points into the vicious cycle, we have to take a nonlinear approach.

TFOS has partly adopted the vicious cycle idea, but they have modified it and made it somewhat complex. My approach is more basic. You have points A, B, C, and D, and effectively, you have an idea of what is causing and self-stimulating dry eye.

What’s on your dry eye wish list as an ophthalmologist?
 

I would say the use of preservative-free eye drops should be the first-line option. In reality, standard artificial tears are in most cases over-the-counter (OTC) products with preservatives, which actually may induce and aggravate dry eye disease. The patient will move progressively from mild to moderate. For moderate conditions, we use preservative-free eye drops, but they’re more expensive. The patient’s symptoms will improve, but they will start to find it a bit too expensive and go back to the OTC eye drops with preservatives. So, preservative-free artificial tears – or those with soft preservatives, for example, Purite or SofZia in the US – would be at the top of my wish list for first-line treatment.

Second, we still need a treatment that really tackles the mechanism of dry eye, such as  cyclosporine. We have a new formulation of cyclosporine, which is good, but we don’t have Lifitegrast in Europe. Lifitegrast hinders the T-cell activation and release of inflammatory mediators, and consequently inhibits the inflammatory pathways in dry eye. We need more treatments like this that really target the mechanism. Blocking inflammation seems to be the most efficient way to treat dry eye. We certainly need other anti-TNF (human tumor necrosis factor) anti-inflammatory or immunomodulatory medications. There is work being done on the role of TNF and interleukin-17 (IL-17) in various ocular surface inflammatory diseases, and that is an area that needs to be expanded.

There is also the issue of pain; some dry eye patients can move progressively to chronic pain. Drugs targeting the nerve receptors could be useful for those patients. There is a tendency now, which in my opinion is partly correct and partly incorrect, to say that when the cornea is not damaged, then this is neuropathic pain, and the treatment recommended antidepressants or strong analgesics. But when we use biomarkers in such patients we often, not always, find inflammatory mediators, inflammatory markers, or inflammatory cells. We didn’t see the origin of the pain because there was no stain, reflected in the saying “no pain, no stain.” So, better biomarkers for identifying those slight and non-visible mechanisms, those sub-clinical mechanisms, would also be on my wish list.

What is planned for the EuDES congress in Madrid?
 

The program is now almost complete! We will be including important topics such as how to recognize meibomian gland dysfunction (MGD) and treat patients with severe cases, and how to treat inflammatory reactions. We will talk about iatrogenic dry eye, which can be difficult to treat – do you go down the path of medication, surgery, laser surgery, or cosmetics? Also, last year we opened the floor to new companies – not to explicitly promote their products, but to show and explain what they are developing. We’ll also be doing that again this year.