Definition The papilla is an area on the retina of the eye. This is where all the nerve fibers of the retina converge and leave the eyeball as a bundled nerve cord in order to be able to transmit the sensory impressions of the eye to the brain. Anatomy The papilla is a circular area … Read more

Papilloedema | Papilla

Papilloedema Papilledema, also called congestion pupil, is a pathological bulge of the optic nerve head, which is normally slightly convex. Unlike optic disc excavation, pressure from behind on the optic nerve is increased, causing it to bulge forward. The causes of papilledema can be very diverse. In addition to the optic nerve, numerous arteries and … Read more

Rods and cones in the eye

Definition The human eye has two types of photoreceptors that enable us to see. On the one hand there are the rod receptors and on the other hand the cone receptors, which are subdivided again: blue, green and red receptors. These photoreceptors represent a layer of the retina and send a signal to the cells … Read more

Function | Rods and cones in the eye

Function The photoreceptors of the human eye are used to detect incident light. The eye is sensitive to light rays with wavelengths between 400 and 750 nm. This corresponds to the colors from blue to green to red. Light rays below this spectrum are referred to as ultraviolet and above as infrared. Both are no … Read more

Tasks | Rods and cones in the eye

Tasks As described above, the cone receptors serve for daytime vision. Through the three types of cones (blue, red and green) and a process of additive color mixing, the colors we see can be seen. This process is different from physical, subtractive color mixing, which is the case, for example, when mixing painter’s colors. In … Read more

Distribution | Rods and cones in the eye

Distribution Due to their different tasks, the cones and rods in the eye are also distributed differently in their density. The cones serve for sharp vision with color differentiation during the day. They are therefore most common in the center of the retina (yellow spot – macula lutea) and are the only receptors present in … Read more

Visual dye | Rods and cones in the eye

Visual dye The human visual pigment consists of a glycoprotein called opsin and the so-called 11-cis-retinal, which is a chemical modification of vitamin A1. This is also the reason why vitamin A is so important for visual acuity. Severe deficiency symptoms can lead to night blindness and in extreme cases to blindness.Together with the 11-cis … Read more