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
What is Pupillary Distance? Pupillary distance (PD) measures the space between the pupils of your eyes. Knowing this measurement is important to make sure your eyes match up with the optical center of your lenses. The average adultâs PD is between 54-74; kids' are between 43-54. How to Measure Your PD? Stand 8 in. away from a mirror. Hold a ruler against your brow. Close your right eye then align the rulerâs 0 mm with the center of your left pupil. Look straight then close your left eye and open your right eye. The mm line that lines up to the center of your right pupil is your PD.