Refractive error tips
Eye axis length: 24.387MM
Ocular refractive power (at rest): +58.64D
Optical constants of the refractive media of the eye
Refractive medium
Refractive index
Refractive power
Radius of curvature
Thickness
Cornea
1.376
43.05
Anterior 7.7 Posterior 6.8
0.5
Atrial fluid
1.336
3.0-3.1
crystalline lens
1.406
19.11
anterior 10 posterior -6
3.6
vitreous humor
1.336
Focal point: the point where the parallel light crosses the main axis after refraction through the lens
Focal length: the distance between the optical center of the lens and the focal point
Node: that is, the optical center of the thin lens, the incident light passing through this point is not refracted.
simplified eye: (the front of the sphere is assumed to be air and the refractive index is 1, then the refractive index of the simplified sphere is 1.366)
Axis of the eye.
Optic axis: AB: also the axis of the eye, i.e., perpendicular to the central corneal surface connected to the posterior pole, passing through the node N and the gyrus R.
Visual axis: ONF: the line between the point of extraocular gaze and the macula.
Fixed axis: the line between the point of extraocular gaze and the point of rotation R.
Gyration point: The eye has a center of rotation in the orbit, the gyration point, which is 13.5 mm from the posterior cornea.
Visual axis: between the light source and the central macular recess, connecting N and N~
Line of sight: the line of light connecting the central macular concavity, passing through the center of the pupil
Pupillary axis: the line perpendicular to the cornea and connecting the center of the pupil
ALPHA angle: the angle between the optic axis and the optical axis, 4 “A” 8
KAPPA angle: the angle between the pupil axis and the optic axis
LAMBDA angle: the angle between the pupil axis and the line of sight
The highest point of the cornea (corneal apex): the point with the steepest curvature
Corneal apex: (corneal vertex):The point where the pupil axis meets the anterior surface of the cornea, assuming that the pupil axis and the optical axis are a line.
Angle of vision: The angle formed by the ends of an external object at the node in the eye, proportional to the size of the object and inversely proportional to the distance.
Angle of view = size of object / distance from object to eye
Regardless of the actual size of the object, the angle of view is as large and the retinal image is as large.
Minimum angle of view: the minimum distance between two points that can be recognized by the human eye to the angle of tension of the node. The minimum angle of view is the critical angle of view, greater than the minimum angle of view can be distinguished, less than the minimum angle of view can not be distinguished.