A retinoscope is an instrument used to objectively determine the refractive power of the eye. It works by allowing the examiner to project a beam of light into the eye and then observe the light as it is reflected back out of the eye. The emerging light will change as it passes through the optical components of th eye, and by judging how much it changes, the examiner can determine the refractive power of the eye.
Types of Retinoscope:
There are basically static retinoscopy and dynamic retinoscopy.
Static retinoscopy is used for routine refractions with the patient viewing a distant target.
Dynamic retinoscopy is performed when the patient focuses on a near target and is helpful in determining the accommodative ability of eyes with decreased vision and in checking for residual accommodation after administering a cycloplegic drug.
is a technique to obtain an objective measurement of the refractive error of a patient’s eyes. The examiner uses a retinoscope to shine light into the patient’s eye and observes the reflection (reflex) off the patient’s retina. While moving the streak or spot of light across the pupil the examiner observes the relative movement of the reflex then uses a phoropter or manually places lenses over the eye (using a trial frame and trial lenses) to “neutralize” the reflex.
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. +2.00dioptre lens for a 50 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.
Retinoscope and Retinoscopy Videos:
Optics : Retinoscopy Part One (Arabic)
Optics : Retinoscopy Part Two (Arabic)
Practical Retinoscopy Part One:
This is the first half lecture on retinoscopy … the technique we use to check prescription in children. This is a hard skill to teach, so hopefully you’ll find these animations useful.
Practical Retinoscopy Part Two:
Here is the second half of the retinoscopy lecture.
scissoring reflex retinoscopy
Retinoscope and Retinoscopy Notes