irisområde

Irisområdet refers to the iris region of the eye, the pigmented circular diaphragm that sits in the anterior segment between the cornea and the lens. The iris surrounds the pupil and regulates the amount of light entering the eye by adjusting pupil size.

Anatomy and function: The iris consists of stroma containing blood vessels and melanocytes, an anterior border layer, and a posterior pigmented epithelium. Two smooth muscle systems govern pupil size: the sphincter pupillae (constricts the pupil) and the dilator pupillae (dilates the pupil). The collarette marks the boundary between the pupillary and ciliary zones. The iris coloration varies among individuals due to melanin. Functionally, the iris forms part of the uvea and contributes to optical quality by controlling light entry and depth of field.

Development and variation: The iris develops from neural crest cells, with the muscles differentiating prenatally. Iris color and pattern show notable individual variation, including common forms such as blue, green, brown, and hazel tones.

Clinical relevance: Inflammation of the iris, iritis or iridocyclitis, causes pain and photophobia and is typically managed with anti-inflammatory eye drops. Congenital absence of the iris is called aniridia, while iris atrophy or sectoral defects can alter pupil shape and visual function. The iris can also be involved in conditions affecting the anterior chamber angle and intraocular pressure.

Diagnostics and imaging: Evaluation is usually by slit-lamp examination. Imaging techniques such as anterior segment optical coherence tomography and ultrasound biomicroscopy can provide detailed views of iris structure and relationships to surrounding tissues.

In summary, irisområdet encompasses the iris’ anatomy, function, and clinical significance within ocular health and disease.