IOL Calculator

Enter independently verified biometry to generate intraocular lens power recommendations.

Patient and calculation details

Patient ID/ Name

Enter the clinic record number or patient name.

Date of birth

Surgeon

Eye to calculate

OD Right eye OS Left eye OU Both eyes

Keratometric index

Match this to the index used by the keratometry or biometry system that produced the K readings.

Sequential Eyes

Refine the second-eye plan using the observed refractive outcome of the first operated eye. The refined and unrefined predictions are shown side by side — neither is a guaranteed outcome.

Settings

Keratometric index

Applies to the K readings of both eyes below.

The second eye uses the same lens model and A-constant as the first eye, and is refined automatically from the first eye's outcome using a fixed, validated rule — there is nothing to adjust. When the first-eye result is on target, no adjustment is carried forward.

First eye

Already operated

Second eye

Planned surgery

Optimise an A-constant using your outcomes

Upload de-identified surgical outcome data to derive lens-specific A-constants that are consistent with the PRIME calculation engine. Constants are optimised separately for each lens model found in your file.

1 · Prepare your dataset

Use one row per operated eye. Before uploading, please check that you have:

Removed direct patient identifiers (names, record numbers, dates of birth).
Confirmed the quality and stability of each postoperative refraction.
Confirmed the lens model and the power actually implanted for every row.
Confirmed laterality and biometry against the source measurements.
Expressed keratometry as standard keratometric dioptres (1.3375 index).

Download spreadsheet template

Columns

Column	Status	Notes
AL	Required	Axial length, mm
K1	Required	Flat keratometry, D
K2	Required	Steep keratometry, D
IOL Name	Required	Lens model as implanted
IOL Power	Required	Power actually implanted, D
SE	Required	Stable postoperative spherical equivalent, D
ACD	Recommended	Anterior chamber depth (epithelium to lens), mm. Strongly recommended. Eyes without an ACD are optimised separately, in AL+K-only mode, and are reported as a distinct row — the constant they produce should not be used for eyes calculated with an ACD.
LT	Recommended	Lens thickness, mm
WTW	Recommended	White-to-white, mm
Gender	Recommended	Male / Female, if recorded
CCT	Optional	Central corneal thickness, µm
Eye	Optional	OD / OS, if recorded
A-constant, Sph, Cyl	Accepted	Present in the template; ensure Sph/Cyl corresponds with the SE.

2 · Upload and optimise

Drag and drop your file here

Accepted: a single .xlsx workbook, up to 4 MB.

Choose file

Optimisation results

Lens model	Eligible eyes	Optimised A-constant	Mean error (D)	Mean absolute error (D)	Status / notes

Mean error and mean absolute error are computed in-sample on the uploaded eyes at the optimised constant. They confirm that the optimisation converged; they are not independent evidence of formula accuracy. Each lens model requires at least 20 eligible eyes. Rows marked AL+K only were optimised from eyes with no ACD: the residual spread is roughly twice that of the ACD path, so at least 50 eyes are advised, and the resulting constant is specific to AL+K-only calculation.

About PRIME

PRIME stands for Power Recommendation through Intelligent Modeling Engine. It is an intraocular lens (IOL) power calculation platform intended to support qualified eye-care professionals in cataract and refractive lens surgery planning.

Intended use

PRIME is an adjunct to clinical assessment and surgical planning. It does not replace physician judgement. Results must be interpreted alongside a comprehensive ophthalmic examination, appropriate diagnostic testing, and independently verified biometric measurements. The treating physician remains solely responsible for lens selection and all clinical decisions.

Main functions

The platform provides four functions: intraocular lens power calculation from standard biometry; second-eye refinement that uses the observed refractive outcome of the first operated eye; A-constant optimisation from a surgeon's own de-identified outcome data; and print-friendly calculation records for the clinical file.

Data privacy

Intellectual property and permitted use

PRIME is based on intellectual property belonging to Dr Jeremy Hu and is provided for authorised educational, internal clinical, and business use only. It may not be copied, modified, reverse engineered, decompiled, redistributed, sublicensed, used to create derivative products, or offered as a service without prior written permission. Read the complete terms.

Contact and feedback

For access requests, feedback, or to report a suspected calculation issue, contact the PRIME team: send feedback by email.