dark in eyes

This is a type of night blindness that could be from a condition called retinitis pigmentosa.  Symptoms of RP usually develop between the ages of 10 and 30 years of age.  RP is a progressive disease and eventually a person afflicted with it will have reduced peripheral vision.  The rod cells are affected; they are responsible for our peripheral vision and the ability to see in dim light or dark rooms, for instance.  You should see an eye doctor who can perform tests to identify this problem.  There is no treatment for it, however.  You will need to go to see an eye doctor to find out if you do have this or not. 

I concur with ybanks522 that this may be RP. Consult with your doctor and I hope all will be well! Good luck.