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  2. Vergence (optics) - Wikipedia

    en.wikipedia.org/wiki/Vergence_(optics)

    In geometrical optics, vergence describes the curvature of optical wavefronts. [1] Vergence is defined as. where n is the medium's refractive index and r is the distance from the point source to the wavefront. Vergence is measured in units of dioptres (D) which are equivalent to m −1. [1] This describes the vergence in terms of optical power.

  3. Accommodative convergence - Wikipedia

    en.wikipedia.org/wiki/Accommodative_convergence

    Accommodative convergence is that portion of the range of inward rotation of both eyes (i.e., convergence) that occurs in response to an increase in optical power for focusing by the crystalline lens (i.e., accommodation). [1] When the human eye engages the accommodation system to focus on a near object, signal is automatically sent to the ...

  4. Vergence - Wikipedia

    en.wikipedia.org/wiki/Vergence

    The two eyes converge to point to the same object. A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision. [1] When a creature with binocular vision looks at an object, the eyes must rotate around a vertical axis so that the projection of the image is in the centre of the retina ...

  5. Subjective refraction - Wikipedia

    en.wikipedia.org/wiki/Subjective_refraction

    Subjective refraction. Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1] It is a clinical examination used by orthoptists, optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses.

  6. Pinhole occluder - Wikipedia

    en.wikipedia.org/wiki/Pinhole_occluder

    Visual acuity. Based on. Pinhole (optics) A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia. Because ...

  7. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    Eye examination for visual acuity. Visual acuity is a measure of the spatial resolution of the visual processing system. VA, as it is sometimes referred to by optical professionals, is tested by requiring the person whose vision is being tested to identify so-called optotypes – stylized letters, Landolt rings, pediatric symbols, symbols for the illiterate, standardized Cyrillic letters in ...

  8. Accommodation reflex - Wikipedia

    en.wikipedia.org/wiki/Accommodation_reflex

    Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.

  9. Amplitude of accommodation - Wikipedia

    en.wikipedia.org/wiki/Amplitude_of_accommodation

    Amplitude of accommodation. The amplitude of accommodation is the maximum potential increase in optical power that an eye can achieve in adjusting its focus. It refers to a certain range of object distances for which the retinal image is as sharply focused as possible. Amplitude of accommodation is measured during routine eye-examination.