Abstract
Purpose:
To investigate the shape features in the myopic optic nerve in glaucoma.
Methods:
Volumetric images of ONH were acquired using a custom 1060nm Swept Source OCT system at a rate of 100 kHz. The images were semi-automatically segmented for inner limiting membrane (ILM), nerve fiber layer (NFL), Bruch’s membrane (BM), and choroid-sclera boundary. 14 age-matched glaucomatous and normal subjects (9 glaucomatous, 5 normal, mean age = 58.9 ± 6.8) and 5 younger normal subjects (mean age = 29.8 ± 3.4) were imaged. All subjects had axial length > 24 mm. The morphometric parameters were: the BM opening (BMO) shape, the posterior bowing of BM, and the thickness of NFL and choroid. Bowing and thickness were plotted in 2D color maps. Multiple regression was performed with age, axial length (AL), and visual field mean deviation (MD).
Results:
The BMO area (r = .78, p < .001) and eccentricity (r = .62, p = .005) were correlated with AL. Several BMOs displayed “saddling” with the longer ends protruding anteriorly. BM bowing was correlated with AL among the older subjects. Inter-eye BM bowing difference was correlated with inter-eye MD difference (r = .-684, p = .002). Choroidal thickness was inversely correlated with age (r = -.474, p = .003) and AL (r = -.484, p = .002). Superior-nasal and nasal region showed the least amount of BM bowing and the thickest choroid.
Conclusions:
We demonstrated a comprehensive shape analysis pipeline in a study of the ONH in normal and glaucomatous subjects with myopia. The results suggest larger axial length is associated with larger and more elliptical BMO, greater BM bowing, and thinner choroid. Severity of glaucoma was associated with increased BM bowing in inter-eye comparison.
Keywords: 550 imaging/image analysis: clinical •
605 myopia