Directional Optical Coherence Tomography Reveals Reliable Outer Nuclear Layer Measurements

Kevin K. Tong, Brandon Lujan, Yixiu Zhou, Meng C. Lin

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

PURPOSE: Directional Optical Coherence Tomography (D-OCT) is a method used to optically segment and identify the outer nuclear layer (ONL) i n vivo. The purpose of this study was to determine the repeatability and reproducibility of D-OCT ONL thickness measurements in healthy eyes. METHODS: Sixteen healthy eyes of sixteen subjects were imaged using the Cirrus SD-OCT. The OCT beam entry position was varied horizontally and vertically through the pupil, and cross-sectional images were obtained at baseline and 1-month follow-up by two observers. Detailed segmentation was performed to quantify the thickness of ONL without the inclusion of overlying Henle Fiber Layer. Inter-observer, intra-observer, and inter-visit variability was evaluated using Bland-Altman and coefficient of variation analysis for each category. RESULTS: All 16 eyes were successfully imaged, registered, and segmented. The maximum mean (SD) inter-operator difference was 2.6 (4.8) μm. The maximum mean (SD) intra-operator difference was 2.4 (5.3) μm. There was no statistically significant difference in ONL measurements detected between baseline and follow-up (p > 0.05). The mean (SD) differences measured across visits by one operator varied from −1.6 (3.1) to 1.1 (6.1) μm. The mean (SD) coefficient of variance (CV%) for all sectors with horizontal orientation was 9.1% (2.3%), 10.1% (2.5%), and 8.6% (2.3%) for inter-observer, intra-observer, and inter-visit, respectively. The mean (SD) coefficient of variance (CV%) for all sectors with vertical orientation was 8.3% (1.8%), 6.9% (1.4%), and 8.3% (2.1%) for inter-observer, intra-observer, and inter-visit, respectively. The majority of the variation of paired repeated measurements originated from between-subject variance. The within-subject variance accounted for less than 1% of the total variability. CONCLUSIONS: ONL thickness measurements can be quantified with good repeatability and reproducibility using D-OCT. Identifying the magnitude of D-OCT variability among normal subjects will allow for improved development of future clinical studies that quantitatively track the progression of macular pathology.

Original languageEnglish (US)
JournalOptometry and Vision Science
DOIs
Publication statusAccepted/In press - Apr 4 2016

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ASJC Scopus subject areas

  • Ophthalmology
  • Optometry

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