Everything We Know About AMD and Dark Adaptation
By Greg Caldwell, OD, FAAO
When automated dark adaptometry was first commercialized, many of us had more questions than answers with regard to using this information for detecting AMD and monitoring disease progression. But with more than seven years of practical in-office experience performing dark adaptation testing on thousands of patients, the tables have turned. This technology offers a safety net for providers and patients—not to mention the potential public health benefits that we are beginning to realize. Better still, optometry is leading the way.
Our profession is at the epicenter of changing a paradigm that simply wasn’t working. Focusing on end-stage disease is ineffective and expensive. It’s not how healthcare providers approach other diseases and it’s not how we should approach one that is a leading cause of irreversible blindness. In the following article, you’ll hear from several optometrists who practice in an array of settings. Each OD will share perspectives on how to raise the bar in AMD diagnosis and care.
Early Diagnosis is Essential
Q: What is the benefit of an early AMD diagnosis if there’s not yet an FDA-approved drug to treat it?
Dr. Dierker: We are fixated on a stage of disease that optometrists can’t do much about (i.e., advanced AMD) instead of taking a hard look at the statistics and asking what we could be doing to turn things around for our patients before things take a turn for the worse. The only way to do that is with early diagnosis.
Dr. Lighthizer: Presenting vision is critical. If a patient comes in and they’re already 20/60 or 20/70, are they going to get back to 20/20 or 20/30? I’d rather catch the asymptomatic patient before their vision is drastically reduced and start working with them to slow progression through lifestyle modification and possibly nutraceutical intervention.
Dr. Bynum: As with most conditions, early detection of AMD is preferred because, when we can detect disease early, we have an opportunity to make adjustments in the hopes of changing course. This option doesn’t exist when you don’t know a disease is present. Admittedly, there will always be factors we can’t control, such as age or DNA, but there are many other things that are within human control, such as diet, smoking, and exercise habits. Just as a prediabetic patient is on track to develop diabetes, early and subclinical AMD patients are on track to develop drusen that can lead to substantial vision loss over time. Don’t they deserve to know this? Particularly as patients live longer, there are more years to safeguard, which is why it’s so essential to educate them about modifications that are within their control.
Dr. Corbin: Imagine a cancer patient being told that they have to undergo chemotherapy or radiation treatment every month for the rest of their lives because the disease is already so advanced. Telling an AMD patient that they need injections or they’ll go blind isn’t much better. But this is how many patients are introduced to the realities of AMD. I consider this paradigm to be unacceptable.
Q: Are you concerned that patients would prefer to remain unaware of their condition?
Dr. Corbin: Telling patients they failed the dark adaptation test is far less difficult than explaining the significance of lots of small drusen. That’s not only scary, it also exposes our uncertainty.
Dr. Dierker: Years back, a few of my colleagues expressed concern that patients don’t want to know that they have a potentially blinding condition before it changes their life. However, at the time, I wasn’t testing every patient age 50 and older. I was giving patients the option and asking them if they wanted to be tested. Not only that, I was charging them $65 for the test. And even under those strict criteria, 50% to 60% of patients elected to have the test so they could be in the know and take control of their health. In short, this illustrated to me that my patients wanted to know.
Dr. Rodman: We shouldn’t get too hung up on words like “early” and “subclinical.” Keep in mind that when a patient has abnormal dark adaptation, structural damage has already caused functional abnormalities. Something is wrong—and it may or may not be AMD. It needs to be investigated and a plan must be developed. It’s not overly ambitious to want to pick up AMD based on functional deficits we can detect before they become the structural deficits that manifest clinically. I can’t think of any other condition where we would say, “don’t tell the patient too soon.”
Dr. Kirman: If you never did mammography, you wouldn’t see much early-stage breast cancer. Likewise with colonoscopies. Until recently, we didn’t see much early AMD. That’s all changed.
Dr. Bynum: We need to start thinking about AMD the way we think about other diseases like diabetes and hypertension. Regardless of what ocular condition we’re talking about, our primary job as optometrists is to preserve patients’ functional vision for as long as possible. That is my passion. I want to alter outcomes and protect my patients. The only way to do that is to detect disease early.
Dr. Lighthizer: I often hear colleagues say that they can easily diagnose AMD exclusively on the basis of structural changes, and I don’t doubt that. By the time a patient has extensive drusen, the diagnosis is obvious. But think about the bigger picture. With any disease, do we want it to get so bad that we easily can see it? With AMD, this approach is even more dangerous because, by the time we can see it, he or she already had clinically abnormal night vision for at least three years. Optometrists play the long game with patients’ ocular health and, if we stay on top of it, AMD can be a long game rather than a short devastating loss. That’s why I won’t wait until I see extensive macular changes to start treating patients. I use dark adaptation testing so I can intervene at the earliest stage possible.
You Can Monitor AMD with Confidence
Q: Does dark adaptation remove all of the guesswork from AMD management?
Dr. Rodman: Not all of it, but interpretation is so simple with dark adaptation. It’s not like trying to subjectively interpret a fundus photo or predict what a patient’s drusen will look like in six months or a year. In my experience, dark adaptation provides clarity in the face of ambiguity.
Dr. Lighthizer: I agree. There’s no perfect test in medicine—not in eye care or in any other specialty. I wish it were that simple, but until we can put our patients in a machine that tells us exactly what’s wrong and exactly what we should do about it, we have to put the pieces together. That used to be pretty challenging because we had a very incomplete picture. We didn’t have the data we needed to make informed decisions. All of that has changed thanks to dark adaptation and OCT. There are other tools as well that allow us to further refine and define, but these two tests are where we start and, in most cases, finish.
Dr. Corbin: I look at four things: clinical findings, acuity, OCT, and dark adaptation. This gives me the whole picture, which is important because it’s rare that each of the tests, individually, tell the same story—at least not until it’s far too late.
Q: Does dark adaptation increase the number of patients you have to refer out to ophthalmology?
Dr. Lowe: Not at all. The additional information dark adaptation provides me makes my referrals timelier. I now have a way to predict who is progressing and how quickly they might progress.
Dr. Dierker: Unfortunately, retina specialty practices are bursting at the seams with patients who have manifested the sequela of undiagnosed or unmanaged disease.
Dr. Corbin: The burden on retinologists is tremendous. They are seeing advanced AMD in patients with many more years of life ahead of them. Unfortunately, they are too often getting the AMD referral after the patient has already lost vision they will never regain.
Dr. Legge: It’s also important to consider how dark adaptation can strengthen optometry if we refer to our optometric colleagues for specialty testing. The opportunities for OD-to-OD referrals are much greater when you embrace dark adaptation testing. For example, optical-focused practices sometimes send patients to our practice for dark adaptation testing. On the other hand, if you are monitoring a case and feel like more advanced tests are needed, you can refer out to an optometric retinal specialty practice.
Dr. Lighthizer: That’s an excellent point. Few of us have all the tests at our fingertips, but that doesn’t mean we should stop looking for answers when they’re this consequential. If you see a steady increase in dark adaptation time over several visits but the OCT still looks dry, OCT angiography can give you important information. If you don’t have angiography, you can refer out to a colleague who does. This advanced test might pick up an early choroidal neovascular membrane so you can detect the conversion to wet AMD that much sooner. This is definitely preferrable to waiting for the patient’s visual acuity to dive or for CNV to catch you unaware.
Take a Common-Sense Approach to Early AMD Treatment
Q: How do you know that early AMD is worth treating?
Dr. Ferrucci: We don’t know that it’s NOT worth treating. Contrary to what you may have heard, the AREDS2 authors never stated that supplements are useless in patients with early disease because that was outside the scope of the study and could not possibly be extrapolated from the data based on the study’s inclusion criteria. Patients with early disease were not included in AREDS2 to begin with. To directly quote the paper, “Enrollment was restricted to people between the ages of 50 and 85 years at high risk of progression to advanced AMD with either bilateral large drusen or large drusen in one eye and advanced AMD in the fellow eye.”ii That means both eyes had to be at the intermediate stage, or one eye at the intermediate stage and one eye at the advanced stage.
Dr. Karpecki: If early AMD weren’t worth treating, companies wouldn’t be spending millions of dollars trying to develop new drugs and devices for it. We may not have a magic bullet yet, but the preventative interventions that we do have are helpful and keep many patients from going blind.
Dr. Gerson: I agree. In the absence of longitudinal studies demonstrating outcomes after 20-plus years of preventative treatment, we have to rely on our medical knowledge to make conclusions derived from proven facts regarding the pathophysiology of AMD. The underlying process that drives the damage is no different in early-stage versus late-stage disease. The only difference is how far down the continuum the patient is. You don’t wait for a patient to have a heart attack before you start working on lowering cholesterol, and you don’t wait to treat a patient with pre-perimetric glaucoma. The same logic applies to early AMD.
Dr. Pizzimenti: It’s also important to note that closer monitoring is, in and of itself, a form of treatment.
Q: What gives you confidence that you’re doing right by your patients when you recommend treatments for early AMD?
Dr. Pizzimenti: We often treat high-risk patients who have small drusen, even when we have no way of confirming they have AMD, so if dark adaptation confirms the diagnosis, I would not hesitate to treat.
Dr. Gerson: We all live by the motto: Do no harm, so I ask myself, “what approach is most likely to help me achieve that end?” Monitoring patients more consistently and prescribing supplements isn’t going to make anyone go blind. I can’t say the same for the alternative. Beyond that, research shows that carotenoid-based supplements improve vision, whether someone has AMD or not. So, if all we do is help a patient see better, is that worth it? That’s why I got into optometry in the first place, and it’s the most obvious of all the clinical decisions I make.
Dr. Ferrucci: Evidence strongly suggests that patients with AMD should be prescribed some form of nutritional supplement.ii
Q: Are you concerned about the cost of supplements and other early AMD interventions?
Dr. Gerson: Blindness is far more expensive. Beyond that, we also need to look at the bigger picture. If a 60- or 70-year-old patient is not currently taking any vitamins, the benefits of an ocular supplement are going to do more than help out with AMD. On the other hand, most of my patients are haphazardly self-selecting supplements. In many cases, prescribing a specific formulation saves them money and ends up being less to swallow—literally.
Talk to Patients About AMD
Q: How do your patients react when you tell them you want to test them for AMD?
Dr. Caldwell: Not in the negative way that you might fear. Most patients have heard of AMD, and they want to avoid or delay vision loss. They’re eager to know as soon as possible so they can take charge of their health, especially if they have a close family member who lost vision. And when you show them the AdaptDx Pro®, they think it’s cool. Better still, if the test is normal, they celebrate.
Dr. Lowe: Even in practices where patients are asked to pay out of pocket for a rapid test, patients want answers.
Dr. Ferrucci: I don’t think there is anything to worry about in terms of how patients will react to our request to perform dark adaptation. Perhaps what some optometrists may be concerned about is the perception of their peers or of ophthalmologists. However, in my opinion, that is outdated thinking. If I went to my primary care doctor and he told me I had very early signs of heart disease that didn’t yet require medication, but it would make sense to start eating healthy, stop smoking, and lose some weight, I would be grateful for the heads up. I don’t understand why anyone, in this day and age, would argue that an early diagnosis is not beneficial.
Dr. Pizzimenti: There’s definitely a school of thought that in order to have true AMD, you have to have visible funduscopic change. But even if you’re afraid to put the AMD label on a patient, delayed dark adaptation indicates a retinal disease process is underway. Think about that in terms of the practical realities of life. Patients don’t always follow up on time. Pandemics happen. If a patient has no idea that they have subclinical AMD—or pre-AMD or borderline AMD or whatever you feel comfortable calling it—you may not see that patient for two years. Conversely, a patient’s risk-benefit ratio looks a lot different when they’re as concerned as you are about the potential consequences of gaps in care.
Q: Are patients nervous about the testing itself?
Dr. Lowe: Patients who have a family history of AMD are usually very nervous long before they’re tested. When you have an aunt or a parent who lost vision, you experience it deeply and you imagine what it would feel like. This nebulous uncertainty can be misery. Conversely, knowing puts the patient in a position of power. If everything looks normal, the patient can breathe a sigh of relief. And if it isn’t normal and we’ve caught it early in most cases, having a plan is much better than having unsubstantiated fear looming over you.
Dr. Bynum: Once they put the headset on and hear TheiaTM, my patients are impressed with our advanced technology. Even my patients in their 70s and 80s are used to talking to Siri and Alexa, so they are very comfortable having a similar personality as part of their medical testing.
Q: How do patients react if they fail the test?
Dr. Rodman: When a patient fails, we lead with, “This is your lucky day because we found a disease that used to be so hard to detect at this early stage, and now we can stay ahead of it, which is a luxury people didn’t used to have.”
Dr. Caldwell: This is where it’s important to empower patients and give them recommendations on how they can help themselves. Diet and lifestyle are important, but most patients opt for a supplement over more kale.
Dr. Ferrucci: If the disease is in a very early stage, it also helps to explain that the short-term chance of vision loss is relatively small. However, we all hope to live long, healthy lives. If that happens, as mortality rates would suggest is likely, we need to be thinking far beyond the next few years. Patients don’t lament having a discussion about how to improve their quality of life over the next 10 years, 20 years or 30 years. They appreciate the optimism and want to be living independently when they’re 90 years old. That’s much harder to do if you’re 90 and blind.
Q: Have new patients sought you out because they heard you adopted dark adaptation?
Dr. Lowe: All the time! There’s a 60-year-old woman at my parish who has AMD and, since we’ve established our AMD Center of Excellence, word has gotten out about our dark adaptation testing. A few months ago, this woman showed up at our practice with her 30-year-old daughter, requesting to be tested with the AdaptDx Pro. Obviously, that’s very young, but she’s a mom of two girls as well, and she’s worried for her whole family. They said, “Pam, we know you’ll be on top of this, so we’re switching to you.”
Dr. Gerson: Having cutting-edge technology to complement high-quality patient care is always a differentiator for any eye care practice. Once my patients experience the headset and the responsive feedback from Theia, they start referring their friends and family to our practice as well.
Dr. Lagunas: Our AMD practice is growing exponentially as a result of dark adaptation testing. It began even before we started using it on every patient over age 50. Now that we’ve fully embraced the AMD Excellence Program®, our growth is off the charts.
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About the Author
Dr. Caldwell is a 1995 graduate of the Pennsylvania College of Optometry. He is a fellow of the American Academy of Optometry (AAO) and a Diplomate of the American Board of Optometry (ABO). Dr. Caldwell currently works in Duncansville and Johnstown, Pennsylvania as an ocular disease consultant. His primary focus is the diagnosis and management of anterior and posterior segment ocular disease and he has been a participant in multiple FDA investigations. Dr. Caldwell has lectured extensively throughout the country and internationally. In 2010 he served as President of the Pennsylvania Optometric Association (POA) and from 2013-2016 he served on the AOA Board of Trustees. He is President of the Blair/Clearfield Association for the Blind.