The Developmental Eye Disorders of Anophthalmia and Microphthalmia
The development of the human body is an exquisite process that involves numerous complicated processes for even the smallest of body parts, including the eyes. The eyes are an extraordinarily complex organ capable of gathering information through refracted light and sending it the brain to assemble a picture. They provide the ability to see and follow a moving object and the capability to tell an approximate distance of an object. When light passes through the cornea and iris pupil, at the anterior portion of the eye, it is focused by the lens onto the retina at the back of the eye. Photoreceptor cells, which are present in the retina, detect the light and send information to interneurons which begin to sort out the information. This information is then sent to ganglion cells which transmits the final information to the brain (Sowden 199). Because the eyes have such complicated and exquisite processes, the likelihood of developmental errors occurring are possible. A large number of these developmental errors lead to congenital defects and abnormalities that effect the individual’s eye sight. Some of these defects and abnormalities can cause serious diseases and syndromes that effect more than just the eyes, but also neurological processes, facial dimorphisms, growth failure, tracheal development, and genitalia anomalies. The eyes begin to develop in the fourth week of life in a human embryo through
To commence with, during development a human being grows at an astonishingly rapid pace. According to Guttmacher Institute, “89% of all abortions in the United States are performed in the first trimester of pregnancy.” (2005). In the first trimester (16 weeks), the baby’s eyes and eyelids, nose, mouth, and tongue have formed, and the baby's reproductive organs also develop. The cardiovascular system is the first system that begins to function. The baby’s heart begins to circulate their own blood, similar to his mother’s heart, twenty-two days after conception. Electrical brain activity can be detected at six or seven
The eye (vision), is ready by the fourth month of pregnancy. The child can know the difference between night and day.
During the third to eighth week of conception, fingers, arm bones, and toes are being formed. Limbs start off as buds that then extend outward. This is all due to the DNA that is in each and every cell in the body.
In the first month of pregnancy head and trunk appear and tiny arm buds begin to form, followed by leg buds. The early embryo seems to have a "tail", but this is really a protective covering for the spinal cord because the central nervous system (brain, spine and spinal cord) is so important. At this point of development the structures that eventually form the face and neck are becoming
S: Page 134 is all about the embryonic period of pregnancy. The embryonic period lasts from week 3 to week 8, and it is a very important time because that is when the ectoderm, mesoderm, and endoderm are being formed. The ectoderm, mesoderm, and endoderm will later for more important oragans and body structures.
babies and the effects on their eyes. There is a fine line walking when protecting the function
How do we know infants can see at birth? They can’t tell us. For this we depend on clues such as eye movement, light sensitivity and the appearance of the eye. Though an infant 's vision is present at birth the strength of their vision is far from mature. However, vision develops rapidly in infants, going from only being able to focus on images 4 to 30 inches away to a rapid ability to see details and shape (Berger, 2014). By 3 months these same infants with immature ability can see patterns color and motion. Surveys and medical research are regularly used to develop a better understanding of infant development.
Shortly after an egg is fertilized stem cells begin to form. These cells are programmed to form every organ and tissue in the body as the baby develops.
The brain continues to grow and rapidly develops in three stages known as Neurogenesis, Synaptogensis, and synaptic pruning. Neurogenesis describes the process of rapid division within the nervous system to create functional regions of the brain where most of the process is complete before birth while some regions continue to form after birth such as hippocampal cells. Synaptogensis forms new connections between neurons as over time connections increase in density where some only form one synapse and others form hundreds of thousands. Synaptic pruning removes synapses due to the fact some are only needed temporarily, some are damaged or become dysfunctional, or that some are not used often enough so they are removed for specialization. The newly formed fetus from weeks 9 to 12 shows signs of simple movement with reflexes in arms and legs while sex organs begin to differentiate. Fingers, fingerprints, and toes are fully formed around week 16 and around week 24 the fetus develops response to sound. More remarkably the brain doubles in size between week 16 and 28, while developing basic behavior. The fetus gains greater coordination skills as the cerebral cortex grows larger and personality also develops. Around the 28th week the fetus can mediate sensory input as thalamic brain connections form, such as responding to bright light from within the dark womb. Growth slows down around the 30th or 32nd week but the fetus continues to gain weight and by week 37 has developed all organ systems necessary to survive outside the uterus. Prenatal development ends with the birth of the fetus around 38 to 40 weeks
Visual imparity is one of the biggest epidemics in the modern world affecting an estimated 285 million people worldwide (WHO, 2014). Of theses 285 million people, roughly 39 million of them are completely blind. Blindness is a ‘debilitating sensory impairment’ according to Lorach(2014), which can limit a person’s ability to perform everyday tasks and can hugely affect their quality of life. Most of the diseases causing visual impairments, such as cataract can be surgically treated. However, some pathologies cannot be treated with existing treatments or medications. Retinitis pigmenstosa (RP) is an example of such pathology. RP is an inherited eye disorder in which light-receiving photoreceptor cells (rods and cons) degenerate. The photoreceptor
According to parents.com, after conception, a fetus begins to develop rather quickly. In the fifth week of pregnancy, a baby’s heart begins to beat. A baby also develops three distinct layers, ectoderm, endoderm, and mesoderm. These three layers will eventually form the body systems that are necessary
According to Baily and Hall, while visual impairment early in life is associated with inherited congenital disorders, abnormal fetal devepment, and problems associated with premature birth, most eye conditions are associated with aging. They claim that over 70% of the visually impaired population in the United States is over 65. Age related maculopathy, also called macular degeneration, or AMD, impairs the center of vision in older individuals. The macula is the region in the back of the retina that surrounds and includes the fovea (Goldstein 1999). It is important to understand that when this degeneration progresses enough, the condition constitutes blindness because the foveal area is what is
First trimester: By 12 weeks of pregnancy the foetus will be fully formed. The ovum grows and develops certain important parts of the baby’s body such as spinal cord, nervous system, gastrointestinal system, heart and lungs in the first four weeks from conception. The heart starts beating and brain and other organs forms by eight weeks. At this stage, the face is formed and arms and legs start to move. The baby grows to 3 inches long and
The prenatal development generally refers to those processes which start at least 40 weeks prior to the birth of the child (1). However, the period of organogenesis happens during the third through the eight weeks of development and gives rise to the the three germ layers known as ectoderm, mesoderm, and endoderm. Those three germs layer will later on form specific tissues and organs. (2). The production and development of the organs also known as organogenesis begins thereafter the formations of the three organs (3). During he development of the different phases, which include growth, morphogenesis, and differentiation, the fetus is completely
The eyelids are made up of four layers, the skin, muscle, connective tissue and conjunctiva. The process of vision occurs when light waves from an object, enter through the iris. Light then passes through the lens of the eye, a double convex structure that is used to focus the light, and then reaches the retina. Inside the retina are rods and cones. Rods are used to sense light and dark, and cones are used for sensing colors. Whether the light entering the eye hits the cones or rods, a signal is sent across the optic nerve to the brain where it is processed and viewed as an image. Some issues people have with eyesight are as follows. Those who are farsighted are unable to see things clearly at a short distance, compared to a long distance. This occurs when the light that enters the eye is focused behind the retina, and not directly onto it. When the cornea is not curved enough, this happens. Nearsightedness is when one can see objects clear at a short distance, but not at a longer distance, and this is often caused by a change in the cornea. A Blind spot is the location the optic disk, where the optic nerve fiber exits, and at this location there are no cones or rods, so there is a blind spot.