Biomedical Engineering Reference
In-Depth Information
H
,
H
′
n
= 1.000
n
′
= 1.333
Optical axis
C
Fovea
F
N
F
′
+5.55 mm
−
16.67 mm
+22.22 mm
Figure 7-1.
The reduced eye consists of a single refracting surface (with a radius
of curvature of
+
5.55 mm) that separates air and aqueous. The principal planes are
coincident with the refracting surface, and the nodal point is located at its center of
curvature. The primary and secondary focal lengths are
−
16.67 and
+
22.22 mm,
respectively.
Now we'll calculate the location of the image when this eye views an infinitely
distant object. The vergence for such an object is zero. The image vergence can be
determined with the ever-so helpful vergence relationship.
L
′
=
L
+
F
L
′
= 0.00
D
+
60.00 D
L
′
= +
60.00 D
0.00 D
+60.00 D
n
= 1.000
n
′
= 1.333
+60.00 D
+22.22 mm
Figure 7-2.
An infinitely distant object is imaged on the retina of the reduced eye. The
eye has a refractive power of
+
60.00 D and an axial length of
+
22.22 mm.
