Stranic - Revision history

imported>Projects221 at 05:01, 21 March 2013

2013-03-21T05:01:46Z

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	== References ==		== References ==

	[1] W. S. Stiles, “The Luminous Efficienty of Monochromatic Rays Entering the Eye Pupil at Different Points and a New Colour Effect," Proc. R. Soc. Lond. B, vol. 123, pp. 90-118, 1937. http://rspb.royalsocietypublishing.org/content/123/830/90

	[2] G. Westheimer, “Directional sensitivity of the retina: 75 year of Stiles-Crawford effect," Proc. R. Soc. B, vol. 275, pp. 2777-2786, 2008. http://rspb.royalsocietypublishing.org/content/275/1653/2777.full.pdf+html		[1] G. Westheimer, “Directional sensitivity of the retina: 75 year of Stiles-Crawford effect," Proc. R. Soc. B, vol. 275, pp. 2777-2786, 2008. http://rspb.royalsocietypublishing.org/content/275/1653/2777.full.pdf+html

			[2] W. S. Stiles, “The Luminous Efficienty of Monochromatic Rays Entering the Eye Pupil at Different Points and a New Colour Effect," Proc. R. Soc. Lond. B, vol. 123, pp. 90-118, 1937. http://rspb.royalsocietypublishing.org/content/123/830/90

	[3] F. Flamant, W. S. Stiles, “The Directional and Spectral Sensitivities of the Retinal Rods to Adapting Fields of Different Wavelengths," J. Physiol., vol. 107, pp. 187-202, 1948. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392159/pdf/jphysiol01481-0065.pdf		[3] F. Flamant, W. S. Stiles, “The Directional and Spectral Sensitivities of the Retinal Rods to Adapting Fields of Different Wavelengths," J. Physiol., vol. 107, pp. 187-202, 1948. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392159/pdf/jphysiol01481-0065.pdf

imported>Projects221 at 03:01, 21 March 2013

2013-03-21T03:01:02Z

← Older revision		Revision as of 03:01, 21 March 2013
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	Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone photoreceptors [4], which are roughly oriented towards the center of the pupil [5]. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides [4,6]. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules [7]. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.		Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone photoreceptors [4], which are roughly oriented towards the center of the pupil [5]. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides [4,6]. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules [7]. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.

	However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations [8] may contribute to the Stiles-Crawford effect. Due to the complexity of a single cone photoreceptor and the layers of the retina which lie ahead of the cone photoreceptor on the light path, as well as the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully model all the factors which may affect the production of the visual stimulus in an eye [1].		However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations [8] may contribute to the Stiles-Crawford effect. Due to the complexity of a single cone photoreceptor and the layers of the retina which lie ahead of the cone photoreceptor on the light path, as well as the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully model all of the factors which may affect the production of the visual stimulus in an eye [1].

	== References ==		== References ==

imported>Projects221 at 03:00, 21 March 2013

2013-03-21T03:00:16Z

← Older revision		Revision as of 03:00, 21 March 2013
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	Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone photoreceptors [4], which are roughly oriented towards the center of the pupil [5]. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides [4,6]. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules [7]. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.		Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone photoreceptors [4], which are roughly oriented towards the center of the pupil [5]. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides [4,6]. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules [7]. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.

	However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations [8] may contribute to the Stiles-Crawford effect. Due to the complexity of a single cone photoreceptor, the layers of the retina which lie ahead of the cone photoreceptor on the light path, ~~and~~ the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully ~~account for~~ all the factors which may affect the production of the visual stimulus in an eye [1].		However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations [8] may contribute to the Stiles-Crawford effect. Due to the complexity of a single cone photoreceptor and the layers of the retina which lie ahead of the cone photoreceptor on the light path, as well as the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully model all the factors which may affect the production of the visual stimulus in an eye [1].

	== References ==		== References ==

imported>Projects221 at 02:57, 21 March 2013

2013-03-21T02:57:18Z

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	== Stiles-Crawford Effect ==		== Stiles-Crawford Effect ==
	[[File:Image_of_Eye.jpg\|250px\|thumb\|right\|Light rays entering the eye at different positions along the pupil. Light rays entering through the pupil strike the retina at an angle.]]		[[File:Image_of_Eye.jpg\|250px\|thumb\|right\|Light rays entering the eye at different positions along the pupil. Light rays entering through the pupil strike the retina at an angle.]]
	The '''Stiles-Crawford effect''' (subdivided into the Stiles Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors [1].		The '''Stiles-Crawford effect''' (subdivided into the Stiles-Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors [1].

	The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater is than expected by the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil [1]. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side [2].		The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater is than expected by the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil [1]. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side [2].
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	== Observations ==		== Observations ==
	[[File:SC_Effect_Plot.png\|250px\|thumb\|right\|Relative luminance efficiency as a function of distance from the center of the pupil. Data represent two separate measurements taken three months apart in the left eye of W. S. Stiles. [2]]]		The Stiles Crawford Effect is quantified as a function of distance (''d'') away from the center of the pupil using the following equation:

	The Stiles Crawford Effect is quantified as a function of distance (d) away from the center of the pupil using the following ~~relationship~~:

	<math>\eta\,\! (d) = \frac{amount\ of\ light\ entering\ through\ the\ center\ of\ the\ pupil\ to\ produce\ a\ certain\ response}{amount\ of\ light\ entering\ at\ a\ distance\ d\ away\ from\ the\ center\ to\ produce\ the\ same\ response}</math>		<math>\eta\,\! (d) = \frac{amount\ of\ light\ entering\ through\ the\ center\ of\ the\ pupil\ to\ produce\ a\ certain\ response}{amount\ of\ light\ entering\ at\ a\ distance\ d\ away\ from\ the\ center\ to\ produce\ the\ same\ response}</math>

			[[File:SC_Effect_Plot.png\|250px\|thumb\|right\|Relative luminance efficiency as a function of distance from the center of the pupil. Data represent two separate measurements taken three months apart in the left eye of W. S. Stiles. [2]]]
	where ''η'' is the relative luminance efficiency, and ''d'' is defined as positive on the temporal side of the pupil and negative on the nasal side of the pupil [1].		where ''η'' is the relative luminance efficiency, and ''d'' is defined as positive on the temporal side of the pupil and negative on the nasal side of the pupil [1].

	Measurements of the relative luminance efficiency are typically largest and symmetric about some distance (d<sub>m</sub>), which is typically ranges from -0.2 to -0.5 mm, away from the center of the pupil towards the nasal side [2]. The significance of the Stiles-Crawford effect is evident by the fact that relative luminance efficiency drops by up to 90% for light entering near the edge of the pupil [1].		Measurements of the relative luminance efficiency are typically largest and symmetric about some distance (''d<sub>m</sub>''), which is typically ranges from -0.2 to -0.5 mm, away from the center of the pupil towards the nasal side [2]. The significance of the Stiles-Crawford effect is evident by the fact that relative luminance efficiency drops by up to 90% for light entering near the edge of the pupil [1].

	Experimental data are fit accurately using the following empirical relationship:		Experimental data are fit accurately using the following empirical relationship:
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	<math>\eta\,\! (d) = \eta\,\! (d_m)10^{-p(\lambda\,\!)(d-d_m)^2} </math>		<math>\eta\,\! (d) = \eta\,\! (d_m)10^{-p(\lambda\,\!)(d-d_m)^2} </math>

	where ''p(λ)'' is a wavelength dependent parameter which represents the magnitude of the Stiles-Crawford effect [2]. Measurements indicate that the value of ''p(λ)'' ranges from 0.05 to 0.08.		where ''p(λ)'' is a wavelength dependent parameter which represents the magnitude of the Stiles-Crawford effect [2], with larger values of ''p'' corresponding to a stronger falloff in the relative luminance efficiency as a function of distance from the center of the pupil. Measurements indicate that the value of ''p(λ)'' ranges from 0.05 to 0.08.

	== Explanation ==		== Explanation ==

imported>Projects221 at 23:23, 20 March 2013

2013-03-20T23:23:19Z

← Older revision		Revision as of 23:23, 20 March 2013
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	[7] J. M. Enoch, “Optical properties of the retinal receptors," J. Opt. Soc. Am., vol. 53, pp. 71-85, 1963. http://rspb.royalsocietypublishing.org/content/275/1653/2777.full.pdf+html		[7] J. M. Enoch, “Optical properties of the retinal receptors," J. Opt. Soc. Am., vol. 53, pp. 71-85, 1963. http://rspb.royalsocietypublishing.org/content/275/1653/2777.full.pdf+html

	[8] P. L. Walraven, M. A. Bouman “Relation ~~between~~ Directional Sensitivity and Spectral Response Curves in Human Cone Vision," J. Opt. Soc. Am., vol. 50, pp. 780-784, 1960. http://www.opticsinfobase.org/josa/abstract.cfm?uri=josa-50-8-780		[8] P. L. Walraven, M. A. Bouman “Relation Between Directional Sensitivity and Spectral Response Curves in Human Cone Vision," J. Opt. Soc. Am., vol. 50, pp. 780-784, 1960. http://www.opticsinfobase.org/josa/abstract.cfm?uri=josa-50-8-780

imported>Projects221 at 22:30, 20 March 2013

2013-03-20T22:30:04Z

Show changes

imported>Projects221 at 22:08, 20 March 2013

2013-03-20T22:08:06Z

← Older revision		Revision as of 22:08, 20 March 2013
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	Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells, which are oriented perpendicular to the retina and point towards the center of the pupil. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.		Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells, which are oriented perpendicular to the retina and point towards the center of the pupil. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.

	However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect.		However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect. Due to the complexity of a single cone photoreceptor, the layers of the retina which lie ahead of the cone photoreceptor on the light path, and the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully account for all the factors which may affect the production of the visual stimulus in an eye.

	== References ==		== References ==

imported>Projects221 at 22:03, 20 March 2013

2013-03-20T22:03:44Z

← Older revision		Revision as of 22:03, 20 March 2013
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	Initially, it was thought that the Stiles-Crawford effect may be caused by the screening of light that passes near the edge of the pupil. This possibility was ruled out because variations in light extinction along different light paths through the pupil do not account for the significant reduction in the luminance efficiency. Furthermore, light screening does not explain the significant wavelength dependence of the Stiles-Crawford effect. Due to the large reduction in the Stiles-Crawford effect for rod vision tested under scotopic conditions, scientists concluded that it must be dependent on properties of the retina; more specifically the photon capture properties of the cone photoreceptors.		Initially, it was thought that the Stiles-Crawford effect may be caused by the screening of light that passes near the edge of the pupil. This possibility was ruled out because variations in light extinction along different light paths through the pupil do not account for the significant reduction in the luminance efficiency. Furthermore, light screening does not explain the significant wavelength dependence of the Stiles-Crawford effect. Due to the large reduction in the Stiles-Crawford effect for rod vision tested under scotopic conditions, scientists concluded that it must be dependent on properties of the retina; more specifically the photon capture properties of the cone photoreceptors.

	Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells, which are oriented perpendicular to the retina and point towards the center of the pupil. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.		Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells, which are oriented perpendicular to the retina and point towards the center of the pupil. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. More specifically, due the narrow confinement of light within cone protoreceptors, destructive or constructive interference of the electromagnetic field may occur within the cone photoreceptors for particular wavelengths of light, thus significantly affecting the overall absorption of light by the photopigment molecules. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.

	However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect.		However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect.

imported>Projects221 at 21:56, 20 March 2013

2013-03-20T21:56:59Z

← Older revision		Revision as of 21:56, 20 March 2013
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	The '''Stiles-Crawford effect''' (subdivided into the Stiles Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors.		The '''Stiles-Crawford effect''' (subdivided into the Stiles Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors.

	The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater is than expected by to the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side.		The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater is than expected by the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side.

	The Stiles-Crawford effect of the second kind is the phenomenon where the observed color of monochromatic light entering the eye near the edge of the pupil is ~~different~~ different compared to that for the same wavelength light entering near the center of the pupil, regardless of the overall intensities of the two lights.		The Stiles-Crawford effect of the second kind is the phenomenon where the observed color of monochromatic light entering the eye near the edge of the pupil is different compared to that for the same wavelength light entering near the center of the pupil, regardless of the overall intensities of the two lights.

	Both of the Stiles-Crawford effects of the first and second kind are highly wavelength dependent, and they are most evident under photopic conditions.		Both of the Stiles-Crawford effects of the first and second kind are highly wavelength dependent, and they are most evident under photopic conditions.
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	Initially, it was thought that the Stiles-Crawford effect may be caused by the screening of light that passes near the edge of the pupil. This possibility was ruled out because variations in light extinction along different light paths through the pupil do not account for the significant reduction in the luminance efficiency. Furthermore, light screening does not explain the significant wavelength dependence of the Stiles-Crawford effect. Due to the large reduction in the Stiles-Crawford effect for rod vision tested under scotopic conditions, scientists concluded that it must be dependent on properties of the retina; more specifically the photon capture properties of the cone photoreceptors.		Initially, it was thought that the Stiles-Crawford effect may be caused by the screening of light that passes near the edge of the pupil. This possibility was ruled out because variations in light extinction along different light paths through the pupil do not account for the significant reduction in the luminance efficiency. Furthermore, light screening does not explain the significant wavelength dependence of the Stiles-Crawford effect. Due to the large reduction in the Stiles-Crawford effect for rod vision tested under scotopic conditions, scientists concluded that it must be dependent on properties of the retina; more specifically the photon capture properties of the cone photoreceptors.

	Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.		Electromagnetic analysis of light rays incident on a model human cone revealed that the Stiles-Crawford effect is explained by the shape, size, and refractive indices of the various parts of cone cells, which are oriented perpendicular to the retina and point towards the center of the pupil. Since the width of human cone cells is on the order of two microns, which is on a similar order of magnitude as the wavelength of visible light, electromagnetic analysis indicated that the light capture phenomena in human cone cells are similar to those observed in optical waveguides. This was the first analysis that sufficiently explained the non-monotonic wavelength dependence of ''p'' parameter that describes the strength the Stiles-Crawford effect.

	However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect.		However, due to simplicity of the cone models and the lack of accurate knowledge of the optical parameters of the human cone cell used in the electromagnetic analysis, it is unclear whether other factors such as the photopigment concentrations may contribute to the Stiles-Crawford effect.

imported>Projects221 at 21:52, 20 March 2013

2013-03-20T21:52:11Z

← Older revision		Revision as of 21:52, 20 March 2013
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	The '''Stiles-Crawford effect''' (subdivided into the Stiles Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors.		The '''Stiles-Crawford effect''' (subdivided into the Stiles Crawford effect of the first and second kind) is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors.

	The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater than expected ~~due~~ to the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side.		The Stiles-Crawford effect of the first kind is the phenomenon where light entering the eye near the edge of the pupil produces a lower photoreceptor response compared to light of equal intensity entering near the center of the pupil. The reduction in the photoreceptor response is significantly greater is than expected by to the reduction in the photoreceptor acceptance angle of light entering near the edge of the pupil. Measurements indicate that the peak photoreceptor sensitivity does not occur for light entering they eye directly through the center of the pupil, but at an offset of approximately 0.2-0.5 mm towards the nasal side.

	The Stiles-Crawford effect of the second kind is the phenomenon where the observed color of monochromatic light entering the eye near the edge of the pupil is different different compared to that for the same wavelength light entering near the center of the pupil, regardless of the overall intensities of the two lights.		The Stiles-Crawford effect of the second kind is the phenomenon where the observed color of monochromatic light entering the eye near the edge of the pupil is different different compared to that for the same wavelength light entering near the center of the pupil, regardless of the overall intensities of the two lights.