Zeiss Humphrey II-i series - Spherical Trial Lens Correction for Central Visual Field Testing of Myopic Patients; Examples of Trial Lens Correction

Table 3.6 Spherical Trial Lens Correction for Central Visual Field Testing of Myopic Patients
Distance R
x
is
-0.50
Distance R
x
is
-1.00
Distance R
x
is
-1.50
Distance R
x
is
-2.00
Distance R
x
is
-2.50
Distance R
x
is
-3.00
Distance R
x
is
over -3.00
Age
Under 30
No trial lens needed No trial lens needed No trial lens needed No trial lens needed No trial lens needed No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
30 - 39
+0.50 D No trial lens needed No trial lens needed No trial lens needed No trial lens needed No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
40 - 44
+1.00 D +0.50 D No trial lens needed No trial lens needed No trial lens needed No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
45 - 49
+1.50 D +1.00 D +0.50 D No trial lens needed No trial lens needed No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
50 - 54
+2.00 D +1.50 D +1.00 D +0.50 D No trial lens needed No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
55 - 59
+2.50 D +2.00 D +1.50 D +1.00 D +0.50 D No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
60 & Over
+2.75 D +2.25 D +1.75 D +1.25 D +0.75 D No trial lens needed (Dist. R
x
) + (+3.25 D)
for trial lens
Humphrey Field Analyzer II- i series User Manual 2660021145640 A
Setting-Up Tests
3-21
Examples of Trial Lens Correction
The following are examples of trial lens corrections using Table 3.5 for hyperopic or emmetropic
patients, or Table 3.6 for myopic patients:
Example A (Emmetropic)
For an emmetropic (plano) 70 year-old patient, use Table 3.5. Follow the Distance R
x
is Zero (Plano)
column to the 60 & Over row. The trial lens correction for this patient is +3.25 D.
Example B (Hyperopic)
For a 61 year-old hyperopic patient with a distance re
fraction of +1.50 +0.50 X 60, use Table 3.5.
First calculate the spherical equivalent (+1.75
). Then follow the Hyperopic Distance R
x
is Greater
than Zero column to the 60 & Over row where you are instructed to add +3.25 to the distance R
x
of
+1.75. The trial lens correction for this patient is +5.00 D.
Example C (Hyperopic)
For the 35 year-old hyperopic patient with a distance refraction of +2.00 +1.50 X 90, refer to
Table 3.5. Use a +1.50 D cylinder lens and rotate the axis to
90 in the trial lens holder. Follow the
Hyperopic Distance R
x
is Greater than Zero column to the 30-39 row where you are instructed to add
+1.00 to the distance R
x
of +2.00. The trial lens correction for this patient is +3.00 +1.50 X 90.
Example D (Myopic)
For a 30 year-old myopic patient with a distance r
efraction of -3.00 +0.25 X 90, use Table 3.6. The
0.25 cylinder is ignored. Follow the -3.00 column to t
he Age 30-39 row. The column entry signifies
that this patient does not need a trial lens correction, as the bowl will be in focus with no correction.