An outline of the shadow of an object filled in with black; a picture painted or produced in this style.
The use of X-rays to view unseen or hard-to-image objects.
The making of film records (radiographs) of internal structures of the body by passing x-rays, or gamma rays, through the body to act on specially sensitized film.
An optical instrument for examining refraction of light in the eyes or the ability of the eyes to bend light so that an image is focused on the retinas.
The study of the retina of the eye by means of the ophthalmoscope.
An instrument for viewing the interior of the eye, particularly the retina. Light is thrown into the eye by a mirror (usually concave) and the interior is then examined with or without the aid of a lens.
An instrument which measures the refractive status of the eyes.
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.
A method of determining the refractive errors of the eyes by using an ophthalmoscope to illuminate the retina through the lenses of the eyes.
The refractive errors of light in the eyes refer to the ability of the eyes to change the direction of light in order to focus it on the retinas of the eyes.
Other related "dark; shadow, shade; black" units: