Understanding the anatomy of the human eye helps us to appreciate the complexities and intricacies of its function. Our eyes, being only 2.5cm in diameter, serves one of the most important functions of the body. The eyes have several functioning parts, all of which work together to help us see. Here’s how they work.
How the Eyes Work
The first step in understanding the anatomy of the human eye is to first learn how the eyes work.
Our eyes function like cameras that process the light reflected off surfaces in order to create images that we can see and understand ourselves. The iris is like an aperture that controls the amount of light that enters the eye. This is exhibited when the light entering our eyes is too bright or strong, our iris reduces pupil size, and the opposite happens when it is dark.
Processing Images
Taking a closer look at how the eyes work, we can observe the following, when trying to understand the anatomy of the human eye:
- Light travels through the cornea, which is the foremost and clear layer of the eye. It is shaped like a dome and serves to bend wavelengths of light in order for the eye to focus.
- A fraction of this light is able to enter the eye and passes through an opening known as the pupil. The iris, which is the part of the eye one may distinguish as colored, focuses on controlling how much light passes through the pupil, by way of lessening the pupil size, or by dilation.
- Once this happens, the light then travels through a clear inner part of the eye, which is called the lens.
- Subsequently, the light eventually comes in contact with the retina, which is the layer of tissue located at the back of the eye that is sensitive to light. Photoreceptors, which are special cells, convert the received light into electrical signals.
- These signals that have been converted by photoreceptors are finally brought to the brain from the retina by way of the optic nerve. The brain in turn converts the signals into images we can process and see.
Understanding the Anatomy of the Human Eye
Understanding the anatomy of the human eye may be accomplished more easily by separating the core structures from the accessory structures.
Accessory Structures
Listed below are the accessory structures of the eye, which have their respective functions:
- Eyelids – Cover the eyes during sleep, and offer protection.
- Eyelashes – Used as a line of defense against airborne irritants and other unwanted aggressors.
- Eyebrows – Aim to help keep one’s eyes clear and clean by keeping wet substances from dripping down into your eyes.
- Extrinsic eye muscles – These muscles extend from the orbit to the sclera and function to move the eye in almost any direction possible.
- Lacrimal Apparatus – Produces and dispenses tears.
Core Structures
Listed below are the core structures of the eye, which also have their respective functions:
- Choroid – Refers to a layer containing blood vessels that surround the eye’s rear. The Choroid is located between the sclera and retina.
- Ciliary body – Is a structure that contains muscles and is found behind the iris.
- Cornea – Is the foremost layer of the eye that is clear. It focuses on transmitting light into the eye.
- Fovea – Regarded as the center of the macula. It is the point of sharpest vision
- Iris – Is the colored part of the eye which helps regulate light entering the eye by controlling the size of the pupil.
- Lens – The lens serves to focus light on the retina. It is known as a replaceable part of the eye and is transparent.
- Macula – is the area of the retina that holds light-sensitive cells. These cells are special because they allow the process of seeing fine details in one’s visual field.
- Optic nerve – Refers to a bundle of nerve fibers carrying messages from the retina to the brain. It is responsible for transporting the electrical signals generated by photoreceptors.
- Pupil – The middle opening of the iris. It is seen as a dark center of the eye which adjusts in size naturally by way of the iris. The pupil’s size is manipulated in order to control the amount of light entering the eye.
- Retina – Refers to the nerves that are layered at the rear part of the eye. The retina functions to sense light and create electrical signals by using special cells called photoreceptors.
- Sclera – Surrounds the iris and is observed as the outer coat of the eye, which is simply known as the white part.
- Vitreous humor – Refers to the gelatinous substance that fills up the eye’s central cavity.
