How to easily measure the pupillary distance of glasses at home: First, use a flashlight or similar device to shine on the cheapest eyeglasses online lens, and you can see two apertures on the lens.

Then adjust the angle of the lower flashlight until the two circles coincide and make a mark (the position of the mark is the optical center of the lens).

The other cheapest eyeglasses online lens is the same, then take a ruler to measure and record the data. Compare the data of pupil distance when you go for a mirror examination. (This method is only applicable for rough measurements)

The size of the frame is much larger than before, so it is normal for you to feel uncomfortable when wearing it. The degree difference is too large. If your degree has increased a bit, it is normal to feel uncomfortable when wearing it.

The tilt angle of the frame, if not correct, can cause the path of light entering the eye through the lens to deviate from the intended path. Eyes may feel uncomfortable (this is why you keep adjusting the frame of the glasses)

How to roughly measure the refractive index of the cheapest eyeglasses online lens at home after excluding these simple situations. First, draw the size of the frame on a piece of white paper. Click on the optical center point of the lens that was already found before.

Record the distance between any point connecting the optical center point to the edge. Measure the thickness of the lens at the same position on the glasses. Record the data and use thickness ➗ Length. The obtained value is only a rough estimate of the refractive index of the lens.