Correlation of anterior segment optical coherence tomography measurements with graft trephine diameter following descemet stripping automated endothelial keratoplasty

Gavin S Tan,Jodhbir S Mehta,Mingguang He,Donald T Tan

doi:10.1186/1471-2342-12-19

Abstract

BackgroundTo assess repeatability of the Zhongshan Assessment Program (ZAP) software measurement of Anterior Segment Optical Coherence Tomography (ASOCT) images and correlate with graft trephine diameter following Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)MethodsRetrospectively evaluated interventional case series. 121 consecutive eyes undergoing DSAEK over a 26 month period underwent ASOCT imaging 1month after their surgery. ASOCT images were processed using ZAP software which measured the graft and cornea parameters including anterior and posterior graft arc length and cord length, posterior cornea arc length (PCAL) and anterior chamber width.ResultsThe graft measurements showed good repeatability on ASOCT using ZAP with high intra class coefficient and small variation in the coefficient of variation. On ASOCT, the mean recipient PCAL was 12.99+/−0.69mm and the anterior chamber width was 11.16+/−0.57mm. The mean Graft anterior arc length was 9.69+/−0.66mm and the mean Graft anterior cord length was 8.92+/−2.94mm. The mean graft posterior arc length was 9.24+/−0.75mm and the mean graft posterior cord length was 8.15+/−0.57mm. Graft posterior arc length (rho=0.788, p< 0.001) correlated best with intra-operative graft trephine diameter. The mean ratio of posterior graft arc length to PCAL was 0.712 +/− 0.056.ConclusionsWe have validated the repeatability of the ZAP software for DSAEK graft measurements from ASOCT images and shown that the graft arc length parameters calculated from the ASOCT images correlate well with the intra-operative graft trephine diameter. This software may help surgeons determine the optimal DSAEK graft size based on pre-operative ASOCT measurements of the recipient eye.

Highlights

To assess repeatability of the Zhongshan Assessment Program (ZAP) software measurement of Anterior Segment Optical Coherence Tomography (ASOCT) images and correlate with graft trephine diameter following Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)
The aim of this study was to (i) assess the reproducibility of post DSAEK graft measurements using the modified ZAP (Zhongshan Assessment Program) software (ii) to validate the measurements obtained from the ZAP readings and correlate this with intra-operative graft trephine measurements; (iii) to retrospectively analyze the graft sizing in our first 121 DSAEK cases to assess the size of the DSAEK graft in relation to the posterior corneal arc length (PCAL)
Patient characteristics A total of 121 eyes underwent DSAEK and had ASOCT done. 12 (9.9%) eyes were excluded because the ASOCT image was of insufficient quality to identify the sclera spur or to process the image with ZAP software

Summary

Introduction

To assess repeatability of the Zhongshan Assessment Program (ZAP) software measurement of Anterior Segment Optical Coherence Tomography (ASOCT) images and correlate with graft trephine diameter following Descemet Stripping Automated Endothelial Keratoplasty (DSAEK). Anterior segment optical coherence tomography (ASOCT) is a non-contact imaging technique that obtains high-resolution cross-sectional images of the cornea and anterior chamber. The aim of this study was to (i) assess the reproducibility of post DSAEK graft measurements using the modified ZAP (Zhongshan Assessment Program) software (ii) to validate the measurements obtained from the ZAP readings and correlate this with intra-operative graft trephine measurements; (iii) to retrospectively analyze the graft sizing in our first 121 DSAEK cases to assess the size of the DSAEK graft in relation to the posterior corneal arc length (PCAL)

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