Try this if you need/wear glasses.

[NejStark]

https://www.youtube.com/watch?v=OydqR_7_DjI

[[ptx]]

I am somewhat nearsighted, but don't wear glasses. This doesn't seem to help nearly enough to be practical in any way.

[Teeth]

As someone who has -4 and -5, if that system is used universally, I am somewhat impressed. It definitely does sharpen, but not sharp or consistently enough to have any practical use. Don't think it fixes cylindrical defects as I see double when doing this.

[NejStark]

I hada little play around with it to try to make it practical. If you pinch your index finger and thumb together like the OK sign with both hands in front of your eyes, you can tweak the angle and 'optimal slit point' so that it matches both eyes, acheiving stereoscopic vision. I surf and sail and dont use my glasses during either, looking forward to using this for both eyes during surfing like tiny binocs, and one hand during sailing for the 'tiny telescope' effect.