Biometry

SIA and lenses database

A few years ago, several surgically induced astigmatism (SIA) calculators were widely available and routinely incorporated into biometry workflows. Over time, however, many of these tools were no longer properly maintained and gradually became outdated. As a result, most of the commonly used calculators still rely on older Microsoft Excel features that are no longer compatible with current software versions, making them impractical for everyday clinical use.

At present, the SIA calculator provided by the American Society of Cataract and Refractive Surgery (ASCRS) remains functional. Nevertheless, it is limited to the input of corneal data only, which restricts its usefulness when attempting to analyze broader surgical and refractive outcomes.

This spreadsheet has been developed to address those limitations and to streamline the routine calculation and analysis of SIA. It includes a dedicated SIA calculator that allows right and left eyes to be analyzed either separately or together, depending on the user’s needs. In addition, cases can be filtered according to incision location for each eye, facilitating a more precise evaluation of surgical techniques and outcomes.

Beyond SIA calculations, the sheet also allows the user to record the selected intraocular lens model, type, and power, as well as postoperative visual acuity. As more cases are added, these data can help identify trends and provide valuable insight into which lens options consistently deliver the best results in your own practice.

An introductory sheet has been included with basic instructions and configurable options. For the sake of accurate analysis, patients with relevant ocular diseases or surgical complications can be excluded from the calculations. For example, a patient with age-related macular degeneration may not achieve optimal visual acuity even with an ideal lens choice. Similarly, surgical complications may require larger-than-usual incisions, potentially affecting SIA outcomes.

The project is still under active development, and new features will be added periodically. The spreadsheet does not use macros or scripts and is entirely hosted on Google Sheets, ensuring broad compatibility and ease of access. Bookmark this site and come back for updates.

The file is unlocked and free to use for non-commercial purposes, provided that proper credit is given to the original developer. Simply open the sheet, make a copy to your own account, and start entering your data.

Modern lenses

List of modern lenses we are using currently, with the updated classification according the European guidelines (ESCRS):