How to Diagnose the Cause of Your Blurred Vision
There are two major categories of blurred vision. Either it is due to:
1) An optical or focusing problem that will be helped by glasses, or by updating an existing pair or
2) A non-optical problem ie due to a possible disease process within the eye.
A quick way to differentiate between the two is by performing the "Pinhole Test". Take a piece of card and perforate it with a pen tip, creating a pinhole about 2mm in diameter. Checking one eye at a time, look at an object that appears slightly blurred. Then look at the same object through the pinhole. If it appears sharper through the pinhole, you probably have a focusing problem. If it does not appear sharper, or looks even more blurred, you should visit an eye doctor without delay to exclude a non optical problem.
I perform this simple and extremely useful test on nearly every patient that comes to the clinic complaining of blurred vision.
88 Ahuza St
Pinhole test using an ocular occluder
Picture adapted from "VISUAL PROBLEMS
by Leonard Hershkowitz, MD