Assuming that the post-opperative target for the patient was to have the lowest possible refractive astigmatism, it can be difficult to know what the best action is to take when this outcome is not achieved. This calculator requires an accurate post- operative subjective refraction, measurement of the anterior chamber depth, knowledge of the IOL sphere and cylinder power, and current position of the toric IOL axis. Keratometric data and the intended axis are not required. The calculator output provides a toric IOL axis to give the lowest refractive astigmatism. This may not be the same as the originally planned axis as it is based on the subjective refraction.

The other calculator output provided is the IOL-plane cylinder power required at the newly adjusted axis to give the lowest refractive astigmatism. If the required cylinder power is greater than halfway to the next available cylinder power produced by your preferred IOL manufacturer, then an IOL exchange may be the best option to give the lowest refractive astigmatism. If the required cylinder power is less than halfway to the next available cylinder power produced, then rotation of the currently implanted IOL may be the best option to produce the lowest refractive astigmatism. These options are not mutually exclusive and potentially a different IOL cylinder power may be needed at an axis different to the current position to minimise refractive astigmatism.

1. Record patient name or patient identifier

2. Record the current post-opperative subjective refraction. This needs to be as accurate as possible so it is important to know that there are no confounding factors decreasing vision such as corneal oedema or macula oedema. This calculator uses a back vertex distance of 12.5mm as default but you can adjust this.

3. Record the post-opperative anterior chamber depth, preferably measured by the same method used pre-operatively i.e. IOLMaster, Lenstar, Pentacam etc.

4. Record the spherical power of the implanted IOL. This is the base sphere power and NOT the spherical equivalent of the lens.

5. Record the cylinder power of the IOL using plus cylinder notation.

6. Record the current IOL axis (between 1 and 180 degrees)

7. Optimal toric IOL axis output provides the axis that the current toric IOL could be rotated to which would give the lowest amount of refractive astigmatism.

8. Optimal IOL Plane Cylinder Power output indicates the cylinder power of the toric IOL that would be required at the newly indicated axis to give the lowest refractive astigmatism.

9. These output values may be used to help decide what the best management option is when a toric refractive surprise occurs. This may involve rotating the IOL to the newly indicated axis; exchanging the IOL for a different cylindrical strength or a combination of both.

10. If the required cylinder power is greater than halfway to the next available cylinder power produced by your preferred IOL manufacturer, then an IOL exchange may be the best option to give the lowest refractive astigmatism. If the required cylinder power is less than halfway to the next available cylinder power produced, then rotation of the currently implanted IOL may be the best option to produce the lowest refractive astigmatism.

11. Refractive surprises in spherical power are not analysed by this calculator. Alterations of IOL cylinder power will affect the spherical ​equivalent of the refractive outcome by approximately half the dioptric value of the cylinder power alteration. The surgeon should judge if that possible sphere equivalent outcome change is significant and adjust the IOL sphere power as they see fit.

12. Other astigmatic refractive surprise corrective procedures including secondary sulcus IOL implantation and laser vision correction may be viable options.

The toric refractive surprise calculator has been designed and put online to serve as an adjunct tool to help ophthalmic surgeons provide better results for their patients undergoing cataract surgery.

It is intended to be used in conjunction with a complete ophthalmic history and comprehensive examination along with appropriate diagnostic tests and all other measurements necessary for cataract surgery.

The output results from this calculator are not intended as instructions from Michael Goggin or Ben LaHood or in any way be definitive.

Neither Michael Goggin or Ben LaHood guarantee that the results of this calculator will be accurate in every case or that post-opperative results will be improved by using the output from this calculator.

Ophthalmologists or their staff or associates who use this calculator must arrive at their own independent decisions regarding the most appropriate and accurate treatment for their own individual patients and are responsible for their refractive outcomes.

By using this toric adjustor calculator on ToricPro, you agree to waive and hold Michael Goggin, Ben LaHood and authors harmless from any claims you may have arising out of your use of this tool.

The information on this calculator is provided without warranty of any kind, express or implied.

Michael Goggin, Ben LaHood, their employees and anyone connected to the construction or content of this website, are not liable for damages of any kind, whether indirect or consequential, arising from the use of information supplied herein, or for any errors or omissions.

The information in this publication is taken from sources believed to be reliable, but it is up to each individual reading this to determine the usefulness therein.

Material from this website and calculator may not be used without prior consent from Associate Professor Michael Goggin.

We recommend that calculator output is printed by users who are then responsible for maintaining patient confidentiality.