An international encyclopedic database for IOL specifications


Learn more about an open-to-all online database that continuously compiles and optimises IOL constants for optimal implantation outcomes after cataract surgery.

When choosing IOLs for implantation after cataract surgery, surgeons know all too well the challenges of this task and that one power does not fit all, numerous parameters are involved, and in some cases, despite the best of intentions, postoperative surprises have occurred all too frequently during the evolution of the art of choosing the optimal IOL for implantation.

“The patient’s visual needs and the biometry of the individual eye are prime considerations when picking an IOL. The IOL constants are the important components that link the biometric measurements to the expected axial lens position in the eyes. An accurate estimation of this effective lens position is needed to determine which IOL power is best suited for an individual patient,” said Achim Langenbucher, PhD.

The realisation of the complexity of obtaining the best fit led to the development of IOLCon, an open-to-all online database that continuously compiles and optimises IOL constants for optimal implantation outcomes after cataract surgery.

Dr Langenbucher explained that “the concept of IOLCon as an encyclopedic database for IOL specifications is evolving in cooperation with the manufacturers of IOLs and biometry devices as well as with cataract surgeons from all around the world.” Dr Langenbucher is chair of Experimental Ophthalmology, Saarland University, Institute of Experimental Ophthalmology, Homburg/Saar, Germany.

Why optimise the IOL constants?

Because they are the keys to choosing the correct IOL powers.

“The choice of IOL powers can be improved through continuous optimisation of IOL constants. Reliable IOL constants require a high number of preoperative biometry measurements together with the respective refractive outcomes. A continuously growing database of refractive success will ensure the increasing reliability of the IOL calculations.”

He explained that the IOLCon platform is based on a PostgreSQL database system. The user-interface and the optimisation algorithms were programmed in the Hypertext Preprocessor language. Optimisation algorithms for the published IOL formulas, i.e., SRK II, SRK/T, Haigis, Hoffer Q, and Holladay 1, were implemented. The graphical user interface provides a tabular listing of IOL specifications and nominal as well as optimised IOL constants.

Two user groups can enter the data. A registered, authorised staff member employed by the IOL manufacturer or distributor can enter the technical data for their IOL products; the responsibility lies with the manufacturers and distributors to maintain the most up-to-date product information.

Cataract surgeons can search IOLCon for one or more IOLs based on the required specifications and available power ranges. A search option allows filtering according to various criteria such as manufacturer, material, and optic size.

Registered surgical centres can upload preoperative and postoperative refractive results via open text file formats to obtain globally or personally optimised IOL constants.

The uploaded files can contain the results of different IOLs, devices, or ethnicities.

Optimisation will be performed according to the needs of the patients using only data obtained with a specific biometer or by the surgeon when sufficient data are available, Dr Langenbucher emphasised.

IOLCon currently includes data from more than 310 IOL models manufactured by 23 different companies. Optimised constants are available for 61 IOL models (based on almost 9,000 clinical results).

For greater convenience, the biometry device manufacturers are implementing the platform’s open XML interface to integrate IOLCon with their devices.

“The use of the platform is free of charge for registered ophthalmic surgeons. The more data that ophthalmic surgeons upload to the platform, the more reliable the optimised constants will be. In the near future, IOLCon will be available for rapid worldwide dissemination of optimised IOL constants,” Dr Langenbucher concluded.

Surgeons can register at to upload data.


DR Achim Langenbucher, PhD
Dr Langenbucher has no financial interests in any aspect of this report.

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