Polarization sensitive optical coherence tomography in the human eye

Abstract

Optical coherence tomography (OCT) has become a well established imaging tool in ophthalmology. The unprecedented depth resolution that is provided by this technique yields valuable information on different ocular tissues ranging from the anterior to the posterior eye segment. Polarization sensitive OCT (PS-OCT) extends the concept of OCT and utilizes the information that is carried by polarized light to obtain additional information on the tissue. Several structures in the eye (e.g. cornea, retinal nerve fiber layer, retinal pigment epithelium) alter the polarization state of the light and show therefore a tissue specific contrast in PS-OCT images. First this review outlines the basic concepts of polarization changing light–tissue interactions and gives a short introduction in PS-OCT instruments for ophthalmic imaging. In a second part a variety of different applications of this technique are presented in ocular imaging that are ranging from the anterior to the posterior eye segment. Finally the benefits of the method for imaging different diseases as, e.g., age related macula degeneration (AMD) or glaucoma is demonstrated.

Depth-encoded all-fiber swept source polarization sensitive OCT

“…The corresponding DPPR image (Fig. 5(B)) shows high DPPR at the RNFL and sclera, and low DPPR in other layers of the retina, consistent with previous reports [13,33,47,48]. The fundus intensity image was generated by projecting all pixels of each A-line onto the en face view (Fig.…”

“…For example, loss of RNFL birefringence is observed during early stages of glaucoma, a leading cause of blindness in the developed world [8,9]. PS-OCT has found many applications, including anterior [10][11][12][13] and posterior eye imaging [13][14][15][16], skin imaging [17][18][19][20], burn depth and thermal damage assessment [21][22][23][24], dental imaging [25,26] and atherosclerotic plaque characterization [27][28][29].…”

Flow Measurement by Lateral Resonant Doppler Optical Coherence Tomography in the Spectral Domain

“…In analogy to the first shift theorem of the Fourier transform, an additional phase ϕ shifted (k,j) is inserted into the real-valued interferometric signal I j (k,z), as shown in Equation (7). According to Equation (8), the fractional shift of each interference spectrum of the lateral resonant scan corresponds to the tangent of the Doppler angle ϑ, where N is the number of points of the Fourier transformation (FT). With this, the originally obliquely running direction of the capillary, and consequently, the Doppler phase shift due to the fast laterally moving X-scanner across the oblique surface of the glass capillary, are eliminated.…”

“…However, functional imaging has become increasingly attractive for the investigation of tissue dynamics and physiology [7][8][9]. This is because the backscattered light not only provides information on the depth-dependent amplitude and phase, but also on physical quantities such as the polarization and the optical frequency shift, which are progressively used for functional tissue imaging.…”

Numerical compensation of system polarization mode dispersion in polarization-sensitive optical coherence tomography

“…For biological tissues, this capability can potentially add compositional information to images of anatomy without requiring exogenous contrast agents [5][6][7]. Early PS-OCT systems were constructed using free-space interferometers that allowed for control of the light polarization state throughout the system.…”