04.10.10 advanced imaging using ubm course

Advanced Imaging Using High Frequency Ultrasound: Techniques for Phakic IOL Sizing Robert P. Rivera MD Barnet Dulaney Perkins Eye Center Phoenix, AZ USA ASCRS Symposium Course 10-304 Boston, MA April 10, 2010

Financial Disclosures Sonomed STAAR Surgical Alcon Bausch & Lomb Ellex

Sizing of the Visian ICL The Visian ICL is a posterior chamber phakic IOL implanted in the ciliary sulcus ICL length selected for each patient is based on horizontal white-to-white (WTW) measurement US FDA Clinical Study based on WTW FDA approval based on WTW Assumption was that external surface WTW measurement would closely follow sulcus-to-sulcus (STS) length

Sizing of the Visian ICL Subsequent results and studies showed this was an inaccurate assumption The WTW measurement could in fact be either longer or shorter than the STS Since the ICL haptics reside in the sulcus, the sulcus dimensions are more important than any external measurement To be fair, UBM technology was not available in earlier days of ICL implantation

Sizing of the Visian ICL 17% of patients in the US clinical trial did not have optimal vault (90-1000 µ) Exchange of an ICL for sizing related issues places patient at higher risk for additional complications Primary concerns of incorrect ICL size: Angle closure, pupillary block ICL too long, excessive vault Cataracts ICL too short, shallow vault

ICL & Ocular Anatomical Relationships Gonvers, et al, 2003 75 ICL cases, 27% cataract rate, all cataracts had vaults less than 90 µ Shin, et al, 2007 WTW technique is inaccurate at predicting the horizontal diameter of the ciliary sulcus Other pioneering work by Matamoros, Lovisolo, Zaldivar showed poor relationship between WTW and STS

ICL Sizing & OCT Rheinstein, et al OCT imaging devices cannot image the sulcus ATA has weak correlation to STS ATA cannot be relied upon for ICL sizing Ciliary sulcus resides in an optical shadow not visible to OCT

Why UBM for Phakic IOL Sizing? 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 & Chung) Good vault range 90-1000 µ

Ideal Vault – 300-600 microns

Case Study—ICL Mismatch WTW called for 13.2 mm ICL Surgeon implanted 13.2 in 1 st eye (OS) 1 week postop OS vault looked excessive 2 nd eye surgery (OD) in 1 week Downsized and implanted 12.6 in OD 1 week postop OD vault looked better, but still excessive

STS Clearly Called for 12.1 mm ICL

STS Method Redefines ICL Sizing Goal is to avoid sizing mismatches like these Obtain consistent measurements that are accurate, reproducible Obtain valuable information that is pertinent to ICL selection If this could be accomplished, sizing mismatches would become nonexistent

Development 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 Analysis 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 after enrollment Wrong length ICL placed Nomogram suggested 13.2mm 12.6mm ICL implanted Subject had 0 vault Prospective Study

Poor correlation (R 2 value) between STS and ATA 58% Poor correlation (R 2 value) between STS and WTW 46% Relationship Between STS, ATA & WTW

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 requiring explantation in a significant percentage 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 Results of STS vs. WTW Methods

Conclusions Using the new nomogram derived from STS measurements, we eliminated all instances of unacceptable ICL vault WTW methods would have resulted in different sized ICLs in 34% (PreVize Optimized) to 65% (FDA Label) of cases

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

Identifying Landmarks Quality scan is important Certain landmarks must be seen Not all images will show the landmarks Start by identifying the appropriate landmarks to confirm good positioning Freeze the frame for caliper positioning Take your measurements

Landmarks for Proper Positioning Corneal echo Anterior Posterior to lens capsule Anterior lens capsule Posterior iris pigment—hyperdense stripe Ciliary sulcus

Landmarks Anterior corneal echo Anterior lens capsule ICL Posterior corneal echos Posterior iris pigment Ciliary sulcus

Applying the Nomogram Submitted for publication in JCRS STS is what it is; no fudge factor is added to the length Nomogram identifies what length ICL to use Technically this is “off label” for ICL surgery until FDA decides otherwise Personally I do STS on 100% of my ICL patients Particularly important if you are doing Short Interval Bilateral Surgery—avoid sizing mismatch in both eyes

04.10.10 advanced imaging using ubm course

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04.10.10 advanced imaging using ubm course