Measuring polarization changes in the human outer retina with polarization-sensitive optical coherence tomography

Area of Science:

• Ophthalmology
• Biomedical Optics
• Retinal Imaging

Background:

• Morphological changes like drusen are key biomarkers for age-related macular degeneration (AMD).
• Subtle, polarization-altering tissue changes may offer earlier diagnostic potential for retinal diseases.
• Retinal pigment epithelium and Bruch's membrane (RPE-BM) complex properties are crucial for retinal health.

Purpose of the Study:

• To investigate age-related changes in the polarization properties of the outer retina.
• To explore the potential of polarization-sensitive optical coherence tomography (PS-OCT) for detecting subtle retinal alterations.
• To correlate polarization changes with age and potential underlying scattering or scrambling effects.

Main Methods:

• Developed and utilized polarization-sensitive optical coherence tomography (PS-OCT) to acquire volumetric macular datasets.
• Recruited two age groups: young (<25 years) and older (>54 years) subjects.
• Measured retardance values of the RPE-BM complex and analyzed the degree of polarization uniformity (DOPU) in the retinal pigment epithelium (RPE).

Main Results:

• Younger subjects and half of the older subjects showed minimal retardance (5°-13°).
• The other half of older subjects exhibited significantly elevated retardance (up to 180°).
• Reduced DOPU (<0.4) in the RPE correlated with elevated double pass phase retardation (DPPR) below the RPE-BM complex, indicating increased scattering or polarization scrambling with age.

Conclusions:

• The outer retina exhibits significant age-related changes in polarization properties.
• Elevated DPPR in older subjects is linked to increased scattering or polarization scrambling.
• PS-OCT can detect these polarization changes, suggesting potential for earlier diagnosis of retinal conditions, even in clinically normal-appearing eyes.