Ocular refraction and the shadow test . from this that theterm— Shadow Test is derived. Plate 141, represents an eye under observation, in which the lightarea has passed from the primary position to a secondary position,the direction in which the light area moved being to the left. Thereflex in the pupil has also moved to the lept, the right half of the pupilbeing occupied by the following shadow. The direction of the move-ment of the reflex nas therefore been the same as that of the lightarea; in other words, the movement of the reflex is with that ofthe light area. Plate 142, shows the light
Ocular refraction and the shadow test . from this that theterm— Shadow Test is derived. Plate 141, represents an eye under observation, in which the lightarea has passed from the primary position to a secondary position,the direction in which the light area moved being to the left. Thereflex in the pupil has also moved to the lept, the right half of the pupilbeing occupied by the following shadow. The direction of the move-ment of the reflex nas therefore been the same as that of the lightarea; in other words, the movement of the reflex is with that ofthe light area. Plate 142, shows the light area in a secondary position, the direc-tion of its movement being to the right, the movement of the reflex R E T I N O S C O P Y. 177 has also been to the right, or ivitli that of the light area. Plate 143, shows the light area in a secondary position, the move-ment being to tlic right, the movement of the reflex in this instance isto the left, or opposite to that of the light area. It is said to be against that of the light Plate 141. Hypermetropia as indicaled by the retinoKcope. The light area on ihc fnce is passing off the pupil to the left, the movement of the reflex is also to the left in the pupil, with the movement of the light area. Theshado-v is seen following the reflex in the pupil. // is this movement of the , with or against the movetnent of thelight area, that ilctermines the character oj the refraction of the eye The conditions illustrated by figures 141, 142 and 143. occur whenthe plane mirror retinoscope is operaietl. Now sweep the light beam from the retinfiscope acruss the fourmodel eyes again, and observe how the moves in each. In thefirst eye, set to represent emmetropia, the movement will be with;in the second eye set to represent myopia of one dioptre there will beno movement, the reflex being choked; in the third eye, set torepresent myopia of four dioptres the movement will be against ;in the fourth eye set to represent hyperm
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