If you're on the fence - as I was - I post this review hoping it will help someone. Facing cataract surgery and deciding which lens -far or near - I was uncertain what to do about "the other vision" and was skeptical when someone suggested the "adjustables". I ended up choosing close up lenses (-4 D) because of my work and then decided to try the Dial-Vision (brand) as a stopgap measure till I can have a prescription ground. I am pleased, they work very well for my distance needs. I can see the individual leaves in the top of my 70' oak tree, the chain links in my back fence some 200' away. I can distinctly see the clearance and landing lights on airplanes some 3 miles away and last nite I went out to watch the moon rise. I could see the larger craters. Trying them for close up I can adjust them to read text at 7-8 feet, which is a little beyond the distance my fixed lenses function (1 to 3 feet) The only disadvantage I find is the "relatively small" useful viewing area in the center (a bit larger than a quarter) and the reflections around the edges. That is why they wouldnt be safe for driving. As someone ese pointed out, no they dont correct astigmatism sad to say. As a backup pair if you break your glasses, for 40 bucks you cant go wrong.
Excellent review. I use these glasses to determine if my retina has the capability of 20/20. (From previous 20/60). For that technical purpose - they are perfect.
The principle of these glasses is adjusting the distance between the front and back lenses. They operate like binoculars, with the back lenses called eyepieces and the front lenses are called objectives. Microscopes work on the same principle. Too bad they don't have a cylindrical correction for people with astigmatism.
