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Thread: Essential Lectures of Refraction videos

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    Default Essential Lectures of Refraction videos

    Retinoscopy (also called skiascopy) is a technique to objectively determine the refractive error of the eye (farsighted, nearsighted, astigmatism) and the need for glasses. The test can be quick, easy, reliably accurate and requires minimal cooperation from the patient.

    Essential Lectures Refraction videos attachment.php?attachmentid=159&stc=1&d=1430391760
    Static retinoscopy is a type of retinoscopy used in determining a patient's refractive error. It relies on Foucault's principle, which states that the examiner should simulate optical infinity to obtain the correct refractive power. Hence, a power corresponding to the working distance is subtracted from the gross retinoscopy value to give the patient's refractive condition, the working distance lens being one which has a focal length of the examiner's distance from the patient (e.g. +1.50 dioptre lens for a 67 cm working distance). Myopes display an "against" reflex, which means that the direction of movement of light observed from the retina is a different direction to that in which the light beam is swept. Hyperopes, on the other hand, display a "with" movement, which means that the direction of movement of light observed from the retina is the same as that in which the light beam is swept.

    Static retinoscopy is performed when the patient has relaxed accommodative status. This can be obtained by the patient viewing a distance target or by the use of cycloplegic drugs (where, for example, a child's lack of reliable fixation of the target can lead to fluctuations in accommodation and thus the results obtained). Dynamic retinoscopy is performed when the patient has active accommodation from viewing a near target.

    Retinoscopy is particularly useful in prescribing corrective lenses for patients who are unable to undergo a subjective refraction that requires a judgement and response from the patient (such as children or those with severe intellectual disabilities or communication problems). In most tests however, it is used as a basis for further refinement by subjective refraction. It is also used to evaluate accommodative ability of the eye and detect latent hyperopia.


    Autorefraction and subjective refraction are other techniques used to determine refractive error. Autorefraction is a method of retinoscopy that is performed by a computing device. This method can be precise, but requires the subject to be still and look at a target for several seconds in order to obtain an accurate measurement. Subjective refraction is a method that can be used to refine the results of retinoscopy or autorefraction. Subjective refraction requires participation in the process by telling the examiner which of a series of choices of lenses provides the clearest vision.


    Ophthalmology - Retinoscopy (Part 1/2) video

    Ophthalmology - Retinoscopy (Part 2/2) video

    Retinoscopy Simulator

    Refracting Tutorials videos











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