Folded interferometer to measure coherence-polarization matrix.

We present and experimentally demonstrate a new, to the best of our knowledge, technique to quantitatively measure coherence-polarization (BCP) matrix with correlations of only two Stokes fluctuations. The BCP matrix is a square matrix with four elements that involves two-point correlations among orthogonal polarization components. A theoretical framework of the technique is developed, and its viability is demonstrated by a proof of principle experiment. Experimental tests and measurement of the elements of the BCP matrix of statistically stationary beams are demonstrated.

Detecting topological index of randomly scattered V-point singularities using Stokes correlations.

Topological defects in vector fields constitute polarization singularities that have numerous applications in classical and quantum optics. These beams are inhomogeneously polarized and are shown to self-heal under symmetric amplitude perturbations. Polarization singular beams are characterized using a singularity index that can be detected using Stokes polarimetry or other interferometric and diffraction approaches. However, the information about the singularity index is lost when these beams travel through random scattering media; this results in a spatially fluctuating polarization pattern known as polarization speckle. This paper proposes and experimentally demonstrates a new method to detect the topological index of these randomly scattered V-point singularities using higher-order Stokes correlations in a lensless condition. A detailed theoretical basis is developed, and the performance of the technique is demonstrated by retrieving the signature of polarization singularities with Poincaré-Hopf index |η|=1 and |η|=2. We also demonstrate that by studying the intensity-intensity correlations of the polarization speckle, it is possible to differentiate between different vector beams having the same magnitude as the Poincaré-Hopf index.

Optical Coherence Tomography Angiography Parameters in Indian Patients With Central Serous Chorioretinopathy.

Background In this study, we aimed to evaluate optical coherence tomography angiography (OCTA) parameters among Indian patients affected with central serous chorioretinopathy (CSCR). Methodology A cross-sectional study on Indian patients having unilateral or bilateral affection with CSCR was conducted at the Department of Ophthalmology, Guru Nanak Eye Centre, and Maulana Azad Medical College, New Delhi. A history of ocular symptoms such as a diminution of vision, metamorphopsia, decreased contrast sensitivity (CS), and defective color vision (CV) and their duration were obtained. A detailed ocular examination for best-corrected visual acuity (BCVA), intraocular pressure (IOP), CV, and CS was done. Following this, fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed. OCT was done for central foveal thickness (CFT), subfoveal choroidal thickness (SFCT), neurosensory detachment (NSD), pigment epithelial detachment (PED), and choroidal neovascular membranes (CNVMs). The OCTA imaging was done to examine the foveal avascular zone (FAZ) size, perimeter and circularity, vessel density (VD), and features such as enlarged/distorted FAZ, dark areas, dark spots, abnormal vessels, and choriocapillaris island (CCI) in the retino-choroidal layers. We compared the OCTA features of affected eyes with those of fellow eyes. Results The study involved 52 eyes of 40 CSCR patients, including 32 (80%) males and eight (20%) females with a mean age of 39.3 ± 6.1 (24-49) years. Of the 40 patients, 12 (30%) had a bilateral involvement. The mean CFT was 300.3 ± 158.4 µ, and the SFCT was 258.5 ± 60.4 µ. The mean distance BCVA was the logarithm of the minimum angle of resolution (logMAR) 0.58 ± 0.32. The OCTA showed features such as enlarged/distorted FAZ (36.53% eyes), dark areas (NSD/PED) (84.61% eyes), dark spots (PED) (5.76% eyes), abnormal vessels (dilated vessels/CNVM) (96.15% eyes), and CCI (17.30% eyes). The mean FAZ area, perimeter, and circularity were 0.40 ± 0.71 mm2, 41.8 ± 280.0 mm, and 0.48 ± 0.12, respectively. The VD in the superficial capillary plexus (SCP) was 25.4 ± 14.1, deep capillary plexus (DCP) 15.0 ± 11.5, outer retina (OR) 5.9 ± 6.8, outer retinal choriocapillaris (ORCC) 33.7 ± 16.9, choriocapillaris 29.7 ± 17.5, and choroid 29.9 ± 17.5. The fellow eyes showed a mean FAZ area, perimeter, and circularity of 0.34 ± 0.23 mm2, 76.8 ± 391.2 mm, and 0.47 ± 0.11, respectively, while VD of SCP was 25.9 ± 13.6, DCP 16.5 ± 11.7, OR 14.3 ± 14.9, ORCC 38.0 ± 16.5, choriocapillaris 36.3 ± 17.7, and choroid 35.5 ± 19.2. Conclusions The CSCR eyes had a thicker fovea and sub-foveal choroid (SFC). The FAZ area of affected eyes was larger, while the perimeter was smaller than that in the fellow eye. In the affected eye, the VD in all the retino-choroidal layers was lower, although it was significantly reduced in OR whole (p = 0.006) and foveal choroid (p = 0.022).

Synthesis of copper-reduced graphene oxide nanomaterials using glucose and study of its antibacterial and anticancer activities.

In this work, glucose-capped copper nanoparticles decorated reduced graphene oxide nanomaterial are synthesized at 100 °C and 200 °C via chemical reduction method and studied for their antibacterial and anticancer activities. Synthesized nanomaterials were characterized using x-ray diffraction, Fourier-transform infrared, transmission electron microscope, and RAMAN. It is observed in transmission electron microscopy and selected area electron diffraction studies that copper nanoparticles deposited onto reduced graphene oxide are smaller than nanoparticles generated in the absence of reduced graphene oxide. Also, the size of copper nanoparticles synthesized at 200 °C is smaller than at 100 °C. Results suggest that Cu/Glu/rGO synthesized at both temperatures showed significant antibacterial activity againstEscherichia coliandBacillus anthracis,similarly, showed significant cell death in cancer cell lines [Cal33 and HCT-116 p53 (+/+)]. Interestingly, the nanomaterials were seen to be more effective against the cancer cell lines harboring aggregating mutant p53. Tumors with aggregating mutants of p53 are difficult to treat hence, Cu/Glu/rGO can be promising therapeutic agents against these difficult cancers. However, the antibacterial and anticancer activity of Cu/Glu/rGO synthesized at 100 °C where Cu2O form is obtained was found to be more effective compared to Cu/Glu/rGO synthesized at 200 °C where Cu form is obtained. Though fine-tuning of the material may be required for its commercial applications.

Color perception on Ishihara plates with red lenses in subjects with low vision due to retinal diseases.

Purpose: This study aimed to evaluate color perception (CP) changes on Ishihara plates following red-tinted contact lenses in subjects with low vision (LV) from retinal diseases. Methods: A cross-sectional observational study without control involved 84 subjects, aged 20-70 years, having LV from retinal diseases to examine CP changes following wearing red-tinted contact lenses. The subjects viewed Ishihara plates, with each eye separately, before and after wearing red lenses in two categories: "plates 1-21" and "plates 22-25". Change in CP with the use of a red lens was the primary outcome measure. Results: There was a significant increase in the number of plates read in both categories, that is, plates 1-21 (P = 0.002) and plates 22-25 (P = 0.032), the latter being used to diagnose the red-green defects. Although 70 eyes could read both digits on plates 22-25 and appeared to have normal color vision (CV) at baseline, this number rose to 99 eyes following the use of red-tinted lenses. There was a significant change in the type of CP (red defect/green defect/normal/undefined defect) (P = 0.022) with the application of a red-tinted lens. Conclusions: The use of red-tinted lenses caused a significant increase in the number of plates read, increased the number of subjects who appeared normal on plates 22-25, and significantly changed CP of LV subjects. These lenses can be a valuable aid for LV subjects. Although Ishihara plates can diagnose only red-green defects, further studies on CV testing techniques that detect both red-green and blue-yellow CV defects are recommended.

The Association of Neovascularization With Optical Coherence Tomography Angiography Parameters in Proliferative Diabetic Retinopathy.

AIM: We aim to find an association between neovascularization (NVn) and optical coherence tomography angiography (OCTA) parameters in proliferative diabetic retinopathy (PDR). METHODS: In a prospective study, 41 subjects including 28 (68%) males and 13 (32%) females having PDR were examined for neovascularization disc (NVD) and neovascularization elsewhere (NVE) clinically and with fundus fluorescein angiography (FFA). A total of 79 eyes were found to be involved. We examined OCTA parameters including foveal avascular zone (FAZ) size, perimeter and circularity, and vessel density (VD) in the superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retina (OR), outer retinal chorio-capillaries (ORCC), chorio-capillaries (CC), and choroid (C) in these subjects. RESULTS:  In eyes with NVD, the central foveal thickness (CFT) (p=0.83) and sub-foveal choroidal thickness (SFCT) (p=0.08) were higher, the FAZ area was significantly larger (p=0.005), and the VD was lower in all retino-choroidal layers. However, it was significantly lower in SCP foveal (p=0.005) and ORCC foveal (p=0.05) than in eyes not having NVD. For NVE, the CFT (p=0.03) and SFCT (p=0.01) were more in affected eyes. The eyes without NVE had a better circularity index (p=0.07) and the highest VD in OR slab (p=0.02) than those eyes that had NVE < ½ disc area (DA) and NVE > ½ DA. On comparing eyes without NVE, NVE < ½ DA, and NVE > ½ DA, the latest had the highest VD in SCP (p=0.59) and lowest VD in DCP (p=0.43) and OR (p=0.02). The VD in ORCC, CC, and choroid was highest in the no NVE group, followed by the NVE > ½ DA and NVE < ½ DA groups in that order. The subjects having vitreous hemorrhage (VH) and intra-retinal microvascular abnormalities (IRMA) had higher values for CFT and SFCT than eyes without these. CONCLUSIONS:  An increased CFT and SFCT are associated with the appearance of NVD, NVE, VH, and IRMA. The presence of NVD, VH, and IRMA is associated with a larger FAZ area, while that of IRMA and NVE is associated with reduced FAZ circularity. Eyes with NVD, VH, and IRMA had lesser VD in all the retino-choroidal layers. Eyes with NVE > ½ DA had the highest VD in SCP and lowest in DCP and OR; this pattern of VD foretells severer affection in NVE. IRMA was associated with a larger FAZ area, larger FAZ perimeter, and lesser circularity, indicating the presence of central ischemia.

Evaluating the Quantitative Foveal Avascular Zone and Retino-Choroidal Vessel Density Using Optical Coherence Tomography Angiography in a Healthy Indian Population.

OBJECTIVE: The foveal avascular zone (FAZ) is the round capillary-free zone within the macula and is supplied only by a single-layered parafoveal capillary arcade. This study aimed to evaluate the quantitative FAZ and retino-choroidal vessel density (VD) using optical coherence tomography angiography (OCTA) in a healthy Indian population. METHODS: This was a cross-sectional observational study that was conducted for evaluating the quantitative FAZ and retino-choroidal VD of 200 eyes of 100 healthy Indian subjects, including 62 males and 38 females (age range 17-50 years) having the best-corrected visual acuity (BCVA) of logMAR 0 (20/20; 6/6) and spherical equivalent refractive error of not more than 1 D. The subjects were examined using OCTA automated software on spectral-domain OCT (SD-OCT; Nidek RS 3000 Advance 2; Nidek, Inc., Fremont, CA) on a 3 x 3 mm OCTA macular scan centred on the fovea. The FAZ size, perimeter and circularity index, VD in superficial, deep, and outer retina (OR), outer retinal chorio-capillaries (ORCC), chorio-capillaries (CC) and choroid (C) were analysed in the circular and quadrant-segmented zones. A correlation was found between the FAZ size, perimeter and circularity, and VD in retino-choroidal layers, and between BCVA, age, central foveal thickness (CFT) and sub-foveal choroidal thickness (SFCT), and OCTA parameters. RESULTS: The FAZ and surrounding vascular arcades were intact in all eyes, showing either a vertical or horizontal oval-shaped symmetrical formation without gaps, holes or interruption of the capillary network. The mean value of CFT was 237.5±26.0 microns and SFCT was 269.6±53.0 microns. The mean FAZ area was 0.42±0.23 mm2, FAZ perimeter was 3.3±1.0 mm and FAZ circularity index was 0.46±0.1. The mean VD in superficial capillary plexus (SCP) was 23.87±10.66, in deep capillary plexus (DCP) was 16.03±9.90, in OR was 13.22± 12.27, in ORCC was 39.74±14.32, in CC was 37.02±16.43 and in choroid was 37.43±16.76. The increasing order of VD in different retino-choroidal layers was OR

Assessing contrast sensitivity change in retinal diseases with use of yellow-amber NoIR glasses.

Purpose: The purpose of this study was to assess change of contrast sensitivity (CS) in subjects having retinal diseases with yellow-amber no infrared (NoIR) glasses used as low vision aid (LVA). Methods: We examined CS in 82 low vision (LV) subjects having retinal diseases with Pelli Robson Chart at 1 m distance before and after wearing yellow-amber NoIR glasses. We also found type of retinal affection and macular optical coherence tomography (OCT) features. Results: The distance and near best-corrected visual acuity (BCVA) was, respectively, 0.68 ± 0.17 (median = 0.70) and 0.72 ± 0.25 (median = 0.70) logmar units. The pre-LVA CS was 0.52 ± 0.29 (median = 0.3) and post- LVA was 0.52 ± 0.28 (median = 0.45) logunits (mean reduction = -0.002 ± 0.24; Median reduction = 0; P = 0.909). The pre-LVA and post-LVA CS showed a negative correlation with logmar distance BCVA [r = -0.090; P = 0.317 and r = -0.152; P = 0.090 respectively]. The pre-LVA and post-LVA CS showed a negative correlation with logmar near BCVA [r = -0.114; P = 0.207 and r = -0.054; P = 0.549 respectively]. The CS did not improve in subjects having macular degeneration, pathological myopia, hereditary maculopathy, and diabetic retinopathy. The macular OCT features like fluid, exudates, scars, drusens, traction, and hole did not significantly influence CS both at pre-LVA and post-LVA stage. Conclusion: This is the first study with yellow-amber NoIR glasses which blocks "both ultraviolet and infrared light." The subjects having macular degeneration, pathological myopia, hereditary maculopathy, and diabetic retinopathy did not improve in CS with filters. The correlation values showed that filters may improve CS in subjects having good baseline BCVA.

Ocular sequelae in severe COVID-19 recovered patients of second wave.

Purpose: To evaluate the retinal microvascular changes in patients, recovered from severe COVID-19 during the second wave of the pandemic in North India. Methods: In this observational cross-sectional study, 70 eyes of 35 patients who recovered from severe COVID-19 during the second wave underwent detailed ophthalmic evaluation 4-6 weeks after discharge. Twelve controls were also enrolled, and the difference in the findings between the case and control groups on optical coherence tomography (OCTA) were studied. Result: The ages of study participants ranged from 27 to 60 years with the male:female ratio being 1.05:1. The fundus changes suggestive of ischemia in the form of cotton wool spots and vascular tortuosity were seen in 25 eyes (35.71%). Increased venous tortuosity was the most common finding seen in 23 eyes (32.85%), of which 10 eyes (28.57%) had concurrent hypertensive retinopathy (HTR) changes. There was a significant reduction in the mean vascular density (VD) and perfusion density (PD) for both the superficial capillary plexus (SCP) and deep capillary plexus (DCP) at inner, outer ring, and whole (P < 0.05). Foveal avascular zone was significantly enlarged in both the SCP (P = 0.01) and the DCP (P = 0.03). The mean ganglion cell-inner plexiform layer (GC-IPL) was significantly reduced in comparison to controls (P < 0.001). Conclusion: Severe COVID-19 can result in microvascular changes at the macula in the form of reduction in vascular and perfusion density, which can be evaluated using OCTA. As structural changes precede functional changes, a close watch is recommended in patients showing compromise in retinal microvasculature.

Surgical outcome after focused parathyroidectomy: experience from a tertiary care centre in North India.

<b style="color: #075541"> Introduction:</b> Focused parathyroidectomy is the gold standard treatment for primary hyperparathyroidism (PHPT) due to single gland disease with a comparable success rate as that of conventional four gland exploration. It is also associated with fewer surgical complications. Despite these benefits, there is still controversy about the high recurrence following the focused approach. </br> </br> <b style="color: #075541">Aim:</b> The aim was to analyse our experience regarding the success rate of focused parathyroidectomy for PHPT. </br> </br> <b style="color: #075541">Methods:</b> This was a retrospective analysis of 192 patients of PHPT between January 2017 and August 2020 who underwent focused parathyroidectomy without intraoperative parathormone analysis, and had a minimum follow up of six months. Demographic profile, biochemical (pre and postoperative), radiological, operative and histological detail of all patients were recorded. Parathyroidectomy was considered curative if the patient maintained normal serum calcium and parathormone (PTH) levels six months after surgery. Persistent hyperparathyroidism was considered if hypercalcemia or high PTH levels persisted, or recurrent disease when a patient had rising serum calcium and / or PTH levels six months after curative parathyroidectomy. </br> </br> <b style="color: #075541">Results:</b> No patient had pain and wound-related complications after parathyroidectomy. Two patients had voice change in the immediate postoperative period which recovered subsequently; no patient had documented vocal cord paralysis. The persistent disease was present in two patients; both required neck exploration. Five patients had recurrence of PHPT within six months of parathyroidectomy; all of them had hyperplasia on the final biopsy. The overall cure rate was 97.92%. </br> </br> <b style="color: #075541">Conclusion:</b> Therefore, we propose focused surgery for sporadic PHPT should be considered as a preferred treatment with acceptable recurrence rate and surgical complications.</br> </br> <b style="color: #075541">KEYWORDS:</b>focused parathyroidectomy, parathyroidectomy, primary hyperparathyroidism.

Role of improved distance and near visual acuity with low vision aids to enhance stereopsis in retinal diseases.

Purpose: The purpose of this study was to examine role of improved distance and near best-corrected visual acuity (DBCVA and NBCVA) with use of magnification devices to enhance stereopsis in low vision (LV) subjects having retinal diseases. Methods: In a cross-sectional observational study without control, 84 subjects having LV due to retinal diseases were examined for an improvement of BCVA with use of magnifying low vision aids (LVAs) (2X for DBCVA and 3X for NBCVA). The stereopsis scores on titmus fly test were recorded with near refractive correction "on" and then with 3X magnification. The improvement in stereopsis for distance was however estimated through statistical correlation values. Results: The DBCVA (P < 0.001), NBCVA (P < 0.001) and stereopsis (P < 0.001) improved statistically significantly (SS) following magnifying LVA. There was no correlation between pre-LVA stereopsis and pre-LVA DBCVA (r = 0.059; P = 0.444;NSS) and post-LVA DBCVA (r = 0.054; P = 0.487;NSS); and no correlation between post-LVA stereopsis and pre-LVA DBCVA (r = 0.042; P = 0.592;NSS) and post-LVA DBCVA (r = 0.08; P = 0.920;NSS). There was no correlation between pre-LVA stereopsis and pre-LVA NBCVA (r = 0.044; P = 0.572;NSS) and no correlation between post-LVA stereopsis and pre-LVA NBCVA (r = 0.108; P = 0.165;NSS). But positive correlation between pre-LVA stereopsis and post-LVA NBCVA (r = 0.347; P < 0.001) and between post-LVA stereopsis and post-LVA NBCVA (r = 0.445; P < 0.001) was SS. Conclusion: The use of magnification as LVA improves both the BCVA and stereopsis. The increase in DBCVA with LVA improves the stereopsis for distance though it may not be SS while improvement in NBCVA with LVA enhances stereopsis for near objects in SS manner.

Role of Bisphosphonates in The Prevention of Postoperative Hungry Bone Syndrome in Primary Hyperparathyroidism: A Meta-Analysis and Need for Randomized Controlled Trials.

Dear Editor,Hungry bone syndrome (HBS) is a clinico-biochemical entity characterized by the development of profound and prolonged hypocalcemia associated with hypophosphatemia, hypomagnesemia, and rising alkaline phosphatase which follows curative parathyroidectomy for severe primary and secondary hyperparathyroidism. The prevalence of HBS after parathyroidectomy in primary hyperparathyroidism (PHPT) is variable with several case series from Asia reporting remarkably higher prevalence rates of 24-87% 1.

Evaluating the effect of strengthening nurse midwifery pre-service education in two Indian states: A single group pre - and post - intervention study.

BACKGROUND: The high focus states of India have higher maternal and neonatal mortality rates as compared to the national average. The quality of pre-service education (PSE) in nursing midwifery institutions in these states was found to be suboptimal. In 2013, Government of India implemented the PSE strengthening program across all public sector nursing midwifery institutions. The program focused on strengthening educational processes, training infrastructure, institutional management and clinical site practices by implementing a set of performance standards. OBJECTIVE: To evaluate the effect of PSE strengthening program on institutional performance and maternal neonatal health (MNH) related competences of nursing midwifery students and faculty. DESIGN: Single group pre-post intervention study. SETTINGS: 15 sampled public sector nursing midwifery institutions in the states of Madhya Pradesh and Odisha, India. PARTICIPANTS: Final-year students and faculty involved in teaching MNH subjects. METHODS: Performance of 15 sampled institutions was assessed at baseline, midline and endline using the performance standards. Additionally, competences of 232, 295 and 298 students and 64, 62 and 63 faculty members at baseline, midline and endline respectively were assessed on six MNH related practices using objective structured clinical examination (OSCE). RESULTS: None of the institutions met 70% standards during baseline. At endline, 13 of the 15 institutions met these standards. The mean OSCE scores of students and faculty at baseline was 17.1 (SD: 8.0) and 23.5 (SD: 14.3) out of 76 respectively. It significantly increased to 66.4 (SD: 8.0) and 71.1 (SD: 5.2) during the endline. The proportion of students and faculty found competent (achieved 75% in OSCE) also significantly increased from none at baseline to 91% and 98% respectively, at endline. CONCLUSION: The combination of attributes included in the PSE strengthening program may have contributed to improvements in institutional performance as well as MNH related competences of nursing midwifery students and faculty.

Prevalence of abdominal obesity in non-obese adolescents: a North Indian adolescent study.

Context Childhood obesity is defined based on body mass index (BMI) criteria. Asian adults have more abdominal adiposity as compared to Western people for an equivalent BMI. Similarly, children who are non-obese/overweight by BMI criteria may have abdominal obesity. It is important to identify and target this population to reduce future cardiovascular risk. Objective To evaluate and inter-relate the prevalence of obesity subtypes (generalized and abdominal) in school going adolescents. Methods A randomized cross-sectional community based study was conducted, which was carried out in 13 schools of Chandigarh, a North Indian city. 10,037 school going adolescents of age 10-18 years were evaluated. Results The prevalence of overweight and generalized obesity in present study was 9.3 and 4.9% respectively. Generalized obesity was observed in 4.2% of males and 5.7% of females (p-Value = 0.001). The abdominal obesity was noted in 5.4% of children and its prevalence increased progressively with age. The prevalence was highest in 16-18 years age-group (7.6%, p<0.001). 39.3% of abdominally obese subjects were not obese by BMI criteria, while prevalence of abdominal obesity in nonobese adolescents was 2.24%. It was more prevalent in females (3.7%) than males (3%, p=0.025). Prevalence of obesity was 7.9 and 1.8% in private and government schools respectively (p<0.001). Conclusions Abdominal obesity is more prevalent than generalized obesity and shows increasing trend with age. Interestingly, over one third of centrally obese adolescents are not obese by BMI criteria. This underlines the importance of waist circumference measurement in addition to BMI while assessing obesity.

Simple virilising congenital adrenal hyperplasia in monozygotic twins: A rare report and review of previous cases.

Congenital adrenal hyperplasia (CAH) occurring in twins is extremely rare. Most of these cases are of classic salt-wasting CAH due to 21-hydroxylase enzyme deficiency. Only two cases of the simple virilising form of CAH have been reported previously, with variable clinical presentations. In this report, we describe a pair of monozygotic twins with classic simple virilising form of CAH, who had a simultaneous onset and similar severity of clinical manifestations. Genetic analysis of the CYP21A2 gene in twin 1 showed the pres-ence of two heterozygous pathogenic sequence variants, c.518T>A and c.955C>T in the CYP21A2 gene, consistent with a diagnosis of CAH due to 21-hydroxylase deficiency. We also present a brief review of previous cases of twins with CAH.