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SSoflexoflex

Toric LensesToric Lenses

By

Moodi Kuperman B.Sc.

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Astigmatism is the most common refractive problem.  It is a vision problem that causes objects to appear distorted and blurry. It often affects both distance and near vision. It is the most common vision problem and it may occur with nearsightedness and farsightedness.

AstigmatismAstigmatism

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AstigmatismAstigmatismAstigmatism is mostly caused by the cornea having an oblong shape, like a football, instead of spherical shape, like a basketball. A cornea with astigmatism has two curves, one flat curve and one that is steep. Light is then focused at two points instead of one. One point of focus may be in front of the retina and the other behind. This causes images to appear distorted in addition to appearing blurry.

Astigmatism may also be caused by an irregularly shaped crystalline lens. This condition is termed "lenticular astigmatism."

More then 40.0% of the population has astigmatism of more than 0.75DS

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Corneal cylinder

Lenticular cylinder

Combination cylinder

Type of Astigmatic CasesType of Astigmatic Cases

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1. Corneal:All the value of the cylinder is from the cornea :

CYL=Rh - Rv (in diopter)

Type of Astigmatic CasesType of Astigmatic Cases

Back toric lens is recommend to correct this type of cylinder.Front toric is a limited choice

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2. Lenticular: All the cylinder is from the internal part of the eye.

Only Front Toric lenses can correct this type of cylinder.

Type of Astigmatic CasesType of Astigmatic Cases

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3. Combination Cylinder: The Cylinder is vectors sum of the corneal and the lenticular astigmatism.

The same direction

Correct with back & front toric lens

Opposite direction

Correct with back & front toric lens

Opposite direction

Correct with front toric lens

Different direction

Correct with front toric lens

corneallenticulartotal

Type of Astigmatic CasesType of Astigmatic Cases

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How to correct astigmatism?

Using of: Spectacles

Contact lenses

Operation• Lasik• Intacts• IOL

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How can contact lenses help?

Contact lenses help by correcting the distortion of the corneal shape. Considerable advances have been made in correcting astigmatism by contact lenses.

Today various types of contact lenses are available to correct almost all types of astigmatism.

Contact lenses are better than the conventional eye glasses in correcting some astigmatism cases.

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Types of contact lenses used to resolve astigmatism:

Material Lens type Cyl source SizeSoft Spheric Corneal Up to -1.00DC

Back toric Corneal Any

Front toric Any Up to -2.50DC

GP Spheric Corneal Up to -2.75DC

Back toric Corneal Any

Front toric Any Up to -2.50DC

Bi toric Combination Any

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SOFLEX Soft Back Toric lensesSOFLEX Soft Back Toric lenses Toric Lite® , Trios, SH Toric (Silicone Hydrogel)

Back toric lens Prism ballast stabilization Large range of parameters Superb comfort High reproducible rate Excellent visual acuity

NO’ 1

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Back Toric Lens DesignBack Toric Lens Design

Peripheral curve

Lenticularcarrier curve

Anterior optic zone Lens

mark

Eccentriclenticular zone Toric

optic zone

Spherical fitting curve

Dt = 14.5mm

Boz =8.6mm

Foz =8.7

Front surface Back surface Cross-section

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Back Toric Lens DesignBack Toric Lens Design Stabilization with Prism ballast

1 2 3

prism Back toricUp thinDown thick

Force the lens down by gravity

Force the back toric structure to fit the corneal astigmatism

Force the lens down in each blink

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Lens Parameters:Lens Parameters:

Base Curve Range: 8.1 , 8.4 , 8.7 , 9.0 , 9.3

Diameter: 13.5 , 14.50 , 15.0 mm

Sphere Power Range: ANY

Cylinder Power: ANY

Axis: ANY

Effective Optic Zone: 9.00 mm

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Toric-Lite / Trios - Lens MaterialsToric-Lite / Trios - Lens Materials

GM3 – 58% water content hydrogel material

provides :

Extreme comfort Water retention Low modulus Deposit resistance Durability Increased moisture during wear

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SH Toric - Lens MaterialsSH Toric - Lens Materials

DEFINITIVE – 74% w/c Silicon Hydrogel material

provides :

Extreme comfort High Oxygen permeability Water retention Low modulus Deposit resistance Durability Increased moisture during wear

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Fitting Procedure: Fitting Procedure:

Patient History along with Normal Slit Lamp Evaluation for C/L

Corneal / topography measurements Rh/axis , Rv evaluate the type of the cylinder:

Corneal, Lenticular or CombinationBack toric design works the best where most of the cyl. is corneal.

Base curve : Kflat + 0.8 to 1.0mm for the Toric Lite / TriosKflat + 0.5 to 0.7mm for the SHToric

Spectacle Rx

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Fitting Procedure: Fitting Procedure: cont.cont.

Correction for the back vertex for the sphere and for the cyl.

For hyperops, add +0.25DS to the sphere For accurate results, when fitting hi-myopes or hi-

hyperops cases, it is recommend to fit first one day disposable lens with the closest sphere power (B.V.P) and then to do over refraction

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SOFLEXSOFLEXToric Lens Calculator

Advanced PC program for calculating the Soflex Toric lenses that takes into account as much parameters as possible:• The type of the cylinder• Size of the cornea• Atmosphere (dry or wet)• Input parameters:

Diopter or mm + cyl or – cyl

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Toric Lens CalculatorToric Lens Calculator22

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Fitting Example:Fitting Example:

Rh= 7.94 (42.50DS)Rv= 7.42 (45.60DS)42.50 / 45.60 X 165o

Rx= -6.25/-3.00x165o

Order

7.94+1.0 = 8.94B.C. = 9.0mmthe cyl is corneal.

-5.75/-2.50x165o

Toric Lite 14.5 9.0(SH Toric 14.5 8.7)-5.75/-2.50x175o

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Troubleshooting:Troubleshooting: When the vision is not satisfactory : 1. Re-check your fitting. 2. Over refract,

and calculate Cross Cyl. and order new lens. Where lens does not

stabilize - change BC Where lens rotates

recalculate according to the L A R S rule

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The L A R S Rule:The L A R S Rule: LLeft eft AAdd dd RRight ight SSubtractubtract

Left Movement

Lens Axis to Order:Cyl axis + Movement axis Cyl axis

Right Movement

Cyl axis + Movement axis

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Fitting Tips:Fitting Tips:

The lens can mask axis error up to ±8o

Order diameter 13.5 / 15.0 when cornea has small / big diameter or according the eye lids space

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CDGM3 – FT / SH SPHERE - FTCDGM3 – FT / SH SPHERE - FTFront Toric hydrogel lensFront Toric hydrogel lens

When the cylinder source is lentiqular or combinate use the Front Toric lens design

Front toric lens Prism ballast stabilization Large range of parameters Superb comfort High reproducible rate Excellent visual acuity

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Lens Parameters:Lens Parameters:

Base Curve Range: 7.6 to 9.0 @ 0.2mm steps

Diameter: 13.5 , 14.50 , 15.0 mm

Sphere Power Range: ANY

Cylinder Power: 0.25 to -2.75 @ 0.25D steps

Axis: ANY

Effective Optic Zone: 9.00 mm

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Lens CareLens Care

Daily cleaning Daily disinfecting with proprietary brands of: - hydrogen peroxide system - one step system - multi purpose solution system

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THANK YOU THANK YOU VERY MUCH !!VERY MUCH !!

QUESTIONS PLEASE