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Web apps are used by a variety of online sellers of eyeglasses where an object of known size, such as a credit card, is needed to assist (size reference) the measurement process. [ 13 ] [ 14 ] Some mobile apps have eliminated the need for a reference object to make accurate PD measurements by leveraging depth imaging and advanced algorithms now ...
The pupil magnification is used in calculations of the effective f-number, which affects a number of important elements related to optics, such as exposure, diffraction, and depth of field. For all symmetric lenses, and for many conventional photographic lenses, the pupils appear the same size and so the pupil magnification is approximately 1.
The pupil gets wider in the dark and narrower in light. When narrow, the diameter be 1.5 to 4 millimeters. [4] In the dark it will be the same at first, but will approach the maximum distance for a wide pupil 3 to 8 mm. [4] However, in any human age group there is considerable variation in maximal pupil size. For example, at the peak age of 15 ...
A manual pupillometer measures pupil size via a comparison chart method. There are several types of manual pupillometers. The most common type is the Haab scale, or Haab's pupillometer, which is a series of graduated filled circles on a slide ruler. [2]
The Jaeger chart is an eye chart used in testing near visual acuity. It is a card on which paragraphs of text are printed, with the text sizes increasing from 0.37 mm to 2.5 mm. [ 1 ] This card is to be held by a patient at a fixed distance from the eye dependent on the J size being read.
The entrance pupil is typically about 4 mm in diameter, although it can range from as narrow as 2 mm (f /8.3) in diameter in a brightly lit place to 8 mm (f /2.1) in the dark as part of adaptation. In rare cases in some individuals are able to dilate their pupils even beyond 8 mm (in scotopic lighting, close to the physical limit of the iris.