Depth of field of plus lenses and reading telescopes.
Using simple optical equations we solved for the depth of field (or range of movement for clear viewing) of plus lenses and near telescopes of the same equivalent power and then compared them. The prevalent clinical wisdom states that reading telescopes have a smaller depth of field than plus lenses. Our results show depth of field to be equal for both and inversely proportional to the square of the equivalent power. A simple nomograph of depth of field vs. power has been prepared for clinicians to use.
Spitzberg
L A
LA
Optical Designs, Inc., Houston, Texas.
Qi
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M
D005139:Eyeglasses; D006801:Humans; D008433:Mathematics; D055095:Optics and Photonics; D012682:Sensory Aids; D015354:Vision, Low / Q000628:therapy; D014794:Visual Fields