Measurement and imaging of birefringence and optic axis orientation by phase resolved polarization sensitive optical coherence tomography

We present an improved method of polarization sensitive optical coherence tomography that enables measurement and imaging of backscattered intensity, birefringence, and fast optic axis orientation simultaneously with only one single A-scan per transverse measurement location. While intensity and birefringence data are obtained in a conventional way, the optic axis orientation is determined from the phase difference recorded in two orthogonal polarization channels. We report on accuracy and precision of the method by measuring birefringence and optic axis orientation of well defined polarization states in a technical object and present maps of birefringence and, what we believe for the first time, of optic axis orientation in biological tissue.

Simultaneous imaging of human cone mosaic with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography

We describe a novel instrument capable of acquiring, simultaneously, adaptive optics enhanced scanning laser ophthalmoscopy and optical coherence tomography (OCT) images of the human cone mosaic in vivo. The OCT system is based on transversal scanning of the sample with a line scan rate of 14 kHz, approximately 20 times faster than a previously reported instrument. We demonstrate the capability of this instrument with the measurement of the human cone spacing in perifoveal retina.

Temporal changes of human cone photoreceptors observed in vivo with SLO/OCT

In this study we use our previously introduced scanning laser ophthalmoscope (SLO) / transverse scanning optical coherence tomography (TS-OCT) instrument to investigate long term changes in cone photoreceptors. The instrument is capable to provide 3D information of the human cone photoreceptors with negligible eye motion artifacts due to an implemented 3D motion correction on a cellular level. This allows for an in vivo investigation of exactly the same location on the retina with cellular resolution over several days. Temporal changes in the backscattered intensity are observed and quantified within the junction between inner and outer segments of cone photoreceptors, the cone outer segments, the end tips of cone photoreceptors and the retinal pigment epithelium. Furthermore, the length of individual cone outer segments is measured and observed over time. We show, to the best of our knowledge for the first time, that bright reflection spots which are located within the outer segment of cone photoreceptors change their position when observed over extended time periods. The average measured bright reflection spot motion speed corresponds well to the expected cone growth speed. We believe that this observation can be associated with the first direct in vivo imaging of the cone renewal process.

Value of polarisation-sensitive optical coherence tomography in diseases affecting the retinal pigment epithelium

OBJECTIVES

To evaluate pathological changes of retinal pigment epithelium (RPE) by polarisation-sensitive optical coherence tomography (PS-OCT).

METHODS

Forty-four eyes (22 patients) with significant pathologies of the RPE were evaluated using PS-OCT. A transversal scanning time domain OCT system was used for two-dimensional cross-sectional imaging of retinal polarisation properties.

RESULTS

The RPE scrambles the polarisation state of backscattered light (ie, acts as a depolarising layer), while the polarisation state of transmitted light is maintained. In patients with RPE pathologies irregularity, elevation, thickening or absence of the RPE is readily visualised by exploiting the depolarisation information. Polarisation scrambling in the sensory retina can be found in cases with advanced dry age-related macular degeneration. Sclera and fibrosis show characteristic birefringence in PS-OCT.

CONCLUSION

PS-OCT allows tissue identification based on polarisation scrambling and birefringence, providing additional information on RPE pathologies. It is a promising new tool for diagnosis, disease follow-up and evaluation of new treatment strategies.

Guillain-Barré Syndrome Associated With Zika Virus Infection in Martinique in 2016: A Prospective Study

Background

Guillain-Barré syndrome (GBS) has been reported to be associated with Zika virus (ZIKV) infection in case reports and retrospective studies, mostly on the basis of serological tests, with the problematic cross-reacting antibodies of the Flavivirus genus. Some GBS cases do not exhibit a high level of diagnostic certainty. This prospective study aimed to describe the clinical profiles and the frequency of GBS associated with ZIKV during the ZIKV outbreak in Martinique in 2016.

Methods

We recorded prospective data from GBS meeting levels 1 or 2 of diagnostic certainty for the Brighton Collaboration, with proof of recent ZIKV infection and negative screening for etiologies of GBS.

Results

Of the sample of 34 patients with suspected GBS during the outbreak, 30 had a proven presence of GBS, and 23 had a recent ZIKV infection. The estimated GBS incidence rate ratio (2016 vs 2006-2015) was 4.52 (95% confidence interval, 2.80-7.64; P = .0001). Recent ZIKV infection was confirmed by urine reverse-transcription polymerase chain reaction (RT-PCR) analysis in 17 cases and by serology in 6 cases. Patients, 65% of whom were male, had a median age of 61 years (interquartile range, 56-71 years) and experienced severe GBS. Electrophysiological tests were consistent with the primary demyelinating form of the disease.

Conclusions

ZIKV infection is usually benign, when symptomatic, but in countries at risk of ZIKV epidemics, adequate intensive care bed capacity is required for management of severe GBS cases. Arbovirus RNA detection by RT-PCR should be part of the management of GBS cases.

Retinal nerve fiber layer birefringence evaluated with polarization sensitive spectral domain OCT and scanning laser polarimetry: a comparison

A polarization-sensitive spectral domain optical coherence tomography (PS-SD-OCT) system is used to measure phase retardation and birefringence of the human retinal nerve fiber layer (RNFL) in vivo. The instrument records three parameters simultaneously: intensity, phase retardation and optic-axis orientation. 3D data sets are recorded in the optic nerve-head area of a healthy and a glaucomatous eye, and the results are presented in various ways: En-face phase-retardation maps of the RNFL are generated from the recorded 3D data and results are compared with scanning laser polarimetry (SLP). The depth information provided by OCT is used to segment the RNFL in the intensity image and measure the RNFL thickness. From the retardation and thickness data, 2D birefringence maps of the RNFL are derived. Circumpapillary plots of RNFL retardation and thickness obtained by PS-SD-OCT are quantitatively compared with those obtained by SLP.

Guillain-Barré Syndrome and Chikungunya: Description of All Cases Diagnosed during the 2014 Outbreak in the French West Indies

The Guillain-Barré syndrome (GBS) has been reported as a possible complication of acute chikungunya infection. The chikungunya epidemics, which occurred in Martinique and Guadeloupe in 2014, affected 308,000 people in these two islands. GBS occurred during or immediately after acute chikungunya infection in 13 patients (10 men, three women; mean age: 61 years). Median time from acute chikungunya to GBS onset was 9 days. Twelve patients were treated with intravenous polyvalent immunoglobulins, nine of whom improved within 7 days. Five of 13 patients required mechanical ventilation. Two patients with severe GBS died. At 6 months of follow-up, 7/13 achieved a good functional recovery with no or minor residual symptoms. A 2-fold increase in incidence was observed during the year of chikungunya outbreak. This study supports prior reports suggesting that GBS may be a complication of chikungunya.

Dynamic focus in optical coherence tomography for retinal imaging

Imaging the human retina still represents the main field of application of optical coherence tomography (OCT). A major advantage of OCT is the decoupling of depth resolution (given by the coherence length of the light source) and transverse resolution (given by the focal spot size). This enables images of the retina with high depth resolution. On the other hand, in most OCT systems, a limited transverse resolution has been accepted to provide a sufficiently large (approximately 1 mm) depth of focus. However, to obtain images with high transverse resolution throughout the whole depth of the retina (especially in the nerve head region) a tracking of coherence gate and focus position (dynamic focus) is essential. This study realizes a dynamic focus in a time domain transversal (en face) scanning system for retinal imaging. We show that maintenance of a transverse resolution of approximately 4.4 microm can be achieved over an optical depth of 1 mm in a model eye and apply our method to imaging the human retina in vivo.

Three-beam Doppler optical coherence tomography using a facet prism telescope and MEMS mirror for improved transversal resolution

An improved three-beam Doppler optical coherence tomography system was developed. It utilizes a custom-made three-facet prism telescope to improve the transversal resolution at the sample. Furthermore, a two-axis gimbal-less MEMS mirror is used to minimize off-pivot beam movement at the pupil of the eye, enabling circular scanning for in vivo retinal measurements. We demonstrate the system's abilities for in vitro circular scanning to measure absolute flow and to reconstruct the full velocity vector on a bifurcation flow phantom. Moreover, in vivo retinal measurements using circular scanning around vessel bifurcations of healthy human volunteers were performed. Measurements of the absolute mean flow and its orientation are in good agreement with the expected values for in vitro measurements. For in vivo measurements, the in- and outflow of blood for retinal vessel bifurcations show an excellent agreement, demonstrating the reliability of the technique.

Direct-acting antiviral treatment against hepatitis C virus infection in HIV-Infected patients - "En route for eradication"?

OBJECTIVES

Direct-Acting Antivirals (DAAs) opened a new era in HCV treatment. We report the impact of HCV treatment in French HIV-HCV coinfected patients.

METHODS

All HIV-HCV patients from the Dat'AIDS cohort followed between 2012 and 2015 were included. HCV status was defined yearly as naive, spontaneous cure, sustained virological response (SVR12), failure or reinfection.

RESULTS

Among 32,945 HIV-infected patients, 15.2% were positive for anti-HCV antibodies. From 2012 to 2015, HCV incidence rate increased from 0.35%PY to 0.69%PY in MSM, while median incidence was 0.08%PY in other patients. Median reinfection rate was 2.56%PY in MSM and 0.22%PY in other patients. HCV treatment initiation rate rose from 8.2% in 2012 to 29.6% (48.0% in pre-treated patients vs 22.6% in naïve patients). SVR12 rate increased from 68.7% to 95.2%. By the end of 2015, 62.7% of the patients were cured either spontaneously or following SVR.

CONCLUSIONS

HCV treatment dramatically increased in HIV-HCV patients in France from 2012 to 2015 resulting in HCV cure in nearly two-thirds of the patients in this cohort. Combined with a declining HCV prevalence, the prevalence of active HCV infection among HIV patients will drastically decrease in the forthcoming years.

Transversal ultrahigh-resolution polarizationsensitive optical coherence tomography for strain mapping in materials

Optical coherence tomography (OCT) and its extension, polarization-sensitive (PS-)OCT, are techniques for contactless and nondestructive imaging of internal structures. In this work, we apply PS-OCT for material characterization. We use a transversal scanning, ultra-high resolution (UHR-)PS-OCT setup providing cross-sectional as well as inplane information about the internal microstructure, the birefringence and the orientation of the optical axis within the material. We perform structural analysis and strain-mapping for different samples: we show the necessity of UHR imaging for a highly strained elastomer sample, and we discuss the effect of large birefringence on the PS-OCT images. Furthermore, we investigate high-aspect ratio photoresist moulds for the production of microelectromechanical parts (MEMS), demonstrating that transversal UHR-PSOCT is a promising tool for non-destructive strain-mapping.

Molecular characterization of HIV type 1 in Brazzaville, Republic of Congo, and first data on resistance to antiretroviral drugs

One hundred patients have been enrolled in the CTA (ambulatory treatment center) of Brazzaville, Republic of Congo, from February to April 2011: 41 naive individuals and 59 patients at failure of first line regimen [two nucleoside reverse transcriptase inhibitors (NRTIs) plus one nonnucleoside reverse transcriptase inhibitor (NNRTI)]. Phylogenetic analysis of HIV-1 isolates allowed identification of subtypes and circulating recombinant forms (CRFs). The drug resistance mutations (DRMs) in reverse transcriptase and protease were analyzed in both subpopulations. Globally, 92 viruses were characterized, exhibiting a high diversity of HIV-1 with a majority of undetermined recombinant forms (URF) followed by CRF02_AG, CRF37_cpx, G, A1, B, D, H, and several other subtypes and CRF: F1, A2, C, CRF13_cpx, CRF11_cpx, CRF20_BG, CRF21_A2D, CRF33_01B G, CRF02_AG, CRF37_cpx, and A1. In naive patients, DRMs were observed with percentages ranging from 4% to 9% depending on drug classes. In treated patients at failure, numerous DRMs could be noted that induce actual or potential resistance to major NRTIs and NNRTIs.

Assessing Zika Virus Transmission Within Households During an Outbreak in Martinique, 2015-2016

Since 2015, Zika virus (ZIKV) has caused large epidemics in the Americas. Households are natural targets for control interventions, but quantification of the contribution of household transmission to overall spread is needed to guide policy. We developed a modeling framework to evaluate this contribution and key epidemic features of the ZIKV epidemic in Martinique in 2015-2016 from the joint analysis of a household transmission study (n = 68 households), a study among symptomatic pregnant women (n = 281), and seroprevalence surveys of blood donors (n = 457). We estimated that the probability of mosquito-mediated within-household transmission (from an infected member to a susceptible one) was 21% (95% credible interval (CrI): 5, 51), and the overall probability of infection from outside the household (i.e., in the community) was 39% (95% CrI: 27, 50). Overall, 50% (95% CrI: 43, 58) of the population was infected, with 22% (95% CrI: 5, 46) of infections acquired in households and 40% (95% CrI: 23, 56) being asymptomatic. The probability of presenting with Zika-like symptoms due to another cause was 16% (95% CrI: 10, 23). This study characterized the contribution of household transmission in ZIKV epidemics, demonstrating the benefits of integrating multiple data sets to gain more insight into epidemic dynamics.

Reaching the WHO target of testing persons in jails in prisons will need diverse efforts and resources

Background

The Caribbean is the second most affected region in the world by human immunodeficiency virus (HIV), and HIV prevalence is significantly higher among persons in jails and prisons than in the free population. The aim of our study was to assess the screening rates of HIV, hepatitis B and C, syphilis and human T cell leukaemia virus type 1 among newly-arrived persons in 2014, at Ducos facility in Martinique and the testing process performance.

Methods

This is an observational monocentric study conducted within the prison’s health unit. The study population consisted of all individuals incarcerated between 01/01/14 and 31/12/14. At the initial medical visit, HIV and STI testing were proposed to every newcomer. The rate of acceptance was calculated, as well as the screening process performance.

Results

In 2014 778 new persons were incarcerated, among those, 461 (59.3%) were tested. The main reasons for missing the testing opportunity were due to organization of the judiciary system (persons on electronic monitoring or day parole, transferred or quickly released before completion of the process) or to individual refusal. Finally, 75 persons did not get their results (all of them negative), 41 of them due to the medical staff work overload.

Conclusions

HIV and STI testing rates among newcomers at Ducos have notable room for improvement. The future availability of combined (HIV, HBV, HCV and syphilis) rapid tests may be very useful in case of short term incarceration, if their cost is not prohibitive. Reaching higher levels of testing will also require more resources.

Olfactory outcomes in Zika virus-associated Guillain-Barré syndrome

BACKGROUND

Zika Virus (ZIKV) infection has been associated with Guillain-Barré Syndrome (GBS). Yet, little is known about the consequence of ZIKV infection on olfaction in humans.

METHODS

Just right before the COVID-19 outbreak, we prospectively investigated the olfactory capacities of 19 patients with ZIKV-associated GBS from the French West Indies and compared them to 9 controls from the same population, with a GBS of similar severity but independent of Zika infection. To provide further evidence that ZIKV infection induces smell alteration, we investigated the consequences of ZIKV infection on olfactory abilities using a mouse model.

RESULTS

Patients with GBS-Zika+ had a poorer olfactory function than GBS-non-Zika, even one to two years after the acute phase. The proportion of patients with hyposmia was significantly higher in GBS-Zika+ than in GBS-non-Zika group (68.4% versus 22.2%, P=0.042). These deficits were characterized by lower threshold and identification scores and were independent from GBS severity. Additionally, ZIKV infection was found to impair olfaction in immunodeficient mice infected with ZIKV. High viral load was observed in their olfactory system and downstream brain structures. ZIKV promoted both cellular damages in the olfactory neuroepithelium and protracted inflammation of the olfactory bulb, likely accounting for smell alteration.

CONCLUSIONS

Patients with ZIKV-related GBS had a poorer long-term olfactory function than patients with GBS-non-Zika and ZIKV-infected mice are hyposmic. These observations suggest that ZIKV belongs to the list of viruses affecting the olfactory system. Clinical evaluation of the olfactory system should be considered for ZIKV-infected patients.

The effects of chikungunya virus infection on people living with HIV during the 2014 Martinique outbreak

Our objective was to describe the clinical presentation of chikungunya virus (CHIKV) infection in patients living with HIV (PLHIV) during the 2014 Martinique outbreak. During the outbreak and the 6 following months, all PLHIV coming in our unit for a medical evaluation answered questions about potential CHIKV related symptoms, and had blood tests to assess the diagnosis. For patients coming in at the acute phase of infection, we are able to provide and analyze CD4+, CD8+ T-cells and HIV viral load evolution before, during and after CHIK infection. Among the 1 003 PLHIV in care in the center at the time of the outbreak, 188 (94 men and 94 women) had confirmed (following the WHO definition) CHIKV infection. Clinical presentation was common in 63% of the cases, severe and atypical forms were scarce. During the acute phase, CD4+ and CD8+ T-cells (evaluated in 30 PLHIV, 15 men and 15 women) absolute numbers dropped significantly, but returned to pre-CHIKV values after the acute phase. Reassuringly, CD4 and CD8 T cells proportions did not decrease during the acute phase. CHIKV infection had no significant impact on this anti-retroviral treated population.

New Surge of Syphilis among Patients Living with Human Immunodeficiency Virus in Martinique in 2015

A syphilis outbreak began in Martinique, French Antilles, in 2004, initially among men who had sex with men (MSM) and who were living with human immunodeficiency virus (HIV). The outbreak subsequently affected all groups at risk, leading to a first epidemic peak in 2008. After an initial decrease, the outbreak started growing again in 2014 among patients living with HIV with unprecedented incidence among MSM. Herein, we describe the change in medical and social parameters of the outbreak since 2005.

Birefringence properties of the human cornea measured with polarization sensitive optical coherence tomography

We map the three-dimensional distribution of birefringence of the normal human cornea and provide insight into structures and mechanisms causing corneal birefringence, establishing standard patterns of 3D birefringence distribution. A polarization sensitive optical coherence tomography (PS-OCT) system was developed that allows measurement and imaging of three tissue parameters simultaneously: reflectivity, retardation, and slow optic axis orientation. This instrument was used to obtain 3D PS-OCT data sets of normal human corneas in vitro. From the 3D data sets, conventional cross sectional, as well as en face images of reflectivity, retardation, and optic axis orientation were derived. Preliminary results from a healthy cornea in vivo and a keratoconus cornea in vitro are also presented. In transversal direction the retardation distribution of the normal cornea has a radially symmetric shape; retardation is lowest at the center of the cornea and increases towards the periphery. At peripheral regions, retardation also increases with depth. The distribution of the optic axis is not constant with the parallel illumination scheme used. Optic axis orientation is an approximately linear function of azimuth angle, however, if averaged over the entire cornea, a preferential optic axis orientation is observed. In a keratoconus cornea, the normal birefringence pattern is heavily distorted. The results provide additional insight into corneal birefringence as compared to published work where corneal birefringence is usually averaged over a larger area. The results can be explained by a birefringence model based on stacked collagen fibril lamellae of different orientations. The observed birefringence patterns in normal corneas might be used as standard patterns for comparisons with pathologic changes.