Advancing DED Diagnostics

Meet Dagny Zhu…
 

I’m Dagny Zhu, cataract and refractive surgeon in private practice in California. In my practice, we use a lot of premium IOLs – my patients tend to want the best outcomes possible which, of course, includes the highest degree of spectacle independence. Screening, diagnosing, and treating dry eye disease (DED) is a huge part of ensuring that we meet those expectations! This is especially true for patients undergoing laser vision correction and refractive lens-based or cataract surgery with a premium IOL, because the slightest presence of ocular surface disease (OSD) will affect the 20/20 outcome they want to achieve.

What's your assessment of the prevalence of DED?
 

We've seen a lot of studies on dry eye disease prevalence, and it's just astonishing in terms of the range. Depending on the population studies, it can be anything from five all the way up to 50 percent, though globally it is estimated at around 11-30 percent. In general, I think DED is absolutely underdiagnosed (1). For the average ophthalmologist seeing cataract and glaucoma, it can certainly feel like the prevalence is close to 100 percent – especially when you take into account that many patients are asymptomatic and/or have never been diagnosed. In cases when patients get closer to the age of needing cataract surgery, they are more likely to have DED – it is age-related, after all. However, even young patients are coming in with DED due to contact lens wear and/or increased screen time. I generally tell all my surgical patients that they have at least some level of DED so that they aren’t surprised postoperatively when dry eye symptoms suddenly manifest or worsen. I want them to know that it’s not an uncommon thing, they shouldn’t be scared of it, and that we have the tools to treat it both preoperatively and postoperatively in order to optimize their surgical outcome.

How do we change the underdiagnosing of the disease?
 

We have seen tremendous advancements when it comes to diagnosing DED compared to just five or 10 years ago, but the majority of ophthalmologists are still not using all the tools available to them. I have to admit, I was one of them. I relied on the basic tools, such as assessing punctate staining and tear breakup time using fluorescein. Placido-disc topography and the quality of the mires also provide clues about a patient’s tear film status. The problem with these modalities is that they are all highly subjective, which makes it difficult to track the efficacy of DED treatment from one visit to the next. The documentation and interpretation of exam findings can also vary significantly between providers. Schrimer’s testing provides a more quantitative approach to measuring the aqueous deficiency form of DED, but we know that patients almost always have a mixed form of DED with an evaporative component. Evaporative DED and tear film instability is easy and frequently missed on routine exam. That’s why I think it’s so important to have a more objective, quantitative tool like osmolarity testing. It gives you a numerical value to better quantify the severity of both aqueous deficiency and evaporative DED.

What are some of the advantages for doctors and patients in putting osmolarity testing into clinical practice?
 

It’s nice to show patients a numerical value, so they can better understand what’s “normal” and “not normal,” which also helps improve their motivation and compliance with treatment. You can say to patients, for example, that the normal range might be 310 or lower and here they are at 325! This resonates with them because they are familiar with other numerical lab values like blood pressure or blood sugar and that we want to get those numbers down! For the doctor, it doesn’t take much extra work or time to incorporate a device that improves our positive DED screening rate and catches asymptomatic patients that we would have otherwise missed. This “red flag” is especially helpful in our preoperative evaluation where we might postpone cataract surgery, add on additional treatments, or avoid selecting a premium IOL in patients with significant DED.

What do you think of the current state of the field in terms of treatment options for dry eye?
 

Dry eye treatment is so much more comprehensive, robust, and targeted than it used to be. In the past it was just lubrication with artificial tears and gels for everyone, but now we have pharmaceutical and procedural modalities that target specific pathways. For example, I will often combine cyclosporine or lifitegrast in conjunction with the usual artificial lubricants for patients with chronic DED. For patients with flare-ups, we have many low potency steroids options (e.g. loteprednol, fluorometholone, etc). On top of that, we have so many in-office treatment options for lid margin disease– a huge advancement over the old DIY advice of twice daily warm compresses and baby shampoo at home.

There have been a number of novel treatments on the market. One is a nasal spray (varenicline solution) that stimulates the pathway for tear production, something I now add for patients who are overburdened or noncompliant with traditional eye drops. I’m also looking forward to trying the newly approved MEIBO drop from Bausch and Lomb, which specifically tackles evaporative dry eye. It’s great to finally have something to address that unmet need. I don’t think any of these new therapeutics are necessarily superior, but they do allow us as physicians to better tailor our approach to make sure we get the best possible response. Using tear osmolarity testing is a great quantitative modality in these cases to monitor the patient’s overall response to DED treatment.

What are some of the issues indicated by hyperosmolarity testing?
 

Hyperosmolarity is both a sign and a cause of DED. When a patient has hyperosmolarity, it means the aqueous component is low, which is a sign of dry eye. However, interestingly, hyperosmolarity itself causes DED as it increases inflammation, causes toxicity to the epithelial cells, and decreases the tear film stability. It’s almost a catch-22 situation – hyperosmolarity indicates inflammation, but also drives that inflammation up further. This is why it’s so important to pick up on hyperosmolarity early and try to break that cycle!

How do you incorporate osmolarity testing into pre- and post-surgical care and follow-up?
 

I have been very deliberate in how I have incorporated osmolarity testing, especially into my pre-surgical workflow. Again, I assume all of my patients have some level of DED, and I want to know what the severity is to guide me in terms of IOL selection, dry eye treatment regimen, and management of patient expectations. All my technicians know that as part of a cataract workup, we’re not just getting biometry. Before anything goes in the eye, we’re first and foremost getting the osmolarity testing done, and we record that value in the patient’s chart. Sometimes, that value is obtained in advance before surgery where we can use it to better guide preoperative DED treatment, but sometimes, patients cannot come in for additional testing until the day of surgery due to their work schedules.

In those cases, I will review the tear osmolarity value on the day of surgery, and if I see that it’s high along with borderline variable keratometry readings or topography scans, I will often change my IOL selection from a premium to a monofocal IOL or even delay the surgery to dedicate more time to managing the patient's ocular surface. I can then show the patient their abnormal osmolarity value and explain that while their DED cannot be cured, it can be improved to give them the best surgical outcome. It is important to have those conversations beforehand because so often, patients assume that the surgery caused their DED. As a wise surgeon once said, “Anything you tell a patient before surgery is an explanation, anything you tell them after surgery is an excuse.”

What else would you like to pass on to eye care professionals about dry eye?
 

I think we really have to get everyone on board with being better about DED diagnosis and treatment. You might hear from KOLs at the podium in a big meeting about the importance of this, but I would love to see it become commonplace in every eye clinic! In the same way that in residency we were always taught that vision, pressure, and pupils were the most important vital signs of the eye, I think that an assessment of the ocular surface is critical because it impacts post-surgical recovery and outcomes as well as the long-term health of the eye. We should all be looking to learn more about the latest advances in ocular surface disease and be open to embracing and adopting new technologies to better diagnose and treat DED. If we don’t, we’re doing our patients a disservice, as it is our responsibility as ophthalmologists to stay up-to-date on the newest technologies that can improve our patients’ lives.