Age-Related Macular Degeneration Diagnosis

Karl Csaky, MD, PhD: Carl, every patient or every provider that sees these symptoms, we always have to reassure them that it’s not always age-related macular degeneration. Can you talk to us about when you see these patients after they’re referred, and they have these symptoms? What are some of the things that you are looking for in terms of differential diagnosis as well?

Carl Regillo, MD, FACS: Yes. Karl, we have a nice background provided from Nancy and Jennifer, and as Nancy mentioned, the hallmark features of AMD [age-related macular degeneration], or drusen, the yellow deposits centrally. Everyone starts off with a dry, early stage of AMD, and that may or may not progress. Most of the patients out there have and will always have dry AMD and not have significant vision problems. A lot of patients get diagnosed with AMD by the primary eye care provider, optometrist, general ophthalmologist, and don’t have symptoms because the eye care provider has identified the drusen and told the patient they have AMD or dry AMD, and then at some point in the course it is possible for there to be a conversion to wet AMD. That can happen at any time, but it’s more likely to happen when there are more numerous, larger drusen.

As the drusen accumulate, and Nancy mentioned this, into larger, more numerous in the macula, that alone can cause some symptoms, but it’s usually mild, subtle, and relatively slow onset. Sudden central visual disturbances, as Jennifer mentioned, central visual blurred distortion, that’s what prompts a referral because the primary eye care provider or even general physician might say, you have a diagnosis of AMD or you have macular degeneration that’s advancing, causing this visual symptom. That usually prompts the referral—visual symptoms, unexplained decreased vision, or the findings of drusen and maybe something more, and that more could be signs of exudation, and that’s the wet form or neovascular form.

The referral is made, and as the retina specialist, and all of us here on the program, will typically be asked to evaluate a patient suspected of or diagnosed with AMD, and if the patient is having symptoms, that usually implies some degree of central decreased acuity or central visual symptoms. On a dilated examination, we’re going to see the drusen, and that would solidify the diagnosis of AMD, and then the decision or the next step to figure out is, [is] it dry or is it wet. That’s an important distinction and we have diagnostic imaging tools to do that. The OCT [optical coherence tomography] device is an essential imaging modality that we use routinely, and that helps us in that initial decision, dry versus wet. A fluorescein angiogram is the traditional way to establish the diagnosis of AMD and to also determine whether it’s dry or wet, because the fluorescein angiogram will help us pick up the neovascular complex which is typically centrally located in the macula. If it’s wet, the fluorescein angiogram will show a leaking neovascular complex, or the OCT might show fluid and/or blood in or under the retina or even under the retinal pigment epithelium. That’s the clue that we’re dealing with the wet form when we start to see these features on an OCT or fluorescein angiogram accordingly.

There are things that can cause central visual disturbance and cause things that look like exudation in the macula. These would be more rare conditions because AMD, dry and wet, are the most common macular conditions of the elderly. If there is a central visual disturbance, especially if we see atrophy, it’s AMD. Some masquerades or things that can look like AMD include macular dystrophies, either of a dry or even sometimes that can become “wet,” and there’s a condition, typically younger patients, 40s, 50s, and 60s, called central serous chorioretinopathy which can produce central visual disturbance and subretinal fluid, but it’s not neovascular and it’s not truly AMD. That can be a masquerade-like condition.

We use these diagnostic tools, fluorescein angiogram and/or OCT, to help distinguish conditions of the macula that might cause vision problems and/or frank signs of exudation. There are things that look like exudation but aren’t. We can get into more variants like vitelliform lesions or things that look like wet AMD that aren’t, and then sometimes an elder patient will present with acute visual disturbance with hemorrhage and/or exudate and it could be a retinal arterial macroaneurysm. In those situations, we don’t see the drusen and a fluorescein angiogram shows the aneurysm quite nicely. I’m sure the rest of the folks on the panel can contribute to other things in terms of the subtleties and challenges of diagnosis. It’s not easy, but most of the time a patient presents with wet AMD or vision loss from advanced dry AMD, geographic atrophy, we can figure it out typically with an OCT, maybe adding in the fluorescein angiogram.

This transcript has been edited for clarity.