Biomedical Engineering Reference
In-Depth Information
1
l
′
L
=
′
(100)(1.00)
l
′
=
−
24.00 D
′
=
−
l
4.17 cm
This image is located 14.17 cm [i.e.,
−
4.17 cm
+
(
−
10.00 cm)
=
−
14.17 cm]
anterior to the cornea.
The eye's refractive error, as measured in the spectacle plane, is
−
5.00 D. The
far point vergence at the eye is calculated as follows:
(100)(1.00)
−
=
−
20.00 cm
5.00 D
=
−
(
−
20.00 cm)
+
(
−
1.3 cm)
21.3 cm
(100)(1.00)
−
=
−
4.69 D
21.3 cm
The required accommodation is:
+
F
A
F
FP
=
L
(100)(1.00)
⎥
⎦
+
−
4.69 D
=
F
A
⎣
−
14.17 cm
F
A
= +
2.37 D
The eye must accommodate 2.37 D.
7. (a)
First, we determine the location of the image produced by the spectacle lens
.
′
=
L
L
+
F
(100)(1.00)
−
⎡
⎥
⎤
⎥
′
=
L
+
(
−
6.00 D)
18.50 cm
′
=
−
L
11.41 D
1
l
′
L
=
′
(100)(1.00)
l
=
−
11.41 D
′
′
=
−
l
8.77 cm
The image is located 10.27 cm [(
−
8.77 cm)
+
(
−
1.5 cm)
=
−
10.27 cm] in
front of the eye.
Next, we determine the far point vergence at the eye
.
