Bryn Mawr College monographs . 10 IS ao ft5 30 jy 40 ^-i MinutesFig. 2. Curves showing the decrease in the amount of light required just to dis-criminate the test-object as the result of dark adaptation. Inforder to standardize theinitial sensitivity, the eye was preadapted in each case for 20 minutes to 8o foot-candles of illumination (vertical component). scotopic acuity before and after adaptation, rated on the illu-mination scale; (b) their light sensitivity before and afteradaptation insofar as it affects the minimum amounts of lightrequired to discriminate the test object; and (c) their
Bryn Mawr College monographs . 10 IS ao ft5 30 jy 40 ^-i MinutesFig. 2. Curves showing the decrease in the amount of light required just to dis-criminate the test-object as the result of dark adaptation. Inforder to standardize theinitial sensitivity, the eye was preadapted in each case for 20 minutes to 8o foot-candles of illumination (vertical component). scotopic acuity before and after adaptation, rated on the illu-mination scale; (b) their light sensitivity before and afteradaptation insofar as it affects the minimum amounts of lightrequired to discriminate the test object; and (c) their relativeamounts of change in sensitivity, measured in terms of effect 354 C. E. FERREE, G. RAND AND D. BUCKLEY on acuity, read on the illumination scale, due to of these features are important for vocational and clinicclassification. In order to make these results more directlycomparable with reference to the last of these points, namely Percentage. O 10 15- 40 4^ MinutesFig. 3. Curves showing the increase in sensitivity as the result of dark adapta-tion, the reciprocal of the amount of light required just to discriminate the test-objectbeing taken as the measure of sensitivity. Percentage increase in sensitivity is plottedagainst time of adaptation. The initial sensitivity of the eye was standardized in eachcase by 20 minutes of preadaptation to 80 foot-candles of light, vertical component. relative amounts of change in sensitivity due to adaptation,the ratios or percentages of increase in sensitivity are plottedin Fig. 3, the reciprocals of the minimum amounts of lightrequired just to discriminate the test-object being taken as A STUDY OF OCULAR FUNCTIONS 355 the measure of sensitivity. That is, the ratio or percentagechange in the value of these reciprocals is plotted againsttime of adaptation, the curves beginning at a common pointor unit ratio. The relative ratings with regard to the secondpoint could of course be represente
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