Retinal topography, cell density and sizes of ganglion cells in the killer whale (Orcinus orca) were analyzed in retinal whole mounts stained with cresyl violet. A distinctive feature of the killer whale’s retina is the large size of ganglion cells and low cell density compared to terrestrial mammals. The ganglion cell diameter ranged from 8 to 100 µm, with the majority of cells within a range of 20–40 µm. The topographic distribution of ganglion cells displayed two spots of high cell density located in the temporal and nasal quadrants, 20 mm from the optic disk. The high-density areas were connected by a horizontal belt-like area passing below the optic disk of the retina. Peak cell densities in these areas were evaluated. Mean peak cell densities were 334 and 288 cells/mm² in the temporal and nasal high-density areas, respectively. With a posterior nodal distance of 19.5 mm, these high-density data predict a retinal resolution of 9.6′ (3.1 cycles/deg.) and 12.6′ (2.4 cycles/deg.) in the temporal and nasal areas, respectively, in water.

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The Eye - a Neglected Organ in Environmental and Occupational Medicine: An Overview of Known Environmental and Occupational Non-Traumatic Effects on the EyesThe objective of this study was to give an overview of the known literature data on the influence of environmental and occupational factors on the eye. Sixty-six articles were selected by searching Medline and PubMed databases using the following key words in different combinations: occupational and environmental factors, dry eye syndrome, cataract, retinal vascular changes.Most of the studies dealt with conditions on the eye surface and used eye discomfort syndrome and dry eye syndrome to outline the effects of air pollutants. Some reported increased frequency of lens opacities due to indoor fuel exposure, in particular biofuel, and negative effects of styrene exposure on colour vision. Investigations of retinal vascular changes and retinopathy after chronic exposure to carbon disulfide (CS2) and of retinal and choroidal haemodynamics after exposure to carbon monoxide (CO) found that CS2 caused an increase in retinal venous diameters and CO caused an increase in arterial and venous diameters, retinal blood flow velocity, and fundus pulsation amplitude. This article also discusses the influence of light exposure on retinal damage. It shows that very little information is available about the influence of environmental and occupational factors on the eye, and retina and retinal vessels in particular.

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