Correct IOL selection and efficient surgery planning

Toric IOL calculation

Clinical challenge

Obtaining the accurate level of corneal astigmatism plays a key role, since up to one third of the errors in practical routine derives from imprecise corneal measurements.1 Based on solid measurement data, the planning of the right toric IOL and the cataract surgery itself can take place. As IOL calculation and selection now also includes a toric component, a new calculation and IOL ordering routine might be needed. Various toric IOL formulas are nowadays offered to assist and compare different IOL calculation results.

  • Clinical challenges in toric IOL calculation

Online toric IOL calculator or onboard toric formulas in the biometer

Clinical solution

A variety of toric IOL calculators are available online or even onboard of biometers making it easy to integrate the calculation into the daily routine. While the axial length and keratometric data are input parameters for all formulas, some formulas also include additional parameters as the ACD, the lens thickness, the white-to-white, or the posterior cornea. After IOL selection, a direct order of the IOL needs to be placed and the planning of the surgery can be completed.

Clinical solutions for toric IOL calculation

Leading ophthalmologists share their experience

  • Toric calculator comparison
  • Mastering the toric workflow: taking your patients' experience to the next level

Three ways of toric IOL calculation with ZEISS

ZEISS solution

Toric IOLs can be calculated directly onboard of the IOLMaster® 700 from ZEISS, allowing to choose between various toric IOL powers and formulas. As a web-based solution Z CALC formula is specifically designed for all ZEISS IOLs. With the ability to calculate with TK values, Z CALC helps to improve toric calculations. The EQ Workplace® from ZEISS allows for a fully digital IOL calculation and surgery preparation which makes IOL implantation even more convenient and provenly more efficient.2

  • Calculating toric IOLs with Z CALC 2.0

ZEISS IOLMaster 700

ZEISS EQ Workplace

Software designed to save time during pre-operative processes, protect against never-events, and access data from anywhere.

  • ZEISS IOLMaster data is transferred automatically to the ZEISS EQ Workplace, to populate the relevant fields for toric IOL calculation and selection
  • Integrated toric formulas: Barrett TK Toric, Barrett Toric, Z CALC 2.0 and Haigis T
  • Pre-plan your surgery remotely: Connect to your ZEISS CALLISTO eye and prepare your surgical assistance functions.
  • Direct online ordering of IOLs in selected countries


The Z CALC online calculator  is a free browser-based web application that supports users in selecting ZEISS toric IOLs.

  • Specifically for ZEISS IOLs optimized proprietary calculation algorithm  predicting the post-operative residual refraction
  • Takes posterior corneal astigmatism into account – either by using ZEISS IOLMaster TK values or with the Z CALC nomogram
  • Allows for adjustment of estimated lens position (ELP)
  • Enables quick and easy ZEISS IOL ordering (in selected countries)

Comprehensive workflow to make treating astigmatism your new standard of care

Explore ZEISS solutions – click to learn more

  • 1

    Hirnschall, N., Findl, O., Bayer, N., Leisser, C., Norrby, S., Zimper, E., & Hoffmann, P. (2020). Sources of Error in Toric Intraocular Lens Power Calculation. J Refract Surg, 36(10), 646-652. doi: 10.3928/1081597X-20200729-03

  • 2

    Brunner, B.S.; Luft, N.; Priglinger, S.G.; Shajari, M.; Mayer, W.J.; Kassumeh, S. (2022). Saving of Time Using a Software-Based versus a Manual Workflow for Toric Intraocular Lens Calculation and Implantation. J. Clin. Med,11, 2907.