Transcript
Dr. Albini:
Welcome. Macular telangiectasia type 2, or MacTel, is a rare disease that is often mistaken for more common macular diseases or degenerations. What are the key features of MacTel that distinguish it from other macular conditions, and how do these features progress over time? This is CME on ReachMD. I'm Thomas Albini, and I'm here with Dr. Roger Goldberg, who's going to help us answer these questions about MacTel.
Dr. Goldberg:
Thanks, Tom. Those are really great questions, and thanks for having me here.MacTel, or macular telangiectasias, type 2, it'sactually a misnomer that telangiectasias are tortuous changes in the blood vessels, are actually a secondary feature, but it's reallya Müller cell dysfunction disease, what they call a Müller cellopathy.
And Müller cells are these really important structural cells that help maintain healthy neurons by secreting certain trophic factors like ciliary neurotrophic factor. And as these Müller cells die, the lack of trophic support to the photoreceptors and to other retinal neurons leads to atrophy and disorganization of the outer retina. And then you get changes in the retinal vascularity that are secondary to the disease.And it was the presence of those vessels that gave the disease its name by Don Gass nearly 50 years ago. But we now know so much more about this disease, and it's really a retinal degenerative disease as opposed to a vascular disease.
Unfortunately, MacTel is a disease that's often misdiagnosed or undiagnosed.One, because the symptoms are nonspecific, and two, because it can resemble other diseases. These patients have pigmentary changes that sometimes look like macular degeneration. They can get CME, which again, can mimic age-related macular degeneration. They sometimes have kind of loss of the retinal tissue, and they can be misdiagnosed asmacular holes. And because these patients often have diabetes, sometimes there'san initial concern and referral for diabetic macular edema.
Dr. Albini:
Also, a lot of these patients have really good vision, 20/25 vision, but it's not until you look deeper for other signs of functional vision loss, such as reading speed, difficulty seeing in low light, and contrast sensitivity, that you pick up on the amount of vision loss that they truly have.
Roger, we've got multiple imaging tools now. What techniques and what features do you look for really in making a diagnosis of MacTel early on in a patient?
Dr. Goldberg:
Sure. So of course, we look on our clinical exam, where you can see graying of the temporal retina. Oftentimes, the vascular changes are absent or not yet evident on FA. Although sometimes they don't have the telangiectasias, but they will have a little bit of leakage present.And unlike a patient with diabetic macularedema, they really don't have lipid exudate or hemorrhages present.
Of course, the OCT is the mainstay of our diagnostic armamentarium. And there you'll see kind of foveal thinning, typically temporal to the fovea, with ellipsoid zone loss. Again, on the FA, there can be some mild leakage and some blunted and dilated venules with some pigment hyperplasia present.
Another thing, as we mentioned, of course, is the cavitations on the OCT, which can look like cystoid spaces with this internal limiting membrane draping over it.
So lots of important features to look for.
Tom, what do you like to look at?
Dr. Albini:
I like OCTA also. I think it has been very helpfullooking at the size of the FAZ, looking at vascular density, the superficial density, and the deep density. And you can see some telangiectatic changes also on the OCTA. SoI think OCT is great. You see the pigmentary changes, the cavitation.And we can do a lot with OCT without the need for a fluorescein injection.
Dr. Goldberg, I think that's all we've got time for. Thank you very much for your descriptions.
Dr. Goldberg:
Thank you.
