Abstract
1. The directional sensitivity (Stiles—Crawford effect) of retinal cones is supposed to be associated with their shape, but only extrafoveal cones have a cone-like shape; cones in the central fovea are elongated and look like rods.
2. To determine whether the directional sensitivity of cones depends on their shape, the Stiles—Crawford effect was measured both in the central fovea and in the parafovea of the human eye.
2. To ensure that the cone population tested was homogeneous, a small brief test flash, brought into the eye through the centre of the pupil, was placed at threshold by varying the intensity of a large adapting field. The directional sensitivity of the cones was determined by finding the efficiency of light to act as an adapting background as a function of position of entry in the pupil.
4. Central foveal cones have a less pronounced directional sensitivity than parafoveal cones and this lends support to the conclusion that the Stiles—Crawford effect is connected with the shape of the retinal receptors.
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Selected References
These references are in PubMed. This may not be the complete list of references from this article.
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