The anterior chamber ( AC) is the

aqueous humor The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posteri ...

-filled space inside the eye between the

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

and the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

's innermost surface, the

endothelium The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vesse ...

Hyphema Hyphema is a condition that occurs when blood enters the front (anterior) chamber of the eye between the iris and the cornea. People usually first notice a loss of vision or decrease in vision. The eye may also appear to have a reddish tinge, o ...

, anterior uveitis and

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

are three main pathologies in this area. In hyphema, blood fills the anterior chamber as a result of a hemorrhage, most commonly after a blunt eye injury. Anterior uveitis is an inflammatory process affecting the

and

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

, with resulting inflammatory signs in the anterior chamber. In

, blockage of the

trabecular meshwork The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the ...

prevents the normal outflow of aqueous humour, resulting in increased

intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated t ...

, progressive damage to the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

head, and eventually

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

. The depth of the anterior chamber of the eye varies between 1.5 and 4.0 mm, averaging 3.0 mm. It tends to become shallower at older age and in eyes with

hypermetropia Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, i ...

(far sightedness). As depth decreases below 2.5 mm, the risk for angle closure glaucoma increases.

Clinical significance

Depth measurement

Determining the anterior chamber depth (ACD) is important in estimating the risk of angle closure glaucoma. There are various method of measuring ACD, including examination through a

slit lamp A slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope. The lamp facilitates an examination of the anterior segme ...

, ultrasound and Scheimpflug photography. These methods require sophisticated examination equipment and expertise. A simpler clinical method of quantitatively estimating ACD using smartphone photography (EZ ratio) was developed by Dr Ehud Zamir from the Centre for Eye Research Australia, the University of Melbourne, and published in 2016.

EZ ratio method

The EZ ratio method is one way to calculate the estimated anterior chamber depth. To start, the patient looks at a target in the distance with one eye covered. The examiner takes a digital photograph of the open, examined eye, from the side, perpendicular to the visual axis (a profile photograph). The following parameters then need to be measured in the photograph, using a

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

or a

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...

(figures 1,2): 1. The

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...

distance between the limbus (the junction between clear

and white sclera) and the front of the

. This distance is referred to as Z. 2. The

distance between the limbus and the centre of the

pupil The pupil is a black hole located in the center of the Iris (anatomy), iris of the Human eye, eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing ...

. This distance is referred to as E. E:Z ratio is the arithmetic

ratio In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...

between E and Z. This

is linearly correlated with the depth of the anterior chamber with the following equation: ''Anterior chamber depth (expressed in millimetres) = -3.3 x EZ ratio + 4.2'' This estimate has been shown to be accurate with a 95% confidence interval of +/– 0.33 mm error, when compared to measurements of the anterior chamber depth by Scheimpflug photography. EZ Ratio calculation

Different anterior chamber depths as seen from the lateral perpendicular view

Associated immune deviation

One peculiar feature of the anterior chamber is dampened immune response to allogenic grafts. This is called ''anterior chamber associated immune deviation'' (ACAID), a term introduced in 1981 by Streilein et al. This phenomenon is relevant to the fact that the eye is considered an " immune privileged site", like the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

and the

testis A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

Pathology

Glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

* Hypopyon *

Intraocular pressure Intraocular pressure (IOP) is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma. Most tonometers are calibrated t ...

Ocular hypertension Ocular hypertension is the presence of elevated fluid pressure inside the eye (intraocular pressure), usually with no optic nerve damage or visual field loss. For most individuals, the normal range of intraocular pressure is between 10 mmHg and 2 ...

Additional images

File:SD OCT - Anterior Chamber Angle Cross-Section (with viewfinder).png, Anterior chamber angle cross-section imaged by an SD-OCT. File:Anterior chamber angle - 3D motion parallax.gif,

Gonioscopy Gonioscopy a routine ophthalmological procedure that measures the angle between the iris and the cornea (the iridocorneal angle), using a goniolens (also known as a gonioscope) together with a slit lamp or operating microscope. Its use is import ...

of the anterior chamber angle File:Kammerwinkel.jpg,

of the anterior chamber angle. Labeled structures: 1.

Schwalbe's line Schwalbe's line is the anatomical line found on the interior surface of the eye's cornea, and delineates the outer limit of the corneal endothelium layer. Specifically, it represents the termination of Descemet's membrane. In many cases it can be ...

, 2.

Trabecular meshwork The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the ...

(TM), 3. Scleral spur, 4.

Ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

, 5.

Iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

File:Intraocular lens under cornea, six years after installation (no flash).jpg, Anterior chamber

IOL Cherchell (Arabic: شرشال) is a town on Algeria's Mediterranean coast, west of Algiers. It is the seat of Cherchell District in Tipaza Province. Under the names Iol and Caesarea, it was formerly a Roman colony and the capital of the kin ...

File:Three Main Layers of the Eye.png, Structures of the eye labeled File:Three Internal chambers of the Eye.svg, This image shows another labeled view of the structures of the eye

References

External links

* - "Sagittal Section Through the Eyeball" {{Authority control Human eye anatomy