The eye is like a sphere with a round window at its front. Light passes through this window, the so-called cornea (7), into the interior of the eye and is concentrated in the process. The iris (9) regulates the light rays like a diaphragm and the eye lens (10) or artificial lens focuses them through the transparent vitreous body (12) onto the retina (13). The retina consists of nerve cells and lines the back of the eye, with the macula (14) having the highest density of photoreceptors in its center. These receptors receive the incoming light as stimuli and translate it into an electrical signal in accordance with the strength and color, which is transmitted to the brain by the optic nerve (15). Through the visual path, this visual signal reaches the brain in the visual cortex, where it is further processed to produce a visual impression.
Our eyes are well protected in the eye sockets, which are embedded in the bony skull. Eye muscles (1) are arranged around the eyeball, which allow the paired sensory organs to move synchronously with each other (squint). There is adipose tissue above the muscles, which, like shock absorbers, absorbs shocks. Only the frontal part of the eye between the upper and lower eyelids (2) is visible to our fellow human beings and takes over a large part of the non-verbal communication (eyelid deformity/eyelid tumories/eye bags). Various glands (3) in the area of the eyelids produce components of the tear fluid (3) and distribute the tear film over the visible surface (4) of the eyeball with every blink of the eye. This section of the eye is kept moist and nourished by the tear fluid (dry eye). The lacrimal fluid then drains via the lacrimal ducts (5) into the nasal cavities and is absorbed again there via the mucous membranes (lacrimation). The Conjunctiva (6) lines the inside of the eyelids and goes to the front of the eye apple (wing skin). It is the entry point for pathogens and ensures the immune response in the eye (conjunctivitia/chlamydia/allergies). The conjunctiva is omitted in the center, where the cornea (4) protrudes like a glass hemisphere (corneal dystrophies/erosion). As a result of its curvature, the transparent cornea refracts the incoming light rays (8) like a collecting lens (corneal curvation/keratoconus). The Iris (9), whose central recess is the pupil, regulates the incidence of light, similar to the aperture of a photo camera. Behind the iris is the natural lens (10), which focuses the light rays precisely on the retina (farsightedness/presbyopia or cataracts). The lens is suspended from the ciliary body via fine zonular fibers. On the one hand, the ciliary body adjusts the lens curvature (accommodation/age-related farsightedness) and, on the other hand, produces the aqueous humor in the front chamber (11), which nourishes the lens (10) and runs off again via the chamber angle (eye pressure/narrow-angle situation/glaucoma). The focused light passes through the gel-like vitreous body (12) (vitreous opacities/vitreous elevation) and forms on the retina (13) a reduced and inverted image of the object being viewed (short/farsightedness). The retina lines the eyeball from within and is basically like the film of a photo camera (retinal detachment). It consists of over 100 million photoreceptors, which, like small sensors, pick up the light stimulus and transmit it to other sensory cells (diabetic retinopathy/retinal vessel occlusion). The density of photoreceptors increases from the outside across the macula (14) to the area of sharpest vision, the fovea (visual field/macular degeneration). The stimuli are interconnected in the retina and reach the brain via the optic nerve (15), where they are processed into an image (glaucoma).
