Instrument Insider

Doctors and Patients Collaborate to Manage Dry AMD

By Paul Garfinkle, M.D.

As a precursor to wet or exudative age-related macular degeneration (AMD), dry AMD represents a crucial stage in the disease's progression. By working together in a collaborative effort, both patient and doctor can create a management plan that incorporates preventive measures to slow or halt vision loss. The following outlines the measures I take with my patients to maximize compliance and produce positive results when it comes to managing dry AMD.

Early Detection Followed by Regular Monitoring

With many medical conditions, early detection has a major influence on treatment efficacy. Continual monitoring is imperative in helping to maximize treatment effectiveness. Because patients in the early stages of AMD may experience few visual changes or be asymptomatic, patients depend on us for diagnosis and management. For healthy seniors, normal protocol should involve a routine annual eye exam to monitor for any sign of vision change. Once early stages of the disease are diagnosed, it is best to administer one-on-one patient education and provide patients with educational material as a follow-up. Patient education materials are helpful for answering questions about uncertainties and also allow patients to do more in-depth research on their own if they desire.

Although standard treatments for dry AMD don't exist yet, there are therapies you can explore with your patients. Assessing risk factors is especially important. Smoking cessation and improving lipid profiles with Omega 3 supplements should be discussed. While AREDS did not identify any benefit from high-dose antioxidants for early AMD (category 2), it can be useful to discuss multivitamins, antioxidants and lutein at this point with patients. Also be sure to schedule an annual exam to ensure regular monitoring of the patient's condition.

When patients are found to be at the intermediate dry AMD stage, during which risk of vision loss increases significantly, it may be necessary to implement a more aggressive monitoring regimen. AREDS vitamins, which have been shown to reduce the risk of vision loss at this stage, paired with quarterly tests with Preferential Hyperacuity Perimetry (Foresee PHP, Sightpath Medical), complement a biannual dilated exam.

By pairing these PHP tests with dilated exams, you and your patients are working together to maximize the chances of early detection and timely treatment. The Bressler et al. study indicates that PHP testing leads to a diagnosis of wet AMD before standard exams and Amsler grid testing in four out of five patients.¹ This 10-minute PHP test can easily be administered by any office staffer, and the results are beneficial to monitoring AMD progression.

The PHP device maps defects within a patient's visual field by analyzing responses to "dot deviation signals" that are flashed on a computer screen in an adaptation of the preferential looking strategy that has been described in preverbal vision testing. After comparing the results to a normative database, the device generates a report disclosing the relative location of macular defects. The PHP has been shown to produce results with 82% sensitivity and 88% specificity,¹ thus making it a reliable test that can give you the satisfaction of knowing you are doing everything in your power to track changes in your patients' visual field resulting from AMD progression.

If the PHP reports abnormalities, it is advisable to repeat the test to confirm the abnormality. Then, follow up with an OCT and a fluorescein angiogram, if indicated, to determine if retinal referral is necessary.

A Case of PED

I have seen firsthand the benefits of using the Foresee PHP and its ability to detect changes in the eye consistent with the conversion from dry AMD to wet. One particular case has cemented my belief in the benefits of this tool. In April 2006, an 80-year-old patient presented with a new choroidal neovascular membrane and poor vision of 20/300 in her left eye. Vision in her right eye was 20/40. The left eye had been treated with five ranibizumab (Lucentis, Genentech) injections, one intravitreal kenalog injection and two treatments with photodynamic therapy (PDT). Unfortunately, her vision remained poor in the count fingers range. Upon her latest injection in December 2006, a PHP test revealed an abnormal area in her right eye (Figure 1).

Figure 1. PHP: abnormal test indicates a high probability of neovascular AMD.

I found the test to be reliable based on indices of false negative and false positive results. After a follow-up OCT confirmed the presence of a pigment epithelial detachment (PED) (Figure 2), I discussed with the patient treatment versus observation. Since PEDs are unpredictable and may be stable for a long time, we elected to watch for now. Upon her return visit after 1 month, her vision had dropped from 20/40 to 20/80 and repeat OCT revealed a larger PED (Figure 3). At that time we instituted Lucentis for the right eye as well. Thus far, she has had a total of seven Lucentis injections, two pegaptanib (Macugen, OSI Pharmaceuticals) injections, one PDT, and two Avastin (Genentech) injections. As of July 2008, the date of her last injection, her vision was stable at 20/60. I believe the information generated by the Foresee PHP saved her sight by picking up her lesion much earlier, allowing me to treat promptly.

Figure 2. Mild pigment epithelial detachment (PED).

Figure 3. Much larger PED after 1 month.

Silver Lining

While dry AMD can progress to wet AMD, and eventually blindness if left undetected and untreated, you and your patients can work together to ensure the best possible visual outcomes by using sophisticated diagnostic technology. PHP can improve monitoring of AMD progression and provide valuable information when making treatment decisions. Many macular degeneration patients know someone who has experienced partial or complete vision loss, thus they are motivated to care for their own vision. As a practitioner, the more you can encourage your patients to take a hands-on approach, the more likely they are to have a positive outcome. OM

Reference

1. Alster Y, Bressler NM, Bressler SB, et al; Preferential Hyperacuity Perimetry Research Group. Preferential Hyperacuity Perimeter (PreView PHP) for detecting choroidal neovascularization study. Ophthalmology. 2005;112:1758-1765.