Comparison of Optic Disc Ovality Index and Rotation Angle Measurements in Myopic Eyes Using Photography and OCT Based Techniques

Abstract

PurposeTo compare optic nerve head (ONH) ovality index and rotation angle measurements based on semi-automated delineation of the clinical ONH margin derived from photographs and automated BMO configuration derived from optical coherence tomography (OCT) images in healthy and glaucomatous eyes with high-, mild- and no axial myopia.MethodsOne hundred seventy-five healthy and glaucomatous eyes of 146 study participants enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) with optic disc photographs and Spectralis OCT ONH scans acquired on the same day were stratified by level of axial myopia (non-myopic [n = 56, axial length (AL) <24 mm], mild-myopic [n = 58, AL 24–26 mm] and high-myopic [n = 32, AL >26 mm]. The clinical disc margin of each photograph was manually annotated, and semi-automated measurements were recorded of the ovality index and rotation angle based on a best-fit ellipse generated using ImageJ software. These semi-automated photograph-based measurements were compared to ovality index and rotation angle generated from custom automated BMO-based analysis using segmented OCT ONH volumes. R2 values from linear mixed effects models were used to describe the associations between semi-automated, photograph-based and automated OCT-based measurements.ResultsAverage (95% CI) axial length was 23.3 (23.0, 23.3) mm, 24.8 (24.7, 25.0) mm and 26.8 (26.6, 27.0) mm in non-myopic, mild-myopic and high-myopic eyes, respectively (ANOVA, p ≤ 0.001 for all). The R2 association (95% CI) between semi-automated photograph-based and automated OCT-based assessment of ONH OI for all eyes was [0.26 (0.16, 0.36); p < 0.001]. This association was weakest in non-myopic eyes [0.09 (0.01, 0.26); p = 0.02], followed by mild-myopic eyes [0.13 (0.02, 0.29); p = 0.004] and strongest in high-myopic eyes [0.40 (0.19, 0.60); p < 0.001]. No significant associations were found between photography- and OCT-based assessment of rotation angle with R2 values ranging from 0.00 (0.00, 0.08) in non-myopic eyes to 0.03 (0.00, 0.21) in high-myopic eyes (all associations p ≥ 0.33).ConclusionsAgreement between photograph-based and automated OCT-based ONH morphology measurements is limited, suggesting that these methods cannot be used interchangeably for characterizing myopic changes in the ONH.

Refractive Associations With Whole Eye Movement Distance and Time Among Chinese University Students: A Corvis ST Study

“…Additionally, it has been suggested that AL is a better indicator of eye size than SE. 45 Furthermore, it is worth exploring the possibility of a mechanical or physical relationship between eye movements and AL. This relationship warrants further investigation to determine the exact cause and underlying mechanism.…”

Update on the Utility of Optical Coherence Tomography in the Analysis of the Optic Nerve Head in Highly Myopic Eyes with and without Glaucoma

“…Using the Spectralis OCT, Rezapour et al found a torsion angle of 34.4° (range 29.9 to 39.0) vs. 33.7° (range 27.6 to 39.9) in mild myopia (mean AXL of 24.8 mm, range 24.7 to 25.0) vs. high myopia (mean AXL of 26.8 mm, range 26.6 to 27.0). In addition, they obtained no association between the photograph-based and OCT-based assessment of the torsion angle in high-axial myopic eyes ( p ≥ 0.33 with R 2 = 0.03 from 0.0 to 0.21) [ 33 ]. It should be highlighted that these different torsion angle values are due to the fact that the OCT-based torsion angle is a BMO-based assessment while the photographed-based torsion angle is measured relative to the clinical disc margin, which does not always correspond with the BMO, especially in myopic eyes.…”

“…Torsion angle 34.4° (range 29.9 to 39.0) vs. 33.7° (range 27.6 to 39.9) in mild 24.8 mm (range 24.7 to 25.0) vs. high 26. 8 mm (range 26.6 to 27.0) myopic eyes [ 33 ]…”

Deep Optic Nerve Head Structures Associated With Increasing Axial Length in Healthy Myopic Eyes of Moderate Axial Length

“…Several reports have investigated the relationship of myopic refractive error and/or axial length (AXL) with individual ONH parameters measured from OCT images in healthy myopic eyes. 8 – 10 , 21 – 26 Myopic ONH structural changes that may be associated with connective tissue remodeling is more directly influenced by myopic AXL elongations. 2 , 27 Furthermore, most of these ONH parameters are well correlated with each other, and it is unclear which ONH parameters are independently associated with longer AXL.…”