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  2. Pinhole glasses - Wikipedia

    en.wikipedia.org/wiki/Pinhole_glasses

    Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. Similar to the workings of a pinhole camera , each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the circle of confusion on the ...

  3. Subjective refraction - Wikipedia

    en.wikipedia.org/wiki/Subjective_refraction

    The entire process of Subjective Refraction involves the patient fixating at the Snellen Chart, whilst the clinician presents a variety of lenses and alters the power of the lenses in the trial frames according to the patient's subjective responses regarding improvements to their vision. 1) INITIAL BEST SPHERE CORRECTION

  4. Pinhole occluder - Wikipedia

    en.wikipedia.org/wiki/Pinhole_occluder

    An improvised pinhole has a similar but better effect. The same principle has also been applied as an alternative to corrective lenses: a screen of pinholes is mounted on an eyeglass frame and worn as pinhole glasses. Differential diagnosis: pinhole worsen vision: Macular diseases, [5] central lens opacities [6] Vision static with pinhole ...

  5. Ophthalmic trial frame - Wikipedia

    en.wikipedia.org/wiki/Ophthalmic_trial_frame

    An ideal trial frame have minimum 3 cells, one each for holding spherical lens, cylindrical lens and other tools like occluder or pinhole. [4] Angle for axis of astigmatism is marked on outermost visible cell There are knobes to adjust pupillary distance, side angle, height and cylindrical lens axis. [ 5 ]

  6. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    This specifies the part of the prescription designed primarily to improve far vision. In a bifocal lens, this generally indicates what is to be placed in the top segment. NV is an abbreviation for near vision. This may represent a single-vision lens prescription to improve near work, or the reading portion of a bifocal lens.

  7. Intraocular lens - Wikipedia

    en.wikipedia.org/wiki/Intraocular_lens

    An intraocular lens (IOL) is a lens implanted in the eye usually as part of a treatment for cataracts or for correcting other vision problems such as short sightedness and long sightedness; a form of refractive surgery. If the natural lens is left in the eye, the IOL is known as phakic, otherwise it is a pseudophakic lens (or false

  8. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye. Contact lenses are worn directly on the surface of the eye.

  9. Pinhole camera - Wikipedia

    en.wikipedia.org/wiki/Pinhole_camera

    A home-made pinhole camera lens A pinhole camera is a simple camera without a lens but with a tiny aperture (the so-called pinhole )—effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura ...