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  2. Refractive error - Wikipedia

    en.wikipedia.org/wiki/Refractive_error

    Single vision prescription lenses They can correct only one form of defective vision, either far-sightedness or near-sightedness. Multifocal lenses The multifocal lenses can correct defective vision in multiple focus, for example: near-vision as well as far-vision. This are particularly beneficial for presbyobia. [37]

  3. Stereoscopic acuity - Wikipedia

    en.wikipedia.org/wiki/Stereoscopic_acuity

    A second peg, below it, can be moved back and forth until it is just detectably nearer than the fixed one. Stereoacuity is defined as the minimum angle detectable, calculated as the difference between the angles subtended by both positions, A and B. Stereoacuity is possible due to binocular disparity , i.e., the difference in their binocular ...

  4. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    The use of improper corrective lenses may not be helpful and can even exacerbate binocular vision disorders. Eyecare professionals (optometrists and ophthalmologists) are trained to determine the specific corrective lenses that will provide the clearest, most comfortable, and most efficient vision, avoiding double vision and maximizing ...

  5. Binocular vision - Wikipedia

    en.wikipedia.org/wiki/Binocular_vision

    Principle of binocular vision with horopter shown. In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an animal has eyes on opposite sides of its head and ...

  6. Prism correction - Wikipedia

    en.wikipedia.org/wiki/Prism_correction

    Yoked prism can move the image away from primary gaze without the need for a constant head tilt or turn. [1] Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex.

  7. Four prism dioptre reflex test - Wikipedia

    en.wikipedia.org/wiki/Four_prism_dioptre_reflex_test

    Used to assess binocular functions; Can confirm presence of microtropia; Proves the presence or absence of normal (bifoveal) binocular single vision - thereby revealing if there is a central or paracentral suppression scotoma; The prism can be mounted in a frame with a handle attached; Test can be performed at any fixation distance - near or far

  8. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    A reference value above which visual acuity is considered normal is called 6/6 vision, the USC equivalent of which is 20/20 vision: At 6 metres or 20 feet, a human eye with that performance is able to separate contours that are approximately 1.75 mm apart. [9] Vision of 6/12 corresponds to lower performance, while vision of 6/3 to better ...

  9. Worth 4 dot test - Wikipedia

    en.wikipedia.org/wiki/Worth_4_dot_test

    It can be used to develop a diagnosis or to support or confirm an initial diagnosis. It can be used when wanting to assess whether the individual has a normal or abnormal binocular single vision response (BSV). It can be used to establish whether a patient has the ability for the eyes to fuse the light that is received from each eye into 4 lights.