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 seen via gonioscopy
Gonioscopy
Gonioscopy describes the use of a goniolens (also known as a gonioscope) in conjunction with a slit lamp or operating microscope to gain a view of the iridocorneal angle, or the anatomical angle formed between the eye's cornea and iris. The importance of this process is in diagnosing and monitoring various eye conditions associated with glaucoma.
What is Schwalbe's line in eye?
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.
What is Schwalbe's line and trabecular meshwork?
Schwalbe's line, 2. Trabecular meshwork (TM), 3. Scleral spur, 4. Ciliary body, 5. Iris 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.
What is Schwalbe's line and scleral spur?
Schwalbe's line, 2. Trabecular meshwork (TM), 3. Scleral spur, 4. Ciliary body, 5. Iris 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.
How do you identify Schwalbe’s line?
The line is often too faint to be identified, particularly in an eye with a very lightly pigmented trabecular meshwork. The corneal wedge, described in Chapter 4, is invaluable in identifying Schwalbe’s line.
What is scleral spur?
The scleral spur is a shelf-like structure formed from a projection of the sclera, bordered anteriorly by the corneoscleral portion of the TM and posteriorly by the longitudinal fibers of the ciliary muscle.
What is a normal eye angle?
The angle between the iris and the cornea is usually wide enough to permit a good view of all angle structures (5‑22). The angle is generally quite wide in myopic eyes (5‑23) and narrower in hyperopic eyes.
What is Descemet's membrane?
The Descemet membrane is the specialized basement membrane of the endothelial cells positioned between the stroma and the endothelial cell layer. Any condition that causes inflammation of the cornea or the anterior chamber can cause Descemet membrane folds.
What are the 5 layers of the cornea?
The corneal layers include epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium [Fig.
Do narrow angles mean glaucoma?
DOES HAVING NARROW ANGLES MEAN YOU HAVE GLAUCOMA? When the 'angle' is narrow, patients are at risk of developing both acute angle closure glaucoma and chronic angle closure glaucoma. It is important however to understand that being at risk for glaucoma and having glaucoma are different.
Is narrow angle the same as glaucoma?
Narrow angle glaucoma is a serious type of glaucoma that occurs suddenly. Although glaucoma is often referred to as the "sneak thief of sight" because most people with the disease do not experience symptoms, narrow angle glaucoma can produce severe symptoms.
Is Descemet's membrane a basement membrane?
Descemet's membrane- which is the basement membrane for the corneal endothelium- is a dense, thick, relatively transparent and cell-free matrix that separates the posterior corneal stroma from the underlying endothelium.
Where is Descemet's membrane?
the corneaDescemet's membrane (or the Descemet membrane) is the basement membrane that lies between the corneal proper substance, also called stroma, and the endothelial layer of the cornea.
How thick is Descemet's membrane?
The thickness of the anterior layer was approximately 3 μm and similar in specimens from patients of all ages. The thickness of the posterior nonbanded layer of Descemet's membrane increased significantly with age, averaging approximately 2 μm at age 10 years and 10 μm at age 80 years.
Which is the strongest corneal layer?
The stroma of the cornea is the thickest layer (comprising 80-85% of cornea) made up of dense connective tissues. The stroma appears characteristically transparent because of the arrangement of stromal fibres and extracellular matrix.
What protects cornea?
Epithelium: Much like skin, acts as a barrier to protect the cornea from dust, debris and bacteria. Stroma: Gives the cornea its strength and dome-like shape--makes up 90% of the corneal thickness, mostly of collagen and other structural materials.
What are the 3 functions of the cornea?
The cornea acts as the eye's outermost lens. It functions like a window that controls and focuses the entry of light into the eye. The cornea contributes between 65-75 percent of the eye's total focusing power.
Do humans have 180 degree vision?
We humans are largely binocular beings. Each eye alone gives us roughly a 130-degree field of vision. With two eyes, we can see nearly 180 degrees. Most of that field is what's called a Cyclopean image -- the single mental picture that a Cyclops might see.
How serious is narrow angle?
Typically, narrow angles are asymptomatic – that is they don't cause any noticeable problem to the patient. On the other hand, angle closure if it develops often leads to dramatic symptoms – an unbearable pressure like headache, blurry vision, nausea, vomiting, redness, extreme eye pain.
What is the maximum angle of vision for healthy human eye?
The visual field of the human eye spans approximately 120 degrees of arc. However, most of that arc is peripheral vision.
Can Narrow angles cause blindness?
Narrow-angle glaucoma is a type of glaucoma that develops suddenly and can lead to sudden and permanent loss of sight. Narrow-angle glaucoma is the cause of less than 10% of all glaucoma diagnosis, but can cause immense pain and sudden loss of sight and even blindness.
What is a thin white line on a gonioscopy?
A thin white or irregularly pigmented line observed on gonioscopy; represents the peripheral margin of the Descemet membrane.
What is the line marking the junction of the epiphysis and diaphysis of a long bone?
A line marking the junction of the epiphysis and diaphysis of a long bone. It is the remnant of the epiphyseal disk.
What is the arcuate line?
1. The lower edge of the iliac fossa of the ilium. The arcuate line is a continuation of the pectineal line of the pubis, and it continues up and back along the ilium to merge with the edge of the sacral ala and then the sacral promontory. The continuous bony ridge, of which the arcuate line is one segment, encircles the pelvic inlet and is called the pelvic brim.
What is the segment of the pelvic brim from the pubic symphysis to the?
The segment of the pelvic brim from the pubic symphysis to the sacrum; this includes the pubic crest, the pectineal line, and the arcuate line.
What is the imaginary line from the inferior orbital margin to the external auditory meatus?
An imaginary line from the inferior orbital margin to the external auditory meatus, used for radiographical positioning of the skull.
What is the line that extends in parallel down the side of the body from the axilla?
The anterior axillary line, the midaxillary line, or the posterior axillary line – imaginary lines that extend in parallel down the side of the body from the axilla.
What is the imaginary line that extends from the ala of the nose to the tragus of the ear?
The line is an estimated point of entry for intraoral dental radiographs of the maxilla and is also used in denture prosthodontics.
Anterior segment
This prominent, anteriorly displaced Schwalbe's line, seen in 8–15% of the normal population appears as a whitish, irregular ridge up to several millimeters from the limbus and is often incomplete. It may be inherited in an autosomal dominant fashion. In isolation, it is not associated with an increased risk of glaucoma.
Developmental and childhood glaucoma
Robert L Stamper MD, ... Michael V Drake MD, in Becker-Shaffer's Diagnosis and Therapy of the Glaucomas (Eighth Edition), 2009
OCULAR HEALTH ASSESSMENT
C. LISA PROKOPICH, ... DAVID B. ELLIOTT, in Clinical Procedures in Primary Eye Care (Third Edition), 2007
Surgical Management
Rajendra K Bansal, ... James C Tsai, in Glaucoma (Second Edition), 2015
Pediatric Cholestatic Syndromes
Ocular abnormalities in patients with AGS may be very diverse. 141 The most common is posterior embryotoxon, an abnormal prominence of the Schwalbe line (junction of the Descemet membrane with the uvea at the angle of the anterior chamber), seen in up to 95% of patients. 141 It requires slit-lamp examination for detection.
PIGMENTARY DISPERSION SYNDROME AND PIGMENTARY GLAUCOMA 365.13
There are radial midperipheral iris transillumination defects, which may be difficult to see with dark and thick iris stroma.
Genetics of glaucoma
Robert L Stamper MD, ... Michael V Drake MD, in Becker-Shaffer's Diagnosis and Therapy of the Glaucomas (Eighth Edition), 2009
Which quadrant is Schwalbe's line most frequently seen in?
5-18 Prominent Schwalbe’s line forming a ridge. Such elevation is most frequently seen in the inferior quadrant.
Where is Schlemm's canal?
In most individuals Schlemm’s canal is not visible. It lies deep within the posterior (pigmented) trabecular meshwork, anterior to the scleral spur, and becomes visible only when filled with blood ( 5‑15 ). Blood can occasionally be found in Schlemm’s canal in normal eyes. It may also be seen in situations where the flow of aqueous humor from Schlemm’s canal to the episcleral venous system is impeded. This can occur when a contact lens with a large diameter (such as a Goldmann lens) is pressed too firmly against the eye, compressing the episcleral veins. It can also be seen when the pressure in the episcleral venous system is high or when the intraocular pressure is low. Pathologic causes of blood in Schlemm’s canal are discussed in Chapter 9.
What is a scleral spur?
The scleral spur is a ridge of scleral tissue that lies anterior to the ciliary body band and marks the posterior border of the trabecular meshwork. It appears as a thin band that is usually white or light gray ( 5‑5) but which may have a yellowish cast in older individuals ( 5‑6 ).
How to distinguish iris from peripheral synechiae?
It is important—and occasionally difficult—to distinguish iris processes from peripheral anterior synechiae. Iris processes are usually fine wisps of iris and extend into the posterior portions of the trabecular meshwork. They usually follow the concavity of the angle recess but can bridge the angle. Iris processes do not inhibit the movement of the iris with indentation and they do not interfere with aqueous outflow. Peripheral anterior synechiae tend to be broad and irregular, attaching iris stroma to the trabecular meshwork. They bridge the angle recess, rather than follow it, and they obscure underlying structures. Synechiae inhibit posterior movement of the iris during indentation gonioscopy. They drag normal radial iris vessels with them. There is frequently pigmentation on the cornea anterior to the synechiae caused by the underlying pathology, such as inflammation or angle closure.
How much blood is in Schlemm's canal?
5-15 Blood in Schlemm’s canal. This can be seen in normal eyes, with increased episcleral venous pressure, in ocular hypotony, and with excessive pressure on the limbus from a large gonioscopic lens. Note that the trabecular band is wide and is darker than the adjacent cornea.
Is trabecular meshwork smooth?
The meshwork is nonpigmented and smooth in infants but becomes coarser and more pigmented with advancing age. Flow through the trabecular meshwork is through the posterior portion. For this reason, the posterior trabecular meshwork is generally more pigmented than the anterior trabecular meshwork.
What is Schwalbe working on?
Schwalbe is working to eradicate the puncture. Cycling is today considered a progressive form of personal transport that offers nothing but advantages – with one unfortunate exception: the tire puncture.
When was Schwalbe Marathon Tire invented?
It was in this context that Schwalbe – established in 1973 – emerged as a standard-setter in the bicycle tire market. The launch of the legendary Schwalbe Marathon tire in 1983, with its unprecedented mileage, was met with great enthusiasm by keen cyclists, bicycle dealers and trade journalists.
What is the scleral spur?
The scleral spur is made up of a ridge of collagen tissue. This is noted by its white color during gonioscopy. Identifying this structure helps to differentiate open angles from closed angles. It is possible for the scleral spur to be covered by small sharp-ended iris processes that reach up to the trabecular meshwork. They do not cross the trabecular meshwork and have no pathologic consequence.
What are some examples of direct goniolenses?
Examples of direct goniolenses include Koeppe, Barkan, Wurst, Swan-Jacob, or Richardson lenses . During direct gonioscopy, the viewer has an erect view of the angle structures. Direct gonioscopy is most easily performed with the patient supine and in the operating room for an exam under anesthesia or a MIGS procedure.
What is a direct gonioscopy?
Direct gonioscopy is most easily performed with the patient in a supine position and is commonly used in the operating room for examination of the eyes of infants under anesthesia. It can be performed using a direct goniolens and either a binocular microscope or a slit-pen light.
How to determine how open or narrow an angle is?
As discussed above, gonioscopy is extremely useful in determining how open or narrow an angle is and the possibility of it becoming closed. There are also many other indications and uses for gonioscopy . Knowing the anatomy described above will help with identifying any pathology that may be present. Blood in Schlemm’s canal can be seen in patients with increased episcleral venous pressure such as carotid cavernous fistulas. It can also be present with hypotony. The formation of peripheral anterior synechiae and the identification of this is extremely important. Depending on the severity, this can decide a treatment approach or indication for a peripheral laser iridotomy. Neovascularization may be noted in patients with uncontrolled diabetes or a history of central retinal vein occlusions. There are other conditions that may cause neovascularization as well. Other findings that can be visible with gonioscopy include hyphemas and microhyphemas. Foreign bodies can also be found on gonioscopy. The extent of iris or uveal tumors can be evaluated. Iridodialysis or other damage to angle structures can also be noted after a history of trauma.
