Characteristics of Henle's fiber layer in healthy and glaucoma eyes assessed by polarization-sensitive optical coherence tomography

Using conventional optical coherence tomography (OCT), it is difficult to image Henle fibers (HF) due to their low backscattering potential. However, fibrous structures exhibit form birefringence, which can be exploited to visualize the presence of HF by polarization-sensitive (PS) OCT. We found a slight asymmetry in the retardation pattern of HF in the fovea region that can be associated with the asymmetric decrease of cone density with eccentricity from the fovea. We introduce a new measure based on a PS-OCT assessment of optic axis orientation to estimate the presence of HF at various eccentricities from the fovea in a large cohort of 150 healthy subjects. By comparing a healthy age-matched sub-group (N = 87) to a cohort of 64 early-stage glaucoma patients, we found no significant difference in HF extension but a slightly decreased retardation at about 2 & DEG; to 7.5 & DEG; eccentricity from the fovea in the glaucoma patients. This potentially indicates that glaucoma affects this neuronal tissue at an early state.

Automated summary

Conventional OCT has difficulty imaging Henle fibers (HF) due to their low backscattering potential. However, polarization-sensitive (PS) OCT can visualize HF by exploiting the form birefringence of fibrous structures. We developed a new measure using PS-OCT to estimate the presence of HF at various eccentricities from the fovea and found that glaucoma patients showed a slightly decreased retardation at 2° to 7.5° from the fovea, indicating potential early effects of glaucoma on this neuronal tissue.