retinoscope


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Related to retinoscope: retinoscopy

retinoscope

 [ret´ĭ-no-skōp″]
skiascope; an instrument used in retinoscopy.

ret·i·no·scope

(ret'i-nō-skōp),
An optic device used to illuminate a subject's retina during retinoscopy.
[retino- + G. skopeō, to view]

retinoscope

(rĕt′n-ə-skōp′)
n.
An optical instrument for examining refraction of light in the eye. Also called skiascope.

ret·i·no·scope

(ret'i-nŏ-skōp)
An optic device used to illuminate a patient's retina during retinoscopy.
[retino- + G. skopeō, to view]

retinoscope

An optical instrument used to determine the state of refraction of the eye by RETINOSCOPY. It is not an instrument for examining the retina but a means of producing a light that is reflected from the retina. The direction of the movement of this light varies with the refraction and with lenses held in front of the eye.

retinoscope 

An instrument for determining objectively the refractive state of the eye. It consists of a light source, a condensing lens and a mirror. The mirror is either semi-transparent or has a hole through which the retinoscopist can view the patient's eye along the retinoscope's beam of light. A patch of light is formed on the patient's retina and by moving that patch in a given direction and observing the direction in which it appears to move after refraction by the patient's eye, the retinoscopist can determine whether the patient's retina is focused in front of, at, or behind the retinoscope's sight hole. If the light reflected from the patient's fundus (called the retinoscopic reflex or light reflex) and observed in the patient's pupil through the retinoscope moves in the same direction as the movement of the mirror (this is referred to as a with movement), the eye is hyperopic. If the reflex moves in the opposite direction to that of the mirror (against movement), the eye is myopic. Sometimes it is impossible to see a clear movement one way or the other but only a bipartite reflex, showing opposite movements in the two sectors of the pupils (this is called a split reflex or a scissors movement). The refractive error is determined by placing lenses of various powers in front of the patient's eye until no movement is seen, i.e. the whole pupil is either illuminated or dark and the image of the patient's retina is then conjugate with the plane of the retinoscope's sight hole. When this phenomenon occurs the neutral point has been reached. The neutral point is measured for each principal meridian of the eye if it is astigmatic. To arrive at the patient's error of refraction the dioptric power corresponding to the distance between patient and retinoscope (called the working distance) is subtracted from the total lens power used to obtain neutralization. The amount of dioptric power subtracted is called the allowance. (Fig. R13) Syn. skiascope. See retinoscopic band; chromoretinoscopy; fundus reflex; velonoskiascopy.
spot retinoscope A retinoscope that projects a circular beam of light upon the patient's retina.
streak retinoscope A retinoscope that projects into the patient's eye an oblong streak, which can be adjusted in width and rotated in various meridians. It is more efficient than the spot retinoscope in determining astigmatism.
Fig. R13 Optical principle of a retinoscope (O, observers eye; P, patients eye; M, semi-silvered mirror)enlarge picture
Fig. R13 Optical principle of a retinoscope (O, observer's eye; P, patient's eye; M, semi-silvered mirror)
References in periodicals archive ?
a) In darkness, fixation being on the retinoscope light, using hand held lenses
b) A 'with' movement indicates the child is accommodating to a point between the retinoscope and the target
A normal red retinal reflex is observed when a beam of light is focused through the pupil using an ophthalmoscope or retinoscope. It arises from partial reflection of light from a highly vascular structure (the retina).
My favourite sunglasses are Serengetti, Optical frames are Delim frames (with the interchangeable temples), contacts right now are Purevision 2 HD, Ophthalmoscope/ Retinoscope I'm partial to Welch Allyn.
The project will support the installation of cutting-edge equipment such as an operating microscope, slit lamps, retinoscopes, a phaco emulsification system, etc.
Using a series of study icons and an easy-to-follow format, Lens provides the basics for understanding retinoscopy, covering optics, including the two main theories of light travel, the index of refraction and the curvature, retinoscopy, including the types of streak retinoscopes and their function, and lenses used to neutralize movement, and refractometry, including refinement techniques and instructions for patients.
Keeler Instruments announces the introduction of two new portable charging units for its hand-held opthalmoscopes and retinoscopes. The Duo-Charger, a sleek well charger, accommodates two handles and can be wall mounted.
The diagnostic and monitoring devices segment has been sub-segmented into optical coherence tomography scanners, perimeters/visual field analyzers, fundus cameras, auto refractors, and keratometers, tonometers, slit lamps, phoropters, ophthalmic ultrasound imaging systems (ophthalmic ultrasound bio microscopes, ophthalmic b-scan ultrasound, ophthalmic A-scan ultrasound, and ophthalmic pachymeters), wavefront aberrometers, ophthalmoscopes, lensmeters, optical biometry systems, corneal topography systems, specular microscopes, chart projectors, retinoscopes, and others.
This equipment is paid for by UK practitioners and consists of ophthalmoscopes, retinoscopes, trial cases, trial frames and other supplementary tests which will enable the new practitioners to go out from their training hospitals and work independently in towns and villages.
The company will have its own Eye Shop for the purchasing of products such as specialist ophthalmoscopes, professional retinoscopes, KAT tonometers and practice essentials.