Optical quality of the human eye

Campbell, F. W.; Gubisch, R. W.

doi:10.1113/jphysiol.1966.sp008056

Cited by 743 publications

(394 citation statements)

References 15 publications

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“…In addition, we took into account the effects of optical scattering in the human eye which effectively broadens the bleached area and correspondingly narrows the spared areas. Using the estimates of Campbell and Gubisch (1966), we determined the relative widths of the dark and light bars which would be appropriate as the test stimulus to be used after the uniform bleach so as to match the areas cont~buting to detection after the grating bleach. In this set of experiments, the independent variable was the spatial frequency of the grating bleach and the dependent variable was the density in the uniform bleach required to match the time course of recovery after each grating bleach early in dark adaptation.…”

Section: Discussionmentioning

confidence: 99%

“…We matched this sensitivity by selecting an intensity of a uniform bleaching light which produces an identical time course of recovery when measurements were made with a grating test which was composed of a pattern light and dark bars matching the reverse protile of the bleaching stimulus after taking into account optical scatter. We estimated the retinal image profile of the bleaching pattern by using the measurements of Campbell and Gubisch (1966) as outlined in the Methods section. We assumed that regions for which light scatter dropped to e-' or less of the value of exposed strips contributed to detection, so that the test stimuli we used after uniform bleaches had a pattern, the reverse of the retinal image of the bleaches, of thin light bars (2.1,3.1 and 4.2 min for the 5,7.5 and 10 min stimuli, respectively) and thicker dark bars.…”

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

“…Error bars are based on between-day variability in measurements made over four separate days. These estimates of the effective bleaching intensity in the regions underlying the dark bars as a function of bar width can be compared to the intensity of the retinal image at its local minimum in the center of the dark bars, estimated from the results of Campbell and Gubisch (1966) as outlined in the Methods section. The data points lie above this curve representing the estimated scattered light.…”

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

“…As in the fovea for this observer, the elevation above the scatter estimate is constant for all bar widths, consistent with the interpretation that this elevation may be due to an underestimate of optical scatter in designing the appropriate test after the uniform bleach. Furthermore, since we estimated optical scatter in the parafovea by using measurements made in the fovea (Campbell & Gubisch, 1966), it is even more likely that scatter has been unde~stimated.…”

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

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The spread of adaptation in human foveal and parafoveal cone vision

1990

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Abstract-We investigated the spread of bleaching adaptation for human cone vision in the central fovea and at an eccentricity of 5 deg in the nasal retina. Cone thresholds measured after adaptation to a grating bleach were compared to those measured after a uniform bleach. We conclude that the fovea1 and parafoveal cone systems show excellent localization of the etfects of adaptation. For areas 2.5-S min removed from the bleach, our measurement show only small sensitivity losses amounting to between 0.10 and 0.25 log unit elevation in threshold, after taking account of optical scatter. AdaptationCones Fovea Parafovea INTRODUCIIONLight adaptation in the human retina entails a number of different mechanisms (see Hood & Finkelstein, 1986, for a review). The mechanism most commonly identified with adaptation involves the loss of sensitivity, or gain, of retinal cells to incremental stimuli as a consequence of exposure to an adapting light. Although it is generally agreed that the gain changes associated with light adaptation occur early in retinal processing, there is still ambiguity about the anatomical sites of action. In the rod system the primary gain changes do not seem to occur in the receptors themselves (Baylor, Nunn & Schnapf, 1984), but at a site where signals from many rods converge (Rushton & Westheimer, 1962). Rushton (1965) pointed out that the scotopic increment threshold begins to rise at a level where individual rods receive, on the average, less than one quantum per second, suggesting that ~nsitivity is controlled by the pooled signals from many rods. This conclusion is supported by physiological evidence for spatial summation of the effects of adaptation as measured in the rod-driven activity of ganglion cells in the cat (e.g. Cleland & Enroth-Cugell, 1968; Enroth-Cugell & Shapley, 1973). Spatial summation is also observed in the loss of sensitivity associated with very bright bleaching *The expmiments reported here were performed while the authors were at the Uni~~ity of California, San Diego.lights (Rushton $ Westheimer, 1962; Andrews &c Butcher, 1981;Barlow & Andrews, 1973; Bonds & Enroth-Cugell, 1979; MacLeod, Chen & Crognale, 1989;Cicerone & Hayhoe, 1990). It is less clear whether there is a similar kind of spatial summation of adaptation in the cone system. Based on a number of lines of evidence, it has commonly been thought that the primary gain adjustment in response to light occurs in the cone photoreceptors themselves (e.g. Shapley & Enroth-Cugell, 1984). The rr mechanisms isolated by Stiles' chromatic adaptation experiments closely resemble the photopigment spectral sensitivities (Pugh & Sigel, 1978), indicating, to a first approximation, that the different cone types adapt independently and much of adaptation occurs in the cones themselves. More clear cut evidence for receptoral adaptation, at least for bleaching lights, is provided by Wi~ams and MacLeod (1979), who found that bleaching exposures gave inde~ndent sensitivity losses in long-and middle-wavelength-sensitive cone sys...

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Section: Discussionmentioning

confidence: 99%

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

Section: A Lower Limit On the Size Of The Summation Area For Adaptationmentioning

confidence: 99%

See 2 more Smart Citations

The spread of adaptation in human foveal and parafoveal cone vision

1990

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“…Visual acuity in the fovea is greater than in the periphery by at least a factor of 40 (Wertheim, 1894). This is the result of many factors including the optics of the eye (Campbell and Green, 1965), photoreceptor sampling density (Williams and Coletta, 1987), spatial averaging due to the size of peripheral receptive fields (Merigan and Katz, 1990), as well as ganglion cell density (Wi\ssle et al, 1990).…”

Section: Space-variant Visionmentioning

confidence: 99%