2015-05: The significance of changes in pupil size and straylight value of human eye with slight changes in environmental light intensity
Part 1 - The amount of light entering one’s eye is regulated by the iris through controlling the size of the pupil by means of two muscles: the circumferential sphincter muscle in the margin of the iris innervated by the parasympathetic nervous system, and the iris dilator muscle which is a smooth muscle, rooting radially in the iris and therefore fits as a dilator. The normal pupil can range in diameter from 8 mm in very dim light down to 1.5 mm under very bright conditions.The significance of the pupil diameter changes with slight change of environmental illumination will be evaluated.
Part 2 - When the light enters one’s eye, it is refracted by the transparent substances of the eye, e.g., the cornea, the crystalline lens in order to form an image on the retina. A small fraction of this light however is scattered in this process and causes a veil of retinal straylight (SL) on the retinal image leading to hazy vision, increased glare, etc. Intraocular SL will be measured and we will investigate whether the environmental illumination affects the outcome of the SL value.