Biomedical Engineering Reference
In-Depth Information
(b)
(100)(1.00)
+
=
+
14.29 cm
7.00 D
=
+
14.29 cm
+
1.20 cm
15.49 cm
(100)(1.00)
+
=
+
6.46 D
15.49 cm
To correct this hyperopic refractive error, the spectacle lens should have a
power of
+
6.50 D.
3. (a)
L
′
=
F
(1000)(1.333)
l
L
+
⎡
⎥
⎤
⎥
= −
10.00 D
+
60.00 D
′
′
=
l
26.67 mm
′
=
(b)
L
F
(1000)(1.333)
+
L
+
⎡
⎥
⎤
⎥
= −
10.00 D
+
F
22.22 mm
=
+
F
70.00 D
4. The eye is corrected with a
+
5.00 D spectacle lens. What is the vergence this
lens produces at the cornea?
(100)(1.00)
+
=
+
20.00 cm
5.00 D
=
+
20.00 cm
−
1.50 cm
18.50 cm
(100)(1.00)
+
=
+
5.41 D
18.50 cm
′
=
L
F
(1000)(1.333)
l
L
+
⎡
⎥
⎤
⎥
= +
5.41 D
+
60.00 D
′
′
=
l
20.38 mm
5. The patient's far point is 25.00 cm anterior to the eye, making her 4.00 D
myopic as measured at the cornea. The appropriate spectacle correction is
determined as follows:
=
−
−
25.00 cm
−
(
−
1.50 cm)
23.50 cm
(100)(1.00)
−
23.50 cm
=
−
4.26 D
To correct this myopic refractive error, the spectacle lens should have a power
of
−
4.25 D.
