In the last 3 days, I've noticed that the vision in my left eye is slightly dimmer than my right eye. If I wasn't having eye strain and headache, and anxious, then it may have passed unnoticed - meaning it's not really obvious when both eyes are open. The reason this concerns me I suppose is that my right eye has always been dimmer than my left eye.

Other pertinent info:

1. About 3 days ago I got a few flecks of a cleaning powder in both my eyes (contains calcium carbonate), but it doesn't seem like that could be the cause.

2. My eyes have been feeling very strained and reading is uncomfortable, more so in the last 3 days, though I was having trouble with eye strain prior to the last 3 days. I can chalk this up to recent anxiety, poor sleep, and dry air.

3. I've had an almost constant pressure in my forehead between my eyes. This has been going on longer than 3 days (I've noticed it over the past 3-4 weeks) and have attributed it to increased anxiety.

So I guess my question is why would my "brighter" eye suddenly become the "dimmer" eye & is it reason to be concerned?