The American encyclopedia and dictionary of ophthalmology Edited by Casey A Wood, assisted by a large staff of collaborators . will reflect them into the right eye (d). A double-convexlens, 1, is placed between d and m, by which an inverted aerialimage of A is formed, which is situated in reality at a betweenthe two mirrors, but which will appear to g to be situated beyondthe mirror, m, at a. In fact the rays emanating from d, instead ofpassing straight on, are bent twice at a right angle, and broughtback to g, without having undergone any change in their relativepositions. Another method is d
The American encyclopedia and dictionary of ophthalmology Edited by Casey A Wood, assisted by a large staff of collaborators . will reflect them into the right eye (d). A double-convexlens, 1, is placed between d and m, by which an inverted aerialimage of A is formed, which is situated in reality at a betweenthe two mirrors, but which will appear to g to be situated beyondthe mirror, m, at a. In fact the rays emanating from d, instead ofpassing straight on, are bent twice at a right angle, and broughtback to g, without having undergone any change in their relativepositions. Another method is described by E. Wessley (Centralhl. f. prakt. AUTO-OPHTHALMOSCOPE 713 Avgenheilk., October, 1897.) for which is needed only an angularlooking glass, which may be readily improvised by taking two smallpieces of mirror glass placed at an angle. Such a glass reflects ob-jects twice, giving doubly-reflected images, one within 120 to 90degrees, the other within 90 to 72 degrees. The head is broughtwithin the angles of the glass and the right eye looks at the imageof the left, and vice versa. As the head cannot be brought much. Wessleys Auto-ophthalmoscope. nearer than reading distance to the glass, the angle of the glass shouldbe about 95 to 75 degrees. (See figure.) A candle flame is then brought near the glass and the eye to beobserved is shadowed, while the other eye is lighted. Before thelatter an ophthalmoscope is held so that the light from its mirror isreflected to the glass and into the pupil of the other eye, which isseen in the looking glass to be lighted, and is fixed by the observingeye. Then a convex lens is placed before the examined eye when it 714 AUTOPERIMETRY is readily observed that the fundus is clearly seen in the mirror, aboutthe same area as one can ordinarily observe in another person. It iseasy to change the angle of the reflecting mirror to bring any partof the eye-ground into the middle of the ophthalmoscopic see the optic nerve head when the eye
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