23 EyeWorld Asia Pacific | June 2024 ASIA-PACIFIC PERSPECTIVES Gaurav Luthra, MD Drishti Eye Institute 16 Subhash Road, Dehradun 248001, Dehradun, India drgl2020@gmail.com When I first started using the Visian ICL after FDA approvals in 2005 it was indicated for an internal AC depth (ACD) of 3.0mm or more in 4 sizes based on white to white (WTW) measured on Orbscan or manual calipers. Tolerance for low and high vaults was poor, predisposing to either anterior subcapsular cataracts or glaucoma respectively. Things changed with the V4C model with the Centraflow allowing better aqueous circulation thereby improving tolerance for lower and higher vaults besides obviating the need for Peripheral iridectomies. With the Centraflow ideal vaults could be between 250 - 750 μm but even smaller (100μm) and higher (1000 μm) vaults could be tolerated well without necessitating ICL exchange in most instances. ICL Sizing continues to remain an evolving but imperfect science due to the poor consistency between WTW and Sulcus to Sulcus (STS) measurements. Automated objective measurement of WTW is possible with various devices like the Pentacam, IOL master 500/700, Lenstar, Itrace, Anterion etc. However, in a study presented by us at ESCRS 2023 comparing 4 devices, we found best consistency of the Pentacam WTW with the Digital calipers. When selecting an ICL size based on the Staar calculator there may be situations where a smaller or bigger size may be recommended for the same WTW based on AC depth. I usually upsize for Toric ICLs, as they may rotate with low vaults, as well as in eyes with good AC depth. Vaults up to a 1000 μm may be tolerated well if ACD is adequate and angles remain open. Similarly, vaults less than 250μm as low as 100μm may again be put on watch with little risk of cataract formation unless the vault is almost nil. UBM has been used to measure STS for ICL sizing for a long time but trials with various UBM machines at our centre found significant interobserver variability in the STS measurements. Dan Reinstein has reported much better sizing and vault prediction with UHF ultrasound for STS measurement. More recently, anterior segment optical coherence tomography (ASOCT) has been successfully used to predict sizing and vault using crystalline lens rise (CLR) and angle to angle (ATA) or spur to spur (SSTSS) measurements without relying on ACD and WTW. Alain Saad and Damien Gatinel have been working on the same with the anterion and data shared by our centre for their nomogram in development showed better vault prediction than the Staar calculator. Even more recently ARCscan imaging and AI driven prediction by Zaldivar have shown promise in better sizing and vault prediction. Promising times are surely ahead for phakic lens enthusiasts. Editors’ note: Dr. Gaurav Luthra disclosed no relevant financial interests. About the Physicians Neda Nikpoor, MD | Aloha Laser Vision, Honolulu, Hawaii | drneda@alohalaser.com Mark Packer, MD | Fort Collins, Colorado | mark@markpackerconsulting.com Roger Zaldivar, MD | Instituto Zaldivar, Mendoza, Argentina | zaldivarroger@gmail.com References 1. Packer M. Meta-analysis and review: effectiveness, safety, and central port design of the intraocular collamer lens. Clin Ophthalmol. 2016; 10:1059–1077. 2. Yiming Y, et al. Evaluation of ciliary body morphology and position of the implantable collamer lens in low-vault eyes using ultrasound biomicroscopy. J Cataract Refract Surg. 2023; 49:1133–1139. 3. Packer M. The Implantable Collamer Lens with a central port: review of the literature. Clin Ophthalmol. 2018; 12:2427–2438. This article originally appeared in the March 2024 issue of EyeWorld. It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. Relevant Disclosures Nikpoor: STAAR Surgical Packer: STAAR Surgical Zaldivar: STAAR Surgical REFRACTIVE SURGERY
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