I assumed he’d estimated it based on how distorted the face appears behind the glasses. I do that all the time.
At this angle it’s hard for me to do that, since I usually use the edges of the face to estimate it. negative glasses pull the line inwards, positive outwards. I can reliably tell when someone is wearing fake glasses (0 strength) for example, and probably estimate strength within 30% of the actual value.
If the image was higher res maybe I could estimate this case too. Or this professional optometrist is just a lot better at it than I am.
Strong negative glasses: (Note the faces contours in the glasses appearing well inside the faces contours around the glassed)
Fake glasses:
Positive glasses:
PS: Searching for generic terms yields 100% fake glasses, so I took a specific person I remember having strong glasses for myopia.
Might depend on the material. I have -3.5dpt on both sides and my glasses have half the width and glare. Or are those some random units again?
I assumed he’d estimated it based on how distorted the face appears behind the glasses. I do that all the time.
At this angle it’s hard for me to do that, since I usually use the edges of the face to estimate it. negative glasses pull the line inwards, positive outwards. I can reliably tell when someone is wearing fake glasses (0 strength) for example, and probably estimate strength within 30% of the actual value.
If the image was higher res maybe I could estimate this case too. Or this professional optometrist is just a lot better at it than I am.
Strong negative glasses: (Note the faces contours in the glasses appearing well inside the faces contours around the glassed)
Fake glasses:
Positive glasses:
PS: Searching for generic terms yields 100% fake glasses, so I took a specific person I remember having strong glasses for myopia.
Just looked in the mirror… Checks out! :)
Thanks for the explanation. And yeah, on the op picture you can’t see any of that clearly, so he needs to have serious practice for that statement.