z EBOD Flashcards
The refractive index of the lens is
14,2
The refractive index of the cornea is
1.377
The refractive index of the aqueous humour is
1.3374
The two surfaces of the cornea have radii of curvature of
+7.8 mm and +6.5 mm
myopic eye - more or less refractive power
more
myopic - The near point is further or closer
closer
myopic - amplitude of accommodation is more or less
less
Myopia is corrected with
diverging, concave or negative lenses
Myopia - prevalence
10-15%
Different types of hyperopia
axial, index, and curvature or refractive
how many newborns are hyperopic
75-80%
with the rule
most common, vertical steepest near 90 st, children
In with-the-rule astigmatism - where is too much + cylinder
the eye has too much “plus” cylinder in the horizontal axis relative to the vertical axis
with the rule - beams of light focus in front
Vertical beams of light focus in front (anterior) to horizontal beams of light
with the rule - how to correct
using spectacles which have a “minus” cylinder placed on this horizontal axis
against-the-rule astigmatism - how to correct
“plus” cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis).
Oblique astigmatism
the steepest curve lies in between 120 and 150 degrees and 30 and 60 degrees
Irregular astigmatism
principal meridians are not perpendicular
Prisms - lower or higher refractive index than the air
higher
If a light ray travels into a medium with a higher refractive index, the angle of refraction will be larger or smaller
smaller than the angle of incidence
Myopia is corrected with
convex lens (plus jak X)
