![]() The photoreceptors are the specialized receptors that respond to light. ‘Light in the Retina’ by Casey Henley is licensed under a Creative Commons Attribution Non-Commercial Share-Alike (CC BY-NC-SA) 4.0 International License. The neuronal communication travels in the opposite direction from the photoreceptors toward the ganglion cells. When light enters the eye, it must pass through the ganglion and bipolar cell layers before reaching the photoreceptors. The photoreceptors then initiate the synaptic communication back toward the ganglion cells. When light enters the eye and strikes the retina, it must pass through all the neuronal cell layers before reaching and activating the photoreceptors. ‘Retinal Neurons’ by Casey Henley is licensed under a Creative Commons Attribution Non-Commercial Share-Alike (CC BY-NC-SA) 4.0 International License. The horizonal cells allow for communication between photoreceptors by interacting with the photoreceptor-bipolar cell synapse, and the amacrine cells allow for communication between bipolar cells by interacting at the bipolar cell-ganglion cell synapse. The photoreceptors synapse on bipolar cells, and the bipolar cells synapse on ganglion cells. Horizontal and amacrine cells allow for communication laterally between the neurons. The photoreceptors synapse on bipolar cells, and the bipolar cells synapse on the ganglion cells. In addition to the photoreceptors, there are four other cell types in the retina. ‘Eye Anatomy’ by Casey Henley is licensed under a Creative Commons Attribution Non-Commercial Share-Alike (CC BY-NC-SA) 4.0 International License. Details about the functions of each region are in the text. The fovea (dark red section) is a small portion of the retina where visual acuity is highest, and the optic disc is located where the optic nerve (tan region) leaves the eye. The retina (red line) is located along the back of the eye. The visible regions of the eye include the cornea, pupil (gray region), and iris (blue region). This region is called the optic disc and is the location of the blind spot in our visual field. Where the optic nerve leaves, there are no photoreceptors since the axons from the neurons are coming together. The optic nerve projects to the brain from the back of the eye, carrying information from the retinal cells. In the middle of the bowl is the fovea, the region of highest visual acuity, meaning the area that can form the sharpest images. The retina covers the entire back portion of the eye, so it’s shaped like a bowl. The retina is the light-sensitive region in the back of the eye where the photoreceptors, the specialized cells that respond to light, are located. Proper focusing requires the lens to stretch or relax, a process called accommodation. The lens refracts light to focus images on the retina. The lens is located behind the pupil and iris. The iris is the colored portion of the eye that surrounds the pupil and along with local muscles can control the size of the pupil to allow for an appropriate amount of light to enter the eye. The pupil is the opening in the iris that allows light to enter the eye. It covers the pupil and the iris and is the first location of light refraction. The cornea is the transparent, external part of the eye. This case was sent by a follower of the page Axenfeld-Rieger syndrome is primarily an eye disorder, although it can also affect other parts of the body.This condition is characterized by abnormalities of the front part of the eye, an area known as the anterior segment People with Axenfeld-Rieger syndrome often have a pupil that is off-center (corectopia) or extra holes in the iris that can look like multiplepupils (polycoria) This condition can also cause abnormalities of the cornea About half of affected individuals develop glaucoma When glaucoma occurs with Axenfeld-Rieger syndrome, it most often develops in late childhood adolescence, although it can occur as early as infancyThe signs and symptoms of Axenfeld-Rieger syndrome can also affect other parts of the body.Many affected individuals have distinctive facial features such as widely spaced eyes (hypertelorism) flattened mid-face with a broad, flat nasal bridge a prominent forehead.The condition is also associated with dental abnormalities including unusually small teeth (microdontia) or fewer than normal teeth (oligodontia).Some people with Axenfeld-Rieger syndrome have extra folds of skin around their belly button (redundant periumbilical skin).Other, less common features can include heart defects, the opening of the urethra on the underside of the penis (hypospadias), narrowing of the anus (anal stenosis), and abnormalities of the pituitary gland that can result in slow growth Researchers have described atleast three types of Axenfeld-Rieger syndrome.The front of the eye consists of the cornea, pupil, iris, and lens. ![]()
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