Coloboma is a congenital eye defect, which is represented by missing pieces of tissue (gaps or notches) in eye structures.
The eye consist of several protective layers and cavities. The outer layer consists of the sclera and the cornea. The front part of the sclera is covered by a transparent membrane called conjunctiva, involved in protecting the eyes and lining the inside of the eyelids. The cornea is a dome-shaped structure in the front of the eye that encloses the anterior chamber of the eye. It is transparent, allowing light to enter the eye, and along with the lens helps focus and direct light onto the retina.
The middle layer of the eye includes the iris, the ciliary body, the lens and the choroid. The iris gives a person’s distinct eye colour, controls the size of the pupil and hence the amount of light entering the eye. It separates the anterior and posterior chambers in the front part of the eye. These chambers contain the aqueous humour, which is important in nourishing the lens and cornea. The lens is a shear, flexible structure, which changes its shape and hence participate in focusing one’s vision on close or distant objects. The vitreous humor is a jelly-like substance that fills the back portion of the eye. It has a structural function and is involved in maintaining the eye’s shape, but also helps transmitting the light to the retina. The choroid is a membrane found between the sclera and the retina. It lines the back of the eye and is rich in blood vessels. It is highly pigmented in order to absorb light and prevent scattering.
The inner layer- the retina lines the inside of the back part of the eye and is the light-sensitive part. It is rich in photoreceptor cells and each photoreceptor is linked to...
... middle of paper ...
...Willer, G.B., Smith, K., Gregg, R.G., and Gross, J.M.(2008) Zebrafish blowout provides genetic evidence for Patched1-mediated negative regulation of Hedgehog signaling within the proximal optic vesicle of the vertebrate eye, Developmental Biology 319(1):10-22
Sanyanusin P., A.McNoe L., J.Sullivan M., Weaver R.Grey. Eccles M.R. (1995) Mutation of PAX2 in two siblings with renal-coloboma syndrome, Human Molecular Genetics Vol. 4, No. 11 2183-2184
Torres M, Gómez-Pardo E., Gruss p. (1996) Pax2 contributes to inner ear patterning and optic nerve trajectory , Development 122, 3381-3391
Viringipurampeer I. A., Ferreira T., DeMaria S., Yoon J. J., Shan X., Moosajee M., Gregory-Evans K., Ngai J., Gregory-Evans C. Y., (2012) Pax2 regulates a fadd-dependent molecular switch that drives tissue fusion during eye development, Human Molecular Genetics, Vol. 21, No. 10 2357–2369
The widespread involvement of Retinal Pigment Epithelium (RPE), flat (placoid) nature of the lesions and absence of overlying serous retinal detachment and minimal choroidal involvement lead Gass to conclude RPE was primary focus of inflammation.(1) ...
Laila confirms that her friends have ordered pizza using her visual system. Through the sensation of light, sensory information is processed and Laila is then able to see the pizza. The pupil absorbs light, by allowing light to enter the eye, and light will then be transferred to the lens. The lens is responsible for refracting light and focusing the light inside of the eye, also known as the retina. The second cranial nerve, or optic nerve, is responsible for carrying the visual signal from the eye to the optic chiasm. The optic nerve, or second cranial nerve, is located in the back of the eye. This cranial nerve transfers visual information to visual centers in the brain through many electric impulses. The optic chiasm has temporal fibers that travel ipsilaterally as nasal fibers transmit information contralaterally, to the opposite side of the associated visual field. The visual cortex can then process sensory information from the opposite eye. Laila’s blind spot is where the optic nerve begins and there are no rod or cone cells in the optic nerve. The brain has to try to compensate for the lack of photosensitive
Sight helps us navigate the world around us more than any of our other senses. In a fraction of a second, our eyes work with our brains to tell us the size, shape, and texture of an object. They also tell us how close it is and if it’s still or moving. The structures of our eyes are incredibly complex, despite how small they are compared to the rest of our organs. The human eyes are extremely delicate. The visible part of the eye is protected by the eyelids and eyelashes, which keep out dirt, dust, and harmful bright light.
There are rods and cones in the back of your eye that are in the retina, these are connected to the bipolar cells and a set of nerves called the interneurons. The first step is the bipolar cells to hook up with the ganglion cells that lead out of the eye. From there the axons and the ganglion cells join with the optic nerve carrying messages from the eye to the brain. Next the axons of all of the ganglion cells join to form the optic nerve. This is taken to a place in the eye on the retina called the blind spot. The blind spot is a place where there are no receptor cells, so when light hits it there will be no imagine seen. After the nerves are made into fiber they leave the eye and enter the brain where they split to either side of the brain at the optic chiasm. The nerve fibers from the
An inspection of the modern animal phyla will reveal that eyes are just as diverse as they are complex. Some organisms like the rag worm have pigmented cup eyes while other like he box jellyfish have two lens eyes and two pairs of pigment pit eyes. To account for the diversity in eye structure, we must first examine the eye ‘prototype’, the original structure that was acted upon by evolution. The simplest organ that can be considered an eye is composed of a single photoreceptor cell and a single pigment cell, without any lens or other refractive body (Arendt, 2003). Such organs are know as eyespots, and...
In this diagram above, the main light-sensing organs are labeled. When light enters the eye, it must first pass through the cornea and the pupil, which is like a window in which light is filtered and floods in. Then, the light gets filtered once again by two walls called the iris, which detects color and sends these messages to the brain. The light continues to pass until it hits the retina or the lining on the back of they eye, which acts as a sort of screen on which to place the image. Here, nerve sensors take the image as impulses and send it to the brain.
The four main components of the eye that are responsible for producing an image are the cornea, lens, ciliary muscles and retina. Incoming light rays first encounter the cornea. The bulging shape of the cornea causes it to refract light similar to a convex lens. Because of the great difference in optical density between the air and the corneal material and because of the shape of the cornea, most of the refraction to incoming light rays takes place here. Light rays then pass through the pupil, and then onto the lens. A small amount of additional refraction takes place here as the light rays are "fine tuned" so that they focus on the retina.
The cornea of the eye is transparent, curved that acts as the cap of the eye which protects the eye from dirt, microorganisms and other harmful substances.(2) It is also important for about 75% of the eyesight. Its clarity and the curvature will affects the eye by how greatly it can focus on an object and produce an image. However, 10% of the incident light will be blocked in normal human cornea. (1)
Fluid circulating inside the front portion of the eye is produced by a structure called the ciliary body, which is located behind the iris. This fluid moves through the opening of the pupil, passes into the space between the iris and the cornea, and drains out of the eye through a tissue called the angle. With glaucoma, the passing of fluid through the angle is either reduced or suddenly stops, and amounts of fluid inside the eye increase. This high fluid pressure hurts the nerve fibers and the eye's optic nerve and causes blind spots. It may lead to blindness in some cases.
Our objective for this lab was to learn more about the distribution and capabilities of sensory cells. In Table 1, the mean for the angle stimulus detected was 78° and the mean for the angle color detected was 58°. The results from the table indicated that I was able to detect an object was near before I was able to detect the color of the object. Being able to detect an object before detecting the objects’ color could be explained by the type of photoreceptors located in the center and periphery of the retina. Based on my results from Table 1, I was able to conclude that the photoreceptor that is most common in the center of my eye is cone cells. I was able to conclude this due to the mean angle to which color was detected. Thus, the photoreceptor most common in the periphery would be the rod cells.
parts to it; the choroids, ciliary body, and the iris. The choroids is what provides
The eye consists of many parts. The part of the eye you can see when you look at someone consists of four parts. The colored part of the eye where the light enters is called the iris. The white part around the iris is the conjunctiva and episclera. This part also contains blood vessels. The cornea is the clear covering of the iris and pupil. The cornea contains no blood vessels. The lens is located behind the iris. The lens is used to focus, as in the cornea, but the lens can move. The retina is responsible for telling the brain what a person is seeing. They determine all the different parts of what is being seen. It then codes them to electrical signals for the brain (Cassel p 4-10).
Macular degeneration in general can affect many people in minor or drastic ways. People who experience this form often complain of vision loss when they are in dim light, especially when they are reading. The "dry" type is often characterized by a more gradual loss of vision compared to the "wet" type. Signs of this disease include an increase in drusen, which is an accumulation of a yellow-white substance, in the underside of the macular retina. A loss of cells can be seen in the macula. The macula is our sensitive sight region, where intricate detail can be seen. Thus, vision in this area is helpful and necessary to drive, read, focus on small details, and recognize familiar faces. The macula is located in the back of the eye known as the retina. The macula is only about 5 mm in diameter, and includes the fovea, which gives us our detailed central vision. If a person suffers from the "dry" form in one eye they will be more likely to develop it in the other eye as well.
This protects the eye from becoming dry.The Cornea, a part of the sclera, is the transparent window of the eye through which light passes. The focusing of the light begins in the cornea.Behind the Cornea is a watery fluid called the aqueous humor. This fluid fills a curved, crescent shaped space, thick in the center and thinner toward the edges. The cornea and the aqueous humor together make an outer lens that refracts, or bends, light and dire...