Do you have muscle spasms or trigger points in your neck, upperback or shoulder muscles?
Those can affect vision temporarily until the spasm/trigger points are calmed down.

I had a very hard time getting my progressives to work for me during my RSI/TOS injury that involved spasms & trigger points.

[In addition, these muscles can be a cause of blurred vision and pain behind the eyes. ]
http://www.pressurepointer.com/Poste...ger_points.htm

here's a full head/neck TrP clickable chart-
http://www.pressurepointer.com/pain_reference_chart.htm
or a PDF option with more info-
http://www.pressurepointer.com/Press...nterManual.pdf

(a specific tool is not required - any object like finger/thumb, small firm ball - against the wall or floor..will work)

http://www.triggerpoints.net/head-and-neck