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The CRW1 Index: Identification of Eyes with Previous Myopic Laser Vision Correction Using Only a Swept-Source OCT
David L Cooke1, Kamran M Riaz2, David A Murphy2
1From the Great Lakes Eye Care, Saint Joseph, Michigan, USA; Department of Neurology and Ophthalmology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA.
Purpose:
To develop and test a novel index (Cooke-Riaz-Wendelstein [CRW1]) that uses swept-source optical coherence tomography (SS-OCT) biometry measurements (IOLMaster700, Zeiss Meditec), including total keratometry, to alert clinicians that previous myopic laser vision correction (M-LVC) was present in a measured eye.
Design:
Retrospective, multicenter, comparative diagnostic analysis.
Methods:
The study took place at 6 centers in the United States and Austria. Anonymized SS-OCT biometry datasets acquired between 2018 and 2020 and containing 49,199 eyes were analyzed. The LVC status, as identified by the biometrist, was used to segregate eyes into LVC and non-LVC eyes. Data were split into training (10,780 eyes) and validation (38,419 eyes) sets. Subset analysis was performed for CRW1 Index accuracy compared to posterior/anterior corneal curvature ratio (Rpost/Rant), topography with corneal analysis software (Atlas 9000 with Pathfinder II, Zeiss Meditec), tomography (Pentacam, Oculus), dual Scheimpflug-Placido system (Galilei G6, Ziemer), and a cloud-based platform for cataract surgery planning (Veracity, Zeiss Meditec). A positive predictive value (PPV) of ≥90% was targeted for the CRW1 index. True positives, true negatives, sensitivity, and specificity were recorded.
Results:
The CRW1 Index compared favorably against Rpost/Rant showing a higher PPV (93% vs 65%), with fewer false-positive results (29 vs 180). CRW1 performed similarly to topography software and better than the corneal imaging devices. The CRW1 cutoff value can be adjusted to increase sensitivity (CRW1-IS) to detect additional M-LVC eyes.
Conclusions:
The CRW1 and CRW1-IS indices offer surgeons and researchers a readily accessible method to use only SS-OCT biometry measurements to detect eyes with a high probability of previous M-LVC.
