Eye Anatomy
Topography:
Anterior pole: It is the center of the corneal curvature.
Posterior pole: The center of the posterior curve of the globe.
Geometric (anatomical) axis: It is the line connecting the anterior and posterior poles.
Visual axis: It is the line drawn from the center of the fovea to the fixation point.
Optical axis: It is the line starting from the anterior pole and extending from the center of the lens to the retina.
The equator is the line that surrounds the eye at the midpoint between the two poles.
Meridian: A circular line perpendicular to the equator, passing through the anterior and posterior poles.
Front rear diameter: 22-26 mm
Perimeter 69-81 mm
Average weight: 7.5 gr, volume 6.5 ml.
Visual physiology
Binocular vision and sense of depth:
Stereoscopic vision: It is the perception of depth when we look with our two eyes.
Color Vision:
Daylight: Responsible for color vision, including black and white perception (cone cells).
Twilight: Achromatic vision (rod cells) is responsible.
Refractory Defects
The refraction of the cornea is 43 diopters (the most refractive medium of the eye is the cornea), the lens is 20 diopters. Humor aqueous and corpus vitreum have little effect on refraction.
Eyes without refractive errors are called emmetropic eyes.
The eye with refractive error is called ametropic eye.
Ametropia:
Myopia
hyperopia
astigmatism
