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Open Access Open Badges Research article

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

Gavin S Tan12, Mingguang He3, Donald T Tan124 and Jodhbir S Mehta1245*

Author Affiliations

1 Singapore National Eye Centre (SNEC), 11 Third Hospital Avenue, Singapore, 168751, Singapore

2 Singapore Eye Research Institute (SERI), 11 Third Hospital Ave, Singapore, 168751, Singapore

3 Zhongshan Ophthalmic Centre, Guangzhou, China

4 Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, Singapore, Singapore

5 Department of Clinical Sciences, Duke-NUS Graduate Medical School, 8 College Rd, Singapore, 169857, Singapore

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BMC Medical Imaging 2012, 12:19  doi:10.1186/1471-2342-12-19

Published: 23 July 2012



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)


Retrospectively 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.


The 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.


We 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.