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The optic disc is located 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. [2] There is a central depression, of variable size, called the optic cup.
An early analogue optical disc system existed in 1935, used on Welte's Lichttonorgel sampling organ. [15] An early analog optical disc used for video recording was invented by David Paul Gregg in 1958 [16] and patented in the US in 1961 and 1969. This form of optical disc was a very early form of the DVD (U.S. patent 3,430,966).
Cup–disc ratio CF: Count fingers vision – state distance c/o or c.o. ... Back optic zone diameter BOZR Back optic zone radius BVP Back vertex power CLAPC/CLIPC
The cup-to-disc ratio compares the diameter of the cup portion of the optic disc with the total diameter of the optic disc. A good analogy to better understand the cup-to-disc ratio is the ratio of a donut hole to a donut. The hole represents the cup and the surrounding area the disc. If the cup fills 1/10 of the disc, the ratio will be 0.1.
The cornea is typically about 11.5 mm (0.45 in) in diameter, and 0.5 mm (500 μm) in thickness near its centre. ... The light circle is the optic disc where the optic ...
The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. [ 2 ] The anatomical macula at a size of 5.5 mm (0.22 in) is much larger than the clinical macula which, at a size of 1.5 mm (0.059 in), corresponds to the anatomical fovea.
The mean disc diameter (DD) is (Vertical diameter of Disc+Horizontal diameter of Disc) divided by 2. The distance between the center of the disc and the macula is DM. Interpretation: When the ratio of DM to DD is greater than 3, ONH is suspected, and when it is greater than 4, Optic Nerve Hypoplasia is definite.
In adult humans, the entire retina is about 72% of a sphere about 22 mm in diameter. The entire retina contains about 7 million cones and 75 to 150 million rods. The optic disc, a part of the retina sometimes called "the blind spot" because it lacks photoreceptors, is located at the optic papilla, where the