Refractive Surgery Screening Calculator

This free browser-based calculator supports ophthalmologists and eye-care professionals with refractive surgery screening. It organises the measurements gathered during a laser vision correction work-up, including manifest refraction, keratometry, pachymetry and corneal tomography, and presents published screening thresholds for LASIK screening, PRK screening, SMILE lenticule extraction, EVO ICL phakic lens implantation and refractive lens exchange.

What the calculator assesses

From the refraction and corneal thickness the tool derives the planned ablation depth, the residual stromal bed and the percent tissue altered. Pentacam-derived corneal tomography values, including the Belin/Ambrósio Enhanced Ectasia Display (BAD-D), maximum keratometry (Kmax), inferior-superior asymmetry, and anterior corneal elevation and posterior corneal elevation against the best-fit sphere, are stratified against published ectasia risk thresholds. Anterior segment biometry, including anterior chamber depth, endothelial cell density, angle width and crystalline lens rise, gates phakic intraocular lens screening and drives ICL vault prediction using the Kojima-Shimizu and Nakamura-Kamiya formulas. From age 40 the tool also outlines presbyopia strategies, including micro-monovision and presbyLASIK blended vision.

Parameters that are not direct inputs here, such as ARTmax and higher-order aberrations including coma and total root mean square (RMS) wavefront error, remain an important part of the full tomographic and aberrometric review. The calculator is designed to be read alongside the complete Pentacam display and the surgeon's own planning software, not instead of them.

Clinical use and limitations

The calculator is a clinical decision-support aid for professionals. It does not replace clinical judgement and it does not determine whether surgery is safe for an individual patient. Measurements should always be interpreted together with the history, examination, corneal imaging and other investigations, and the numerical thresholds shown are screening guides rather than absolute indications or contraindications to surgery. No data entered into the calculator is stored or transmitted: all calculations run locally in the browser.

The tool was created by Dr Dean van der Westhuizen (Doctor Dean), an ophthalmologist practising at the Lowveld Eye Institute in Mbombela, South Africa. More ophthalmology tools and patient information are available at doctordean.co.za.