Posterior chamber of the eyeball | |
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Details | |
Identifiers | |
Latin | camera posterior bulbi oculi |
TA98 | A15.2.06.005 A15.2.06.001 |
TA2 | 6794 |
FMA | 58080 |
Anatomical terminology |
The posterior chamber is a narrow space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens and the ciliary processes. The posterior chamber consists of small space directly posterior to the iris but anterior to the lens. The posterior chamber is part of the anterior segment[1] and should not be confused with the vitreous chamber (in the posterior segment).
Posterior chamber is an important structure involved in production and circulation of aqueous humor. Aqueous humor produced by the epithelium of the ciliary body is secreted into the posterior chamber, from which it flows through the pupil to enter the anterior chamber.[2]
The hypermature cataractous lens[3] or, the intraocular lens[4] implanted after cataract surgery may obstruct the aqueous flow through the pupil. The block in flow of aqueous from the posterior to the anterior chamber will lead to a condition known as Iris bombe. In this condition, pressure in the posterior chamber rises, resulting in anterior bowing of the peripheral iris and obstruction of the trabecular meshwork. This may result in an acute attack of angle closure glaucoma.[5] Surgical management of Glaucoma due to Iris bombe include making a small hole in the iris which allows passage of aqueous from posterior chamber to anterior chamber either by YAG or Argon laser iridotomy [6] or by manual iridectomy.[7]
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Development of Glaucoma Animation, Open Angle vs Angle Closure Glaucoma.
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Vitreous humour
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Transcription
Glaucoma is a group of eye diseases in which the optic nerve is damaged leading to irreversible loss of vision. In most cases, this damage is due to an increased pressure within the eye. The eye produces a fluid called aqueous humor which is secreted by the ciliary body into the posterior chamber - a space between the iris and the lens. It then flows through the pupil into the anterior chamber between the iris and the cornea. From here, it drains through a sponge-like structure located at the base of the iris called the trabecular meshwork and leaves the eye. In a healthy eye, the rate of secretion balances the rate of drainage. In people with glaucoma, the drainage canal is partially or completely blocked. Fluid builds up in the chambers and this increases pressure within the eye. The pressure drives the lens back and presses on the vitreous body which in turn compresses and damages the blood vessels and nerve fibers running at the back of the eye. These damaged nerve fibers result in patches of vision loss, and if left untreated, may lead to total blindness. There are two main types of glaucoma: open-angle and angle-closure. Open-angle glaucoma , or chronic glaucoma, is caused by partial blockage of the drainage canal. The angle between the cornea and the iris is "open", meaning the entrance to the drain is clear, but the flow of aqueous humor is somewhat slow. The pressure builds up gradually in the eye over a long period of time. Symptoms appear gradually, starting from peripheral vision loss, and may go on unnoticed until the central vision is affected. Progression of glaucoma can be stopped with medical treatments, but part of vision that is already lost can not be restored. This is why it's very important to detect signs of glaucoma early with regular eye exams. Angle-closure glaucoma, or acute glaucoma, is caused by a sudden and complete blockage of aqueous humor drainage. The pressure within the eye rises rapidly and may lead to total vision loss quickly. Certain anatomical features of the eye such as narrow drainage angle, shallow anterior chamber, thin and droopy iris, make it easier to develop acute glaucoma. Typically, this happens when the pupil is dilated and the lens is stuck to the back of the iris. This prevents the aqueous humor from flowing through the pupil into the anterior chamber. Accumulation of fluid in the posterior chamber presses on the iris causing it to bulge outward and block the drainage angle completely. Acute angle-closure glaucoma is a medical emergency and requires immediate attention.
Additional images
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The upper half of a sagittal section through the front of the eyeball (posterior chamber of eye labeled at center right)
See also
References
This article incorporates text in the public domain from page 1012 of the 20th edition of Gray's Anatomy (1918)
- ^ www.arkeo.com, produced by Arkeo, Inc. "Visual System - Segments of the Eye". teaching.pharmacy.umn.edu. Archived from the original on 2018-12-19. Retrieved 2016-05-10.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "Flow of Aqueous Humor". yale.
- ^ Harpreet Gill, MD Staff Physician, Henry Ford Ophthalmology (Sep 20, 2018). "Phacomorphic Glaucoma". Medscape.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ Mitchell V Gossman, MD (May 2, 2018). "Pseudophakic Pupillary Block". Medscape.
- ^ Christopher Kirkpatrick, MD (October 10, 2013). "Iris Bombe". University of Iowa Carver College of Medicine Department of Ophthalmology & Visual Sciences.
- ^ "Iris Bombe". Colombiauniversity Department of Ophthalmology. 17 March 2022.
- ^ Daljit singh (11 September 2016). "Iridectomy and Iridotomy". Entokey.
External links
- Anatomy figure: 29:05-11 at Human Anatomy Online, SUNY Downstate Medical Center
- Atlas image: eye_2 at the University of Michigan Health System - "Sagittal Section Through the Eyeball"