Retina

The Retina is located on the back of the inner wall of the eye and is instrumental in creating image information for the brain. Age, illness and congenital disorders can hinder the function of the complex retina in many ways. There are a large number of successful therapeutic methods.

What is the retina?

The Retina is a light-sensitive layer of tissue on the inner wall of the eye. The light that hits the inside of the eye and the retina through the pupil images the external environment on it; the retina functions in a similar way to the film in a photo camera.

The incidence of light stimulates chemicals and nerves. These nerve impulses then reach the brain as information via the optic nerve. In embryonic growth, the retina and the optic nerve form out of the brain, it is therefore seen as part of the central nervous system and is brain tissue.

The retina is the only part of the central nervous system that can be viewed non-inversively. The retina is made up of several layers of tissue, with many layers of neurons connected by synapses. The only neurons that are directly exposed to light are called photoreceptors and consist of the rods and cones that are labeled.

Anatomy & structure

The Retina consists of 10 different layers. These are (listed from the vitreous humor to the optic nerve):

Inner boundary membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner granular layer, outer plexiform layer, outer boundary membrane, inner segment, outer segment, retinal pigment epithelium.

These layers can be broken down into four basic stages: photo reception, transmission to bipolar cells, transmission to ganglion cells (which also have photoreceptors), the photosensitive ganglion cells, and transmission to the optic nerve.

At each synaptic level there are also connections between horizontal and amacrine cells. The optic nerve is a central nerve strand of many axons of ganglion cells, which mainly connect the corpus geniculatum laterale with the forebrain.

Function & tasks

An image is created by irritating the cones and rods within the Retina. The cones react to bright daylight and transmit high-resolution colors during the day.

The rods react even to less light and are responsible for monochrome outlines. In most light situations, an interaction between suppositories and rods is required. The reaction of the cones to different light waves is called their spectral sensitivity. It is divided into subgroups.

If one of these subgroups does not react correctly, it leads to numerous eye problems, such as color blindness. The light particles (photons) hit the outer layer of the retina and activate a cone or rod. In the cones and rods there is a lined-up stack of visual membranes, in which the visual pigment rhodopsin is in turn. Rhodopsin stimulates transducin, a protein which in turn stimulates an enzyme that breaks down into cyclic guanosine monophosphate.

This GMP is forwarded to the next membrane. When light falls on the rods, this process practically aligns red and green wave information through stimulation of the activated rods, and the relationship is passed on to the optic nerve. What exactly happens to this information after it is passed on is still obscure.

Illnesses & ailments

There are a variety of congenital disorders or nascent diseases that affect the Retina can affect. These include:

Retinopathia pigmentosa: A group of congenital visual defects that lead to night blindness.

Macular degeneration: Describes a group of disorders that lead to a piecewise deterioration of the central field of vision.

Cone-rod dystrophy: A disorder during which the cones begin to lose their function and then slowly spread to the rods. Retinal detachment: This can have many causes and must be treated quickly before the damage to vision becomes irreparable.

Hypertensive or diabetic retinopathy: Both high blood pressure and diabetes can disrupt the blood supply to the retina. This degrades functions and generally leads to poor eyesight.

Retinoblastoma: This is a malignant tumor on the retina that, if left untreated, not only causes visual impairment but also death. However, the chances of recovery with treatment are very good.

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