Robert Rivera MD ASCRS Symposium & Congress Boston 2010 The author has received research support, travel support, honoraria and consulting fees from the.

Sizing Nomogram for ICL Vault Determination Using Sizing Nomogram for ICL Vault Determination Using Sulcus-to-Sulcus Measurements Obtained with High Sulcus-to-Sulcus Measurements Obtained with High

Frequency UltrasoundFrequency Ultrasound

Robert Rivera MDRobert Rivera MD

ASCRS Symposium & CongressASCRS Symposium & CongressBoston 2010Boston 2010

The author has received research support, travel support, The author has received research support, travel support, honoraria and consulting fees from the following:honoraria and consulting fees from the following:

Sonomed, STAAR Surgical, AlconSonomed, STAAR Surgical, Alcon

Sizing of the Visian ICLSizing of the Visian ICL

• ICL size chosen for implantation is based on white-to-white (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 ICLSizing 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 VaultIdeal 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

& Chung)• “Good” vault range 90-1000 µ

Development of a Sizing NomogramDevelopment of a Sizing Nomogram

• Retrospective Study– 73 eyes of 48 subjects with STS and vault

measurements taken on Sonomed VuMax 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 Multi-Center Prospective Analysis of UBM for ICL SizingAnalysis of UBM for ICL Sizing

• Prospective multi-center trial• Sonomed VuMax 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

• 61 eyes of 61 subjects• Age 21-45• Average myopia treated –7.6D• No history of previous refractive surgery• IRB approval and informed consent obtained• 1 eye excluded

– Wrong length ICL placed – Nomogram suggested 13.2mm– 12.6mm ICL implanted

Subject had 0 vault

Prospective StudyProspective Study

• 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 PreVize Optimized WTW method of sizing ICLs was used,

34% of cases would have received a different size ICL than the STS Method

• Poor correlation (R2 value) between STS and ATA (58%); STS and WTW (46%)

Results of STS vs. WTW MethodsResults of STS vs. WTW Methods

ConclusionsConclusions

• 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

ConclusionsConclusions

• 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 [email protected]