Information about Optic Disc
| Interior of posterior half of bulb of left eye. The veins are darker in appearance than the arteries. | |
| The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. | |
| subject #225 1015 | |
| MeSH | Optic+Disk |
The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive rods or cones to respond to a light stimulus at this point thus it is also known as "the blind spot" or "anatomical blind spot"; the break in the visual field created by the optic disc is also called "the blind spot" or "physiological blind spot". The optic nerve head in a normal human eye carries from 1 to 1.2 million neurons from the eye towards the brain.
Anatomy
The optic disc is placed 3 to 4 mm to the nasal side of the fovea. It is a vertical oval, with average dimensions of 1.76mm horizontally by 1.92mm vertically.[1] There is a central depression, of variable size, called the optic cup.Clinical examination
The eye is unique due to the transparency of its optical media. Almost all eye structures can be examined with appropriate optical equipment and lenses. Using a modern direct ophthalmoscope gives a view of the optic disc using the principle of reversibility of light. A slit lamp biomicroscopic examination along with an appropriate aspheric focusing lens (+66D, +78D or +90D) is required for a detailed stereoscopic view of the optic disc and structures inside the eye. Inspection of the optic disc by ophthalmoscopy or biomicroscopy can give an indication of the health of the optic nerve. In particular, the eye care physician notes the colour, cupping size (as a cup-to-disc ratio), sharpness of edge, swelling, hemorrhages, notching in the optic disc and any other unusual anomalies. It is useful for finding evidence corroborating the diagnosis of glaucoma and other optic neuropathies, optic neuritis, anterior ischemic optic neuropathy or papilledema (i.e. optic disc swelling produced by raised intracranial pressure). Women in advanced stage of pregnancy with pre-eclampsia should be screened by an ophthalmoscopic examination of the optic disc for early evidence of rise in intracranial pressure.)
Schematic diagram of the human eye, with the optical disc, or blind spot, at the bottom.
Imaging of the optic disc
Traditional colour-film camera images are the gold standard in imaging, requiring an expert ophthalmic photographer, ophthalmic technician, optometrist or an ophthalmologist for taking standardised pictures of the optic disc. Stereoscopic images offer an excellent investigative tool for serial follow-up of suspected changes in the hands of an expert optometrist or ophthalmologist. However, since not everybody can be trained so well, automated techniques have been devised to supplant or replace the human expertise. Heidelberg Retinal Tomography (HRT-II), GDx-VCC and optical coherence tomography (Stratus-OCT 3) are the currently available computerised techniques for imaging various structures of the eyes, including the optic disc. They quantitate the nerve fiber layer of disc and surrounding retina and statistically correlate the findings with a database of previously screened population of normals. They are useful for baseline and serial follow-up to monitor minute changes in optic disc morphology. It should be noted that imaging won't provide conclusive evidence for clinical diagnosis however, and the evidence needs to be supplanted by serial physiological testing for functional changes. Such tests may include visual field charting, and final clinical interpretation of the complete eye examination by an eye care physician. Ophthalmologists and Optometrists are able to provide this service.)
Retinography photograph showing the optic disc as a bright area on the right where blood vessels converge.
References
External links
Sensory system - Visual system - Eye | |
|---|---|
| Fibrous tunic (outer) | Conjunctiva • Sclera • Schlemm's canal • Trabecular meshwork • Limbus Cornea (Epithelium, Bowman's, Stroma, Descemet's, Endothelium) |
| Uvea (middle) | Choroid (Ciliary processes, Choriocapillaris, Bruch's membrane) • Iris (Stroma) • Pupil • Ciliary body |
| Retina (inner) | Macula • Fovea • Optic disc |
| Anterior segment | Anterior chamber • Aqueous humour • Posterior chamber • Lens |
| Posterior segment | Vitreous humour • Zonular fibers • Zonule of Zinn |
vein is a blood vessel that carries blood toward the heart. The majority of veins in the body carry low-oxygen blood from the tissues back to the heart; the exceptions being the pulmonary and umbilical veins which both carry oxygenated blood.
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Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.
The circulatory system is extremely important for sustaining life.
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The circulatory system is extremely important for sustaining life.
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Optic Nerve may be a reference to:
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- Optic nerve, the anatomical structure;
- Optic Nerve (comic), the comic book series;
- Optic Nerve (1998), the seminal release from the Irish hip hop act known as Exile Eye; or
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Eyes are organs of vision that detect light. Different kinds of light-sensitive organs are found in a variety of organisms. The simplest eyes do nothing but detect whether the surroundings are light or dark, while more complex eyes can distinguish shapes and colors.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Location Varies by type
Function Varies but often excitatory projection
Morphology Varies
A ganglion cell (more correctly, a retinal ganglion cell) is a type of neuron typically located near the inner surface of the retina of the eye that
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Function Varies but often excitatory projection
Morphology Varies
A ganglion cell (more correctly, a retinal ganglion cell) is a type of neuron typically located near the inner surface of the retina of the eye that
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Eyes are organs of vision that detect light. Different kinds of light-sensitive organs are found in a variety of organisms. The simplest eyes do nothing but detect whether the surroundings are light or dark, while more complex eyes can distinguish shapes and colors.
..... Click the link for more information.
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Optic Nerve may be a reference to:
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- Optic nerve, the anatomical structure;
- Optic Nerve (comic), the comic book series;
- Optic Nerve (1998), the seminal release from the Irish hip hop act known as Exile Eye; or
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Photoreceptor can refer to:
In anatomy/cell biology:
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In anatomy/cell biology:
- Photoreceptor cell: a photosensitive cell, most commonly referring to a specialized type of neuron found in the retina of vertebrate eyes that is capable of phototransduction;
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Light is electromagnetic radiation of a wavelength that is visible to the eye (visible light). In a scientific context, the word "light" is sometimes used to refer to the entire electromagnetic spectrum.
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The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments" (J.
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For other uses, see Blind spot.
A blind spot, also known as a scotoma, is an obscuration of the visual field. A particular blind spot known as the blind spot, or physiological blind spot
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Neurons (also known as neurones and nerve cells) are electrically excitable cells in the nervous system that process and transmit information. In vertebrate animals, neurons are the core components of the brain, spinal cord and peripheral nerves.
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fovea, also known as the fovea centralis, is a part of the eye, located in the center of the macula region of the retina. [1] [2] The fovea is responsible for sharp central vision, which is necessary in humans for reading, watching television or movies,
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Optic cup can refer to:
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- Optic cup (embryology)
- Optic cup (ophthalmology)
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The ophthalmoscope is an instrument used to examine the eye. Its use is crucial in determining the health of the retina and the vitreous humor.
In patients with headaches, the finding of swollen optic discs, or papilledema, on ophthalmoscopy is a key sign, as this indicates
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In patients with headaches, the finding of swollen optic discs, or papilledema, on ophthalmoscopy is a key sign, as this indicates
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slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine as a slit. It is used in conjunction with a microscope. The lamp facilitates an examination which looks at anterior segment, or frontal structures, of the human eye, which includes
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eye examination is a battery of tests performed by an ophthalmologist or optometrist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes.
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The ophthalmoscope is an instrument used to examine the eye. Its use is crucial in determining the health of the retina and the vitreous humor.
In patients with headaches, the finding of swollen optic discs, or papilledema, on ophthalmoscopy is a key sign, as this indicates
..... Click the link for more information.
In patients with headaches, the finding of swollen optic discs, or papilledema, on ophthalmoscopy is a key sign, as this indicates
..... Click the link for more information.
slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine as a slit. It is used in conjunction with a microscope. The lamp facilitates an examination which looks at anterior segment, or frontal structures, of the human eye, which includes
..... Click the link for more information.
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cupping. But glaucoma, which is due to an increase in intra-ocular pressure, produces additional pathological cupping of the optic disc.
The cup-to-disc ratio compares the diameter of the "cup" portion of the optic disc with the total diameter of the optic disc.
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The cup-to-disc ratio compares the diameter of the "cup" portion of the optic disc with the total diameter of the optic disc.
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pink rim of disc contains nerve fibers. The white cup is a pit with no nerve fibers. As glaucoma advances, the cup enlarges until it occupies most of the disc area. Courtesy AgingEye Times
ICD-10 H 40. -H 42.
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ICD-10 H 40. -H 42.
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Optic neuritis
Classification & external resources
ICD-10 H 46.
ICD-9 377.3
DiseasesDB 9242
MedlinePlus 000741
eMedicine radio/488
MeSH D009902 Optic neuritis, sometimes called retrobulbar neuritis
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Classification & external resources
ICD-10 H 46.
ICD-9 377.3
DiseasesDB 9242
MedlinePlus 000741
eMedicine radio/488
MeSH D009902 Optic neuritis, sometimes called retrobulbar neuritis
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Anterior ischemic optic neuropathy (AION) is a medical condition involving loss of vision due to damage to the optic nerve from insufficient blood supply. AION is generally divided into two types: arteritic AION (or AAION) and non-arteritic AION (NAION or simply AION).
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Papilledema
Classification & external resources
ICD-10 H 47.1
ICD-9 377.0
DiseasesDB 9580
eMedicine oph/187
MeSH D010211 Papilledema (or papilloedema
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Classification & external resources
ICD-10 H 47.1
ICD-9 377.0
DiseasesDB 9580
eMedicine oph/187
MeSH D010211 Papilledema (or papilloedema
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Intracranial pressure, (ICP), is the pressure exerted by the cranium on the brain tissue, cerebrospinal fluid (CSF), and the brain's circulating blood volume. ICP is a dynamic phenomenon constantly fluctuating in response to activities such as exercise, coughing, straining,
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Pre-eclampsia
Classification & external resources
ICD-10 O 11. , O 13. , O 14.
ICD-9 642.4 - 642.7
DiseasesDB 10494
MedlinePlus 000898
eMedicine med/1905 ped/1885
Pre-eclampsia (US: preeclampsia
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Classification & external resources
ICD-10 O 11. , O 13. , O 14.
ICD-9 642.4 - 642.7
DiseasesDB 10494
MedlinePlus 000898
eMedicine med/1905 ped/1885
Pre-eclampsia (US: preeclampsia
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Intracranial pressure, (ICP), is the pressure exerted by the cranium on the brain tissue, cerebrospinal fluid (CSF), and the brain's circulating blood volume. ICP is a dynamic phenomenon constantly fluctuating in response to activities such as exercise, coughing, straining,
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Optical coherence tomography (OCT) is an interferometric, non-invasive optical tomographic imaging technique offering millimeter penetration (approximately 2-3 mm in tissue) with micrometer-scale axial and lateral resolution.
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The term morphology in biology refers to the outward appearance (shape, structure, color, pattern) of an organism or taxon and its component parts. This is in contrast to physiology, which deals primarily with function.
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