خرید و دانلود نسخه کامل کتاب Adaptive Optics for Vision Science Principles Practices Design and Applications – Original PDF

Figure 1.6 shows the pointing direction of each cone relative to the center of the pupil for two subjects. For each subject, all the cones are tuned to approximately the same direction. The disarray in cone pointing direction is only about 0.11 times the width of the tuning function for a single cone, imply- ing that the Stiles–Crawford effect is a good estimate of the angular tuning of single cones. Additional experiments using adaptive optics have revealed new optical properties of the cone photoreceptors. Pallikaris et al. observed large differ- ences in the reflectance of different cones and that the reflectance of the same cone changed sometimes several-fold over time [50]. These changes were found in all three cone classes and were not caused by changes in the direc- tionality of individual cones. While the changes Pallikaris et al. observed occurred over time scales of minutes to days, Don Miller’s group has recently demonstrated that there are also short-term fluctuations in cone reflectance [51]. They have also shown that these changes can be induced by photopig- ment bleaching. The cause or causes of these temporal variations remains a matter of investigation, but they may ultimately provide a valuable optical diagnostic of functional activity with each cell. 1.2.2.2 Imaging the Trichromatic Cone Mosaic One of the first demonstra- tions of the scientific value of retinal imaging with adaptive optics was its use FIGURE 1.6 Pupils of two subjects with the origin corresponding to the geometric center of the pupil. Each dot represents the location where the optical axis of a single cone intersects the pupil plane. These locations are tightly clustered, with standard deviations of 180 and 160 mm, respectively, indicative of the small amount of disarray in the alignment of cones within the retina. (From Roorda and Williams [49]. Reprinted with permission of the Association for Research in Vision and Ophthalmology.