Retina anatomy

What is the Retina? The retina is a thin tissue lining the inside back wall of the eye. Within the retina are millions of light-sensitive cells known as cones and rods. Rods and cones receive visual information and send signals to the brain for interpretation. This enables you to see. For you to see clearly, the cornea and lens must focus light rays precisely on the retina. Anatomy The human retina measures 30 to 40 mm and covers roughly 1,100 square mm in each eye. 1 The retina is about 0.5 millimeters thick. It’s thicker towards the optic nerve head and increasingly thinner at the ora serrata. The ora serrata is the junction between the non-light-sensitive area and the light sensitive area of the retina. During an eye examination, an ophthalmologist will look at the following important parts of the eye: The Posterior Pole The posterior pole is the back part of the retina that includes the macula and optic nerve. 2 The optic nerve is a bundle of fibers that transmit visual messages to the brain for interpretation, which enables you to see. 3 Macula The macula is 5mm in diameter and is responsible for your central vision, color vision, and fine detail. The macula contains a high concentration of photoreceptor cells (cones and rods). Optic Nerve Head Also known as the optic disc, the optic nerve head is the face of the optic nerve bundle as it enters the back of the eye. It allows the exit of the retinal ganglion cell axons and the entry and exit of the retinal blood vess...

Helga Kolb 1. Overview. When an ophthalmologist uses an ophthalmoscope to look into your eye he sees the following view of the retina (Fig. 1). In the center of the retina is the optic nerve, a circular to oval white area measuring about 2 x 1.5 mm across. From the center of the optic nerve radiates the major blood vessels of the retina. Approximately 17 degrees (4.5-5 mm), or two and half disc diameters to the left of the disc, can be seen the slightly oval-shaped, blood vessel-free reddish spot, the fovea, which is at the center of the area known as the macula by ophthalmologists. A circular field of approximately 6 mm around the fovea is considered the central retina while beyond this is peripheral retina stretching to the ora serrata, 21 mm from the center of the retina (fovea). The total retina is a circular disc of between 30 and 40 mm in diameter (Polyak, 1941; Van Buren, 1963; Kolb, 1991). The retina is approximately 0.5 mm thick and lines the back of the eye. The optic nerve contains the ganglion cell axons running to the brain and, additionally, incoming blood vessels that open into the retina to vascularize the retinal layers and neurons (Fig. 1.1). A radial section of a portion of the retina reveals that the ganglion cells (the output neurons of the retina) lie innermost in the retina closest to the lens and front of the eye, and the photosensors (the rods and cones) lie outermost in the retina against the pigment epithelium and choroid. Light must, therefore, ...

The retina is the innermost of the three coats of the eye. This layer is responsible for converting relevant information from the image of the external environment into neural impulses that are transmitted to the brain. Broadly retina consists of two primary layers: an inner neurosensory retina and retinal pigment epithelium (RPE). 1 ​ Sensory retina develops from the inner layer of the neuroectoderm, whereas RPE is derived from the outer layer of the neuroectoderm. The RPE is continuous anteriorly with the pigment epithelium of the ciliary body. Sensory retina extends from the optic disc to ora serrata, where it is continuous with non-pigmented ciliary epithelium. 1 Between the neural retina and RPE, there is a potential space known as subretinal space. The adhesion between neural retina and RPE is relatively weak. The neural retina is firmly attached at its anterior termination, the ora serrata, and at the margins of the optic nerve head. The ora serrata is located 4-6 mm behind ciliary epithelium and corresponds to the insertion of medial and lateral rectus muscles. Ora serrata has a smooth appearance temporally but serrated nasally. The retina is bound externally by Bruch's membrane and on its internal aspect by the vitreous. It is continuous with the optic nerve posteriorly, the site of exit of ganglion cell axons from the eye. The topography of the Retina: Human retina measures 32 mm from ora to ora along the horizontal meridian and t he total surface area of the ret...