. Physiological optics : being an essay contributed to the American encyclopedia of ophthalmology . reshold value of visibility or meter-candle, (b) formedium illumination of meter-candles and (c) for high illuminationor 600 meter-candles. The maximum visibility region under the in- 246 PHYSIOLOGICAL OPTICS tensities of illumination specified in the above three cases is 5,110Angstroms for curve (a), 5,370 Angstroms for curve (b) and 5,650Angstroms for curve (c). 216. It is of interest to compare the luminosity curves of the eyeobtained when the yellow spot, the regions just outside t
. Physiological optics : being an essay contributed to the American encyclopedia of ophthalmology . reshold value of visibility or meter-candle, (b) formedium illumination of meter-candles and (c) for high illuminationor 600 meter-candles. The maximum visibility region under the in- 246 PHYSIOLOGICAL OPTICS tensities of illumination specified in the above three cases is 5,110Angstroms for curve (a), 5,370 Angstroms for curve (b) and 5,650Angstroms for curve (c). 216. It is of interest to compare the luminosity curves of the eyeobtained when the yellow spot, the regions just outside the yellow spotand the fovea centralis are the subject of investigation. The compara-tive luminosities of the spectral colors as seen on the yellow spot areobtained by various color-patch and flicker methods either previouslydescribed or to be discussed later under color-vision. To get luminositycurves outside the yellow spot the following simple plan is adopteddependent upon the fact that in order that the images of the patches,for example, in the Abney methods, may fall outside the yellow spot. 6 3 »* & ~0 z-} Z& 5Z 3£ T &> *H 4% 5 »SS96 Fig. 128.—Sensitivity Curves of the Fovea Centralis, Yellow Spot and Area Ten Degrees from Center of Eetina. they should be received on the retina at least 5° from the center ofthe macula. If a spot is marked in a horizontal direction 5 inchesaway from the outside of the color rectangles used for comparisonand the observers eyes are 5 feet away from the patch and then thespot is looked at, the image of the rectangles will be received outsidethe extreme edge of the yellow spot. If this outside spot is illuminatedby Balmains paint and the axis of the eye under test, the other beingoccluded, is directed toward this point, the rectangles of white andcolor used for comparison will be clearly defined and the luminositiescan be compared; they can, as a matter of fact, be compared with evengreater facility than when observed with the center o
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