Iris (anatomy) - Wikipedia
The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds that is responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Eye color is defined by the iris.
Iris of the Eye: Anatomy, Functions & Associated Conditions
2024年10月31日 · The iris is the colored part of the human eye and a component of the uvea (uveal layer or uvea coat). The uvea is a pigmented layer found between the retina and the sclera (white of the eye). In addition to the iris, the uvea also consists of the choroid and ciliary body. The choroid is a vascular layer found between the retina and the sclera.
Iris of the Eye: Definition, Anatomy & Function - Cleveland Clinic
2024年7月24日 · Your iris squeezes or releases your pupil to change the amount of light that reaches the rest of your eye. This constant change in size helps you see in lighter and dimmer places. Your iris adjusts your pupil without you controlling it or thinking about it.
虹膜 - 维基百科，自由的百科全书
虹膜表面距瞳孔缘约1.5mm处，有一环形锯齿状隆起，称虹膜卷缩轮（iris frill）是虹膜小动脉环所在处。 以此为界可以划分为两个区域： 虹膜睫状体部，为外部区域，延伸到睫状体。 虹膜的动脉位于基质层内，从虹膜边缘到中心呈放射状，提供了血液供应。 [5] 虹膜根部和睫状体前部有一粗大的血管环，称为虹膜动脉大环。 虹膜大环从虹膜周边发出放射状分支走向中央，在瞳孔卷縮轮处发出许多小支并改变方向呈环形走行，形成虹膜动脉小环。 从前到后，虹膜可细分为： 虹膜 …
What Is the Iris of the Eye? - Verywell Health
2024年11月4日 · The iris is the colored part of the eye that controls the amount of light that enters into the eye. It is the most visible part of the eye. The iris lies in front of the crystalline lens and separates the anterior chamber form the posterior chamber. The iris in part of the uveal tract which includes the ciliary body that also lies behind the iris.
Iris: Anatomy, Function, and Associated Conditions - Verywell …
2024年10月22日 · The iris is the colored part of your eye. It is the muscular curtain that sits near the front between the cornea and the lens. The iris determines the size of the pupil (the small, black opening) to regulate how much light gets to the retina (the portion of the eye that initially processes visual information and delivers it to the brain).
Anatomy of Iris :Topography and layers of Iris - INSIGHT …
In this post we discuss in detail the gross, microscopic and clinical anatomy of the Iris. The iris is the anterior most part of the uveal tract. It has 2 surfaces, anterior and posterior. There are 4 layers in iris namely the anterior limiting layer, iris …
The Iris of the Eye: Understanding its Definition, Anatomy
2024年7月7日 · The iris is the colored portion of the eye encircling the pupil, responsible for regulating light entry into the eye. It is a vital component of ocular anatomy, playing a crucial role in vision and overall eye health. Composed of muscular tissue and pigmentation, the iris derives its distinctive color from these elements.
Iris | Eye, Structure, Anatomy, & Function | Britannica
2024年11月15日 · In human anatomy, the iris is the colored, muscular part of the eye surrounding the pupil. The iris is in front of the lens and behind the cornea and is bathed in front and behind by a fluid known as the aqueous humor.
Iris and Uvea of the Eye - All About Vision
2019年2月27日 · The uvea is the pigmented middle layer of the eyeball. It has three segments: the iris, the ciliary body and the choroid. Iris: The iris of the eye is the thin, circular structure made of connective tissue and muscle that surrounds the pupil. The color of our eyes is determined by the amount of pigment in the iris. [Learn more about eye color.]