According to what they taught us in school, when a person has an eye defect the image is formed either in front or at the back of the retina. How then can there be bifocal lenses? Doesn't it mean that the image is formed in front of the retina as well as at the back of it? Isn't it absurd?
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How do Bifocal lenses work? How can an eye have both myopia and hypermetropia?