Simplifying Soft Torics - SECO2011.com
Simplifying Soft Torics - SECO2011.com
Simplifying Soft Torics - SECO2011.com
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
DISCLOSURE STATEMENT<br />
CEO Visioncare Research Ltd<br />
Consultant for: Johnson & Johnson, Alcon,<br />
CooperVision, Ocutec, Bausch & Lomb<br />
Welcome to SECO 2009<br />
SECO 2011<br />
March 2-6, 2011<br />
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
Graeme Young MPhil, PhD, FCOptom, DCLP, FAAO<br />
Please silence all mobile devices<br />
At the conclusion of this course, please properly<br />
dispose of your trash as you leave this room
<strong>Soft</strong> Toric Lens Fitting – The<br />
Simpler Way<br />
Graeme Young MPhil PhD FCOptom DCLP FAAO
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
Astigmatism & its Prevalence
Astigmatism & its Prevalence<br />
sphere / cylinder x axis<br />
-3.00 / -1.50 x 180<br />
In plus cylinder form:<br />
-4.50 / +1.50 x 90<br />
-4.50D<br />
-3.00D
Prevalence<br />
80%<br />
70%<br />
60%<br />
50%<br />
40%<br />
30%<br />
20%<br />
10%<br />
0%<br />
Astigmatism & its Prevalence<br />
How many patients need TSLs?<br />
Prevalence of threshold astigmatism by patient (Px) and eye.<br />
N=11,624<br />
0.75D M<br />
47%<br />
0.75 B<br />
24%<br />
1D M<br />
32%<br />
≥0.50DC ≥0.75DC ≥1.00DC ≥1.25DC ≥1.50DC ≥1.75DC ≥2.00DC<br />
Cylinder (D)<br />
Eyes<br />
Px BE<br />
Px One Eye
Astigmatism & its Prevalence<br />
How many patients need TSLs?<br />
cylinder<br />
axis
Astigmatism & its Prevalence<br />
How many patients need TSLs?<br />
• Approx 50% of pxs have significant astigmatism<br />
• Approx one-third of CL pxs need astigmatic correction<br />
• Only ~21% of soft lenses fitted are torics in US (Morgan 2011)<br />
• Disproportionately high % of CL drop-outs are astigmats<br />
51%: �0.75DC both eyes or �1.50DC one eye<br />
(Young, Veys, Pritchard, Coleman 2002)
Short History of Toric <strong>Soft</strong> Lenses?
Who to fit with TSLs<br />
Rules of thumb<br />
• 1.00D or more of astigmatism
Who to fit with TSLs<br />
Rules of thumb<br />
• 1.00D 0.75D or more of astigmatism<br />
• Sphere power -<br />
1/4 of sphere power usually acceptable<br />
e.g. -5.00/-1.25 x 5 �<br />
-2.00/-1.25 x 5 �<br />
• WTR vs. ATR vs. Oblique astigmatism
Vertical world
With vs. against the rule<br />
Against ↕<br />
With ↔
Who to fit with TSLs<br />
Indications for toric soft lenses<br />
(vs. rigid lenses)<br />
• Rigid lens intolerance<br />
• ATR astigmatism<br />
• Difference in corneal & refractive astigmatism<br />
• Existing spherical soft lens wearers<br />
• Sports or part-time use
Who to fit with TSLs<br />
Contra-indications for TSLs<br />
• Successful rigid lens wearer<br />
- px’s assessment<br />
• Cylinder > sphere power<br />
e.g. -0.50 / -1.75 x 180<br />
• Monocular pxs.<br />
• Small palpebral aperture<br />
• Tight lids<br />
Possibly
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
Toric <strong>Soft</strong> Lens Designs<br />
Methods of Stabilisation
Toric <strong>Soft</strong> Lens Designs<br />
Factors Affecting Stabilisation<br />
‘Watermelon seed principle’<br />
Hanks AJ. Contact Lens Forum<br />
1983; 8(9)31-35
Static<br />
lid force<br />
Dynamic<br />
lid force<br />
Toric <strong>Soft</strong> Lens Designs<br />
Forces acting on a TSL<br />
Gravity<br />
Static<br />
lid force<br />
Dynamic<br />
lid force
Factors Influencing Toric <strong>Soft</strong> Lens Fit
Factors Influencing Toric <strong>Soft</strong> Lens Fit<br />
Patient factors vs. orientation<br />
PATIENT<br />
FACTORS<br />
Palpebral<br />
aperture<br />
Myopia<br />
Lower central<br />
lid angle<br />
Inter-canthal<br />
angle<br />
Upper central lid<br />
angle<br />
ORIENTATION<br />
Orientation<br />
stability<br />
Re-orientation<br />
speed<br />
Orientation<br />
Inf.-temporal<br />
Solid line: P
Factors Influencing Toric <strong>Soft</strong> Lens Fit<br />
Inter-canthal angle vs. orientation<br />
Orientation (º)<br />
40<br />
30<br />
20<br />
10<br />
0<br />
-10<br />
-20<br />
-30<br />
-40<br />
Inferior<br />
Nasal<br />
Inferior<br />
Temporal<br />
y = -1.3293x + 3.3593<br />
R 2 = 0.172<br />
-15 -10 -5 0 5 10 15<br />
Inter-canthal Angle (º)
Factors Influencing Toric <strong>Soft</strong> Lens Fit<br />
Patient factors vs. orientation<br />
PATIENT<br />
FACTORS<br />
Palpebral<br />
aperture<br />
Myopia<br />
Lower central<br />
lid angle<br />
Inter-canthal<br />
angle<br />
Upper central lid<br />
angle<br />
ORIENTATION<br />
Orientation<br />
stability<br />
Re-orientation<br />
speed<br />
Orientation<br />
Inf.-temporal<br />
Solid line: P
Stabilisation<br />
Effect of gravity
Orientation (º)<br />
50<br />
40<br />
30<br />
20<br />
10<br />
Stabilisation<br />
Effect of gravity & dynamic upper lid force<br />
0<br />
0 10 20 30 40<br />
40<br />
35<br />
30<br />
25<br />
20<br />
n=10 15<br />
Time (no. of blinks)<br />
Orientation (º)<br />
0<br />
Green lines indicate blink<br />
Time (4 blinks)
Blink-induced Rotation
Prism Ballasted <strong>Soft</strong> Toric<br />
Thickness Profile<br />
Horizontal iso-thickness
Prism Ballasted Toric Thickness Profile
Dynamic stabilization<br />
Lo-torque<br />
Toric <strong>Soft</strong> Lens Designs<br />
Branded TSL Designs<br />
Horizontal iso-thickness<br />
Accelerated stabilization<br />
Precision balance 8-4<br />
B<br />
A<br />
C<br />
A<br />
C<br />
B
A A<br />
B B<br />
C<br />
C<br />
Toric <strong>Soft</strong> Lens Designs<br />
Lo-torque<br />
1. 360 degree comfort chamfer<br />
2. Prism Ballasting stabilising geometry<br />
3. Refined optic zone<br />
4. Balanced vertical thickness profile
Toric <strong>Soft</strong> Lens Designs<br />
Precision balance 8-4
Toric <strong>Soft</strong> Lens Designs<br />
Horizontal iso-thickness
Toric <strong>Soft</strong> Lens Designs<br />
Accelerated stabilization
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
How to fit toric soft lenses<br />
Traditional method<br />
1. Insert trial lens approx. 1.0mm flatter than<br />
mean-K, closest to Rx<br />
2. Allow to settle for 20-30 minutes<br />
3. Assess rotation from vertical (usually inf-nasal)<br />
4. Do sphero-cylindrical over-refraction<br />
5. Order lens based on:<br />
lens power + orientation + over-refraction<br />
6. Repeat steps 1-5 until suicidal
How to fit toric soft lenses<br />
Simple method<br />
1. Do accurate refraction �<br />
2. Insert lens nearest to refraction (vertex-<br />
corrected) - with goal of dispensing �<br />
3. Allow 5-10 minutes settling �<br />
4. Assess for fit and orientation �<br />
5. If necessary change lens to allow for rotation<br />
6. Repeat steps 2-5
FITTING TSLs - PREPARATION<br />
Replacement period<br />
Daily: Part-time<br />
Previous history<br />
2-, 4-weekly: Default<br />
>Monthly: Hard-to-fit<br />
High Rxs
FITTING TSLs - PREPARATION<br />
Design / brand<br />
• Silicone hydrogel vs. conventional<br />
hydrogel<br />
• Rx availability<br />
• Lid shape<br />
• Inventory
Disposable TSLs
Disposable <strong>Soft</strong> Toric Lenses<br />
Acuvue Toric +6 to -9<br />
Biomedics Toric +4 to -6<br />
Spheres (D) Cyls (-ve) Other<br />
0.75 - 1.75<br />
in 0.50 steps<br />
0.75, 1.25, 1.75,<br />
2.25<br />
Dble slab-off<br />
Predictable<br />
orientation<br />
Focus Toric +4 to -6 1.00, 1.75, 2.50* 2 BCs<br />
Proclear Toric +4 to -6<br />
Soflens 66 Toric +6 to -9<br />
Frequency Excel<br />
(Vertex) Toric<br />
+6 to -8<br />
0.75, 1.25, 1.75,<br />
2.25<br />
0.75*, 1.25, 1.75,<br />
2.25, 2.75*<br />
0.75 – 2.25<br />
in 0.50 steps<br />
2 BCs: 8.4, 8.8<br />
Wider range in XR<br />
version<br />
Rel. large & loose<br />
Also XR:<br />
3.75 cyl in 5° axes
SiH <strong>Soft</strong> Toric Lenses<br />
Acuvue Advance for Astigmatism 47 +6 to -9<br />
Acuvue Oasys for Astigmatism 38 +6 to -9<br />
WC (%) Spheres (D) Cyls (-ve) Other<br />
0.75, 1.25, 1.75,<br />
2.25*<br />
0.75, 1.25, 1.75,<br />
2.25*<br />
Avaira Toric 48 0 to -6 0.75, 1.25, 1.75<br />
Air Optix for Astigmatism 33 +6 to -10<br />
Biofinity Toric 48 +8 to -10<br />
Purevision Toric 36 +6 to -9<br />
0.75, 1.25, 1.75,<br />
2.25*<br />
0.75, 1.25, 1.75,<br />
2.25<br />
0.75, 1.25, 1.75,<br />
2.25<br />
Predictable<br />
Limited axes<br />
outside 0 to -6:<br />
H&V +/-10<br />
All axes<br />
14.0mm
Daily Disposable Toric Lenses<br />
Spheres (D) Cyls (-ve) Other<br />
Focus Dailies Toric +4 to -8 0.75, 1.50<br />
1-Day Acuvue for<br />
Astigmatism<br />
Plano -9.00<br />
0.75 – 1.75<br />
in 0.50 steps<br />
Limited axes -<br />
70,90,110,160,180,20<br />
14.2mm<br />
Limited axes<br />
90,180,20,160
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic vs inventory fitting<br />
• Empirical<br />
• Diagnostic<br />
– basic fit<br />
– orientation<br />
• Inventory (fitting bank)<br />
414 lenses - 85% astig. myopes
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
Top<br />
Tip<br />
FITTING TSLs – POWER DETERMINATION<br />
Power<br />
Accurate refraction �<br />
• Don’t rely on someone else’s<br />
refraction<br />
• Determine full cylinder<br />
• Refract cyl. to nearest 2.5 deg<br />
• Note accurate VA
FITTING TSLs – POWER DETERMINATION<br />
Vertex correction<br />
-4.50/-1.50 x 2
FITTING TSLs – POWER DETERMINATION<br />
Vertex correction<br />
-4.50/-1.50 x 2 � -4.25/-1.25 x 180<br />
• � -4.00D subtract 0.25D<br />
� -6.00D subtract 0.50D<br />
Top<br />
Tip<br />
• Err towards lower cyl. power where<br />
necessary
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
FITTING TSLs –AXIS DETERMINATION<br />
TSL vs Spectacle Rx axis
Fitting <strong>Soft</strong> <strong>Torics</strong><br />
3. Allow 5-10 minutes settling �<br />
• Insert close to base down position<br />
• Do quick check on insertion
FITTING TSLs – Axis Determination<br />
Assessing orientation position<br />
Graticule
FITTING TSLs – Axis Determination<br />
Assessing orientation position<br />
S66T<br />
30deg<br />
AT<br />
10deg
FITTING TSLs – Axis Determination<br />
Decentration may affect apparent orientation
FITTING TSLs – Axis Determination
FITTING TSLs – Axis Determination
FITTING TSLs – Axis Determination<br />
Assessing fit and orientation �<br />
• Assessing orientation over a short period of time<br />
and note the range<br />
e.g. 0-7 deg. Nasal<br />
• Helps when limited by cyl. axis availability<br />
e.g. RE: -3.00/-1.50 x 5 order -3.00/-1.25 x 180<br />
• Note also whether unstable<br />
i.e. > 15 deg. variation
Fitting <strong>Soft</strong> <strong>Torics</strong><br />
4. Assess for fit and orientation �<br />
• Assessing orientation over a short period of time<br />
and note the range<br />
e.g. 0-7 deg. Nasal<br />
• Helps when limited by cyl. axis availability<br />
e.g. RE: -3.00/-1.50 x 5 order -3.00/-1.25 x 180<br />
• Note also whether unstable<br />
i.e. � 15 deg. variation
Orientation stability
Fitting <strong>Soft</strong> <strong>Torics</strong><br />
Adjustment for rotation<br />
Clockwise rotation - add to cylinder axis<br />
Add<br />
�<br />
Subtract<br />
�<br />
LARS - L add, R subtract
Fitting TSLs - Adjustment for rotation<br />
Examples<br />
Example 1:<br />
-2.00 / -1.25 x 10 rotates 10° CW (LA)<br />
-2.00 / -1.25 x 20 needed
Fitting TSLs - Adjustment for rotation<br />
Examples<br />
Example 2:<br />
Spec Rx: -2.00 / -1.50 x 180<br />
orientates 5-10° Anti-CW (LARS)<br />
cyls. available = 1.25, 1.75D<br />
-2.00 / -1.25 x 170 needed
Fitting TSLs - Adjustment for rotation<br />
Examples<br />
Example 3:<br />
Spec. Rx: -4.25 / -2.25 x 22.5 @12mm<br />
vertex corrected: -4.00 / -2.00 x 22.5<br />
cyls. available = 1.25, 1.75, 2.25D<br />
orientates 0-5° Anti-CW (LARS)<br />
-4.00 / -1.75 x 20 needed
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
Custom soft torics<br />
• Expensive<br />
• Slow delivery<br />
• Poor reproducibility<br />
• Thicker
CUSTOM TSLs<br />
When to use custom torics<br />
• Higher cylinders >3.50DC<br />
• Higher sphere powers<br />
• Fitting difficulties<br />
• Bored, in need of a challenge
CUSTOM TSLs<br />
Fitting procedure<br />
• Accurate refraction<br />
• ? Diagnostic lens
Hybrid lenses - Synergeyes
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
Problem-solving TSLs<br />
Possible problems include:<br />
• Poor VA<br />
• Unstable vision<br />
• Poor comfort<br />
• Corneal staining<br />
• Corneal oedema or other SL findings
Problem-solving TSLs<br />
Poor Vision<br />
Possible sources of error include:<br />
• Lens orientation<br />
• Lens Rx (inc. prism, distortion)<br />
• Refraction<br />
• Human error<br />
• That’s it
Problem-solving TSLs<br />
Poor Vision<br />
• Lens orientation - Rotate and recheck vision<br />
• Lens Rx - Verify lens power<br />
(or try another lens, same Rx)
Problem-solving TSLs<br />
Lens checking
Problem-solving TSLs<br />
Poor Vision<br />
• Lens orientation - Rotate and recheck vision<br />
• Lens Rx - Verify lens power<br />
(or try another lens, same Rx)<br />
• Refraction - Check refraction<br />
• Human error - Check px records, lens labels etc
Problem-solving TSLs<br />
Poor Vision<br />
• Lens orientation - Rotate and recheck vision<br />
• Lens Rx - Verify lens power<br />
(or try another lens, same Rx)<br />
• Refraction - Check refraction<br />
• Human error - Check px records, lens labels etc
Problem-solving TSLs<br />
Toric Calculators
Problem-solving TSLs<br />
Oblique cylinder calculator<br />
www.visioncare.co.uk
Problem-solving TSLs<br />
Unstable Vision<br />
Possible causes include:<br />
• Variable orientation<br />
• Mis-orientation - stable but with intermittently<br />
correct orientation<br />
• Loose fit � excessive movement
<strong>Soft</strong> Toric Lens Fitting – The Simpler Way<br />
BACKGROUND<br />
Astigmatism and its prevalence<br />
A short history of toric soft lenses (TSLs).<br />
Who to fit with TSLs<br />
TORIC SOFT LENS (TSL) DESIGNS<br />
Methods of stabilization<br />
Factors affecting stabilization<br />
Branded toric soft designs<br />
FITTING TSLs - PREPARATION<br />
Empirical vs. diagnostic fitting<br />
Hydrogel vs. silicone hydrogel<br />
Replacement period<br />
Selection of design/brand<br />
FITTING TSLs – POWER DETERMINATION<br />
Refraction<br />
Vertex correction<br />
Cross-cylinder calculations<br />
- BREAK -<br />
FITTING TSLs – AXIS DETERMINATION<br />
TSL vs Rx axis<br />
Assessment of orientation<br />
Adjustment for rotation<br />
FITTING TSLs – LENS FIT ASSESMENT<br />
Settling time<br />
Basic soft lens fit<br />
Orientation stability<br />
CUSTOM TSLs<br />
Who to fit with custom TSLs<br />
Fitting procedure<br />
Examples<br />
PROBLEM SOLVING<br />
Discomfort<br />
Poor VA<br />
Unstable vision<br />
Corneal staining<br />
Other physiological problems<br />
CASE EXAMPLES & DISCUSSION
<strong>Simplifying</strong> <strong>Soft</strong> <strong>Torics</strong><br />
CONCLUSIONS<br />
<strong>Soft</strong> torics now much easier due to improved<br />
designs, better reproducibility & FR options.<br />
<strong>Soft</strong> torics are now an integral part of basic CL<br />
practice.
Thank you<br />
Akiyoshi's illusion pages www.ritsumei.ac.jp/~akitaoka/index-e