If you are of a certain age, you will remember that in the 1980s first mobile phone were car phones. In fact, they were something of a status symbol, since they weren’t cheap. So, executives and high-end real estate agents were the ones who most likely had a car phone. Well, thanks to advances in technology, the mobile phone when from the car to our pocket and now in the 2020s we are urged not to call or text while driving.
What do car phones have to do with vision? Actually nothing, still I bring up car phones because it demonstrates the advances in technology. Advances in technology also lead to a greater understanding of vision and the eye. High tech imaging of the eye uncovered details about two rare eye disorders.
Vitelliform Macular Dystrophy (VMD)
Vitelliform Macular Dystrophy (VMD) is an inherited genetic disease that lead to progressive vision loss through the deterioration of the retina. The genes involved in this disease include BEST1, PRPH2, IMPG1, and IMPG2.
Using multimodal imaging, which utilizes adaptive optics, a technique that uses mirrors to improve resolution, researchers from the National Eye Institute (NEI) were able to learn that retinal lesions from VMD vary by gene mutation. Focusing on these differences might be key in developing effective treatment for this and other rare diseases.
VMD affects 1 in 5,500 people in the U.S. and there is no treatment for this disease. Depending on the gene and mutation, the age of onset and the disease severity vary. Still, what all forms of the disease have in common is a lesion in the macula that looks like an egg yolk. There is also a build-up of toxic fatty material known as lipofuscin. Researchers worked with doctors at the NEI Eye Clinic to label 11 participants using genetic testing and other clinical assessment. Next they assessed the participants retinas using the multimodal imaging. Assessments of cell densities near the lesion showed differences in cell density according to different mutations. The IMPG1 and IMPG2 mutations effected the photoreceptor cell density more than it effected retinal pigment epithelium cell density. The opposite was true with BEST1 and PRPH2 mutations.
Researchers plan to use this kind of imaging for other rare eye disease, as well as common ones, like age related macular degeneration.
Details about Choroideremia
The same group of researchers who studied VMD utilized adaptive optics to learn more about choroideremia, another rare genetic disorder that leads to blindness.
Choroideremia affects men more than women due to the fact that the gene that leads to this disease is located on the X chromosome. Men only have one copy of the X chromosome, so a mutation in the gene leads to the development of more severe symptoms. Women have two copies of the X chromosome, so they develop milder symptoms of this disease.
Researchers combined adaptive optics with a green dye to view live cells in the retina, including photoreceptors, retinal pigment epithelium and choroidal blood vessels. The scientists were able to see in detail how choroideremia messes up these tissues. While adaptive optics aren’t part of routine diagnostic test, researcher found that enlarged retinal pigment epithelium cells could be detected when using a commercially available scanning laser ophthalmoscope along with the green dye. The images produced via adaptive optics provide information that could lead to effective treatments for choroideremia and other eye diseases.
While treatments are years away, these insights can inform future treatments for VMD and Choroideremia.