Comparison Of Six Sizing Algorithms To Predict Lens Separation Vault In Myopic Implantable Collamer Lens (Icl) Surgery

To compare implantable collamer lens (ICL) achieved vault with lens sizing using the Reinstein sizing formula with the predicted vault based on five other sizing methods.

London Vision Clinic, London, UK

Retrospective analysis of consecutive V4c EVO and EVO+ ICL procedures where lens size was chosen using the Reinstein sizing formula derived from Artemis Insight 100 VHF digital ultrasound biometry. The achieved vault at 1 month was measured by MS-39 OCT (CSO Italia). The Reinstein sizing formula was used to calculate the predicted vault based on the recommended lens size for the following formulae: STAAR OCOS website, sulcus-based Dougherty and Kojima formulae, and OCT-based Nakamura (NK2) and Igarashi formulae. If the same lens size was recommended as implanted, the actual achieved vault was used. Otherwise, the model-predicted vault was used, adjusted by the accuracy of the achieved vault relative to the target vault.

The Reinstein sizing formula was used for 105 eyes (53 patients. Central vault relative-to-target was +47±124µm, range (-278 to +354µm) and interquartile range 155µm. Achieved vault was within ±100µm in 61% and ±300µm in 96% of eyes. Predicted vault was ±100µm in 45% and ±300µm in 90% for the Dougherty formula, ±100µm in 19% and ±300µm in 66% for the Kojima formula, ±100µm in 23% and ±300µm in 64% for the NK2 formula, ±100µm in 28% and ±300µm in 71% for the Igarashi formula, and ±100µm in 18% and ±300µm in 51% for the STAAR OCOS website.

Central vault was well controlled by the Reinstein sizing formula, based on ciliary body inner diameter, lens rise above the sulcus plane, scotopic pupil, ICL power, and ICL size. Predicted vault results were less accurate for the other sizing formulae. The sulcus-based Dougherty formula was the most similar, and the lowest vault accuracy was predicted for the white-to-white based STAAR OCOS wesbite.