Sizing Nomogram for ICL Vault Determination Using SulcustoSulcus

Sizing Nomogram for ICL Vault Determination Using Sulcus-to-Sulcus Measurements Obtained with High Frequency Ultrasound Robert Rivera MD ASCRS Symposium & Congress Boston 2010 The author has received research support, travel support, honoraria and consulting fees from the following: Sonomed, STAAR Surgical, Alcon

Sizing of the Visian ICL • ICL size chosen for implantation is based on white-towhite (WTW) measurement – US FDA Clinical Study was based on WTW – FDA approval based on WTW • Assumption was that surface WTW measurement would closely follow sulcus-to-sulcus (STS) length • Subsequent results and studies have shown this is not a valid assumption • Note that UBM technology was not available in earlier days of ICL implantation; WTW was the best approximation available

Sizing of the Visian ICL • 17% of patients in the US clinical trial did not have optimal vault (90 -1000 µ) • Gonvers, et al, 2003 75 ICL cases, 27% cataract rate, all cataracts had vaults less than 90 µ • Choi and Chung, 2007 – ICL length determined by UBM achieved ideal vault compared to conventional WTW – 100% of UBM group had ideal vault after 6 months, compared to 52. 9% in the WTW group

Ideal Vault • Truly “ideal” vault would be 500 µ • Inadequate vault defined as <90 µ (Gonvers 27% cataract rate = vaults less than 90 µ) • Excessive vault defined as >1000 µ (Choi, Chung & Chung) • “Good” vault range 90 -1000 µ

Development of a Sizing Nomogram • Retrospective Study – 73 eyes of 48 subjects with STS and vault measurements taken on Sonomed Vu. Max II • Matamoros regression equation – Modified with input from experienced ICL and Sonomed users – Outcome analysis used to generate a spreadsheet of ideal ICL length, based upon STS measurements

Multi-Center Prospective Analysis of UBM for ICL Sizing • Prospective multi-center trial • Sonomed Vu. Max II used to image sulcus images • Investigators: – David Brown, MD – Paul Dougherty, MD – Stephen Lane, MD – Robert Rivera, MD – David Schneider, MD – John Vukich, MD

Prospective Study • • • 61 eyes of 61 subjects Age 21 -45 Average myopia treated – 7. 6 D No history of previous refractive surgery IRB approval and informed consent obtained 1 eye excluded – Wrong length ICL placed – Nomogram suggested 13. 2 mm – 12. 6 mm ICL implanted Subject had 0 vault

ICL Vault Avg: 344 Min: 93 Max: 952

Results of STS vs. WTW Methods • If the FDA label WTW method of sizing ICLs was used, 65% of cases would have received a different size ICL than the STS Method, potentially requiring explantation in a significant number of patients • If the improved Pre. Vize Optimized WTW method of sizing ICLs was used, 34% of cases would have received a different size ICL than the STS Method • Poor correlation (R 2 value) between STS and ATA (58%); STS and WTW (46%)

Conclusions • Using our Sonomed study nomogram derived from STS Measurements, no cases fell within an unacceptable range of ICL vault compared to a reported 15%-20% of cases based upon WTW measurements • Average Vault was 344 µ (range 93 -952) • WTW methods would have resulted in different sized ICLs in 34% to 65% of cases compared to the STS method

Conclusions • Further refinement of nomogram may allow improvement in higher and lower ranges of vault • UBM STS measurements are far superior to WTW for the purposes of ICL selection with a far greater margin of safety • Despite the FDA label, surface WTW measurements may lead to incorrect ICL selection in a significant percentage of patients • In our opinion, careful systematic UBM STS should become the standard of care in ICL size selection

Thank You rpriveramd@aol. com