Transcript Does size-threshold text legibility relate to performance

Occupational
Progressive Lenses
Jim Sheedy
•Butzon SP, Sheedy JE, Nilsen E. The efficacy of computer
glasses at reducing worker symptoms. Journal of the
American Optometric Association 2002;73(4):221-30.
•Sheedy JE, Hardy RF. The Optics of Occupational
Progressive Lenses. Optometry 2005;76:432-441.
Common optical
corrections for
presbyopia – how do
they work at the
computer?
Bifocals
 Progressive Addition Lenses

Visual Symptoms
Eye strain or ache
 Dry, irritated eyes
 Tired eyes
 Headaches
 Blurred vision
 Neck and back
aches

PAL vs. OPL
Far I
D
I
I
A
N
N
B
OPL Features


Lower amount of distortion –
hence easy adaptation
Can wear when walking around
the office
– Don’t need to take on and off all the
time


Full near power in bottom of lens
Unwanted distortions are higher
in the lens – because indoor work
is performed with downward
gaze.
Occupational
Progressive Lenses
All designs are based upon
your usual distance/near
prescription
 Lens powers are based upon
the near power


“Degression” is power
difference between top and
bottom of lens
Prescribing OPLs
Prescribe the usual Distance
Rx with normal 40 cm add
 Specify the OPL of choice
 Customize if needed

Rotlex
instrument
Measurement methods

Lenses
– Ordered for plano distance, +2.50 add
– Emmetropic patient without accommodation
• Therefore viewing distance is a direct
function of add power

Rotlex measurements were parsed
– Center of coordinate system is pupil as
specified by manufacturer
– Areas limited by 15 mm above and 25 mm
below pupil
• Based upon generous estimate of foveal
usage area.
– Areas constrained by 0.50 D astigmatism
Cosmolit Office
AO Technica
Hoya Tact
Essilor Interview
Sola Access
Shamir Office
Zeiss Gradal RD
Area of viewing zones
(mm2)
Add
Power
AO
Technica
Cosmolit
Office
Essilor
Interview
Hoya
Tact
Shamir
Office
Sola
Access
Zeiss
Gradal
RD
0
0.25
0.0
43.0
0.0
0.0
0.0
0.0
48.0
21.8
0.0
0.0
0.0
0.0
0.0
0.0
Far
43.0
0.0
0.0
69.7
0.0
0.0
0.0
0.5
0.75
1
30.5
17.7
16.0
0.0
272.5
102.3
0.0
0.0
0.0
14.8
16.8
10.6
54.4
13.0
7.7
0.0
0.0
0.0
0.0
419.5
236.2
FarInter
64.2
374.8
0.0
42.3
75.1
0.0
655.6
1.25
1.5
1.75
12.7
7.7
10.1
57.1
30.4
19.3
0.0
0.0
465.3
10.4
13.7
15.1
7.6
10.0
8.8
234.6
35.7
24.8
23.2
18.6
14.2
NearInter
30.5
106.8
465.3
39.1
26.4
295.1
55.9
2
2.25
2.5
10.3
23.9
322.6
14.5
18.3
90.4
324.3
215.2
832.3
20.7
27.1
126.4
15.5
40.9
242.7
9.0
22.9
581.9
15.4
28.1
146.4
Near
356.9
123.2
1371.7
174.1
299.1
613.9
189.9
PALs – Intermediate range is 15-25 mm2, near range is 40-80 mm2
Display Height

The screen center should be
4-9 inches lower than your
eyes
– 10-20 degrees of ocular
depression
Visual comfort
contours
Downward viewing is
preferred (Menozzi et al, 1994)
Add
Power
Cosmolit
Office
Shamir
Office
Sola
Access
Far
FarInter
NearInter
Near
0.0
0.0
0.0
374.8
75.1
0.0
106.8
123.2
26.4
299.1
295.1
613.9
Cosmolit Office
Shamir Office
OPLs with
degressio
n series
Sola Access
Other approaches

Zeiss Gradal
– A degression for each add power
– Always designed to have +0.50D in
top of lens

Essilor Interview
– Only 1 degression – 0.86D
– Works best for person who spends
continuous time at computer
– Probably need to remove or change
glasses to walk around office
Add
Power
Essilor
Interview
Zeiss
Gradal
RD
Far
FarInter
NearInter
Near
0.0
0.0
0.0
655.6
465.3
1371.7
55.9
189.9
Essilor Interview
Other
approaches
Zeiss Gradal RD
Essilor Interview



Prescribe like a reading lens
2 degressions: 0.80 D and 1.30 D
Designed for steady computer
work
Zeiss Gradal RD

Many degressions
– Selected to provide +0.50 in top
Other approaches

Small area of distance power
in top of lens
– Hoya Tact
– AO Technica

For uses where a small area
of distance clarity is required
Area (mm2)
Add
Power
AO
Technica
Hoya
Tact
Far
FarInter
NearInter
Near
43.0
69.7
64.2
42.3
30.5
356.9
39.1
174.1
AO Technica
OPLs with
distance
power
Hoya Tact
AO Technica



Has full distance power
Steady power change
Lateral aberrations
Hoya Tact



Full distance power
Steady power change
Lateral aberrations
Area of viewing zones
(mm2)
Add
Power
AO
Technica
Cosmolit
Office
Essilor
Interview
Hoya
Tact
Shamir
Office
Sola
Access
Zeiss
Gradal
RD
0
0.25
0.0
43.0
0.0
0.0
0.0
0.0
48.0
21.8
0.0
0.0
0.0
0.0
0.0
0.0
Far
43.0
0.0
0.0
69.7
0.0
0.0
0.0
0.5
0.75
1
30.5
17.7
16.0
0.0
272.5
102.3
0.0
0.0
0.0
14.8
16.8
10.6
54.4
13.0
7.7
0.0
0.0
0.0
0.0
419.5
236.2
FarInter
64.2
374.8
0.0
42.3
75.1
0.0
655.6
1.25
1.5
1.75
12.7
7.7
10.1
57.1
30.4
19.3
0.0
0.0
465.3
10.4
13.7
15.1
7.6
10.0
8.8
234.6
35.7
24.8
23.2
18.6
14.2
NearInter
30.5
106.8
465.3
39.1
26.4
295.1
55.9
2
2.25
2.5
10.3
23.9
322.6
14.5
18.3
90.4
324.3
215.2
832.3
20.7
27.1
126.4
15.5
40.9
242.7
9.0
22.9
581.9
15.4
28.1
146.4
Near
356.9
123.2
1371.7
174.1
299.1
613.9
189.9
PALs – Intermediate range is 15-25 mm2, near range is 40-80 mm2
Locations of viewing
zones
40
15
Y location (mm)
35
10
30
5
Far
25
0
20
-5
Far-Int
15
-10
Near-Int
-15
10
Near
5
-20
0
-25
AO
Technica
Cosmolit
Office
Essilor Hoya Tact
Interview
Shamir
Office
Sola
Access
Zeiss
Gradal RD
Summary
Viewi
ng
Zone
AO
Technica
Cosmolit
Office
Far
Yes
No
FarInter
OK
Very
large
NearInter
Small
Large
Near
Large
Small
Essilor
Interview
Hoya
Tact
No
Yes
Only for
low
adds
Small
Very
large
but high Small
Very
large
OK
Shamir
Office
Sola
Access
Zeiss
Gradal
RD
No
No
Not for
high
adds
Very
large
but high
Very
large
No
OK
Small
and
high
Large
Very
large
OK
OK

Member
– Vision Ease

Affiliate Members
– Lens Crafters
– Shamir Insight
– Carl Zeiss Vision
– J&J Spectacle Lens Group

Supporting groups
– Optical Laboratories Association
– COLTS laboratories
Collaborators










Charles Campbell
Ray Hardy
John R. Hayes
Chunning Huang
Matt Helfrich
Ewen King-Smith
Priya Ramamoorthy
Allan Yi
Karl Citek
Bret Andre