Ventricular Angle: Structure, Function & Diseases

In the anterior chamber of each eye lies the angle of the ventricle, where the cornea, iris, and eye chamber meet. The most important function of this structure is to regulate fluid in the eye, keeping intraocular pressure at a normal level. In diseases of the ventricular angle, the fluid-regulating function of the structure may be disrupted, causing intraocular pressure to rise, increasing the risk of glaucoma.

What are the chamber angles?

The cornea, iris, and anterior chamber of the eye meet in an angular structure in the anterior segment of each eye. This structure is called the chamber angle. The medical profession also refers to it as the iridocorneal angulus, which is directly connected to structures such as the Schwalbe’s line, the scleral spur, the ciliary body ligament, and the trabecular meshwork. The anterior chamber angle allows drainage of the aqueous humor produced by the eye chamber to nourish the cornea. Diseases of the chamber angle structures are commonly associated with blindness and usually involve impaired outflow of aqueous humor. During the so-called gonioscopy, the ophthalmologist checks the functionality of the chamber angle. For example, he checks the permeability of all the chamber angle channels. If a finding is made, he may be able to surgically lower the intraocular pressure with selective laser trabeculoplasty and thus avert serious secondary diseases.

Anatomy and structure

Physicians distinguish an unpigmented anterior chamber angle portion near the Schwalbe line from a more posterior and usually colored portion. The posterior portion is the functional part of the chamber angle structure and performs the regulatory functions of the system. In short, the posterior pigmentary portion of the chamber angle is where aqueous humor drains. This is where, among other things, the so-called Schlemm canal is located, which is connected to the bloodstream in a sophisticated canal system. The posterior part of the chamber angle structures is also called the trabecular meshwork. The anterior part, on the other hand, is formed by the Schwalbe line. This is where the endothelium of the cornea meets the trabecular meshwork. This meeting gives rise to a delicate gray line. The white line between the trabecular meshwork and the ciliary body band is also called scleral spur. Often this structure is overlaid by pigment components and is therefore not directly visible. The ciliary body band is a mostly dark gray part of the ciliary muscle located in the chamber angle between the iris base and the scleral spur.

Function and Tasks

In the corner behind the iris sits the so-called ciliary body. This ciliary body permanently produces new ocular fluid. It thus protects the eye from drying out and releases fluid into the anterior chamber of the eye. This fluid serves to nourish the cornea and remains stored in the chamber. An excess of this fluid causes the intraocular pressure to rise and can have serious consequences. Therefore, the function of the ventricular angle is to reduce the risk of increased intraocular pressure by removing fluid. For this reason, excess fluid is drained into the bloodstream through the canal system of the ventricular angle. The Schlemm canal plays a key role in this process. This canal system is actually a circular vein between the cornea and the sclera. Through this vein, the angle of the chamber can release water into intra- and episcleral veins, from where it is directed into the venous system via drainage. Thus, in the eye, the angle of the ventricle primarily performs a regulating function, thus ensuring a balanced intraocular pressure. In addition to this main task, however, some structures of the ventricular angle are also involved in additional functions. For example, the ciliary muscle in the chamber angle runs out into the ciliary body ligament. This muscle system is responsible for deforming the lens, which is necessary for near vision. Thus, in the broadest sense, the chamber angle is also related to purely vision-related tasks.

Diseases

When the outflow of aqueous humor through the chamber angle is disturbed, intraocular pressure rises. Almost all diseases of the angle of the ventricle do not cause any pain, but manifest themselves at most as a throbbing or pressing feeling of heaviness on the eyes. In diseases of the angle of the ventricle, the physician differentiates causally between a drainage disturbance due to narrowed channels and a disturbance due to an impairment of the fine-meshed trabecular meshwork structures.In most cases, scarring, cystic changes, deposits or injuries are associated with a dysfunctional chamber angle. In acute cases, a disturbed chamber angle outflow due to the increase in intraocular pressure can trigger a glaucoma attack. In some circumstances, chronically elevated intraocular pressure also leads to classic glaucoma. In the worst case, this disease can ultimately cause the eye to go blind. In this context, the ophthalmologist also refers to narrow-angle glaucoma. If, on the other hand, there are pathological changes in the chamber angle canals, we are talking about a degenerative phenomenon of the trabecular meshwork, which can cause chronic open-angle glaucoma. The chamber angle may also be affected by embryonic developmental abnormalities. In this case, the Schwalbe line is malformed. A malformed Schwalbe line in turn often causes congenital glaucoma. Sometimes pigmentary deposits occur in the chamber angle. These changes may be related to pigment dispersion glaucoma or a receded angle block attack. In rare cases, pigmented changes of the chamber angle may also be due to tumors of the anterior uvea. Other diseases of the anterior chamber angle are present when the vessels of the system take on abnormal growth forms. This often refers to conditions such as neovascular glaucoma or Fuchs heterochromocyclitis. Incidentally, as with most other structures of the eye, a foreign body can become lodged in the chamber angle. When such a finding is present, the ophthalmologist usually removes the foreign body without damaging the structures around it.

Typical and common eye diseases

  • Eye inflammation
  • Eye pain
  • Conjunctivitis
  • Double vision (diplopia)
  • Light sensitivity