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Biological Effects: Why We Care About Laser Exposure
Published in Ken Barat, Laser Safety Management, 2017
Symptoms of a laser burn in the eye include a headache shortly after exposure, excessive watering of the eyes, and sudden appearance of floaters. Floaters are swirling distortions that occur randomly in normal vision, usually after a blink or when eyes have been closed for a couple of seconds. Floaters are caused by dead cells that detach from the retina and choroid and float in the vitreous humor. Ophthalmologists often dismiss minor laser injuries as floaters because of it is difficult to detect minor retinal injuries. Minor corneal burns cause a gritty feeling, like sand in the eye.
Phase retrieval for studying the structure of vitreous floaters simulated in a model eye
Published in Journal of Modern Optics, 2021
Varis Karitans, Sergejs Fomins, Maris Ozolinsh
Vitreous floaters belong to a class of entoptic phenomena and are experienced by most people as chains, bubbles, cobwebs and other structures floating in the field of view. Vitreous floaters are transparent phase objects, i.e. cells, fibrils, clumps of proteins floating in a liquified vitreous body [1,2]. Typical size of the elements causing vitreous floaters lies in the range from a few to few tens of micrometers [3]. Vitreous floaters manifest themselves as diffraction patterns due to the mismatch between the refractive indices of the floating elements and the surrounding media [4,5]. In most cases, vitreous floaters cause merely visual discomfort and do not indicate any serious ocular condition, however, a sudden increase in the number of vitreous floaters may point to retinal detachment, inflammation, hemorrhage, or other pathologies. In most cases, people are able to adapt to vitreous floaters, however, if vitreous floaters become symptomatic, patients may want to remove them. Currently, vitreolysis and vitrectomy are the most efficient treatment options [6], however, both options are associated with high risks (retinal detachment, tears, hemorrhage, burns and others) and their necessity must be carefully considered. In order to neutralize vitreous floaters safely, a non-invasive method is preferred. A reasonable and safe method how to cancel or reduce the effects of vitreous floaters can be based on spatial modulation of the light entering the eye. In order to know the required modulation of the incoming light, the structure of the elements causing vitreous floaters must be determined. Once the structure of these elements has been determined, the shape of a wavefront modulator can be adjusted so that the phase distortions caused by the floating elements can be eliminated. Currently, optical coherence tomography (OCT) [7] and ultrasonography [8] can be used to determine the structure of elements floating in a liquified vitreous body. These methods, however, can be difficult to be incorporated into an optical system performing the dual task, i.e. analysing the structure of the floating elements and compensating the phase distortions.