Better Patient Monitoring

Today's technologies can improve compliance by producing meaningful data for AMD patients and practitioners.

Dr. Smick: Imagine that a primary care optometrist has a patient with dry AMD who has 20/25 visual acuity and the practitioner starts to see changes. How should the patient be educated to ensure effective monitoring?

Dr. Gerson: Getting the patient to buy in to disease management is very important. Someone with 20/25 visual acuity sometimes fails to appreciate the potential dangers of his eye condition. Any test that helps demonstrate the problem and shows that you can monitor for abnormalities will be extremely helpful. When talking to patients, I use the analogy of puzzle pieces, telling them that we need to look at different pieces of the puzzle to figure out what the whole picture looks like. Different tests help educate me so I can educate them on what needs to happen.

Increased monitoring

Dr. Smick: Routine monitoring is critical to detect changes in the earlier stages of AMD, to enable us to refer for earlier treatment, but it can be difficult to get patients to comply with a more frequent follow-up schedule.

Dr. Shechtman: Compliance is always an issue. Consider how difficult it is to get glaucoma patients to use their drops as prescribed, even though they know glaucoma is a blinding disease. Sometimes using the diagnostic tools can help educate the patients and increase awareness. The more proactive we can be, the better off our patients will be. Taking 5 extra minutes to talk to the patient can make a big difference, keeping in mind that our role is both early diagnosis and to decrease the prevalence and progression of the disease.

Dr. Smick: Let's talk about all of the diagnostic tools that are available. Which tools are most valuable for helping us diagnose and manage AMD?

Dr. Ferrucci: In our practice, we have a room designated for macular degeneration testing. It includes a digital camera with fluorescein capabilities, an OCT, the Foresee PHP (Reichert) and the QuantifEye macular pigment optical density instrument (ZeaVision). I believe we need to use multiple tools for AMD, just as we do for glaucoma.^1,2

Dr. Shechtman: Working at a diabetic and macular clinic/referral center, we have a specialized area for AMD patients. I have access to the QuantifEye, the PHP and a Cirrus HD-OCT (Carl Zeiss Meditec). As much as possible, we should use all of these instruments, which complement each other. Each is unique, measuring a different aspect of the patient's pathology.

How is PHP different?

Dr. Smick: How would you say the PHP compares to the traditional visual fields used to monitor glaucoma? What value does this new technology offer in diagnosing and managing AMD patients?

Dr. Gerson: The PHP is comparable to a regular perimeter, but there are some significant differences. During the test, a patient observes a line of dots moving horizontally across a screen. Using a special pen, the patient marks any deviations that he sees on the dotted line. The PHP produces varying magnitudes of artificial distortions of the straight horizontal dotted line. These artificial distortions compete with pathological distortions caused by AMD and by a rise in retinal pigment epithelium (RPE). If a patient has a pathological distortion that is more pronounced than the artificial distortion, the patient will use the pen to mark his pathological distortion. This process is called preferential looking. The RPE abnormalities that cause these changes are often related to choroidal neovascular membranes (CNM) in AMD patients.

Patient response patterns are recorded and analyzed by a customized algorithm, which compares the responses to a normative database. Test results are generated immediately in a detailed report. PHP technology can identify CNV lesions when they are small and when visual symptoms could still go unnoticed.

Dr. Smick: Do you find the PHP to be accurate?

Dr. Gerson: Absolutely—the printout is also very helpful because it provides a plot that's similar to what an Amsler grid provides. The printout identifies trouble spots in a patient's field of vision, showing you where in the macula those trouble spots might be. It provides probability numbers and shows changes over time.

Dr. Smick: I use the PHP as well. I like putting the printouts in the chart. Each time a patient visits, we repeat the test, so he can see how he's doing. It encourages compliance.

Key PHP functions

Dr. Shechtman: The PHP is reliable, reproducible and sensitive. It certainly can help evaluate an early functional change, which may or may not occur with associated structural change. Just as we find in glaucoma, both functional and structural changes need to be assessed and monitored in patients with AMD.

Dr. Smick: How does the nomenclature of visual fields—such as 10-2 visual fields or microperimetry—relate to PHP?

Dr. Shechtman: PHP principles rely on vernier acuity. If a patient has a growth under the RPE, a displacement of RPE cells can occur with overlying photoreceptors displacement. The PHP is quite sensitive in detecting this. Visual field defects don't rely on the same principle. PHP and microperimetry are not exactly synonymous.

Dr. Ferrucci: The Humphrey visual field test was designed to check for glaucomatous changes, based on a glaucoma patient database. The Foresee PHP has been designed to evaluate AMD and CNM, based on an AMD patient database.

Reducing referrals

Dr. Smick: I want to talk about another area of AMD care where better information is making a difference. Primary care optometrists have been accused of referring too much. In the past, many of us would refer AMD patients to retinal specialists at the first sign of trouble, as if we were afraid of patients going blind on our watch.

But a new approach is emerging. We're much more informed about the significance of retinal changes. Part of this progress is linked to the diagnostic technology we're discussing.

Dr. Gerson: In the past, if someone demonstrated a change in vision and we saw some drusen, we assumed a CNM was involved, even though drusen could have been causing the change. Now, if I look clinically and don't see a CNM developing, I can use PHP to confirm this finding and confidently hold off on referring. We should refer patients only when they need treatment. This approach will reinforce our position as the doctors our patients should see for follow-up care.

Dr. Shechtman: Neovascular AMD affects more than 1.75 million Americans aged 40 and older, and that number is expected to grow to nearly 3 million by 2020.³ Another 7 million already have large drusen (≥125 microns) in one or both eyes.³ There aren't enough retina specialists to see all of these patients. In essence, they will become our patients, thus we need to take a proactive role in the evaluation and management of them.

Follow-up frequency

Dr. Smick: In our increased primary care role, how often should AMD patients return for monitoring with PHP and other tests? Is every 3 months standard?

Dr. Gerson: No single technology should dictate how often we see a patient. I talk to my patients about family history and lifestyle, including nutrition and smoking. I also order genetic testing to assess risk levels. This information helps me determine when to bring patients back for OCT or PHP. These interventions also show patients why I'm asking them to return, whether it's every 3 months, 4 months or 6 months. They understand that I've asked questions, that I've done tests and they know there's a reason I'm asking them to return.

Evaluating risk factors

Dr. Ferrucci: Smoking has been found in multiple studies to be the number one modifiable risk factor for AMD, followed by poor nutrition and increased body mass index.^4-6 Patients can reduce the risk of developing AMD by making lifestyle changes—quitting smoking, reducing high blood pressure, decreasing body mass index, increasing consumption of dark green leafy vegetables, taking vitamin supplements and wearing sunglasses that block ultraviolet and high-energy radiation.^7,8

All of these factors should be considered when counseling patients. I also like to get a baseline PHP, much as you would to establish a baseline visual field for a glaucoma patient. I think patients with intermediate AMD or worse require quarterly PHP evaluations. The growth of choroidal vascular membranes warrants this degree of follow-up.

Future trends

Dr. Smick: I want to conclude our discussion by looking into our diagnostic crystal ball. Do you envision additional uses for PHP in the future?

Dr. Gerson: In Kansas City, we see many patients with histoplasmosis and PHP could help. The test demonstrates good sensitivity and specificity for related choroidal neovascular membranes. It's also useful in conditions that don't involve choroidal neovascular membranes, such as hydroxychloroquine (Plaquenil) toxicity.^9,10

Dr. Shechtman: Other potential uses of PHP in the future could include other causes for CNV such as myopic degeneration, histoplamosis and angioid streaks. The test is approved for patients with macular degeneration, but I believe it could play a role in other diseases.

Dr. Gerson: Another issue that will become more important going forward is the use of a home version of PHP. This device will complement the office-based version. Neither will replace the other. The effect of supplementary, home use of PHP will be increased test frequency, adding to the benefit of this technology as a monitoring device.¹¹

Increasing Optometry's Role

Dr. Smick: We're excited about the future of optometry and our growing role as primary care providers. We applaud our colleagues for the progress they've made in the area of diagnosis, tracking and treatment of AMD. As we acquire more information and better technology, we'll become even better equipped to provide top-notch care. For the present time, we have to emphasize the need for speedy referrals to those specialists who utilize the modern injections for this terrible disease. We need to spread the word that there is technology available to greatly assist in diagnosing dry-to-wet conversions.

In the past, if someone demonstrated a change in vision and we saw some drusen, we assumed a CNM was involved, even though drusen could have been causing the change. Jeffry D. Gerson, OD, FAAO