Difference between revisions of Eyeballs
Jump to navigation
Jump to search
m
→Parts of the eye: add a picture
m (→Back-of-the-envelope calculations: link to near point) |
m (→Parts of the eye: add a picture) |
||
| Line 1: | Line 1: | ||
== Parts of the eye == | == Parts of the eye == | ||
[[File:Schematic diagram of the human eye en.svg|Schematic diagram of the human eye en|right]] | |||
* '''Sclera''' - The white of the eye | * '''Sclera''' - The white of the eye | ||
* '''Cornea''' is the clear outer layer of the eye through which you can see the [[Iris]] and [[Pupil]]. It has an [[Index of Refraction]] of 1.376<ref name="Scale Model of Eye">{{Cite web |title=Scale Model of Eye |url=http://hyperphysics.phy-astr.gsu.edu/hbase/vision/eyescal.html |last=Nave |first=R |date=2020-05-25 |website=HyperPhysics}}</ref>, and a curved outer surface, contributing to the [[refractive state]] of the eye. The Cornea provides about 80% of the eye's total refracting power. If you have [[LASIK]] or [[PRK]] surgery it thins the cornea to change your refractive state. | * '''Cornea''' is the clear outer layer of the eye through which you can see the [[Iris]] and [[Pupil]]. It has an [[Index of Refraction]] of 1.376<ref name="Scale Model of Eye">{{Cite web |title=Scale Model of Eye |url=http://hyperphysics.phy-astr.gsu.edu/hbase/vision/eyescal.html |last=Nave |first=R |date=2020-05-25 |website=HyperPhysics}}</ref>, and a curved outer surface, contributing to the [[refractive state]] of the eye. The Cornea provides about 80% of the eye's total refracting power. If you have [[LASIK]] or [[PRK]] surgery it thins the cornea to change your refractive state. | ||
| Line 15: | Line 16: | ||
* '''Vitreous humor''' is the clear gel filling the majority of the eyeball. It is where true [[floaters]] live. This gel is important for helping the eye hold its shape and maintain the correct pressures inside the eye even when air pressure changes. In adults, the gel has a complex structure, with different thicknesses in different parts. | * '''Vitreous humor''' is the clear gel filling the majority of the eyeball. It is where true [[floaters]] live. This gel is important for helping the eye hold its shape and maintain the correct pressures inside the eye even when air pressure changes. In adults, the gel has a complex structure, with different thicknesses in different parts. | ||
* '''Vitreous detachment''' is attached to the outer wall of the eye in multiple locations, but can become separated. When separated from the retina it does not support the retina fully, and puts you at higher risk for [[retinal detachment]]. It can also leave behind a large [[floater]] that impairs vision. | * '''Vitreous detachment''' is attached to the outer wall of the eye in multiple locations, but can become separated. When separated from the retina it does not support the retina fully, and puts you at higher risk for [[retinal detachment]]. It can also leave behind a large [[floater]] that impairs vision. | ||
== Axial Length == | == Axial Length == | ||
The primary cause of differences in [[refractive state]] is the length of the eye, referred to as axial length, relative to the focusing power. Long eyeballs are associated with myopia, as the natural lens of the eye, even when fully relaxed, focuses light too far forward of the retina. | The primary cause of differences in [[refractive state]] is the length of the eye, referred to as axial length, relative to the focusing power. Long eyeballs are associated with myopia, as the natural lens of the eye, even when fully relaxed, focuses light too far forward of the retina. | ||