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Under the full daylight condition they generally over

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Unformatted text preview: f (1) the individual's dark focus of accommodation and (2) the reduction of lumi- nance. These results indicate that, even under optimal stimulus conditions-i. e., relatively unrestricted binoc- FIG. 4. Schematic diagram of ofpparatus alluminated scene rich in ular observation a a brightly i nd outdoor scene Leibowitz, H. W., & Owens, est night Nightccommodation is determined was changed details, yopia. L the intermediate employed to t D. A. (1975). ma myopia and uminance level by two factors, dark focus of accommodation. Journal of the Optical Society of the by inserting neutral stimulus distance and the individual's dark focus America, 65(10), 1121–1128. density filters into the window aperture of accommodation. As stimulus effectiveness is degraded in front of the subject. Friday, 6 September 2013 by decreasing the luminance, accommodation is influenced less by the stimulus distance and is biased pro- .4- .4-- 0 2 Accommodation was measured under four normal daylight, daylight reduced by a facto daylight reduced by a factor of 0. 000063, a ness. The reduced-daylight conditions had ance of dusk and a brightly moon-lit night, 0 The subjects were instructed to fixate caref 1 vicinity of the roof2top for the conditions in 3 Focus v outdoor scene was in isible, and to relax the Total Darkness Under the dark condition. (diopters) all conditions, t FIG. 5. Scatter diagrams that illustrate the change of accompattern was presented for 0. 5 s at irregular modative response to a distant outdoor scene as luminance is 24 Problems with the Retina • Glaucoma • Increased pressure in the eyeball • Retinal Tear • Retinal Detachment Friday, 6 September 2013 25 Here is the normal funduscopic appearance of the retina. Note the arteries (brighter red) emanating from the central optic disk. The larger caliber and darker retinal veins extend back to the optic disk. The vessels are evenly distributed. Note that the margins of the optic disk are sharp and clear. Friday, 6 September 2013 26 This is marked cupping of the optic disk indicative of glaucoma. Glaucoma results from increased intraocular pressure with damage to the ganglion cells and their axons. This pressure over time leads to deepening of the optic cup with excavation. The vessels shown here appear to "fall into" the deepened optic cup. Friday, 6 September 2013 27 LOH Left Retina 1 June 2001 Friday, 6 September 2013 28 Diabetic Retina Friday, 6 September 2013 29 Retinal Tear Friday, 6 September 2013 30 Retinal Detachment Retinal Detachment Friday, 6 September 2013 31 The Normal Retina Friday, 6 September 2013 32 The normal histologic appearance of the retina shows many layers. The lowest layer just above the connective tissue is the layer of rods and cones. Above this are layers of external and internal plexiform and nuclear lamina. The nerve fibers are at the top and collect together to enter the optic nerve at the optic disk. Friday, 6 September 2013 33 Courtesy of Max Snodderly, U...
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