A simplified method to measure choroidal thickness using adaptive compensation in enhanced depth imaging optical coherence tomography

Preeti Gupta; Elizabeth Sidhartha; Michael J A Girard; Jean Martial Mari; Tien-Yin Wong; Ching-Yu Cheng

doi:10.1371/journal.pone.0096661

A simplified method to measure choroidal thickness using adaptive compensation in enhanced depth imaging optical coherence tomography

PLoS One. 2014 May 5;9(5):e96661. doi: 10.1371/journal.pone.0096661. eCollection 2014.

Authors

Preeti Gupta¹, Elizabeth Sidhartha¹, Michael J A Girard², Jean Martial Mari³, Tien-Yin Wong⁴, Ching-Yu Cheng⁴

Affiliations

¹ Singapore Eye Research Institute and Singapore National Eye Centre, Singapore, Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore.
² Singapore Eye Research Institute and Singapore National Eye Centre, Singapore, Singapore; Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore.
³ Department of Bioengineering, Faculty of Engineering Science, University College London, London, United Kingdom.
⁴ Singapore Eye Research Institute and Singapore National Eye Centre, Singapore, Singapore; Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Singapore; Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore, Singapore; Centre for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Singapore.

Abstract

Purpose: To evaluate a simplified method to measure choroidal thickness (CT) using commercially available enhanced depth imaging (EDI) spectral domain optical coherence tomography (SD-OCT).

Methods: We measured CT in 31 subjects without ocular diseases using Spectralis EDI SD-OCT. The choroid-scleral interface of the acquired images was first enhanced using a post-processing compensation algorithm. The enhanced images were then analysed using Photoshop. Two graders independently graded the images to assess inter-grader reliability. One grader re-graded the images after 2 weeks to determine intra-grader reliability. Statistical analysis was performed using intra-class correlation coefficient (ICC) and Bland-Altman plot analyses.

Results: Using adaptive compensation both the intra-grader reliability (ICC: 0.95 to 0.97) and inter-grader reliability (ICC: 0.93 to 0.97) were perfect for all five locations of CT. However, with the conventional technique of manual CT measurements using built-in callipers provided with the Heidelberg explorer software, the intra- (ICC: 0.87 to 0.94) and inter-grader reliability (ICC: 0.90 to 0.93) for all the measured locations is lower. Using adaptive compensation, the mean differences (95% limits of agreement) for intra- and inter-grader sub-foveal CT measurements were -1.3 (-3.33 to 30.8) µm and -1.2 (-36.6 to 34.2) µm, respectively.

Conclusions: The measurement of CT obtained from EDI SD-OCT using our simplified method was highly reliable and efficient. Our method is an easy and practical approach to improve the quality of choroidal images and the precision of CT measurement.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Aged, 80 and over
Algorithms
Choroid / pathology*
Eye Diseases / diagnosis
Female
Humans
Image Processing, Computer-Assisted / methods*
Male
Middle Aged
Observer Variation
Reproducibility of Results
Sclera / pathology
Software
Tomography, Optical Coherence / methods*

Grants and funding

This study was supported by a grant (R760/44/2010) from National Medical Research Council, Singapore. Image post-processing techniques were supported by the Ministry of Education, Academic Research Funds, Tier 1, Singapore (MJAG). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.