But new Johns Hopkins research in mice suggests that neural stem cells, the bodyâs source of new brain cells, are resistant to radiation, and can be roused from a hibernation-like state to reproduce and generate new cells able to migrate, replace injured cells and potentially restore lost function.
Pupillary Distance (PD) You'll need to know your PD if you want to order glasses from EyeBuyDirect. Don't worry if your glasses prescription doesn't include your PD, we can show you how to measure it by yourself. How to measure your pd
However, the PDâs for progressive and bifocal lenses are generally measured in terms of two, two-digit numbers like â63/62.â This means that the general PD is 63 when the eyes are straight forward and 62 when there turned inward at a âclose-upâ angle such as for reading.