Iris or iris (Latin iris ) is the front part of the middle eyelid, the most impressive for the fact that it contains the pigment that determines the color of the eye, and prevents the entry of excessive amounts of light into the eye like a shutter in a camera.
In its center there is a round opening, i.e. the pupil (Latin pupilla ). S obzirom na to da u šarenici postoje i mišićne niti, zjenica se može širiti i sužavati. Musculus dilatator pupillae (mišić rastezač zjenice) širi zjenicu, a musculus sphincter pupillae (mišić stezač zjenice) sužava zjenicu, tako da njihov rad može promijeniti promjer zjenice.
Threads of the autonomic nervous system are also present in the iris, so the pupil expands or narrows during certain types of sensations (fear, love). The iris is also connected with focusing, so when looking at a closer object, it will narrow the pupil to increase the sharpness of the image.
The pigment is responsible for the different color of the iris, the color depends on the amount and arrangement of the pigment. More pigment means darker eyes and less pigment means lighter eyes. Just as fingerprints are individual and unique, each iris is individual in each person. It is impossible to copy the iris in order to deceive identification, therefore it is used more and more in protective systems such as alarms, vaults, etc.
If we are not satisfied with our iris color, we can change it by wearing colored contact lenses. Before starting to wear contact lenses, it is absolutely necessary to perform a control examination in order to choose the appropriate contact lenses and to see how the eye tolerates them, so as not to injure the eye.
The middle layer of the eye, which consists of the iris, the corpus callosum and the choroid, is called the uvea, and its inflammation is called uveitis. Iridocyclitis represents inflammatory changes of the iris ( iris ) and the corpus ciliare ( corpus ciliare ) at the same time. Since the iris and the ray body are in a very close anatomical relationship, the inflammatory process usually affects both at the same time, which is also called anterior uveitis ( Uveitis anterior ).
Division of uveitis according to the cause:
- Exogenous uveitis
- Endogenous uveitis
- Microorganism infections
- Non-infectious uveitis
Autor:
bc. Livio Svržnjak, optometrist
Literature:
M.Sc. sc. Pavan Dr. Joško, “Eye Diseases”, Zagreb 2003.
