Retinopathy is usually found in people that have high blood pressure and diabetics. It is most commonly in people that have diabetes. The cause of retinopathy occurs when the blood vessels swell and leak fluid or even close off completely. Some cases abnormal new blood cells grows on the surface of the retina. People with diabetic retinopathy get it in both eyes. Most diabetics do not notice any visual complications at an early stage’s of the disease. As this disease progresses, usually cause vision loss that usually cannot be reversed. Different parts of the retina can be affected like the macula, the outer part of the retina or both. Which can make retinopathy more serious. Background retinopathy doesn’t change the sight. With this you have tiny leaks fluid and tiny bleeds in various parts of the retina. Pre-proliferative retina is more extensive, signs of blood flow becoming more restive, but not yet showing signs of new blood vessels growing. Maculopathy shows damage to the macula. Proliferative retinopathy when damage blood vessels in the retina make chemicals called growth factors. The form new blood vessels which are not normal. Without laser treatment, vision is most likely become badly affected.
The cornea is the dome shape outer covering of the eye and also where light is focused. There are no blood vessels in the cornea due to the blood vessels would block the light from entering. It receive it nutrients and oxygen from tears and aqueous humor. The sclera is the outer white portion of the eye. Which supply protection and structure of the inner parts of the eye. Conjunctiva is a mucus layer that keep the eyes moist. This also covers the sclera and the inner surfaces of the eye. Vitreous humors makes up for 80 percent of the eyeball. It is located between the lens and retina. It also is a gel-like substance that is in the back part of the eye that provides the shape of the eyeball. Vitreous cavity also provides a clear pathway for light going through the eye and retina. Aqueous humor is the region in front of the eyeball. There are two sections, the anterior chamber in front of the iris and the posterior behind it. Aqueous humor main function is to carry nutrients to the cornea and the lens. Also removes waste product an inside of the front of the eye. The pupil is the dark, black in the center of the eye, which contract when exposed to bright light and expands in darkness to allow in more light. The iris is the color part of eye, that contains the sphincter pupillae used to narrow the pupil and the dilator pupillae used to widen the pupil. Also control how much light enters the eye. The lens is a clear area behind the pupil. The main purpose of the lens is to focus light by changing shape. The ceiliary body the muscles attached to the lens that helps the lens change it shape to better focus on the retina. The eye works by refracting and focusing the light on the retina. When the light strikes the retina, millions of rhodopsin’containing rods, these rods are responsible for night vision. There is millions of cones of the retina that contain iodopsin which are used for bright light vision and color perception. The retina is a multi-layered sheet composed of neurons, photoreceptors and support cells. The retina is the most metabolically active organ of the body and extremely sensitive in ischemia and nutrient imbalance. In the retina the outer third receives it blood supply from the choriocapillaris, a vascular network that is between the retina and sclera. The inner two thirds is supplied by branches of the central retinal artery. This artery comes from the ophthalmic artery, which is the first branch off the internal carotid artery. Central rental artery exits out the optic nerve (2 cranial nerve). The optic nerve is what carries messages from the eye to the brain. Also branches arch temporarily both above and below the macula. The macula and fovea are so close together that a lot times used are interchangeable, but they are two separate parts. The macula is the center portion of the retina. This is used to provide clear distinct central vision. The fovea is the center portion of the macula which provides the sharpest vision and the fovea only contains cones. The choroid is located between the retinal pigment epithelium and the back wall of the eye. Also carries nutrients to the retina and retina pigment epithelium. The choroid is made of melanin that absorb extraneous light that may interfere with image the eye is sending to the brain. The retina pigment epithelium is located between the retina and the choroids. The main duty is to support the photoreceptors and get rid of degenerated photoreceptors. There are 6 eye muscles that are attached to the outer portion of the eye wall in each eye. These muscle work together allowing both eye see an image simultaneously. The 6 eye muscles can be broken down to three groups. The muscles inside the eyeball, the muscles of the eyelids and extra-ocular muscles which are rotate the eyeball with in its orbit. The orbit is a pocket of tissue of each eyeball sits in. Seven facial bones that creates a walls of the orbit. Beside the eyeball, several muscles, nerves, blood vessels, fat and lacrimal drainage system. The optic nerve rest on the back of the orbit. The eyelids main function is to protect eyes by blinking, which prevents debris from getting into the eyes. On average the eye blinks fifteen to twenty times per minute. Lacrimal drainage system has lacrimal glands that are part of the drainage system and produce tears. This functions of the lacrimal drainage system distributing the tears over the surface of the eye and removing excess tears. The puncta (tear ducts) small hole that allow tears to drain from the eyes into the nose. Contains the nasolacrimal sac and the nasolacrimal duct. The sacs is a pouch located under the skin between eye and the nose. Which its main function is to collect tears leaving the eye and ensure they continue on their path out of eye and into the nose. Tears are made up three components; water, lipid and mucus. Tears provide moisture and nourishment for the cornea and remove surface debris. After they have performed their duties, they enter the puncta and travel through the nasolacrimal sac and duct, making their way into the nose and down the throat.
The Orbital region is the area of the face overlying orbit and the eyeball. Includes upper and lower eyelids and lacrimal apparatus. They are bilateral boney cavities in the face that resemble hollow, quadrangular pyramids with their bases anterolaterally and apices posteromedially. Furthermore medial walls of the orbit separated by the ethmoidall sinuses and the upper parts of the nasal cavity, are nearly parallel and whereas the lateral walls roughly at right angles. Therefore the bones of the orbit are frontal, zygomatic, maxilla, nasal, sphenoid, ethmoid and lacrimal bones. Furthermore, spaces with in the orbit that are not occupied all filled in with orbital fat, in addition this forms the matrix for which the imbedded. The base of the orbit is outlined by the orbital margin, also the bone that reinforced to allow for protection of the orbital contents and provides for attachment for the orbital septum, a fibrous membrane that extends into the eyelids. The superior wall is roughly horizontal, also formed mainly by the orbital part of the frontal bone. Therefore it separates the orbital the anterior cranial fossa, also the superior wall is formed by the lesser wing of the sphenoid, plus the depression of the frontal bone is called the fossa for lacrimal glands, which accommodates the lacrimal glands. The medial walls of the orbit are parallel and formed by the orbital plate of the ethmoid bone, along with the contributions from the frontal process of the maxilla, lacrimal groove and fossa for lacrimal sac. Much of the forming medial wall is paper thin. Inferior wall is mainly formed by the maxilla and partly by the zygomatic bone and palatine plate. The lateral walls are formed by the frontal process of zygomatic bone and the greater wing of sphenoid. This wall is the strongest, thickest wall because it is most exposed and susceptible to direct trauma. The posterior part separates the orbit from the temporal and middle cranial fossa. The apex of the orbit is at the optic canal in the lesser wing of the sphenoid. The periorbita is continuous: 1) optic canal and the superior orbital fissure with the periosteal of the Dura mater. 2) Over the orbital margins and through inferior orbital fissure with the periostuem covering the external of surface of the pericranium. 3) With the orbital septa at the orbital margins. 4) With the facial sheaths with the extra-ocular muscles. 5) With the orbital fascia that form the facial sheath of the eyeball.
Diabetic microvascular disease is unknown, hyperglycemia is believed to be cause endothelial damage, selective loss of pertcytes, basement membr.ne thickening, which contributes to leaky, ineffectual blood vessels. The uptake of glucose cells is regulated by the hormone insulin that is produced by the beta cells of the islets of Langerhans of the pancreas. A rise in blood glucose stimulates insulin secretions, a lowering blood glucose caused by the action of insulin inhibits further insulin secretions through the negative feedback system. The negative is serum glucose elevated and reduction in serum glucose levels. The pancreas is an elongated organ next to the first part of the small intestines. It contains a group of cells called islets of
Langerhans, which beta cells secrete insulin and the alpha cells secrete glucagon. Islets of Langerhans haves a rich blood supply, supplying both the endocrine and exocrine portion of the pancreas. Additionally they innervated by sympathetic and parasympathic nerves. The islets of Langerhans contains for types of hormones secreting cells. The following are the four types of hormones: 1) Alpha cells ‘ secretes glucagon 2) Beta cells ‘ secretes insulin 3) Delta cells ‘ secrete gastrin 4) F cells ‘ produces pancreatic polypeptide. These cells are not randomly distributed, beta cells occupy the central portion and which are surrounded by the alpha, delta and F cells. The production of insulin takes place in the beta cells and is stored in granule form of the pancreas. Attachment of insulin to the alpha sub-units causes the beta sub-units to auto phosphorylate thus activating the catalytic activity of the receptor in the cytoplasm. Which then signals the vesicle containing GLUT 4 to move from inside the cell to the membrane to form an integral protein.
DM (Diabetes Mellitus) type 1 the etiology is still unknown, even though it is thought to be the result of genic, chemicals and environmental factors. Type 1 is not directly inherited, but individuals may inherit a predisposition, in that people with certain Human Leukocyte Antigen, which is located in the short arm of chromosome 6, showed increase susceptibility to Type 1 DM. Type 1 DM is portrayed by the failure of pancreatic beta cells to secret insulin, which appears to be due to the destruction of the beta cells by the immune system.
Type 2 DM is a condition where the synthesis and secretion of insulin by islets of Langerhans is diminishing or there is increased insulin does not move into the cells. A combination of genetic and environmental factors contributes to the development of type 2.
Whatever the cause, the results is a deficiency of insulin or insufficient insulin function. This leads to insufficient transportation of glucose into the cells for energy production and conversion of excess glucose into glycogen or fat storage. So glucose accumulates in the blood plasma causing hyperglycemia.
References
Works Cited
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