R&D relating to the design, fabrication, and testing of plastic lenses, particularly
"Negative Dysphotopsia" is where some patients with intraocular lenses (IOLs) see bothersome "dark shadows" in the far periphery. This is probably due to vignetting at the IOL. See Dysphotopsia, Publications, and Downloads.
The limit of vision in all directions is rarely measured, including "Far Peripheral Vision", and calculations indicate that this is reduced with an IOL. These limits should be evaluated, and compared in particular to the level of myopia, because we use the entire visual field, and other factors than defocus may affect eye growth.
The "Nodal Point" can linearly scale the retinal image to very large angles, but this is due to the highly curved cornea and retina, and the iris location, rather than to "paraxial" concepts (which are defined using flat surfaces and very small angles).
The EFL or "effective focal length" or "equivalent focal length" are all the same thing for a lens in air, but for the eye the nodal point is at f'/n'.
August 2023 Conferences
Simpson MJ. "Intraocular Lens Tilt, the Pupil, and Simple Eye Models".
VPO 2023, Antwerp, Belgium.
Strasburger H, Simpson MJ. "Is Visual Angle
Equal to Retinal Angle" .
ECVP 2023 (Eur Conf Vis Percep) ,Crete.
Michael J. Simpson, Ph.D.
Dr Simpson worked in industry for over 25 years in the Research and Development of Intraocular Lenses (IOLs), and is continuing to support R&D work relating to ophthalmic lenses and other topics.
Simpson MJ, "Optical modeling of the entire visual field of the eye," J. Opt. Soc. Am. A 40, D7 (2023) https://doi.org/10.1364/JOSAA.488033
Simpson MJ. "Focal Length, EFL, and the Eye". Applied Optics, v62, n7, 1 Mar. 2023 p1853-1857.
Simpson MJ, "Nodal points and the eye," Appl. Opt. 61, 2797-2804 (2022) https://doi.org/10.1364/AO.455464
Disclaimer. Simpson Optics LLC does not provide medical advice, and neither does this website. If you have concerns about your vision, you should see a specialist, such as an Ophthalmologist or Optometrist.
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