The Cause Of Retinitis Pigmentosa (RP)

A medical definition of vision impairment is a sine qua non that prohibits 20/20 vision in one or both eyes (Bowman, Bowman, Dutton & Royal National Institute for the Blind, 2001; Vision Australia, 2015; Webster & Roe, 1998). Examples of vision impairment include, cataracts, which has the lens inside the eye increasingly cloudy; albinism, which is passed down genetically affecting clear vision and causes sensitivity to bright light; optic nerve damage, which affects field of vision as those nerves controlling vision are disrupted; macular degeneration, where parts of the retina that control colour and fine details are affected; retinitis pigmentosa, which is an ongoing reduction of the field of vision available and nystagmus, where the eye flickers involuntary (Bowman, Bowman, Dutton & Royal National Institute for the Blind, 2001; American Foundation for the Blind, 2015; Vision Australia, 2015 ; Baton Rouge Regional Eye Bank, 2015). John suffers from retinitis

Macular Degeneration is a disease of the eye that gradually causes loss of a person’s central vision. Approximately 1.75 million Americans suffer from vision loss associated with the disease (All About Vision 1). The leading cause of blindness in people over the age of 60, Macular Degeneration, exists in two types (National Eye Institute 1). Both the wet and dry versions of the disease have similarities in risk factors, but differ in symptoms and treatments.

Retinitis pigmentosa is a group of inheritable diseases that is characterized by gradual deterioration of the photoreceptors in the retina. The photoreceptor cells in the retina, rod cells, are light sensitive cells that are able to sense low levels of light. The frequency of retinitis pigmentosa is one in four thousand births (Deng et al., 2015; Fahim et al., 2012; Haddad et al., 2016; Shu et al., 2012) People affected by retinitis pigmentosa will typically exhibit symptoms of night-blindness first, and this will precede a loss in the patient’s visual acuity field that starts from the outer edge and gradually moves inward resulting in a much smaller visual field and loss of peripheral vision, also known as tunnel vision (Haddad et al., 2016).

To understand the diverse causes of RP, a basic understanding of visual perception is required. Phototransduction (conversion of light to electrical signals) occurs first, which is initiated by two types of photoreceptors: rods and cones. These two types vary in their function as rods are primarily responsible for night vision and lack sensitivity to color while cones function in color vision. Light contacts these photoreceptors, and isomerizes a retinaldehydechromophore (retinal) which is bound to varying types of opsin proteins corresponding in their reactivity to different wavelengths of light. Upon absorption of a photon of light, the chromophore 11-cis-retinal is isomerized to the all-trans confirmation, which subsequently causes a series of molecular interactions which ultimately result in the electrical response of the photoreceptors (Vugler 2010). As 11-cis-retinal is required to absorb photons of light, this compound must be regenerated, a function that is performed with the aid of nearby cells of the retinal pigment epithelium

Macular Degeneration is a disease that affects the retina of the eye. The retina is a layer in the back of the eye that helps us to see. It is also the lining of the eye that helps us respond to light. However, when having macular degeneration there are major changes in a person's central vision. The disease causes central images to appear blurred and then dark spots may begin to appear that get larger and larger. It may also be very hard to see straight lines as Macular Degeneration may cause them to be curved. When having this disease color may appear to be darker and less vivid than normal.

As humans, we don't always see with our eyes, but often with our imagination (Grunwald, 2016). Often times as people we never realize how useful our vision really is to us. You really don't think about something like that until it would actual happen to you. Throughout this essay, you will learn how the body is affected by Macular Degeneration (MD). Different signs and symptoms, as well as the etiology of MD, will be discussed. In the following, diagnosis tests and treatments may also be listed in order to help others who would like to know more about MD. Not to mention, you will learn the incidence and progression of MD. Furthermore, information though agencies and associations, as well as new research about MD will be given.

1. Red – retinal arterioles, hemorrhaging, neovascularization, vascular anomalies, vascular tumors, retinal breaks, holes in retinoschisis, cilioretinal artery, and inner portion of thin areas of retina

Phase one: clinically occult changes occur to the circuitry of the neural retina in early stages.

Retinopathy is classified as background retinopathy, preproliferative retinopathy and proliferative retinopathy. Background retinopathy is where there is partial occlusion of the small blood vessels in the retina which result in microaneurysms in the capillary wall. These microaneurysms are weak and capillary fluid leaks out causing edema and intraretinal haemorrhages.

Oculocutaneous albinism or OCA is a set of four (or seven, including subdivisions) rare genetic disorders that are caused by mutations in up to seven different genes and are characterized by a complete lack or reduction of the pigment melanin in the eyes, hair, and skin. An estimated 1 in 20,000 people worldwide are born with this disorder. The conditions of OCA are caused by mutations in genes that are responsible and necessary for producing the melanin pigment in specialized cells (melanocytes). Not having enough of the melanin pigment can result in abnormal eye development, resulting in vision problems, and light skin that is easily damaged by the sun, at times resulting in different skin cancers, including an aggressive form called melanoma. Symptoms of this condition can also include nystagmus (involuntary back and forth movement of eyes), iris transillumination (reduced pigment in iris), reduced pigment in the retina, macular hypoplasia (poor development of the macula, resulting in abnormal foveal development in the retina), generally poor visual sharpness, photophobia (increased sensitivity to light), and strabismus (abnormal connection of the nerves from retina to brain, keeping the eyes from tracking

Retina Fundus Image is obtained by using a fundus camera. This photograph captures the image of the retina which includes the optic disc, blood vessels and the macula region. Usually non mydriatic retinal photographs are taken unless if the patient’s pupils are too small where a mild drop is given to dilate the pupil, especially among children (Bruce, Newman, Perez, Biousse, 2013). With the captured image, ophthalmologists can use to follow-up on eye conditions, diagnosing eye diseases such as

tumours develop in the cells of the retina, the light sensitive lining of the eye (1) (see figure 1). The cancer develops due to the loss or mutation of both of the Rb genes within a retinal cell and can be inherited or sporadic. With the inherited form, sufferers have a germline mutation of the Rb gene, making most cases bilateral, but with the sporadic form the first ‘hit’ occurs randomly in a retinal cell, hence the majority of cases are unilateral. The number of infants diagnosed with retinoblastoma has doubled over the past forty years (2) with the disease now being

One of the challenges with this therapy is to determine how late in the disease process one can therapeutically intervene. Though mutations in the RPE65 gene lead to critical vision loss, the retina’s structure remains undamaged for a time period, which is unknown. Too soon the retinal cells would soon begin to die and at some point the disease will no longer be treatable with gene therapy.

A lesion that destroys the optic nerve will destroy all input from that retina, leading to monocular visual loss (blindness in that eye).

Retinitis Pigmentosa is a group of inherited diseases that damage the light-sensitive rods and cones located in the retina, the back part of our eyes. Rods, which provide side and night vision are affected more than the cones that provide color and clear central vision. The prevalence of Retinitis Pigmentosa worldwide is approximately one in 4000. Up to one-quarter of all patients with Retinitis Pigmentosa will become legally blind in both eyes, it is rare to lose all vision. More than half of all patients with Retinitis Pigmentosa have visual acuity of 20/40 or better in at least one eye.