kowa Avansee Toric Calculator

avansee™ preload1P TORIC
Kowa

User Guide

Procedure

This Calculator is a tool to assist users using Avansee Preloaded 1P Toric / Toric Clear in calculations. Please read the following "Warnings and Precautions" carefully before use.

This Tool produces two types of calculation, and one the residual corneal astigmatism after cataract surgery by summing up anterior corneal astigmatism, assumed induced astigmatism (surgical incision site), and posterior corneal astigmatism as each astigmatism vector. In addition, residual refractive astigmatism in the entire eyeball will be calculated if three types of Toric IOLs are inserted. Case 1 is displayed when a model with small astigmatism reduction is inserted, Case 2 is displayed when a model with small residual refractive astigmatism is inserted, and Case 3 is displayed when a model with large astigmatism reduction is inserted.
Another calculation estimates the angle deviation of Toric IOL.

Recommended use environment

  • OS
    [PC] Windows / Mac OS X
    [Tablet / smartphone] iOS / Android OS *1
  • Internet browser *2 *3
    [PC] Google Chrome / Firefox / Internet Explorer / Microsoft Edge / Safari
    [Tablet / smartphone] Safari (iOS only) / Google Chrome (Android only)

*(1) Those whose support from the developer has not expired, *2 The latest version is recommended, *3 Javascript shall be operable.

Access to the Calculator

This Calculator can be used with devices that can be connected to the internet (PC or smartphone, etc.).

Avansee Preload 1P Toric / Toric Clear is distributed only in the displayed countries and we will not bear any responsibility for use in other countries.
Please be aware that languages not displayed are not currently supported.

Warnings and Precautions

  • The results calculated by this Calculator are for reference and do not replace the Surgeon’s medical opinion or judgment.
  • The Calculator will perform calculations based on the data entered according to the "calculation method" shown below. Please be very careful about erroneous data entry or reading.
  • It may not be applicable if there is a concern about abnormal corneal shape (conical cornea, corneal transplanted eye, refractive surgery eye, etc.).
  • There are data to be entered based on user experience such as the amount of induced astigmatism and the amount of posterior astigmatism.
  • The Toric IOL model displayed as a calculation result is an example, and when using a Toric lens, select the model at the user's discretion.
  • The data selected and entered in this Calculator (including IP address) will be recorded for Internet maintenance, but they are not personally identifiable and cannot be viewed or edited by a third party.

Step 1 - Calculation of postoperative corneal astigmatism and calculation of residual refractive astigmatism after insertion of a Toric IOL -

1. Select the country to be used and the language to be displayed and click the "Submit" button.

2. Read the license thoroughly and click the "Accept" button.

You cannot use this Calculator without accepting the Terms of Use.

3. Select or enter the required information.

You can also enter data by clicking the "+" or "-" buttons. You can also enter it by moving the slider.
Click the "Calculation" button to perform the calculation.

Icon Explanation
You can enter here if necessary.
You can enter here if necessary.
Select the right eye or left eye and click.
You can change the value by clicking the "+" or "-" button.
Drag the slider to change the value.
The steep and flat meridians are visually displayed. The incision site is also displayed.
Click the cell to enter the amount of induced astigmatism to display an example of a numerical value, which can be entered if selected. Click the cell to enter the incision site to display an example of the direction, which can be entered if selected.
It can also be entered manually, but the incision site cannot be set in the following positions and is automatically displayed by rotation of 180°.
Right eye: 0° to +45°, 0° to -135°
Left eye: +135° to +180°, -90° to -180°
Click "Use" to use posterior astigmatism.
If posterior astigmatism is used enter the amount and axis angle. With-the-rule or against-the-rule astigmatism can be selected for axis angle.
Click the "Calculate" button.
To delete an input value, press the "Clear" button.
[Reference] When entering R1 or R2 and you want to change the refractive index of the cornea, change it from the pull-down list.
You can enter here if necessary.

4. Pressing the Calculate button automatically scrolls the window and displays the calculation results.

Icon Explanation
Indicating information on corneal astigmatism.
  • Preoperative corneal (anterior) astigmatism
  • Induced astigmatism
  • Preoperative posterior corneal astigmatism (If "Use" is selected)
  • Postoperative total corneal astigmatism
Indicating the assumed Toric model and the fixation angle.
The Reference column shows the virtual reduction in astigmatism where the calculated residual refractive astigmatism is 0.
Indicating the residual refractive astigmatism and its axis angle if a Toric IOL is inserted.
Case 2 shows the result of with-the-rule astigmatism of 0.35D or less.
Indicating that the astigmatic axis changes by 90° from the preoperative angle.
Indicating right eye or left eye.
The image of the insertion state of the Toric IOL is overlapped over the eyes.
The dashed line indicates the axial direction (steep meridian) of postoperative corneal astigmatism.
The arc mark indicates the incision site.
The positional relationships between the target eye, ear, and nose are shown in an illustration.
As an example, the lens model for Case2 is shown in the upper left.
The result calculated as the insertion angle is shown in the upper right.
You can change the image orientation by clicking the button.
To print, click the "Print" button.
Please make notes if necessary before printing. Please note that the notes will not be saved.
In addition to the example, a line-up model is shown.

5. Error messages

Error Explanation
Right eye or left eye is not selected. Select either right or left.
No information on corneal refractive power is entered.
Enter the required information.
The flat meridian (K1) and the steep meridian (K2) may have been entered in reverse. Click the button that appears to replace the input value.
You have exceeded the range of application of this Toric Calculator.
Message displayed before the value is cleared
This is displayed when you do not accept the Terms of Use.
You cannot use this calculator without accepting the Terms of Use.
No internet connection or communication failure.
Check your internet connection.

Step 2 - Investigation of the status of astigmatism correction from the postoperative information -

Click the tab on the top right of the screen.

Select the most appropriate one from the three calculation methods and enter the required data.
You can enter here if necessary. (Doctor*(Operator), Patients information, note)

Calculation of fixation angle deviation

Calculate residual refractive astigmatism when the fixed Toric IOL is rotated.

Enter the following data:

  1. Information on preoperative anterior corneal astigmatism
    (Astigmatic amount and axis angle)
  2. Information on induced astigmatism
    (Amount of induced astigmatism and incision site)
  3. Information on preoperative posterior corneal astigmatism
    (Astigmatic amount and axis angle)
  4. Model name of inserted Toric IOL
  5. Angle deviation of Toric IOL

Ideal angle calculation 1

Calculate the difference between the current angle and the ideal angle of the Toric IOL from postoperative information, and calculate the residual refractive astigmatism at the ideal angle.

It is assumed that [postoperative total corneal astigmatism] and [postoperative residual refractive astigmatism] are known.

Enter the following data:

  1. Information on corneal astigmatism including postoperative anterior and posterior astigmatism
    (Astigmatic amount and axis angle)
  2. Information on postoperative residual refractive astigmatism
    (Astigmatic amount and axis angle)

Ideal angle calculation 2

Calculate the difference between the current angle and the ideal angle of the Toric IOL from postoperative information, and calculate the residual refractive astigmatism at the ideal angle. It is assumed that [anterior corneal astigmatism], [induced astigmatism], and [posterior astigmatism] are known.

Enter the following data:

  1. Information on preoperative anterior corneal astigmatism
    (Astigmatic amount and axis angle)
  2. Information on induced astigmatism
    (Amount of induced astigmatism and incision site)
  3. Information on preoperative posterior corneal astigmatism
    (Astigmatic amount and axis angle)
  4. Information on postoperative residual refractive astigmatism
    (Astigmatic amount and axis angle)

Pressing the Calculate button automatically scrolls and displays the calculation results.
Colored values are the calculation results. Please note that uncolored results are for confirmation of input values.

Icon Explanation
Indicating postoperative total corneal astigmatism.
This section presents the results of prediction of the inserted Toric model from the input data under the assumption that the Kowa’s Toric IOL is inserted.
Indicating the angle at which the Toric IOL is currently inserted (current angle) and the angle at which the Toric IOL is maximized (ideal angle).
Indicating the difference between the current and ideal angle of the Toric IOL. It shows the angle toward the ideal angle based on the current angle.
Indicating residual refractive astigmatism when the Toric IOL is at the current angle and residual refractive astigmatism when the Toric IOL is at the ideal angle.

Calculation method

This tool calculates postoperative astigmatism and lens angle when the Kowa’s Toric IOL is inserted based on the "Alpins method" using information such as the cornea and incision site information, etc.

Angle definition

The angle is 0° in the right horizontal direction and positive in counterclockwise direction. Therefore, the negative angle indicates clockwise.

Vector definition

Symbol Meaning Vector value
Anterior corneal astigmatism vector [Acos(2α),Asin(2α)]
Induced astigmatism vector [Scos(2θ),Ssin(2θ)]
Posterior corneal astigmatism vector [Bcos(2β),Bsin(2β)]
Toric IOL vector [Tcos(2τ),Tsin(2τ)]
Postoperative corneal astigmatism vector (including anterior and posterior vectors) [Ccos(2γ),Csin(2γ)]
Postoperative residual refractive astigmatism vector [Dcos(2δ),Dsin(2δ)]
Toric IOL vector considering angle deviation [Tcos(2τ+2Δτ),Tsin(2τ+2Δτ)]
Ideal postoperative residual refractive astigmatism [D'cos(2δ),D'sin(2δ)]

A, S, B, T, C, and D indicate the size of astigmatism, α, θ, β, τ, γ, and δ indicate the axis angle (directions of flat meridian and Toric mark), and ⊿τ represents the angle deviation.

Calculation 1: Calculation of postoperative corneal astigmatism and calculation of residual refractive astigmatism after insertion of a Toric IOL

Calculations are performed as follows:
(1) Enter the data entered into each vector described above.
(2) Calculate the postoperative corneal astigmatism vector using the following formulae.

(3) Calculate postoperative residual refractive astigmatism from three Toric IOL vectors and postoperative corneal astigmatism vectors.

Calculation 2: Investigation of astigmatism correction status from postoperative information

A. Calculation of insertion angle deviation (calculation of residual refractive astigmatism after rotation of Toric IOL)

Calculations are performed as follows:
(1) Enter the data entered into each vector described above.
(2) Calculate postoperative residual refractive astigmatism by the following formulae.

B. Calculation of ideal angle 1 (Calculation from postoperative total corneal astigmatism and postoperative residual refractive astigmatism)

Calculations are performed as follows:
(1) Enter the data entered into each vector described above.
(2) Calculate the Toric IOL vector including angle deviations using the following formula: However,

(3) Calculate the residual refractive astigmatism vector when the Toric IOL is in the ideal angle position.

C. Calculation of ideal angle 2 (Calculation from preoperative corneal astigmatism, induced astigmatism, posterior astigmatism, and postoperative residual refractive astigmatism.)

Calculations are performed as follows:
(1) Enter the data entered into each vector described above.
(2) First, calculate the postoperative corneal astigmatism vector.

(3) Then, calculate the Toric IOL vector including the angle deviations as in B. Calculation of angle correction 1.
(4) Calculate the residual refractive astigmatism vector when the Toric IOL is in the ideal angle position, as in B. Calculation of ideal angle 1.

Other

Links are at the bottom of each page. Please check the content when necessary. Please note that the input values and calculation results are cleared when transitioning to the screen.

Links Explanation
You can view our privacy policy.
You can check the precautions for use.
You can change your country or language.
You can check how to use it.

References

  1. Alpins NA :A new method of analyzing vectors for change in astigmatism. J Cataract Refract Surg. 19:524-533,1993.
  2. Eydelman MB,Drum Bb, Holladay J,Hilmantel G, Kezirian G,Durrie D, Stulting RD, Sanders D, Wong B:
    Standardized analyses of correction of astigmatism by laser systems that reshape the cornea. J Refract Surg,22:81-95,2006.