Courtesy Pat Caroline
Vinita Allee Henry, OD, FAAO
UMSL College of Optometry
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Cross on the front of the eye
Football
Have the patient take their spectacles off, so
that they can rotate the specs in front of their
eye
Spectacle correction versus CL (Stable versus
rotation)
Spherical CL versus Toric CL (Fees, rotation,
expense due to manufacturing & fit time)
How much astigmatism?
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Spherical GP’s for?
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<2D corneal
astigmatism
Toric GP’s for?
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<1D of astigmatism
Aspheric Soft for?
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>2D corneal
astigmatism
Front toric for
lenticular
astigmatism
Spherical Soft for ?
0.50-0.75D
astigmatism
Toric Soft for?
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>0.75D astigmatism
> 0.25D = 76.5%
> 0.50D = 61.5%
> 0.75D = 45.5%
> 1.00D = 34.8%
> 1.25D = 24.8%
> 1.50D = 19.2%
> 1.75D = 15.8%
> 2.25D = 10.0%
> 2.50D = 6.0%
> 3.00D = 3.4%
Courtesy of D. Becherer
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Demonstrate with phoropter-may give an idea
if toric lens will help
As cylinder goes up, rotational stability is more
critical
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Low amounts of astigmatism
More astigmatism error than spherical error
More spherical error than astigmatism error
Presbyopes
Need to be good soft lens candidate
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Subjective refraction in phoropter
Twist cylinder knob until patient notices blur
20 degrees or > = 90% success first lens
10 degrees = 70% success with 3 lenses
5 degrees = <5% chance of success
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Sphere > 2(minus cylinder)
Becherer Rule of Thumb
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Sphere > 3(minus cylinder if oblique)
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Do not optically correct astigmatism
May improve spherical aberration of CL & eye
Enhance focus by minimizing aberration,
improve contrast sensitivity, enhance optics
May report better vision even if not
measurably so
Spherical Aberration
Becherer and CLS Snyder
Spherical Aberration
Becherer & CLS Snyder
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Frequency Aspherics, Biomedics XC,
Biomedics 55 Premier
PureVision
Focus N&D, O2 Optix, Air Optix
Biofinity, Avaira
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Prism Ballast
Double Slab Off/Thin Zones
Eccentric Lenticulation
Accelerated Stabilization Design
Back Surface Toric
Front Surface Toric
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Upper lid tends to push away the thickest
portion, like squeezing a watermelon seed
between your fingers, the thickest portion will
be forced out.
Works with prism ballast and double thin
zones-more so double thin zones
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Vertex Toric, Proclear Toric & Frequency Toric
– Back surface
Focus Toric – Back surface
Extreme H2O Toric – Back surface
Optima Toric – Front surface
SF 66 & PureVision Toric – Back surface
Air Optix for Astig. – Thin at 6, thick at 4&8
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Hydrasoft Toric –Back surface
Use non-prism lens
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Freshlook Toric – Back surface
AV Toric – Back surface
Torisoft – Front surface
Focus Dailies Toric – Back Surface
Accelerated Stabilization Design
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AV Advance for Astigmatism (4 active zones, midperiphery)
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Realistic expectations
Use up-to-date Refraction, not previous Toric
CL Rx
Cyl and axis match Rx (Less is better)
Figure nasal rotation?
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Vertex both meridians > + 4D
Check Parameter Availability
Can insert with laser markings in correct
location
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If the Rx you need is not available, then order
correct lens
Go lower than expected cyl, works well (e.g.
Focus Dailies Toric)
Rx -4.00-1.75 X 180
Converts to -4.00 @ 180 to -3.75
-5.75 @090 to -5.25
-3.75 -1.50 X180, try on -3.75-1.25 X 180
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Allow 15-20 minutes
to settle
Lag up & down,
rotate little
Large & Steep to
stabilize
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Be familiar with
markings and
separation
Poor fit, ditch the lens
prior to VA and OR
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Oblique and ATR astigmatism harder to fit
than WTR- more effects from blink
OR sphere first, then sphere/cyl
Try to OR on axis
Use cross cyl calculator
1.4-1.6 lenses /eye for successful result
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Quick rotational
return
Try forced lid closure
and see how lens
rotates
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>30degree rotationget new lens
Inconsistent rotationget new lens
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Tends toward nasal due to temporal-nasal
motion of upper lid
Higher outer canthus tends toward temporal
rotation
Higher nasal canthus tends toward nasal
rotation
Dial axis to proper location and see if VA
improves
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Large axis shifts cause minimal change, then
insufficient cyl correction
Steep fit-Locks in at incorrect location, slow
return when dialed off
Flat fit- Variable vision due to blink, unstable
rotation
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Check Tyler’s Quarterly for cyl power & axis
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(-1.75 and off 180 & 90 more than 20 degrees)
Consult with company
Available lenses:
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CooperVision (Vertex XR, Proclear XR, Frequency
XR, Preference XR, Hydrasoft Torics)
Bausch & Lomb (Optima Toric)
Ciba (Durasoft Optifit Toric)
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Left
Add
Right
Subtract
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Add to Spectacle Rx, Dr’s perspective
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Trial frame and low power cyl lens
Narrow slit and SL protractor scale
Measuring reticule in ocular
Clock dial-guesstimate
Final Rx?
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AOA CLS EZ fitter-Dr. Paul Whitten
www.eyedock.com
Check company websites for calculators
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(Vistakon, CooperVision & Ciba)
Cylinder 90 degrees away means too much cyl,
cyl at same axis add, cyl at oblique axis means
change axis
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Based on practitioner viewpoint
Based on base of lens
Scribe mark indicates base not axis
Make change from spectacle axis
After compensation, want new lens to rotate
the same way
Vertex back both meridians
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Blurry vision
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Fluctuating vision
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Incorrect Rx, rotation, poor fit
Poor stabilization, poor fit, rotation
Variable vision
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Check fit, change design
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Consistent blur – adjust power/axis
Intermittent blur – adjust fitting
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Use rewetting drop before lens removal
Twist lens one way to remove and the other the
following night – alternating the spot that is
pinched off
AV Advance for
Astigmatism
AV Oasys for
Astigmatism
PureVision
Toric
Air Optix for
Astigmatism
Material
Galyfilcon A
Senofilcon A
Balafilcon A
Lotrafilcon B
Dk
60
103
91
103
Water
content
47%
38%
36%
33%
Powers
+6 to -9
+6 to -9
+6 to -9
+6 to -9
Cylinder
-0.75 to -2.25
-0.75 to -2.25
-0.75 to 2.25
-0.75 to 2.25
BCR
8.6
8.6
8.7
8.7
Avail
axis
steps
Restrictions in
steps
Restrictions in
steps
0-180 in 10° Restrictions
in steps
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2 week replacement
Laser markings at 6 & 12
Accelerated Stabilization Design
UV inhibitor
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Anterior Aspheric Optics to reduce spherical
aberration
Prism ballast with 360° comfort chamfer for
enhanced rotational stability
Laser markings at 5,6,7
Monthly replacement
DW or 30 day CW
Bausch & Lomb
Ciba Vision
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Monthly replacement
Laser marks 3,6,9
DW or 6 nights EW
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Lenses may rotate when the eyes converge for
near tasks
No backup lens if one lens rotates off-axis
Consistent rotation important
Patient has the following Spec Rx:
OD – 5.00-2.50 X170
OS -5.00-2.00 X 5
Trial lenses selected:
Patient has the following correction:
Spec Rx OD -3.00
OS -2.00-1.25 X180
Trial lens design?
Patient has the following Spec Rx:
OD -5.00-0.75 X180
OS -5.50-0.75 X180
Trials lenses?
Patient has the following Spec Rx:
OD -2.50-0.75 X90
OS -2.75-0.75 X90
Trial lenses match Rx. OD rotates 10 degrees
nasal & OS rotates 5 degrees nasal.
If you correct for rotation, the final lenses would
be?
Which of the following patients makes the best
candidate for toric lenses?
a.
-0.75-3.00 X 180
b.
-2.00-1.25 X 45
c.
-4.00-1.00 X 180
d.
-3.00-0.75 X 90
Patient is fit with the following lenses:
Frequency 55 Toric, 8.7 BCR
OD -3.00-1.75 X10
OS -2.75-1.25 X 170
The lenses center and cover well, but the laser
mark rotates from 10 degrees nasal to right on
and sometimes 10 degrees temporal.
Suggestion?
College student wears Biomedic Torics. He
sometimes studies late and works some
evenings until 2 am. His eyes are mildly
injected and have some neovascularization.
Suggestions?
Patient is long-time wearer of spherical soft
lenses. Her Spec Rx is OD -2.00-1.00 X 20, OS 2.50 -0.75 X 180. Her CL Rx is OD -2.50 and OS
-2.75. She has started a job that requires a lot of
reading. She feels her vision is a little blurry.
Solution:
Patient is a new patient to you. He comes in
wearing soft torics. He brings the box and
shows you that they are PureVision Torics, 8.6
OD -3.00 -1.25 X10 and OS -3.75 -1.75 X 170.
The lenses fit well and the vision is 20/20 OD
& OS. The OD lens is rotated 10° temporal and
the OS is 10° temporal. Anything you want to
know? What lenses will you order?