What is the structure of the optic disc?
Structure. 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. There is a central depression, of variable size, called the optic cup.
What is optic disc?
Optic disc: The circular area in the back of the inside of the eye where the optic nerve connects to the retina. Also called the optic nerve head.
What is optic disc made of?
Encyclopædia Britannica, Inc. The optic nerve begins at the optic disk, a structure that is 1.5 mm (0.06 inch) in diameter and is located at the back of the eye. The optic disk forms from the convergence of ganglion cell output fibres (called axons) as they pass out of the eye.
What is the histology of the eye?
Consists of five layers: epithelium (non-keratinized, stratified squamous epithelium), Bowman layer, stroma (also called substantia propria), Descemet’s membrane, corneal endothelium. Corneal epithelium: fast growing, regenerating multicellular layer which interacts directly with the tear film.
How is the optic disc formed?
Formation of the optic fissure, which consists of the retinal fissure and the optic groove, dictates where the optic disc will form. The optic fissure acts as an entrance for mesenchymal cells that migrate to form the hyaloid artery (a main blood supply for the eye).
Does the optic disc contain rods and cones?
There are no photoreceptors (i.e., rods or cones) in the optic disk, and, therefore, there is no image detection in this area. The blind spot of the right eye is located to the right of the centre of vision and vice versa in the left eye.
Where is the optic disk located?
The optic disk can be seen in the back of the eye with an ophthalmoscope. It is located on the nasal side of the macula lutea, is oval in shape, and is approximately 1.5 mm (0.06 inch) in diameter. It is also the entry point into the eye for major blood vessels that serve the retina.
What is the corneal epithelium?
The corneal epithelium is the outermost layer of the cornea, whose functions include transparency, and protection from the external environment.
What is ciliary epithelium?
The ciliary epithelium of the ciliary processes produces aqueous humor, which is responsible for providing oxygen, nutrients, and metabolic waste removal to the lens and the cornea, which do not have their own blood supply.
What kind of cells make up the optic nerve?
The optic nerve is composed of retinal ganglion cell axons and Portort cells. It leaves the eye via the optic canal, running postero-medially towards the optic chiasm where there’s a partial decussation (crossing) of fibers from the temporal visual fields of both eyes.
Why is the optic disc pink?
The normal optic disc is pink in color due to the fact that light entering the optic disc is conducted along the transparent nerve fibers and they diffuse among columns of glial tissue and capillaries.
Does the optic disc have photoreceptors?
Why is optic disk called blind spot?
blind spot, small portion of the visual field of each eye that corresponds to the position of the optic disk (also known as the optic nerve head) within the retina. There are no photoreceptors (i.e., rods or cones) in the optic disk, and, therefore, there is no image detection in this area.
What are the 5 layers of the cornea?
The corneal layers include epithelium, Bowman’s layer, stroma, Descemet’s membrane, and endothelium [Fig.
Why is corneal epithelium non Keratinized?
The cells continue to stratify upwards, and continue to flatten and form the superficial cell layers, which contain tight junctions. Unlike the epidermis, corneal epithelium cells do not lose their nucleus or undergo extensive keratinization.
What type of epithelium is found in the ciliary body?
Ciliary epithelia. The outer layer is the pigmented epithelium, which is composed of low cuboidal cells and is adjacent to the stroma and continuous with the retinal pigmented epithelium.
What are the 2 layers of epithelium that cover the ciliary body?
The ciliary processes are covered by 2 layers of epithelium:
- The inner layer is a pigmented layer of simple columnar epithelium that is rich in melanin.
- The outer layer that faces the lumen is a non-pigmented columnar epithelium that is continuous with the ganglion cell layer of the retina.
How many neurons are in the optic nerve?
It has about 100 million neurons, of five distinct kinds. Light-sensitive cells feed wide spanning horizontal cells and narrower bipolar cells, which are interconnected by amacrine cells, and finally ganglion cells, whose outgoing fibers bundle to form the optic nerve.