The lotrafilcon A lens resulted in significantly faster corneal reepithelialization and reduced patient discomfort in most patients during the first 48 hours after PRK.
Abstract. The temporal interval between flashing lights that is required to perceive nonsimultaneity decreases as the refractive error increases from 0 to +2 diopters. The interval then __ remains constant with further increases to 3 and 4 diopters. The results are discussed in terms 0 of the relative increase of transient to sustained visual channels and of the increase in apparent 1l• movement."--M-In a number of studies the amount of time that must elapse between the presentation S-of two spatially disparate stimuli for the perception of temporal order or of nonsimul-___ taneity have been measured (Efron 1963;Hirsch and Sherrick 1961;Lichtenstein • • 1961;Mayzner and Agresti 1978;Parks 1968;Robinson 1967;Rutschmann 1966Rutschmann , 1973Sweet 1953;Westheimer and McKee 1977). From these studies it has been concluded that the perception of temporal order requires a temporal interval of from 3 to 50 ms, depending on the experimental conditions and criteria. It is clear that a number of variables have an effect on the value. One of the variables which has apparently not been studied is the effect of defocussing the visual display. One might expect this to degrade visual performance as it does, for example, with foveal or Snellen visual acuity. But this is not always the case. Although refractive error quickly degrades Snellen acuity, it has little effect on peripheral acuity (Millodot et al 1975) and even less effect on grating acuity (Thorn and Schwartz 1990). Refractive error affects size constancy but not shape constancy (Leibowitz et al 1978). In some cases, defocussing of the retinal image actually results in an improvement in visual performance: Harmon (1973) showed that recognition of block faces is improved, and Gordon and Field (1978) reported better performance on pseudoisochromatic plates.Of more relevance to the question of the perception of temporal order are the findings of Di Lollo and Woods (1981): defocussing the image decreases the duration of visual persistence. This suggests that the ability to perceive that two stimuli are not simultaneous may be enhanced in this way.2 Method 2.1 Subjects Ten staff members of the laboratory volunteered to serve as subjects. They ranged in age from 23 to 62 years (mean, 40.8 ± 10.7 years). All but one were corrected to 20/20 visual acuity; the tenth subject could only be corrected to 20/30, but his results were the same as the others and were therefore included. Only two of the subjects had any knowledge about the purpose of the experiment. ApparatusThe observers viewed two lights flashing every 2 s. The flashing lights were produced by two sets of two concentric cylinders. The two inner cylinders were yoked and made to rotate in opposite directions (figure 1). The left cylinder rotated at a given
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