Molecular Imaging of Macular Degeneration

The development of new blood vessels underneath the retina—choroidal neovascularization—is the primary cause of vision loss in patients with several diseases including age-related macular degeneration (AMD). Over time, AMD can progress from its dry form to the more advanced wet form. It is at this point that choroidal neovascularization does most of its damage. All too often, the diagnosis comes late, after a patient notices significant vision loss and has retinal bleeding. By that time, the effectiveness of the current standard treatment—intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF)—can be limited.

With support of an NIH-R01 grant, retinal surgeon and biomedical engineering researcher Yannis Paulus, M.D., is developing a new molecular imaging platform with the potential to revolutionize the early diagnosis and treatment monitoring of AMD.

Dr. Paulus’ new imaging system marries one established modality with two next-gen advances:

Light —Optical Coherence Tomography (OCT), the standard non-invasive retinal imaging technology, creates cross-sectional images of the retina using light waves.

Sound —Low-energy Photoacoustic Microscopy uses nanosecond-duration laser pulses of light and captures the resulting sound from tissue. “Like thunder accompanying lightning,” he says.

Fluorescence —Dr. Paulus is also refining a new nanoparticle contrast agent to detect levels of VEGF in tissue more accurately and safely.

The eventual clinical goal: predicting which patient will benefit from a given treatment and which will not. Another promising benefit: fine-tuning how often patients need treatment.

“Today’s anti-VEGF injections are not easy for patients, so we attempt to extend the time interval between treatments,” Dr. Paulus explains. “But that can be risky. Sometimes a change of just a week can lead to vision loss. If we can see molecular changes while they are happening, instead of just seeing an eye bleed, we can respond with the right therapy in time to preserve vision.”

Dr. Paulus’ new imaging system holds the promise of changing the AMD paradigm—accelerating the development of new treatments, facilitating earlier diagnosis, and making possible more individualized, personalized therapies and treatment planning.

Header image caption: Yannis Paulus, MD