2a EyeBrain

6 september 2013 19 astigmatism friday 6 september

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Unformatted text preview: y, 6 September 2013 21 Resting Point 1122 H. W. LEIBOWITZ 5 ~0 EyeChart(0.25D) Argon Laser -Ltens Glass creen S ilter Filler Mirro FIG. 1. Schematic diagram of apparatus used to evaluate accommodation while viewing the clinical test chart and a diffuse laser pattern. Leibowitz, H. W., & Owens, D. A. (1975). Night myopia and the intermediate dark focus of accommodation. Journal of the Optical Society of America, 65(10), 1121–1128. Friday, 6 September 2013 22 Resting Focus of the Eye 35 Leibowitz, H. W., & Owens, D. A. (1978). New evidence for the intermediate position of relaxed accommodation. Documenta Ophthalmologica, 46(1), 133–147. 30 N = 220 Mean = 1.52 SD = 0.77 Frequency 25 20 15 10 5 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 0 Resting Point of Accommodation (Dioptres) ∞ 2 1 0.5 0.33 Resting Point Distance (meters) Friday, 6 September 2013 23 1124 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 x SD 2.35 1.80 1.10 2.04 1.29 1.16 2.68 2.19 1.05 1.51 2.89 1.82 1.83 1.39 2.87 1.53 1.55 1.45 1.80 0.62 1.21 0.81 0.59 0.81 0.73 H. 0.44 1.26 0.94 0.67 0.89 0.71 0.75 0. 36 - .0.01 0.39 0.68 0.86 0.95 0.71 0.27 1.13 1.26 0.87 0.76 0.79 . W 0.89 1.39 1.07 0.92 0.94 1.29 1.03 0.71 0.12 1.87 0.78 1.00 0.94 0.93 0.32 1.71 2.23 0.86 1.16 0.99 LEIBOWITZ 1.32 2.28 2.15 1.07 1.62 2.63 1.16 1.67 0.65 2.57 1.10 1.29 1.07 1.36 0.56 3 AND D. A. OWENS 2 on a clear morning. Observations were ma months of February and March, at a latitud 40' 47. 5' N. The luminances provided by n light could be attenuated by placing al1. 95 n a) sity0 filter in the 20x 25 cm filter holder tha 0. 0 the aperture frame. Further reduction of l was3achieved by requiring the subject to we a) quality neutral spectacles that had a density 2U Conditions of total darkness were obtained c2 black construction board between the glass tU) window pane. Care was taken to ensure he window pane was clean at all times and that C 0 in ous light was visible during the low-luminan 0 cs Thirty undergraduate 0 psychology students V 24, served aI s.ubjects. 3 ll had near and f s A _0 2 c1: E 3 acuities of at least 20/20, without correction E 0 sured by the Titmus Vision Tester. 0 .4- .- 0 4-P (e.g., #6 and #13). Pearson product-moment correlations showed significant positive correlations between the accommodative responses for each of the luminance conditions and the dark focus. The highest correlation was that obtained under the lowest luminance condition (r= 0. 70, p < 0. 001); successively smaller correlations were found for the intermediate (r = 0. 63, p < 0. 001) and highest luminance levels (r= 0, 38, p < 0. 05). Lines of regression for these correlations are indicated by the broken lines in Fig. 5. Although all subjects had demonstrated a far visual acuity of at least 20/20 and claimed to see the outdoor scene clearly under the full-daylight condition, they generally over accommodated; the magnitude of the myopia increased as a function o...
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