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Setonite, also called African bloodstone, is composed of red jasper, grey chalcedony, and pyrite. Dragon's Blood, sometimes called Australian bloodstone, is composed of red jasper and green epidote. The name heliotrope derives from ancient beliefs about the manner in which the mineral reflects light.
Schematic diagram of the human eye. It shows a horizontal section through the right eye. The eye is made up of three coats, or layers, enclosing various anatomical structures. The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures.
The ophthalmic artery (OA) is an artery of the head.It is the first branch of the internal carotid artery distal to the cavernous sinus.Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some structures in the nose, face, and meninges.
Unlike the topographic maps of the senses, the neurons of the motor cortex are efferent neurons that exit the brain instead of bringing information to the brain through afferent connections. The motor system is responsible for initiating voluntary or planned movements ( reflexes are mediated at the spinal cord level, so movements associated ...
The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. [1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. [2]
A subconjunctival hemorrhage appears as a bright red patch on the white of the eye and is commonly referred to as a burst blood vessel. In hyphema, blood pools in the anterior chamber, where the iris (the colored part of the eye) and the pupil are located. Hyphemas are graded based on the amount of blood covering the cornea.
Apposition eyes work by gathering a number of images, one from each eye, and combining them in the brain, with each eye typically contributing a single point of information. The typical apposition eye has a lens focusing light from one direction on the rhabdom, while light from other directions is absorbed by the dark wall of the ommatidium .
Thus if the central retinal artery gets occluded, there is complete loss of vision in that eye even though the fovea is not affected. The entire retina (with the exception of the fovea) becomes pale and swollen and opaque while the central fovea still appears reddish (this is because the choroid color shows through).