Hyaloid Canal Essay

956 Words 4 Pages
Hyaloid canal: The hyaloid canal is a small, transparent tunnel that traces its path through the vitreous body of the eye, spanning the optic nerve disc to the lens. In an adult person, the hyaloid canal carries lymph to help change the volume of the lens. When the lens expands, the hyaloid canal compresses, so that the eye’s internal pressure and volume remain constant (Merriam-Webster).
Optic nerve: A part of the central nervous system, the optic nerve connects the eye to the brain, carrying electrical signals formed by the retina to be interpreted as images (Medicine Net).
Central retinal vein: The central retinal vein is where blood circulating in the eye is returned to the heart to be cleaned. It forms the arterioles, branches of an
…show more content…
It carries the electrical impulses that communicate of light to the visual cortex, where signals become images (CHW).
Macula: The macula is the focusing portion of the eye that allows it to view fine details (CHW). At its center is the fovea.
Fovea: The fovea is located at the center of the macula. It facilitates clear central vision, or the type of sight used to observe details, such as reading. (Retinary).
Retina: The retina a tissue essential to sight that lines the inside of the eye. It’s the home of the photoreceptor cells where light is transformed into electrical impulses, which are then brought to the brain by the optic nerve, where it finally becomes an image. The retina’s photoreceptors come in two types: rods and cones (VisionAware).
Rods: Rods are highly light-sensitive processing cells that provide “scotopic vision,” or eyesight in low light conditions, unlike cones, which process visual information in high light conditions (VisionAware): because of rods, an eye can adapt to the dark. With the cones responsible for central vision, the rods provide peripheral (side) vision (American Optometric Association) and are most sensitive to motion. Rods far outnumber cones: the average retina houses 120-150 million rods, all primarily in the outer retina, as opposed to 6-7 million
…show more content…
Rays that enter the eye parallelly must be bent into focusing at a point; this is called “refraction,” or bending light rays as they pass from one medium into another of a different density: solid into liquid, or, in the specific case of the eye, air into water. The light that enters and is refracted inside the cornea then passes through the pupil, a round opening at the center of the iris. The amount of light let in is determined by environmental factors and the iris, which acts as an adjustable diaphragm controlling the dilation of the pupil (Health Guidance). In dim lighting, the the iris will expand the pupil, or dilate it, to permit more rays in. If it is bright, however, the pupil will shrink to avoid damage. Once past the pupil, light then hits the eye’s lens. The lens of the eye works very much like the lens of a camera, altering its width to bring the light into focus (NKFC). The lens is crystalline and pliable, casting an upside-down image onto the wall of the retina (Sciencing). The retina, a layer of light-sensitive photoreceptor cells, registers this image with rods and cones. Here, in the retina, the rays are focuses into a point (Glasses Crafter); and here, several things can go wrong while translating light into an image. For example, myopia, or nearsightedness, occurs when light rays are bent too far for the retina to focus on; meanwhile,

Related Documents