Pediatric IOL Calculator

Input Data

Load from BiomAPI

Browse PDF, Image or JSON

Patient

Surgeon

Patient Name

Patient ID

Date of Birth *

Date of Surgery *

Age at Surgery

Biometry

Eye *

Biometer *

AL (mm) *

K Index *

K1 (D) *

K2 (D) *

ACD (mm)

CCT (um)

LT (mm)

WTW (mm)

Calculation Parameters

Predict future AL Predict future K

Target at 21y

Target at current age

IOL Manufacturer

IOL Model

A-Constant *

Selected IOL

Target (D) *

Nomogram Suggestion

About this tool...

Disclaimer

This tool is for research purposes and should be considered experimental. By using this tool, you agree to waive and hold the author harmless from any claims you may have arising out of your use of these tools. No personally identifiable information (name and ID) is stored on our servers or transmitted through external API calls.

Authors

António Carlos Lottelli (Botucatu Medical School, Brazil)
Miguel Raimundo (ULS Coimbra, Portugal)
Rupal H. Trivedi (MUSC Storm Eye Institute, USA)
Larissa Gouvea (MUSC Storm Eye Institute, USA)
M. Edward Wilson (MUSC Storm Eye Institute, USA)

Description

This tool assists with IOL calculations in pediatric cataract surgery. It predicts axial length (AL) at age 21 using the Lottelli GEE model, and optionally predicts keratometry (K) using the Gouvea model. K prediction is automatically disabled for patients aged 7 years or older and can be manually re-enabled. By default the user provides a future refractive target at age 21. Optionally, this target can be set for the current age.

Standard A-constants for optical biometry can be used even with ultrasound measurements, as these are recalibrated to an optical equivalent (see reference below). Axial lengths obtained by contact ultrasound are automatically increased by 0.1 mm to account for globe compression.

IOL constants are sourced from the IOLCon database (export dated 2026-04-15). SRK/T optimized constants are used when available, falling back to ULIB and then nominal constants.

Formulas

T2 formula — A two-variable formula requiring only AL and keratometry (K1 and K2); the other biometric variables are not used for calculation.

Cooke K6 formula — Requires reliable optical biometry measurements (disabled for ultrasound), including the biometer model (defaults to "Optical - Other"). Mandatory parameters: AL, keratometry (K1 and K2), and ACD. LT is mandatory when using the Argos biometer, otherwise optional. CCT and WTW are optional. The IOL Family field (defaults to "Other") can refine predictions for specific IOL models.

IOL calculations are performed using the T2 and Cooke K6 formula APIs.

Prediction Models References

Lottelli AC, Marques JLP, Gouvea L, Trivedi RH, Lottelli LA, Wilson ME. 2026. "Mathematical Models for Predicting Postoperative Axial Length in Children With Bilateral Cataract and Primary IOL Implantation." American Journal of Ophthalmology 285:30-38.

Gouvea L, Wilson ME, Trivedi RH, Lottelli AC. 2025. "Postoperative Keratometry Prediction Model in Children Undergoing Bilateral Cataract Surgery with Primary IOL Implantation." J Refract Surg 41(3):e207-e212.

Other Relevant References

Cooke, David L., Rhonda Waldron, Giacomo Savini, Kamran M. Riaz, Leonardo Taroni, David A. Murphy, and Fabio Guaraldi. 2021. "Immersion Ultrasound Biometry vs. Optical Biometry." Journal of Cataract and Refractive Surgery. [using the recalibrated ultrasound axial length formula to allow the use of standard optical biometry constants]