Hypopyon
Encyclopedia
Hypopyon is pus in the eye
.
It is a leukocytic exudate, seen in the anterior chamber
, usually accompanied by redness of the conjunctiva
and the underlying episclera
. It is a sign of inflammation of the anterior uvea
and iris
, i.e. iritis
, which is a form of anterior uveitis
. The exudate settles at the bottom due to gravity.
, particularly of fungal etiology like Aspergillus and Fusarium sp., Behcet's disease
, endophthalmitis
, and panuveitis
/panophthalmitis
.
Hypopyon is also known as sterile pus, as it occurs due to the release of toxins and not by the actual invasion of pathogens. The toxins secreted by the pathogens mediate the outpouring of leukocytes that settle down in the anterior chamber of the eye. Hypopyon is the only pus in the body that does not require any specific treatment as treatment of the underlying cause results in its resolution.
An inverse hypopyon needs to be differentiated from a standard hypopyon. Inverse hypopyon is seen sometimes after a pars plana vitrectomy with insertion of silicon oil (as a replacement of the vitreous humour that has been removed in the operation; the silicon oil maintains internal tamponade). When the silicon oil emulsifies, it seeps into the anterior chamber and settles at the top of the anterior chamber. Compare from the hypopyon resulting due to the toxins where the leukocytes settle at the bottom of the anterior chamber. This is due to the effect of gravity, hence the name inverse hypopyon.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
.
It is a leukocytic exudate, seen in the anterior chamber
Anterior chamber
The anterior chamber is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Aqueous humor is the fluid that fills the anterior chamber. Hyphema and glaucoma are two main pathologies in this area. In hyphema, blood fills the anterior chamber...
, usually accompanied by redness of the conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
and the underlying episclera
Episclera
The episclera is the outermost layer of the sclera. It is composed of loose, fibrous, elastic tissue and attaches to Tenon's capsule.A vascular plexus is found between the conjunctiva and the sclera consisting of two layers of vessels, the superficial episcleral vessels and the deep episcleral...
. It is a sign of inflammation of the anterior uvea
Uvea
The uvea , also called the uveal layer, uveal coat, uveal tract, or vascular tunic, is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when...
and iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
, i.e. iritis
Iritis
Iritis is a form of anterior uveitis and refers to the inflammation of the iris of the eye.-Types:There are two main types of iritis: acute and chronic. They differ in numerous ways....
, which is a form of anterior uveitis
Uveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
. The exudate settles at the bottom due to gravity.
Differential diagnosis
Hypopyon can also be present in a corneal ulcerCorneal ulcer
A corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
, particularly of fungal etiology like Aspergillus and Fusarium sp., Behcet's disease
Behçet's disease
Behçet's disease is a rare immune-mediated systemic vasculitis that often presents with mucous membrane ulceration and ocular involvements...
, endophthalmitis
Endophthalmitis
Endophthalmitis is an inflammation of the internal coats of the eye. It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. Infectious etiology is the most common and various bacteria and fungi have been isolated as...
, and panuveitis
Uveitis
Uveitis specifically refers to inflammation of the middle layer of the eye, termed the "uvea" but in common usage may refer to any inflammatory process involving the interior of the eye....
/panophthalmitis
Panophthalmitis
Panophthalmitis is the inflammation of all coats of the eye including intraocular structures....
.
Hypopyon is also known as sterile pus, as it occurs due to the release of toxins and not by the actual invasion of pathogens. The toxins secreted by the pathogens mediate the outpouring of leukocytes that settle down in the anterior chamber of the eye. Hypopyon is the only pus in the body that does not require any specific treatment as treatment of the underlying cause results in its resolution.
An inverse hypopyon needs to be differentiated from a standard hypopyon. Inverse hypopyon is seen sometimes after a pars plana vitrectomy with insertion of silicon oil (as a replacement of the vitreous humour that has been removed in the operation; the silicon oil maintains internal tamponade). When the silicon oil emulsifies, it seeps into the anterior chamber and settles at the top of the anterior chamber. Compare from the hypopyon resulting due to the toxins where the leukocytes settle at the bottom of the anterior chamber. This is due to the effect of gravity, hence the name inverse hypopyon.