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Polarization-sensitive optical coherence tomography (PS-OCT) allows the recording of depth-resolved polarimetric measurements. It has been reported that phase retardation and local birefringence images can noninvasively detect fibrotic area in blebs after glaucoma surgery. Evaluation of scar fibrosis in blebs is important not only for predicting bleb function, but also for planning revision trabeculectomy. Herein, we characterize the intensity, phase retardation, and local birefringence images of blebs using PS-OCT. A total of 85 blebs from 85 patients who had undergone trabeculectomy were examined. Both phase retardation and local birefringence images detected fibrotic changes in blebs after glaucoma surgery. Phase retardation images detected slight fibrotic change during the early stage after surgery, whereas local birefringence images showed localized fibrotic tissue. There are two main patterns of local birefringence image changes in blebs: plate-like birefringence changes and diffuse changes. The area of plate-like birefringence change was significantly larger in poorly functioning blebs and is thus correlated with bleb function. These data suggest that the plate-like fibrotic change evaluation by PS-OCT may be useful not only for noninvasive evaluation of fibrotic scar tissue in blebs, but also for developing strategies for revision trabeculectomy.

Purpose: Polarization-sensitive optical coherence tomography (PS-OCT) can detect and evaluate scar fibrosis of the filtering blebs after glaucoma surgery. Although the change in phase retardation reportedly reflects bleb function, quantitative assessment of phase retardation in ocular tissues has not been conducted. We aimed to establish quantitative methods to investigate changes in phase retardation in the blebs after surgery using PS-OCT., Methods: Twenty-two blebs of 22 patients who had undergone glaucoma filtration surgery were consecutively examined for 4 months. Phase retardation was measured by PS-OCT and quantitatively analyzed to evaluate its relationship with bleb function based on intraocular pressure and medication use. Cross-sectional re-evaluation was also performed for a previous data set of 153 blebs of 122 patients., Results: In consecutive measurements, all blebs showed a low phase retardation value and good bleb function until 2 weeks. One month postoperatively, the phase retardation value was significantly increased, whereas bleb function was still good. The phase retardation value at 1 month postoperatively was significantly correlated with bleb function at 4 months postoperatively. While 55.6% of blebs with a high phase retardation value at 1 month subsequently lost function, only 7.7% with a low phase retardation value had bleb failure. In the cross-sectional re-evaluation, the quantitatively evaluated phase retardation value was highly correlated with bleb function (β = 0.770, P < 0.001)., Conclusions: An increase in phase retardation preceded deterioration of bleb function. The change in phase retardation may provide a prognostic metric for bleb function in the early stage after surgery.

Purpose: Polarization-sensitive optical coherence tomography (PS-OCT) can evaluate internal tissue structures of the cornea, such as collagen fibers, by phase retardation measurement. In this study, we assessed the repeatability of corneal phase retardation measurements using anterior segment PS-OCT., Methods: A total of 173 eyes of 173 patients were measured using PS-OCT. In total, 58 eyes of young subjects with normal corneas, 28 eyes of old subjects with normal corneas, 26 eyes with corneal dystrophy or degeneration, 37 eyes with corneal transplantation, and 24 eyes with keratoconus were evaluated. The 3-mm diameter average of en face phase retardation of the posterior corneal surface was examined using PS-OCT. To evaluate the repeatability, intraclass correlation coefficients (ICCs) were calculated for intraobserver repeatability and interobserver repeatability analysis., Results: Polarization-sensitive OCT showed good repeatability for corneal measurements. Intraclass correlation coefficients of intraobserver and interobserver repeatability of all the subjects were 0.989 and 0.980, respectively. Intraclass correlation coefficients of the intraobserver for each group, that is, young and old subjects with normal cornea, cornea dystrophy/degeneration, corneal transplantation, and keratoconus, were 0.961, 0.975, 0.984, 0.978, and 0.996, respectively. Interobserver ICCs for the above-mentioned respective groups were 0.952, 0.964, 0.988, 0.959, and 0.975, respectively., Conclusions: Polarization-sensitive OCT showed good repeatability for phase retardation measurements of central corneas not only for normal corneas, but also for various diseased corneas. Polarization-sensitive OCT might be useful for evaluating corneal phase retardation, which is one of the parameters that defines birefringence.

Purpose: Evaluation of bleb morphology using anterior segment optical coherence tomography (OCT) can offer important information regarding bleb function after glaucoma surgery. However, analysis of tissue properties, such as scar fibrosis of blebs, is difficult with conventional OCT. The birefringence of the blebs as susceptible measure of fibrosis scar was evaluated using polarization-sensitive OCT (PS-OCT) and its relation with bleb function was assessed., Methods: One hundred and fifty-three blebs of 122 patients that had undergone trabeculectomy or an Ex-Press tube shunt were examined. Also, in 14 blebs of 12 patients, consecutive measurements were performed for 2 months after surgery. The birefringence of blebs was evaluated by measuring alteration of phase retardation using PS-OCT. Functionality of the bleb was classified according to IOP and medication. The bleb morphology in terms of size and characteristics was evaluated using three-dimensional (3D) cornea and anterior segment OCT., Results: The alteration of phase retardation of blebs had the largest impact on bleb functionality than bleb morphology as shown by multiple regression analysis. In consecutive measurements, no blebs showed abnormal phase retardation until 1 week after surgery. Some blebs showed partial increase of phase retardation at 1 month after surgery., Conclusions: Intrableb fibrosis can be noninvasively evaluated with PS-OCT. Evaluation of birefringence by measuring phase retardation alterations using PS-OCT suggests new approaches for the postoperative management of glaucoma blebs regarding antifibrotic treatment for preventing IOP increases., (Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.)

This paper presents the theory and numerical implementation of a maximum likelihood estimator for local phase retardation (i.e., birefringence) measured using Jones-matrix-based polarization sensitive optical coherence tomography. Previous studies have shown conventional mean estimations of phase retardation and birefringence are significantly biased in the presence of system noise. Our estimator design is based on a Bayes' rule that relates the distributions of the measured birefringence under a particular true birefringence and the true birefringence under a particular measured birefringence. We used a Monte-Carlo method to calculate the likelihood function that describes the relationship between the distributions and numerically implement the estimator. Our numerical and experimental results show that the proposed estimator was asymptotically unbiased even with low signal-to-noise ratio and/or for the true phase retardations close to the edge of the measurement range. The estimator revealed detailed clinical features when applied to the in vivo anterior human eye.

Purpose: To investigate the tissue properties of keratoconic and normal corneas in vivo by using polarization-sensitive optical coherence tomography (PS-OCT), and to evaluate early keratoconus by the area under the receiver operating characteristic curve (AUROC) and Mahalanobis distance analysis., Methods: Thirty-one eyes of 20 patients with keratoconus, 7 eyes of 7 patients with keratoconus suspect, and 25 eyes of 25 normal subjects were investigated by PS-OCT and corneal and anterior segment (CAS)-OCT. Average of en face phase retardation of the posterior surface of the cornea, curvature, videokeratographic parameters, regular and irregular astigmatism, pachymetry map, and elevation were measured. The AUROC of each parameter was calculated to evaluate the diagnostic power to detect keratoconus and keratoconus suspect., Results: While in normal controls, the center of the en face phase retardation map showed low and homogeneous birefringence, in keratoconic corneas the birefringence increased with disease severity. Some keratoconus suspects had apparent high birefringence values without displaying morphologic signs of keratoconus in the anterior surface. The phase retardation values for normal, keratoconus suspect, and keratoconus subjects were, respectively, 0.20 ± 0.06, 0.35 ± 0.06, and 0.50 ± 0.14 radians in 3 mm diameter and 0.29 ± 0.22, 0.33 ± 0.13, and 0.74 ± 0.45 radians in 6 mm diameter. Outer morphological parameters such as curvature, videokeratographic parameters, regular and irregular astigmatism, and elevation showed high AUROCs for discriminating keratoconus from normal controls. On the other hand, using Mahalanobis distance, the AUROC of phase retardation, which represents microstructural properties of tissue, showed high value (0.989-1.000) for discriminating between keratoconus suspects and normal controls., Conclusions: Average of en face phase retardation of the posterior surface of the cornea was increased in keratoconus patients due to changes in the lamellar structure of collagen fibers. Phase retardation was sensitive with regard to discriminating keratoconus suspect and might be useful for detecting very early or even subclinical keratoconus.

S100B is an astrocytic calcium-binding protein which has been proposed as a biochemical marker of brain damage or dysfunction in acute and chronic diseases. We investigated whether serum S100B levels could be related to systemic lupus erythematosus (SLE) activity. Patients were grouped as having inactive SLE (ISLE), active SLE without central nervous system (CNS) involvement (ASLE), or active SLE with unequivocal neurologic or psychiatric manifestation (NPSLE). The control group consisted of age- and sex-matched healthy blood donors. S100B levels were determined using a luminescence immunoassay. All SLE groups had higher levels of serum S100B than the control group. Among the SLE groups, significantly higher levels of serum S100B protein were found in the NPSLE group than in the ISLE and ASLE groups, and there was no significant difference in S100B levels between the ISLE and ASLE groups. These preliminary results point to a putative relevance of serum S100B protein levels in SLE patients, specifically concerning CNS involvement present in this disease.