Darker Eye Vision From My Left Eye

Thank you for taking the time to read this, I have a bit of concern about something I started experiencing 48 hours ago. Its seems to be that my left eye has a darker vision than my right eye. When I close my right eye and see only with my left, I can still see, but darker and a bit more difficult to see fine details in the evening or dark setting room, and with the right eye all is normal. Not sure if this is serious or not, but I am going to go the get it checked out, was just curious if any one might possibly know what it might be.