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  2. Progressive lens - Wikipedia

    en.wikipedia.org/wiki/Progressive_lens

    The symmetric design, however, was difficult to accept for patients, because the eyes in general work asymmetrically. When you look to your right, your right eye views distal (i.e. looking through the lens near to the arm of the spectacles) while your left eye views nasal (i.e. looking through the lens near to the bridge). Modern sophisticated ...

  3. Refractive error - Wikipedia

    en.wikipedia.org/wiki/Refractive_error

    In order to see a clear image, the eye must focus rays of light on to the light-sensing part of the eye - the retina, which is located in the back of the eye.This focusing - called refraction - is performed mainly by the cornea and the lens, which are located at the front of the eye, the anterior segment.

  4. Laser blended vision - Wikipedia

    en.wikipedia.org/wiki/Laser_blended_vision

    Laser blended vision. Laser blended vision is a laser eye treatment which is used to treat presbyopia (ageing eyes; [1] progressive loss of the ability to focus on nearby objects) or other age-related eye conditions. [1] It can be used to help people that simply need reading glasses, and also those who have started to need bifocal or varifocal ...

  5. Eye movement in reading - Wikipedia

    en.wikipedia.org/wiki/Eye_movement_in_reading

    Eye tracking device is a tool created to help measure eye and head movements. The first devices for tracking eye movement took two main forms: those that relied on a mechanical connection between participant and recording instrument, and those in which light or some other form of electromagnetic energy was directed at the participant's eyes and its reflection measured and recorded.

  6. Snellen chart - Wikipedia

    en.wikipedia.org/wiki/Snellen_chart

    Snellen chart. Purpose. Snellen chart is used to estimate visual acuity (last three rows are 20/15, 20/13 and 20/10) A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula ...

  7. Aberrations of the eye - Wikipedia

    en.wikipedia.org/wiki/Aberrations_of_the_eye

    The small improvement in depth of focus with the conventional IOLs enhances uncorrected near vision and contribute to reading ability. [15] Wavefront customized lenses can be used in eyeglasses. Based on Wavefront map of the eye and with the use of laser a lens is shaped to compensate for the aberrations of the eye and then put in the eyeglasses.

  8. Visual system - Wikipedia

    en.wikipedia.org/wiki/Visual_system

    The eye's lens becomes too inflexible to accommodate to normal reading distance, focus tending to remain fixed at long distance. Glaucoma is a type of blindness that begins at the edge of the visual field and progresses inward. It may result in tunnel vision. This typically involves the outer layers of the optic nerve, sometimes as a result of ...

  9. Scotopic vision - Wikipedia

    en.wikipedia.org/wiki/Scotopic_vision

    The normal human observer's relative wavelength sensitivity will not change due to background illumination under scotopic vision. The wavelength sensitivity is determined by the rhodopsin photopigment. This is a red pigment seen at the back of the eye in animals that have a white background to their eye called Tapetum lucidum.