The FullMonte® IOL software system is different from a lens calculator. It is an adaptive, optimizing process- not a formula - based on the Markov Chain Monte Carlo process....


Help is just around the corner! If you want text based help - look here - If you would like to watch a 30 minute webinar with an overview of the technology, look here - More videos and a start-up wizard are here...


Whats's new in Fullmonte IOL 2.0? Now Data collection for FullMonte IOL Calculator is simple, with the direct connection between the Haag-Streit LenStar 900 and the FullMonte Database - Just take measurements with the LenStar 900, and click...

Why do I need a new

Intraocular Lens Calculator?

The FullMonte IOL software system is different from a lens calculator. It is an adaptive, optimizing process – not a formula – based on the Markov Chain Monte Carlo process. It does not give you a simple number answer, an IOL power for emmetropia, but instead a probability curve that gives you an enormous amount of information to help you choose the best IOL power to implant. To understand this, we first need to go through a short history of intraocular lens calculations.
The initial formulas were based on optical formulas and were first proposed by Binkhorst, Fyodorov, and Colenbrander. These crude approximations of the thin lens approximation resulted in approximate 50% significant errors. This certainly wasn’t satisfactory. ...Read More

The Fullmonte


FullMonte is not just another IOL formula. It is a learning algorithm which combines modern theoretical formulas (SRK/T, Holladay I, Haigis, etc.) with data from your practice’s post-operative record to offer you the best possible predictive ability in effective lens power. Using FullMonte you can see your expected refraction on a graph of probability distributions, allowing you to make more informed decisions on lens selection and even make guarantees to patients in refractive outcomes.
Our software continuously optimizes itself with your data, and all of our surgeons'data, adapting to long eyes, short eyes, and other variables — including new sulcus-to-sulcus models. In doing so, FullMonte allows you to achieve outstanding results even with cases of unique anatomy or with post- refractive patients where current IOL formulas fall short.
In two controlled studies, the FullMonte calculator reduced the median absolute error versus the SRK/T formula by over 40%, and significantly decreased the standard deviation. Over 90% were within 0.50 Diopters of planned Refraction, 67% within 0.25 Diopters.

How Good Is My Prediction?

As mentioned above, FullMonte IOL provides graphs of predicted results. Here is one: Each probability curve is calculated for different lens powers. The central probability (black line) is the most likely expected refraction after implantation with each lens. We would choose the lens with closest probability to the planned refraction.
In two prospective, controlled studies comparing the FullMonte IOL Monte Carlo Markov Chain (MCMC) process versus the optimized SRK/T formula, the MCMC variance was found to be almost half the SRK/T formula. (0.26 vs 0.47) and (0.13 vs 0.40)
  • Reduced StdDev from 0.44 (SRKT) to 0.36 (FMG)
  • Significant – at p-value = 0.05478
  • FMG better predictor 53 times – versus 21 for SRKT, 18 equal
  • 90% of Eyes within 0.50 diopters of intended refraction
  • 61% of Eyes within 0.25 diopters of intended refraction