Polarization uniformity imaging of macular disease using jones-matrix optical coherence tomography

Abstract

 

Purpose

 

Imaging retinal pigment epithelium (RPE) abnormalities can help in macular degeneration diagnosis. The use of Jones-matrix optical coherence tomography (JM-OCT) to create 3D maps of pigmented tissue can highlight RPE abnormalities and complement the existing methods of fluorescein angiography (FA) and fundus auto-fluorescence (FAF). Here clinical case studies are used to compare JM-OCT observations of macular disease with FA and FAF images.

 

Methods

 

Eight eyes of eight patients with macular disease were examined, with conditions ranging from choroidal neovascularization (CNV, 3 cases), angioid streaks (1 case), polypoidal choroidal vasculopathy (PCV, 2 cases), geographic atrophy (GA, 1 case) and wet age-related macular degeneration (AMD, 1 case). Pathologic regions were scanned with 512 A-lines × 256 B-scans × 4 frames using a 1µm wavelength JM-OCT at 100,000 A-scans/s. A newly developed pigmented tissue imaging method called modified degree of polarization uniformity (M-DOPU) was applied to the JM-OCT images. M-DOPU has high noise immunity, thereby providing robust and quantitative imaging. As its imaging contrast originates from the randomization of the polarization state of backscattered light, it mainly contrasts the melanin of the posterior part of the eye. Three-dimensional mapping of pigmented tissues and en-face images of the distribution of melanin were visualized. En-face M-DOPU images were compared with FA and FAF images, and details were investigated in the cross-sectional M-DOPU images.

 

Results

 

Figure 1 shows an example of PCV in the left eye of a 58 year old man. The (b) FA shows a region of hyper- fluorescence. The corresponding location in (a) FAF shows hypo-autofluorescence. The (c) en-face M-DOPU image indicates a region with high M-DOPU (arrows), suggesting RPE damage (or pigmentation reduction). By examining the B-scan at the corresponding location in Fig. 2(b), the region of the RPE shows a high M-DOPU value (circle). Similar features of high M-DOPU at FA hyper-fluorescence were seen in four other subjects (2 PCV, 1 CNV and 1 GA).

 

Conclusions

 

As M-DOPU provides selective contrast related to the depigmentation of the posterior part of the eye, it may be a useful complement to AF and FAF in identifying abnormalities in the RPE.  

 

Fig. 1: Eye with PCV (a) FAF (b) FA (c) DOPU-OCT en-face.

 

 

Fig. 2: B-scans (a) OCT (b) M-DOPU.