Purpose:
To quantitatively and qualitatively investigate the age-related changes of the structures comprising the trabecular pathway, namely, the trabecular meshwork (TM), Schlemm’s canal (SC), the collector channels (CC) and the intrascleral vascular plexus (IVP) in normal human eyes using high definition anterior segment Fourier-domain OCT (ASFDOCT).
Methods:
3 subjects per decade, from the 2nd to the 9th were imaged over the right temporal limbus. The area was first inspected for CC; when a clearly visible CC was identified, a standardized protocol of serial radial and tangential scans was performed. The image capturing the same CC in both scan orientations was selected for analysis. The structures assessed in the radial scans included: SC cross sectional area, maximum width and length; TM thickness (measured at the posterior third), CC maximum diameter and ostium diameter; diameter of the vessel associated with the same CC. The tangential scans were evaluated for the maximum and minimum width of SC in a 500 µm section.
Results:
SC area, width and length presented a significant negative correlation with age (all p<0.001) from the 5th decade (area=4,000, length=307, width=20 µm) to the 9th decade (area=1,330, length=142, width=10 µm). The CC undergo a significant reduction in their dimensions until the 7th decade (p<0.001).
Conclusions:
The microstructures of the trabecular pathway can be quantitatively evaluated using ASFDOCT and is enhanced by the use serial radial and tangential imaging. This is the first study evaluating the morphology of the trabecular pathway morphology at different stages of life in vivo in normal human eyes. Our results should be considered in future anatomical studies comparing normal and glaucomatous eyes.
Keywords: trabecular meshwork • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)