What is optic disc segmentation?
Segmenting the optic disc (OD) is an important and essential step in creating a frame of reference for diagnosing optic nerve head pathologies such as glaucoma. Therefore, a reliable OD segmentation technique is necessary for automatic screening of optic nerve head abnormalities.
What is an optic cup?
Definition of optic cup : the optic vesicle after invaginating to form a 2-layered cup from which the retina and pigmented layer of the eye will develop. — called also eyecup.
What does a large optic cup mean?
Glaucoma is caused by high pressure in the eye damaging the optic nerve, which results in loss of individual nerve cells. This causes a subsequent increase in the size of the cup, also called cupping.
What is the optic disc VS Cup?
The cup-to-disc ratio (often notated CDR) is a measurement used in ophthalmology and optometry to assess the progression of glaucoma. The optic disc is the anatomical location of the eye’s “blind spot”, the area where the optic nerve and blood vessels enter the retina.
How do you identify an optic cup?
Neuroretinal rim Therefore, in most cases, the boundaries of the optic cup are best identified by following the track and kink of the blood vessels within the ONH. PPA can cause the wrong determination of the boundary of the optic disc and the misinterpretation as NRR.
How is optic cup formed?
During embryonic development of the eye, the outer wall of the bulb of the optic vesicles becomes thickened and invaginated, and the bulb is thus converted into a cup, the optic cup (or ophthalmic cup), consisting of two strata of cells.
Where is optic cup derived?
As the optic cup has its origins as a continuous layer of the surface of the forebrain we can directly describe the choroid and the sclera as being ‘like’ the pia mater and the dura mater of the brain. These develop from the mesenchyme immediately adjacent to the posterior part of the developing eye.
What causes large optic cups?
The Glaucoma Research Foundation says glaucoma is a common cause of optic cupping. When you have glaucoma, your eye is filled with an unusual amount of fluid, and it puts immense pressure on all the tissues in your eye. Nerves are delicate, and they can’t stand the pressure.
What is the optic disc and what is its significance?
The optic disc represents the beginning of the optic nerve and is the point where the axons of retinal ganglion cells come together. The optic disc is also the entry point for the major blood vessels that supply the retina.
What is optic stalk?
The optic stalk is a structure that connects the optic cup to the brain, and it is readily distinguished at 4 weeks of gestation (Rizzo, 2005; Watanabe et al., 2008). The optic stalk has a ventral groove, the choroid fissure, which contains hyaloid vessels.
What structure does the optic stalk develop into?
Development
| Tissue of Origin | Embryonic Structure |
|---|---|
| Neuroectoderm of the diencephalon | Optic stalk |
| Surface ectoderm of the head | Lens placode |
| Mesoderm of the head | |
| Hyaloid artery and vein |
What is optic disc and optic cup segmentation?
The optic disc and optic cup segmentation techniques are used to isolate the relevant parts of the retinal image and to calculate the cup-to-disc ratio.
What is the threshold value for Cup segmentation in the image?
The threshold of cup segmentation is more compared to the disc because the cup is the brightest region. The CDR value is calculated by computing the disc and cup area. The ratio of the area is called CDR. This is the threshold value used to identify whether the patient is glaucomatous from the fundus image. This value is set as 0.3 by the author.
What is the difference between CDR and Cup segmentation?
The threshold of cup segmentation is more compared to the disc because the cup is the brightest region. The CDR value is calculated by computing the disc and cup area. The ratio of the area is called CDR. This is the threshold value used to identify whether the patient is glaucomatous from the fundus image.
Can the red plane help in segmentation of the Cup disc region?
From the histogram a threshold value is computed to separate the foreground pixels from background pixels. In this paper the author AND’s the blue plane and green plane to help in segmentation of the cup if the red plane does not produce a better identification of the cup disc region.