Medically reviewed by Alicen Nelson MD, MPH Although the risk is very low, stifling a sneeze can cause a ruptured eardrum, ...

During an eye examination, the diameter of small blood vessels (left) and the dilation of vessels in response to light pulses (right) can be measured. Both are altered in people with long Covid.

Researchers discovered the blood vessels at the back of the eye -- called retinal microvasculature -- can show early signs someone is at risk of developing dementia.