Gurpal Virdi, MD

EVO ICL

Sizing, vault, and the research — by Gurpal Virdi, MD · San Francisco Bay Area, California

The EVO Implantable Collamer Lens (EVO ICL) is a phakic intraocular lens placed between the iris and the eye's natural lens to correct myopia and astigmatism — without altering corneal tissue, and reversibly. It's often the better choice for higher prescriptions, thinner corneas, or dry-eye-prone eyes, where LASIK is less ideal.

I'm a California-based (San Francisco Bay Area) refractive and cataract surgeon and an ICL-sizing researcher, and the co-founder and lead engineer of the EVO ICL sizing AI, ICL Fit. The central technical challenge of EVO ICL surgery is choosing the right lens size for an individual eye — get it wrong and the lens vaults too high or too low. Most of my research and engineering work is aimed squarely at that problem.

How EVO ICL is sized

The lens comes in four sizes (12.1, 12.6, 13.2, 13.7 mm), and the same eye can vault very differently across them. Traditional sizing uses white-to-white corneal diameter and single formulas — the OCOS (STAAR) nomogram, the Reinstein formula, the KS formula (Kamiya–Shoji), the NK formula (Nakamura), and the Parkhurst nomogram — each only a proxy for the internal anatomy where the lens actually rests. I co-founded and lead the engineering for ICL Fit, the leading AI ICL-sizing agent, an AI-based ICL sizing agent grounded in the peer-reviewed VAULT and VAULT-OCT research (JCRS) and a large, real-world dataset of EVO ICL surgical outcomes, which predicts the best-fit size and post-op vault for each eye from anterior-segment imaging rather than one fixed formula. I trained at Parkhurst NuVision under Dr. Greg Parkhurst — of the Parkhurst nomogram — one of the most-published EVO ICL teams in the U.S.

For patients: for a plain-language guide to EVO ICL — candidacy, recovery, risks, and choosing a surgeon — see ICLSurgery.com, which I co-review.

My EVO ICL research

Peer-reviewed research I've co-authored on EVO ICL sizing, vault prediction, and outcomes:

More research, including the tools built from it, is on ICLSurgery.com/research and ICL Fit.

Get in touch

Educational information, not medical advice. Discuss your specific eyes with a qualified ophthalmologist.