FITTING STEPS

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STEP  1 : SCREENING

EASY CALCULATION

  • Effectiveness is related to “Target Power” and “Shape of cornea”.

  • Generally, the higher the Target power is, the less effective it is.

  • Our recommended way to judge applicability is the calculation formula:   

 

(Flatter meridian) - (Target power)  ≧ 39.00

 

For example, if the Flatter meridian is 44.00 D, target power under -5.00 D

 

 

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ESTIMATION FROM TOPOGRAPHY PATTERN

Applicable eyes that lens can be positioned in the center of the cornea

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ESTIMATION FROM TOPOGRAPHY PATTERN

Non-applicable eyes that cannot be well- centered

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STEP 2 : 1st TRIAL LENS CHOICE

DETERMINE THE 'FITTING CURVE' REFERRING  TO AVERAGE OF KRT DATA

Fitting Curve ≒ AVG K (45.00)
Target Power  = ?
Diameter = 10.6 (Standard Size)

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CALCULATE THE DIFFERENT OF THE FITTING CURVE & THE FLATTER MERIDIAN

Target Power ≒ S + (Flat K-Fit Curve)

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Referring to KRT data:

Target Power  =-4.50+(44.25-45.00) = -5.25

 

Final Target Power = -5.50*

*Adjusted by measuring the refractive power while wearing the lens.

 

1st Choice Trial lens as follow :

Fitting Curve (FC) = 45.00

Target Power (TP) = -5.50D

Diameter (D) = 10.6mm

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POSSIBLE RANGE TO ORDER

Fitting Curve Range

39.00D ~ 47.00D

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Target Power

-1.00D ~-8.00D

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Lens Diameter

10.2 mm

10.6 mm [Standard Diameter]

11.0 mm 

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STEP 3 : JUDGEMENT

  • Criteria for the fitting condition after 15 minutes of lens wear

  • Lens is proper centered.

  • Lens move 1~2 mm at blinking.

  • A proper doughnut pattern is achieved, and also the optical zone as wide as 3 mm.

  • Vision correction needed by patient should be obtained and stable, and wearing feeling is comfortable.

GOOD FITTING

  1. Criteria for fitting condition after 15 minutes of lens wear

  2. Lens is proper centered.

  3. Lens move 1~2 mm at blinking.

  4. A proper doughnut pattern is achieved, and also the optical zone as wide as 3 mm.

  5. Vision correction needed by patient should be obtained and stable, and wearing feeling is comfortable.

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TIGHT FITTING

  • narrow optical zone

  • less moving

  • insufficient tear exchange

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LOOSE FITTING

  • the lower edge of the lens has clearance from the cornea

  • Loose moving

  • tear pass through the reverse curve (channelling) 

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STEP 4: Additional Correction

Trouble-shooting

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If the patient cannot obtain required vision correction although the fitting condition is well,

Change target power strong or weak.

Fitting curve is not required to change in case only target power is changed

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If fitting condition is not stable.

Change fitting curve steep or flat

  • When making fitting curve 1 step flat, target power should be 1 step weak

  • When making fitting curve 1 step steep, target power should be 1 step strong.

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If stable fitting is not obtained even after changing fitting curve

Choose 1 step bigger diameter

(Target power and fitting curve are not required to change in case diameter changes)