![]() Moreover, light reflected more or less diffusely from the fundus also contributes to retinal straylight. Along the normal optical path, the cornea, crystalline lens, and vitreous may scatter light. Different structures in the eye have been identified as sources of retinal straylight. 1 2 3This not only leads to glare while driving at night, but also to other complaints such as haziness of vision. The scattered-light results in a veil of straylight over the retina, which in turn reduces the contrast of the retinal image. Measurement of straylight under large angle and small pupil conditions can be used for quantitative assessment of eye wall translucency.įor a discussion of these questions, it is important to realize that glare originates from the phenomenon of light-scattering in the eye’s optical media. In normal eyes, straylight values measured with photopic pupils are by approximation also valid for mesopic and scotopic pupils, such as in night driving. Pupil diameters decreased to photopic values under typical night-driving glare conditions.Ĭonclusions. For large scatter angles and small pupil diameters, eye wall translucency contributes significantly to straylight in a wavelength- and pigmentation-dependent manner. For natural pupils (between 2 and 7 mm diameter), straylight weakly depends on pupil diameter (within 0.2 log units). To estimate the order of magnitude of pupil contraction in the typical glare situation, pupil reflexes resulting from the sudden appearance of headlight-equivalent bright lights were recorded in three subjects in a laboratory environment. Data were analyzed to assess effects of (1) inhomogeneity of light-scattering over the pupil plane, (2) translucency of the eye wall, and (3) effects of the periphery of the lens. In the study of red-free light, a yellow-LED based system was used with the same five subjects for scattering angles of 3.5°, 10°, and 28°. ![]() Straylight was measured as a function of pupil diameter ranging from 1.3 to >8 mm in five normal subjects by using a white-light, CRT-based system for scattering angles of 3.5°, 7°, and 14°. In this study, the effects of pupil diameter and, especially in the case of small pupils, of eye wall translucency on the amount of retinal straylight were investigated. The typical disability glare is known to result from retinal straylight. Glare problems originating from bright lights are generally experienced more strongly at night.
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