Staphyloma
Encyclopedia
A staphyloma is an abnormal protrusion of the uvea
l tissue through a weak point in the eyeball
. The protrusion is generally black in colour, due to the inner layers of the eye
. It occurs due to weakening of outer layer of eye (cornea or sclera) by an inflammatory or degenerative condition.
It may be of 5 types, depending on the location on the eye ball
(bulbus oculi).
of the eye, involving the cornea
and the nearby sclera
.
of the eye, typically diagnosed at the region of the macula
, deforming the eye in a way that the eye-length is extended associated with myopia
(nearsightedness). It is diagnosed by ophthalmoscopy, which shows an area of retinal excavation in the region of the staphyloma.
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...
l tissue through a weak point in the eyeball
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...
. The protrusion is generally black in colour, due to the inner layers of the eye
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 occurs due to weakening of outer layer of eye (cornea or sclera) by an inflammatory or degenerative condition.
It may be of 5 types, depending on the location on the eye ball
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...
(bulbus oculi).
Anterior (corneal) staphyloma
In the anterior segmentAnterior segment
The anterior segment is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens.Within the anterior segment are two fluid-filled spaces:...
of the eye, involving the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
and the nearby sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...
.
Intercalary staphyloma
It is the name given to the localised bulge in limbal area, lined by the root of the iris. It results due to ectasia of weak scar tissue formed at the limbus, following healing of a perforating injury or a peripheral corneal ulcer. There may be associated secondary angle closure glaucoma, may cause progression of the bulge if not treated. Defective vision occurs due to marked corneal astigmatism. Treatment consists of localised staphylectomy under heavy doses of oral steroids.Ciliary staphyloma
As the name implies, it is the bulge of weak sclera lined by ciliary body, which occurs about 2–3 mm away from the limbus. Its common causes are thinning of sclera following perforating injury, scleritis & absolute glaucoma.Equatorial staphyloma
On the equator of the eye (region circumferencing the largest diameter orthogonal to the visual axis). Its causes are scleritis & degeneration of sclera in pathological myopia. It occurs more commonly in the regions of sclera which are perforated by vortex veins.Posterior staphyloma
In the posterior segmentPosterior segment
The posterior segment is the back two-thirds of the eye that includes the anterior hyaloid membrane and all of the optical structures behind it: the vitreous humor, retina, choroid, and optic nerve....
of the eye, typically diagnosed at the region of the macula
Macula
The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells...
, deforming the eye in a way that the eye-length is extended associated with myopia
Myopia
Myopia , "shortsightedness" ) is a refractive defect of the eye in which collimated light produces image focus in front of the retina under conditions of accommodation. In simpler terms, myopia is a condition of the eye where the light that comes in does not directly focus on the retina but in...
(nearsightedness). It is diagnosed by ophthalmoscopy, which shows an area of retinal excavation in the region of the staphyloma.