عینک eyewear

The anterior segment of the eye is composed of the conjunctiva, cornea, anterior chamber, and iris. Behind the iris, actually visible through the pupil, lies the lens. The ciliary body is a doughnut shaped muscle behind the base of the iris that functions in accommodation and secretes the aqueous.

Anterior segment optical coherence tomography (AS‐OCT) has become one of the cornerstones of non‐contact imaging modalities for assessing such structures as the cornea, anterior chamber angle, aqueous outflow pathway, sclera, and ocular surface structures.

What does anterior eye mean?

The word anterior means front, and the anterior chamber is named after its location at the front of your eye. It holds a clear fluid called aqueous humor. While this small chamber and the clear liquid inside it might not seem all that important, it's actually a critical structure and plays a key role in your vision.

To compare the location of body parts relative to each other, anatomy uses some universal directional terms: anterior, posterior, ventral, dorsal, distal, proximal, medial, lateral, median, superior, inferior, external, internal, frontal, occipital, rostral, caudal, superficial, deep, central, peripheral, ipsilateral, ...

What is the opposite of anterior? Anterior and posterior

Anterior (from Latin ante 'before') describes what is in front, and

posterior (from Latin post 'after') describes what is to the back of something.

• قدامی (anterior) == جلویی، پیشین ( پیش یعنی جلو )
• خلفی (posterior) == عقبی، پسین ( پس یعنی عقب )

What does the anterior chamber do?

The structure of your eyes is a key part of how they work, and the anterior chamber is one of the most important structures.

If you’ve ever used a magnifying lens, you know that the distance between what you’re looking at, the lens and your eye all have to be just right to get the sharpest view. It’s the same for your eyes. Your corneas must be the right distance from your lens and retina.

This is why the anterior chamber is so important. The fluid inside the anterior chamber creates internal pressure (intraocular pressure) that keeps your eyeball “inflated.” That’s how the cornea stays at the right distance to do its part in focusing light.

How aqueous humor travels through the anterior chamber?

When everything is working as it should, the parts of your eye work together to maintain the right balance of aqueous humor in your

anterior chamber. This fluid does more than provide internal pressure so that your eyeball keeps its shape. It also carries oxygen and nutrients, and plays a part in your eye’s immune defenses. The fluid in the anterior chamber contributes to the pressure in your eye.

Too much or too little pressure may lead to eye damage.

Here’s how the aqueous humor gets to and leaves your anterior chamber:

• Your ciliary body makes aqueous humor.
• It flows into your posterior chamber. This is a small, fluid-filled space behind your iris.
• The fluid flows through your pupil, which opens to your anterior chamber.
• Most of the aqueous humor exits your anterior chamber through the drainage angle. This is near the outer rim of your anterior chamber, where your iris and the outer wall (sclera) of your eye meet.
• The fluid goes into a drainage network called the trabecular meshwork.

Eventually, the aqueous humor moves into the veins in your sclera where it merges with your blood.

The anterior segment or anterior cavity is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. eResearch by Navid Ajamin -- autumn 2025

Within the anterior segment are two fluid-filled spaces:

1. the anterior chamber between the posterior surface of the cornea (i.e. the corneal endothelium) and the iris.
2. the posterior chamber between the iris and the front face of the vitreous.

Aqueous humour fills these spaces within the anterior segment and provides nutrients to the surrounding structures.

Some ophthalmologists and optometrists specialize in the treatment and management of anterior segment disorders and diseases.

Three chambers of fluid:

• The Anterior chamber (between cornea and iris)
• The Posterior chamber (between iris, zonule fibers and lens)
• The Vitreous chamber (between the lens and the retina).

Diagram of anterior segment of a human eye (horizontal section of the right eye)
1. Lens, 2. Zonule of Zinn or ciliary zonule, 3. Posterior chamber 4. Anterior chamber 5. Aqueous humour flow; 6. Pupil, 7. Corneosclera 8. Cornea, 9. Trabecular meshwork and Schlemm's canal. 10. Corneal limbus 11. Sclera; 12. Conjunctiva, 13. Uvea 14. Iris, 15. Ciliary body.

In ophthalmology, the eye is divided into two sections:

the anterior and the posterior eye segments.

The conjunctiva, cornea, iris and lens belong to this section, also called the optics of the eye. This sensitive area can be impaired by inflammation, infection, mechanical injuries and medical conditions.

During the examination of the anterior sections of the eye, the ophthalmologist examines the constituent parts in the front part of the eye using a special microscope, the slit lamp. This procedure is painless, simple and takes only a few minutes. The slit lamp is an ophthalmologist's most important tool.

The slit lamp is an ophthalmologist’s most important tool. It helps him/her to see precise details in the front part of the eye (the so-called ‘anterior section of the eye’).

Eye drops are used if necessary to enlarge the pupil. These can also cause significant dazzling in normal daylight, so you should not drive following the examination.

Reference:

• semanticscholar.org/paper/Cornea-and-anterior-eye-assessment-with-slit-lamp-Martín
• augenzentrum-kiener.ch/examination-of-anterior-sections-of-the-eye/?lang=en
• catalyzex.com/paper/angle-closure-detection-in-anterior-segment
• my.clevelandclinic.org/health/body/anterior-chamber
• aao.org/education/image/anterior-segment-anatomy-2
• en.wikipedia.org/wiki/Anterior_segment_of_eyeball
• tandfonline.com/doi/full/10.1111/cxo.12869
• pubmed.ncbi.nlm.nih.gov/38259819
• ncbi.nlm.nih.gov/books/NBK11534
• heidelbergengineering.com
• know-the-eye.com