Ocular straylight
Ocular straylight is a phenomenon where parts of the eye scatter light, creating glare. It is analogous to stray light in other optical systems; scattered light reaches the retina but does not contribute to forming a correct image.
One can observe the effect of straylight by looking at a distant bright light source against a dark background. If the source is small, it would look like a small bright spot if they eye imaged it perfectly. Scattering in the eye makes the source appear spread out, surrounded by glare. The disability glare caused by such a situation has been found to correspond precisely to the effect of true light.[1] As a consequence, disability glare was subsequently defined by this true light, called "straylight".[1]
Individual differences
Straylight can differ considerably between individuals. Aging of the crystalline lens of the human eye causes straylight to become worse.[2] Lens extraction and artificial lens implantation is an effective treatment.
Less common causes for straylight include:
- Diseases of the cornea, e.g. Fuchs' dystrophy.[3]
- Lack of pigmentation, e.g. albinism.[4]
- Laser refractive surgery, with occasional haze formation.[5]
- Excessive floaters in the vitreous humour.[6]
- Contact lenses.[7]
References
- 1 2 Vos JJ. "Disability glare - a state of the art report". Commission International de l'Eclairage Journal. 1984;3/2:39-53
- ↑ Van den Berg TJTP et al. "Straylight effects with aging and lens extraction". Am J Ophthalmol. 2007;144:358-363
- ↑ Van der Meulen IJ et al. "Quality of vision in patients with Fuchs Endothelial dystrophy and after DSEK". Arch Ophthalmol 2011
- ↑ Kruijt B et al. "Ocular straylight in albinism". Optom Vis Sc 2011;88:E585-E592
- ↑ Van Bree MC et al. "Straylight values after refractive surgery". Ophthalmology 2011;118:945-953.
- ↑ Mura M et al. "Surgery for floaters". Ophthalmology 2011;118:1894
- ↑ Van der Meulen IJ et al. "Straylight measurement in contact lens wear". Cornea 2010;29:516-522