MRI and Clinical Biomarkers Overlap between Glaucoma and Alzheimer's Disease

Glaucoma is the leading cause of blindness worldwide. It is classically associated with structural and functional changes in the optic nerve head and retinal nerve fiber layer, but the damage is not limited to the eye. The involvement of the central visual pathways and disruption of brain network organization have been reported using advanced neuroimaging techniques. The brain structural changes at the level of the areas implied in processing visual information could justify the discrepancy between signs and symptoms and underlie the analogy of this disease with neurodegenerative dementias, such as Alzheimer's disease, and with the complex group of pathologies commonly referred to as "disconnection syndromes." This review aims to summarize the current state of the art on the use of advanced neuroimaging techniques in glaucoma and Alzheimer's disease, highlighting the emerging biomarkers shared by both diseases.

Biochemical-molecular-genetic biomarkers in the tear film, aqueous humor, and blood of primary open-angle glaucoma patients

Introduction

Glaucoma is a chronic neurodegenerative disease, which is the leading cause of irreversible blindness worldwide. As a response to high intraocular pressure, the clinical and molecular glaucoma biomarkers indicate the biological state of the visual system. Classical and uncovering novel biomarkers of glaucoma development and progression, follow-up, and monitoring the response to treatment are key objectives to improve vision outcomes. While the glaucoma imaging field has successfully validated biomarkers of disease progression, there is still a considerable need for developing new biomarkers of early glaucoma, that is, at the preclinical and initial glaucoma stages. Outstanding clinical trials and animal-model study designs, innovative technology, and analytical approaches in bioinformatics are essential tools to successfully uncover novel glaucoma biomarkers with a high potential for translation into clinical practice.

Methods

To better understand the clinical and biochemical-molecular-genetic glaucoma pathogenesis, we conducted an analytical, observational, and case-comparative/control study in 358 primary open-angle glaucoma (POAG) patients and 226 comparative-control individuals (CG) to collect tears, aqueous humor, and blood samples to be processed for identifying POAG biomarkers by exploring several biological pathways, such as inflammation, neurotransmitter/neurotrophin alteration, oxidative stress, gene expression, miRNAs fingerprint and its biological targets, and vascular endothelial dysfunction, Statistics were done by using the IBM SPSS 25.0 program. Differences were considered statistically significant when p ≤ 0.05.

Results

Mean age of the POAG patients was 70.03 ± 9.23 years, and 70.62 ± 7.89 years in the CG. Malondialdehyde (MDA), nitric oxide (NO), interleuquin (IL)-6, endothelin-1 (ET-1), and 5 hydroxyindolacetic acid (5-HIAA), displayed significantly higher levels in the POAG patients vs. the CG (p < 0.001). Total antioxidant capacity (TAC), brain derived neurotrophic factor (BDNF), 5-hydroxy tryptamine (5-HT), solute carrier family 23-nucleobase transporters-member 2 (SLC23A2) gene, and the glutathione peroxidase 4 (GPX4) gene, showed significantly lower levelsin the POAG patients than in the CG (p < 0.001). The miRNAs that differentially expressed in tear samples of the POAG patients respect to the CG were the hsa miR-26b-5p (involved in cell proliferation and apoptosis), hsa miR-152-3p (regulator of cell proliferation, and extracellular matrix expression), hsa miR-30e-5p (regulator of autophagy and apoptosis), and hsa miR-151a-3p (regulator of myoblast proliferation).

Discussion

We are incredibly enthusiastic gathering as much information as possible on POAG biomarkers to learn how the above information can be used to better steer the diagnosis and therapy of glaucoma to prevent blindness in the predictable future. In fact, we may suggest that the design and development of blended biomarkers is a more appropriate solution in ophthalmological practice for early diagnosis and to predict therapeutic response in the POAG patients.

Combined use of coenzyme Q10 and citicoline: A new possibility for patients with glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Several risk factors have been involved in the pathogenesis of the disease. By now, the main treatable risk factor is elevated intraocular pressure. Nevertheless, some patients, whose intraocular pressure is considered in the target level, still experience a progression of the disease. Glaucoma is a form of multifactorial ocular neurodegeneration with complex etiology, pathogenesis, and pathology. New evidence strongly suggests brain involvement in all aspects of this disease. This hypothesis and the need to prevent glaucomatous progression led to a growing interest in the pharmacological research of new neuroprotective, non-IOP-lowering, agents. The aim of this paper is to report evidence of the usefulness of Coenzyme Q10 and Citicoline, eventually combined, in the prevention of glaucomatous neurodegeneration.

Optical coherence tomography angiography in the multimodal assessment of the retinal posterior pole in autosomal dominant optic atrophy

PURPOSE

To assess retinal vascular involvement in patients with autosomal dominant optic atrophy (ADOA) genetically confirmed by the presence of the OPA1 (Optic Atrophy 1) gene mutation using a multimodal protocol of investigation of retinal posterior pole.

METHODS

In this cross-sectional, case-control, observational study, both eyes of 13 patients with a genetic diagnosis of ADOA were compared with both eyes of 13 healthy controls (HCs). All subjects underwent full ophthalmological examination, spectral domain-optical coherence tomography (SD-OCT), fundus perimetry (FP) and OCT angiography (OCTA).

RESULTS

Vessel density (VD) of the superficial and deep macular vascular plexi and of the radial peripapillary capillary plexus were significantly decreased (p ≤ 0.001) in ADOA patients compared with HCs. The area under the receiver operating characteristics analysis also revealed high values of sensitivity and specificity of OCTA parameters in distinguish between patients and HCs. A strong correlation (Pearson Coefficient, r = 0.91) emerged between OCTA VD of the superficial retinal plexus and the average Ganglion Cell Layer (GCL) thickness as measured by SD-OCT; a slightly lower correlation (Pearson Coefficient, r = 0.89) was also found between VD of the deep plexus and the average GCL thickness of the same eyes in patients with ADOA. The correlation among values of differential light sensitivity (DLS) measured by FP with VD and GCL thickness parameters was also investigated. The correlation analysis among DLS and the VD parameters showed from low-to-moderate correlation (ranging from r = 0.29 for the deep fovea VD to r = 0.59 for the deep whole image VD). The correlation coefficient between the mean DLS and the average thickness of GCL was more significant (Pearson Coefficient, r = 0.75). A significant correlation emerged also between the VD and the visual acuity, in terms of LogMAR BCVA (best-corrected visual acuity), especially for the VD of the deep capillary plexus (Pearson Coefficient for the Deep whole Image VD and LogMAR BCVA r = -0.75; for the Deep parafovea VD and LogMAR BCVA r = -0.78).

CONCLUSION

Retinal microvascular assessment by OCTA angiography can provide relevant clinical information on retinal involvement in ADOA patients. In patients with genetically confirmed OPA1-related ADOA, there is a decrease in retinal vessel density associated with GCL thinning and DLS reduction.

Evaluation of putative differences in vessel density and flow area in normal tension and high-pressure glaucoma using OCT-angiography

PURPOSE

To evaluate the putative differences in terms of vessel density and flow area between control (CTRL), high-pressure glaucoma (HPG) and normal tension glaucoma (NTG) subjects at macular and peripapillary level. To assess the correlation between Visual Field Index (VFI), the stage of glaucoma, and optical coherence tomography angiography (OCT-A) parameters.

MATERIAL AND METHODS

In this pilot, prospective study 46 eyes of 46 glaucomatous patients (19 NTG+27 HPG) and 25 control eyes (CTRL) of 25 subjects were recruited. All patients underwent a complete ophthalmologic examination and visual field testing. A 3×3mm volumetric macular scan (Angio Retina [3.0]) and a 4.5×4.5mm diameter peripapillary scan (Angio Disc [4.5]) were performed in the right eye using RTVue-XR Avanti (Optovue, Inc.) OCT-A.

RESULTS

Groups were homogeneous for age (P=0.784) and gender (P=0.623). Among the evaluated optic nerve head (ONH) and macular OCT-A parameters, ONH whole image (P<0.001), inside disc (P=0.021), peripapillary (P<0.001), ONH flow area (P<0.026), macula whole image (P<0.001), fovea (P<0.001), parafovea (P<0.001) showed a significant difference when CTRL group was compared to HPG group at the post hoc test. Similarly, ONH whole image (P<0.001), inside disc (P=0.005), peripapillary (P<0.001), ONH flow area (P<0.026), macula whole image (P<0.001), FOVEA (P<0.001), parafovea (P<0.001) showed a significant difference were CTRL were compared to NTG group. On the contrary, no significant difference was found when NTG and HPG groups were compared. Age was not significantly correlated with any of the OCT-A parameters. The stage of the disease showed a high, significant, correlation with ONH whole image (r=-0.81; P<0.0001), inside disc (r=-0.42; P<0.0001), peripapillary (r=-0.81; P<0.0001), RNFL (r=-0.79; P<0.0001), macula whole image (r=0.56; P<0.0001), fovea (r=-0.78; P<0.0001) and parafovea (r=0.67; P<0.0001). On the contrary, VFI showed a high, significant, correlation with ONH whole image (r=0.77; P<0.0001), inside disc (r=0.39; P=0.0018), peripapillary (r=0.713; P<0.0001), RNFL (r=0.63; P<0.0001), macula whole image (r=-0.39; P=0.0007), fovea (r=0.60; P<0.0001) and parafovea (r=-0.52; P<0.0001).

CONCLUSIONS

Our data support the usefulness of the OCT-A in the common clinical practice for diagnosis, staging, evaluating the progression of the disease as well as for better understanding of its pathogenic mechanisms.

Complex Rearrangement of the Entire Retinal Posterior Pole in Patients with Relapsing Remitting Multiple Sclerosis

There are consolidated data about multiple sclerosis (MS)–dependent retinal neurodegeneration occurring in the optic disk and the macula, although it is unclear whether other retinal regions are affected. Our objective is to evaluate, for the first time, the involvement of the entire retinal posterior pole in patients diagnosed with relapsing remitting multiple sclerosis (RRMS) unaffected by optic neuritis using Spectral Domain–Optical Coherence Tomography (SD–OCT). The study protocol was approved by Tor Vergata Hospital Institutional Ethics Committee (Approval number 107/16), and conforms to the tenets of the Declaration of Helsinki. After a comprehensive neurological and ophthalmological examination, 53 untreated RRMS patients (aged 37.4 ± 10) and 53 matched controls (aged 36.11 ± 12.94) were enrolled. In addition, each patient underwent an examination of the posterior pole using the SD-OCT built-in Spectralis posterior pole scanning protocol. After segmentation, the mean thickness, as well as the thickness of the 64 single regions of interest, were calculated for each retinal layer. No statistically significant difference in terms of average retinal thickness was found between the groups. However, MS patients showed both a significantly thinner ganglion cell layer (p < 0.001), and, although not statistically significant, a thinner inner nuclear layer (p = 0.072) and retinal nerve fiber layer (p = 0.074). In contrast, the retinal pigment epithelium (p = 0.014) and photoreceptor layers p < 0.001) resulted significantly thicker in these patients. Interestingly, the analysis of the region of interest showed that neurodegeneration was non-homogeneously distributed across each layer. This is the first report that suggests a complex rearrangement that affects, layer by layer, the entire retinal posterior pole of RRMS retinas in response to the underlying neurotoxic insult.

F/OH ratio in a rare fluorine-poor blue topaz from Padre Paraíso (Minas Gerais, Brazil) to unravel topaz's ambient of formation

Topaz [Al₂SiO₄(F,OH)₂] is one of the main fluorine-bearing silicates occurring in environments where variably acidic (F)/aqueous (OH) fluids saturate the silicate system. In this work we fully characterized blue topaz from Padre Paraíso (Minas Gerais, Brazil) by means of in situ synchrotron X-Ray and neutron powder diffraction measurements (temperature range 298-1273 K) combined with EDS microanalyses. Understanding the role of OH/F substitution in topaz is important in order to determine the hydrophilicity and the exchange reactions of fluorine by hydroxyl groups, and ultimately to characterize the environmental redox conditions (H₂O/F) required for mineral formation. The fluorine content estimated from neutron diffraction data is ~ 1.03 a.f.u (10.34 wt%), in agreement with the chemical data (on average 10.0 wt%). The X_OH [OH/(OH + F)] (0.484) is close to the maximum X_OH value (0.5), and represents the OH- richest topaz composition so far analysed in the Minas Gerais district. Topaz crystallinity and fluorine content sharply decrease at 1170 K, while mullite phase starts growing. On the basis of this behaviour, we suggest that this temperature may represent the potential initial topaz's crystallization temperature from supercritical fluids in a pegmatite system. The log(fH₂O/fHF^)fluid (1.27 (0.06)) is coherent with the fluorine activity calculated for hydrothermal fluids (pegmatitic stage) in equilibrium with the forming mineral (log(fH₂O/fHF)^fluid = 1.2-6.5) and clearly different from pure magmatic (granitic) residual melts [log(fH₂O/fHF)^fluid < 1]. The modelled H₂O saturated fluids with the F content not exceeding 1 wt% may represent an anomalous water-dominant / fluorine-poor pegmatite lens of the Padre Paraíso Pegmatite Field.

Diffusional Kurtosis Imaging of White Matter Degeneration in Glaucoma

Glaucoma is an optic neuropathy characterized by death of retinal ganglion cells and loss of their axons, progressively leading to blindness. Recently, glaucoma has been conceptualized as a more diffuse neurodegenerative disorder involving the optic nerve and also the entire brain. Consistently, previous studies have used a variety of magnetic resonance imaging (MRI) techniques and described widespread changes in the grey and white matter of patients. Diffusion kurtosis imaging (DKI) provides additional information as compared with diffusion tensor imaging (DTI), and consistently provides higher sensitivity to early microstructural white matter modification. In this study, we employ DKI to evaluate differences among healthy controls and a mixed population of primary open angle glaucoma patients ranging from stage I to V according to Hodapp–Parrish–Anderson visual field impairment classification. To this end, a cohort of patients affected by primary open angle glaucoma (n = 23) and a group of healthy volunteers (n = 15) were prospectively enrolled and underwent an ophthalmological evaluation followed by magnetic resonance imaging (MRI) using a 3T MR scanner. After estimating both DTI indices, whole-brain, voxel-wise statistical comparisons were performed in white matter using Tract-Based Spatial Statistics (TBSS). We found widespread differences in several white matter tracts in patients with glaucoma relative to controls in several metrics (mean kurtosis, kurtosis anisotropy, radial kurtosis, and fractional anisotropy) which involved localization well beyond the visual pathways, and involved cognitive, motor, face recognition, and orientation functions amongst others. Our findings lend further support to a causal brain involvement in glaucoma and offer alternative explanations for a number of multidomain impairments often observed in glaucoma patients.

Reorganization of the structural connectome in primary open angle Glaucoma

Primary open angle Glaucoma (POAG) is one of the most common causes of permanent blindness in the world. Recent studies have suggested the hypothesis that POAG is also a central nervous system disorder which may result in additional (i.e., extra-ocular) involvement. The aim of this study is to assess possible structural, whole-brain connectivity alterations in POAG patients. We evaluated 23 POAG patients and 15 healthy controls by combining multi-shell diffusion weighted imaging, multi-shell, multi-tissue probabilistic tractography, graph theoretical measures and a recently designed 'disruption index', which evaluates the global reorganization of brain networks. We also studied the associations between the whole-brain structural connectivity measures and indices of visual acuity including the field index (VFI) and two Optical Coherence Tomography (OCT) parameters, namely the Macula Ganglion Cell Layer (MaculaGCL) and Retinal Nerve Fiber Layer (RNFL) thicknesses. We found both global and local structural connectivity differences between POAG patients and controls, which extended well beyond the primary visual pathway and were localized in the left calcarine gyrus (clustering coefficient p = 0.036), left lateral occipital cortex (clustering coefficient p = 0.017, local efficiency p = 0.035), right lingual gyrus (clustering coefficient p = 0.009), and right paracentral lobule (clustering coefficient p = 0.009, local efficiency p = 0.018). Group-wise (clustering coefficient, p = 6.59∙10-7 and local efficiency p = 6.23·10-8) and subject-wise disruption indices (clustering coefficient, p = 0.018 and local efficiency, p = 0.01) also differed between POAG patients and controls. In addition, we found negative associations between RNFL thickness and local measures (clustering coefficient, local efficiency and strength) in the right amygdala (local efficiency p = 0.008, local strength p = 0.016), right inferior temporal gyrus (clustering coefficient p = 0.036, local efficiency p = 0.042), and right temporal pole (local strength p = 0.008). Overall, we show, in patients with POAG, a whole-brain structural reorganization that spans across a variety of brain regions involved in visual processing, motor control, and emotional/cognitive functions. We also identified a pattern of brain structural changes in relation to POAG clinical severity. Taken together, our findings support the hypothesis that the reduction in visual acuity from POAG can be driven by a combination of local (i.e., in the eye) and more extended (i.e., brain) effects.

Brain networks reorganization and functional disability in glaucoma

Glaucoma is an optic neuropathy characterized by progressive loss of retinal ganglion cells with associated structural and functional changes of the optic nerve head and retinal nerve fiber layer. However, recent studies employing advanced neuroimaging techniques confirmed that glaucomatous damage is not limited to the eye but extends to the brain, affecting it also beyond the central visual pathways and disrupting brain network organization. We therefore posit that, while visual field changes play an important role in glaucoma-induced disability, central nervous pathways and mechanisms may play an important role in sustaining functional and daily living disability caused by the disease. Here we to summarize the current state of the art on the involvement of central brain circuits and possibly related disabilities in patients with glaucoma.

Retinal and Choroidal Vasculature in Patients with Marfan Syndrome

Purpose

To assess the retinal and choroidal vasculature in patients with genetically confirmed Marfan syndrome (MfS).

Methods

This prospective, case-control, observational study included 48 eyes of 24 patients with a genetic diagnosis of MfS and compared them with 52 eyes of 26 healthy controls. Best-corrected visual acuity, choroidal and retinal thickness measured by spectral domain-optical coherence tomography, retinal and choroidal vasculature characterized by optical coherence tomography angiography, were collected. A genetic counseling was carried out. A transthoracic echocardiogram was performed to evaluate the dimension of the aortic root, the ascending aorta and the left ventricle function and dimensions.

Results

A significant decrease in the superficial and deep retinal capillary plexi vessel density (VD) was evident, such as a decrease in the choriocapillaris plexus VD. In patients with MfS, a negative correlation between left ventricular diameter and the VD of the superficial and deep plexi was observed. Patients with MfS with greater posterior wall and interventricular septum dimensions had lower VD in both plexi (P < 0.05). Moreover, there was a negative correlation between the dimension of the ascending aorta and foveal choriocapillary VD. In patients with MfS, increasing diameter of the ascending aorta was associated with a lower foveal choriocapillary VD (P < 0.05).

Conclusions

The severity of MfS correlates with the impairment of the retinal and choroidal vasculature.

Translational Relevance

Optical coherence tomography angiography may be a reproducible and noninvasive tool to study retinal blood flow in patients with MfS, with potential diagnostic and prognostic value.

Disruption of structural brain networks in Primary Open Angle Glaucoma

Primary open angle glaucoma (POAG) is one of the most common causes of permanent blindness in the world. Recent studies have originated the hypothesis that POAG could be considered as a central nervous system pathology which results in secondary visual involvement. The aim of this study is to assess possible structural whole brain connectivity alterations in POAG by combining multi-shell diffusion weighted imaging, multi-shell multi-tissue probabilistic tractography, graph theoretical measures and a newly designed disruption index, which evaluates the global reorganization of brain networks in group-wise comparisons. We found global differences in structural connectivity between Glaucoma patients and controls, as well as in local graph theoretical measures. These changes extended well beyond the primary visual pathway. Furthermore, group-wise and subject-wise disruption indices were found to be statistically different between glaucoma patients and controls, with a positive slope. Overall, our results support the hypothesis of a whole-brain structural reorganization in glaucoma which is specific to structural connectivity, possibly placing this disease within the recently defined groups of brain disconnection syndrome.

Is there a relationship between dopamine and rhegmatogenous retinal detachment?

Dopamine and its receptors have been widely studied in the neurological conditions and in the retina. In this study, we evaluated the possible role of dopamine in rhegmatogenous retinal detachment (RRD) by comparing the amount of 3,4-dihydroxyphenylacetic acid (DOPAC), a surrogate index of retinal dopamine levels, in the vitreous sample of patients affected by RRD with those affected by macular pucker and vitreous hemorrhage. Our results showed that significantly higher levels of DOPAC were found in the vitreous sample of patients affected by RRD compared with those affected by vitreous hemorrhage and macular pucker (P = 0.002). Specifically, no trace of the substance was found in vitreous hemorrhage and macular pucker samples. A slightly significant positive correlation was found among DOPAC and post-operative best corrected visual acuity (r = 0.470, P = 0.049). No correlation was found between DOPAC and the days elapsed between diagnosis and surgery (P = 0.317). For the first time our findings suggest that DOPAC is released in RRD, but not in other retinal diseases such as vitreous hemorrhage and macular pucker. Moreover, we showed a correlation between visual acuity outcome and the amount of DOPAC in the vitreous. This might have a potential, although still unknown, implication in the pathogenesis of the disease and/or in the associated photoreceptors loss. This study was approved by the Ethics Committee of Rome Tor Vergata University Hospital (R.S.92.10) on September 24, 2010.

Primary Open Angle Glaucoma Is Associated With Functional Brain Network Reorganization

Background: Resting-state functional magnetic resonance imaging (rs-fMRI) is commonly employed to study changes in functional brain connectivity. The recent hypothesis of a brain involvement in primary open angle Glaucoma has sprung interest for neuroimaging studies in this classically ophthalmological pathology.

Object: We explored a putative reorganization of functional brain networks in Glaucomatous patients, and evaluated the potential of functional network disruption indices as biomarkers of disease severity in terms of their relationship to clinical variables as well as select retinal layer thicknesses.

Methods: Nineteen Glaucoma patients and 16 healthy control subjects (age: 50–76, mean 61.0 ± 8.2 years) underwent rs-fMRI examination at 3T. After preprocessing, rs-fMRI time series were parcellated into 116 regions using the Automated Anatomical Labeling atlas and adjacency matrices were computed based on partial correlations. Graph-theoretical measures of integration, segregation and centrality as well as group-wise and subject-wise disruption index estimates (which use regression of graph-theoretical metrics across subjects to quantify overall network changes) were then generated for all subjects. All subjects also underwent Optical Coherence Tomography (OCT) and visual field index (VFI) quantification. We then examined associations between brain network measures and VFI, as well as thickness of retinal nerve fiber layer (RNFL) and macular ganglion cell layer (MaculaGCL).

Results: In Glaucoma, group-wise disruption indices were negative for all graph theoretical metrics. Also, we found statistically significant group-wise differences in subject-wise disruption indexes in all local metrics. Two brain regions serving as hubs in healthy controls were not present in the Glaucoma group. Instead, three hub regions were present in Glaucoma patients but not in controls. We found significant associations between all disruption indices and VFI, RNFL as well as MaculaGCL. The disruption index based on the clustering coefficient yielded the best discriminative power for differentiating Glaucoma patients from healthy controls [Area Under the ROC curve (AUC) 0.91, sensitivity, 100%; specificity, 78.95%].

Conclusions: Our findings support a possible relationship between functional brain changes and disease severity in Glaucoma, as well as alternative explanations for motor and cognitive symptoms in Glaucoma, possibly pointing toward an inclusion of this pathology in the heterogeneous group of disconnection syndromes.

Neurodegenerative Process Linking the Eye and the Brain

Recent literature agrees that neurodegenerative processes involve both the retina and the central nervous system, which are two strictly related anatomical structures. However, the causal mechanisms of this dual involvement are still uncertain. To date, anterograde transsynaptic neurodegeneration, triggered by retinal ganglion cells' death, and retrograde transsynaptic neurodegeneration, induced by neurodegenerative processes of the central nervous system, has been considered the major possible causal mechanisms. The development of novel neuroimaging techniques has recently supported both the study of the central stations of the visual pathway as well as the study of the retina which is possibly an open window to the central nervous system.

Disruption of brain network organization in primary open angle glaucoma

Resting-state functional magnetic resonance imaging (rs-fMRI) is commonly employed to study changes in functional brain connectivity. Recently, the hypothesis of a brain involvement in primary open angle glaucoma has sprung interest for neuroimaging studies in this pathology. The purpose of this study is to evaluate a putative reorganization of brain networks in glaucomatous patients through graph-theoretical measures of integration, segregation and centrality by exploiting a multivariate networks association measure and a recently introduced global and local brain network disruption index. Nineteen glaucoma patients and sixteen healthy control subjects (age: 50 - 76, mean 61 years) underwent rs-fMRI examination at 3T. After preprocessing, rs-fMRI time series were parcellated into 116 regions (AAL atlas), adjacency matrices were computed based on partial correlations and graph-theoretical measures of integration, segregation and centrality as well as group-wise and subject-wise disruption index estimates were generated for all subjects. We found that the group-wise disruption index was negative and statistically different from 0 in for all graph theoretical metrics. Additionally, statistically significant group-wise differences in subject-wise disruption indexes were found in all local metrics. The differences in local network measures highlight cerebral reorganization of brain networks in glaucoma patients, supporting the interpretation of glaucoma as central nervous system disease, likely part of the heterogeneous group of recently described disconnection syndromes.

Evidence on neuroprotective properties of coenzyme Q10 in the treatment of glaucoma

Glaucoma, the leading cause of visual impairment and irreversible blindness worldwide, is a multifactorial, progressive optic neuropathy characterized by loss of retinal ganglion cells, alterations of the optic nerve head, and specific visual field defects. Clinical evidence shows that intraocular pressure is the major risk factor of the treatable disease. However, in some patients, glaucoma develops and continues to progress despite normal intraocular pressure values, suggesting that other risk factors are involved in the disease. Consequently, neuroprotective treatments, focused on preventing retinal ganglion cells death by acting on different therapeutic strategies but not focused on intraocular pressure reduction, has therefore become of great interest. In this contest, coenzyme Q10, showing evidence in slowing or reversing pathological changes typical of the disease, has been proposed as a potential neuroprotective agent in glaucoma. In this review, we describe the possible mechanisms of action of coenzyme Q10 and the recent evidence in literature regarding the neuroprotective activity of the molecule.

Glaucoma and Alzheimer Disease: One Age-Related Neurodegenerative Disease of the Brain

Background:

Open Angle Glaucoma (POAG) is the leading causes of irreversible blindness worldwide. Elevated intraocular pressure is considered an important risk factor for glaucoma; however, a subset of patients experiences a progression of the disease even in presence of normal intraocular pressure values. This implies that risk factors other than intraocular pressure are involved in the pathogenesis of glaucoma. A possible relationship between glaucoma and neurodegenerative diseases such as Alzheimer Disease has been suggested. In this regard, we recently described a high prevalence of alterations typical of glaucoma, using Heidelberg Retinal Tomograph-3, in a group of patients with Alzheimer Disease. Interestingly, these alterations were not associated with elevated intraocular pressure or abnormal Central Corneal Thickness values. Alzheimer Disease is the most common form of dementia with progressive deterioration of memory and cognition. Complaints related to vision are common among Alzheimer Disease patients.

Methods:

In this paper researches related to glaucoma and Alzheimer disease are reviewed.

Results:

Diseases characteristics, i.e. common features, risk factors and pathophysiological mechanisms gathered in the recent literature do suggest that Alzheimer Disease and glaucoma can be considered both age-related neurodegenerative diseases that may co-exist in the elderly.

Conclusion:

In conclusion, preclinical and clinical evidence gathered so far support the notion that glaucoma is a widespread neurodegenerative condition whose common pathogenetic mechanisms with other diseases, i.e. Alzheimer Disease, should be further investigated as they may shed new light on these diseases improving both diagnosis and treatments.

Morphological and Functional Modifications of Optical Thin Films for Space Applications Irradiated with Low-Energy Helium Ions

Future space missions will operate in increasingly hostile environments, such as those in low-perihelion solar orbits and Jovian magnetosphere. This exploration involves the selection of optical materials and components resistant to the environmental agents. The conditions in space are reproduced on ground through the use of ion accelerators. The effects of He particles coming from the solar wind impinging on a gold thin film have been systematically investigated, considering absorbed doses compatible with the duration of the European Space Agency Solar Orbiter mission. Structural and morphological changes have been proved to be dependent not only on the dose but also on the irradiation flux. A predictive model of the variation of thin film reflectance has been developed for the case of lower flux irradiation. The results are discussed regarding reliability and limitations of laboratory testing. The outcomes are important to address the procedures for the space qualification tests of optical coatings.

Macular ganglion cells alteration in a patient with left homonymous hemianopia subsequent to surgical excision of an arteriovenous malformation

Purpose

To report the case of a 57 years old woman who showed a macular ganglion cell complex (GCC), that is a combination of ganglion cell layer and inner plexiform layer, and peripapillary Retinal Nerve Fiber Layer (pRNFL) thickness reduction in association with left homonymous hemianopia subsequent to surgical excision of an arteriovenous malformation in the cerebral right occipital lobe 37 years before.

Observations

One patient with left homonymous hemianopia due to surgical excision of an arteriovenous malformation in the right cerebral occipital lobe came to our attention for transient blurred vision.Measurement of the GCC and pRNFL thickness was performed using spectral domain optical coherence tomography (SDOCT; Cirrus HD-OCT model 400). Visual field (VF) defects were assessed using Humphrey field analyzer using the central 30-2 Swedish Interactive Threshold Algorithm (SITA) program with appropriate trial lenses (Humphrey Field Analyzer II, Carl Zeiss Meditech, Inc, Dublin, California).The average pRNFL thickness was bilaterally reduced, showing a symmetry value of 39%. The patients showed a significant GCC thinning in the projecting sector of the retina mapping to the brain lesion. Corresponding VF defects were found.

Conclusions and importance

These findings show SDOCT potentials in the field of neuro-ophthalmology, supporting the usefulness of GCC thickness as a possible imaging marker before and after brain surgery, and, possibly, in the diagnosis of neurodegenerative conditions.

Anterior Segment Optical Coherence Tomography Analysis of Iris Morphometric Changes Induced by Prostaglandin Analogues Treatment in Patients with Primary Open Angle Glaucoma or Ocular Hypertension

Background:

The study aimed to evaluate iris thickness changes in patients with Primary Open Angle Glaucoma (POAG) or Ocular Hypertension (OHT) under treatment with Prostaglandin Analogues (PG).

Objectives:

Primary outcome measures were iris thickness at the region of Dilator Muscle Region (DMR) and Sphincter Muscle Region (SMR). DMR/SMR ratio was also evaluated. The secondary outcome was the correlation between PG treatment length and iris parameters.

Methods:

The charts of patients with POAG or OHT who underwent Visante OCT were retrospectively selected. The patients were divided in a group using PG for at least 6 months and a group using hypotensive drops not including PG or alpha-adrenergic agonists. A third group included healthy subjects.

Result:

98 subjects were selected. Patients with POAG or OHT using PG eyedrops showed a significant iris thickness reduction at DMR compared to healthy subjects and to patients using hypotensive eyedrops not containing PG. Significantly higher SMR thickness values were found in PG group compared to both control groups. DMR/SMR ratio significantly reduced in PG group. No correlation was found between PG treatment length and iris parameters.

Conclusion:

The present data indicate that PG treatment induced DMR thickness reduction and an increase in SMR thickness. These changes were not related to the duration of PG exposure.

Physicochemical regeneration of high silica zeolite Y used to clean-up water polluted with sulfonamide antibiotics

High silica zeolite Y has been positively evaluated to clean-up water polluted with sulfonamides, an antibiotic family which is known to be involved in the antibiotic resistance evolution. To define possible strategies for the exhausted zeolite regeneration, the efficacy of some chemico-physical treatments on the zeolite loaded with four different sulfonamides was evaluated. The evolution of photolysis, Fenton-like reaction, thermal treatments, and solvent extractions and the occurrence in the zeolite pores of organic residues eventually entrapped was elucidated by a combined thermogravimetric (TGA-DTA), diffractometric (XRPD), and spectroscopic (FT-IR) approach. The chemical processes were not able to remove the organic guest from zeolite pores and a limited transformation on embedded molecules was observed. On the contrary, both thermal treatment and solvent extraction succeeded in the regeneration of the zeolite loaded from deionized and natural fresh water. The recyclability of regenerated zeolite was evaluated over several adsorption/regeneration cycles, due to the treatment efficacy and its stability as well as the ability to regain the structural features of the unloaded material.

Competitive adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5

Adsorption equilibria of methyl tert-butyl ether (MTBE)/toluene (TOL), and 1,2-dichloroethane (DCE)/MTBE binary mixtures in aqueous solution on ZSM-5 were measured over a wide range of concentrations.

Association Between Alzheimer's Disease and Glaucoma: A Study Based on Heidelberg Retinal Tomography and Frequency Doubling Technology Perimetry

Aim: To assess the frequency of glaucoma-like alterations in Alzheimer's disease (AD) patients using Heidelberg Retinal Tomograph III (HRT-3) and Frequency Doubling Technology (FDT) perimetry.

Methods: The study included 51 eyes of 51 AD subjects and 67 eyes of 67 age- and sex-matched controls. Subjects underwent an ophthalmological examination including measurements of intraocular pressure (IOP), Matrix FDT visual field testing, optic nerve head morphology and retinal nerve fiber layer thickness (RNFLt) assessment by slit-lamp biomicroscopy and HRT-3.

Results: The frequency of alterations was significantly higher in the AD group (27.5 vs. 7.5%; p = 0.003; OR = 4.69). AD patients showed lower IOP (p = 0.000) despite not significantly different values of central corneal thickness (CCT) between the groups (p = 0.336). Of all the stereometric parameters measured by HRT-3, RNFLt was significantly lower in AD patients (p = 0.013). This group also had significantly worse results in terms of Moorfields Regression Analysis (p = 0.027). Matrix showed significantly worse Mean Deviation (MD) (p = 0.000) and Pattern Standard Deviation (PSD) (p = 0.000) values and more altered Glaucoma Hemifield Test (p = 0.006) in AD patients. Pearson's R correlation test showed that Mini Mental State Examination is directly correlated with MD (R = 0.349; p = 0.034) and inversely correlated with PSD (R = −0.357; p = 0.030).

Conclusion: Patients with AD have a higher frequency of glaucoma-like alterations, as detected by the use of HRT-3. These alterations were not associated with elevated IOP or abnormal CCT values.

Influence of water on the retention of methyl tertiary-butyl ether by high silica ZSM-5 and Y zeolites: a multidisciplinary study on the adsorption from liquid and gas phase

Ambient temperature adsorption isotherms have been determined for methyltert-butyl ether (MTBE) in aqueous solutions on high silica ZSM-5 and Y zeolites which differ from each other in framework topology and pore window apertures.

Vertebral body compression fracture after percutaneous pedicle screw removal in a young man

Hazards and potential complications associated with pedicle screw insertions have been reported. In contrast, complications due to implant removal are rarely described. An unreported case of acute vertebral body compression fracture following pedicle screw removal in a young man occurred during an episode of forceful coughing. Spinal implants need to be removed in cases of complications, pain or tissue irritation, and removal is mandatory when fixation involves L2 or the lower segments. Complications associated with spinal implant removal are rare but possible, and patients must be informed of this potential risk.

Evaluation of pupillary response to light in patients with glaucoma: a study using computerized pupillometry

The aim of this study was to evaluate pupillary response to light stimulation in patients with different stages of glaucoma using computerized pupillometry. We conducted a retrospective study on a group of 44 glaucoma patients who had undergone complete ophthalmological examination, visual field test (Humphrey SITA Standard 24-2) and monocular dynamic pupillometry (MonCV3 Metrovision). Eyes were classified into stages of glaucoma according to visual field damage using the Glaucoma Staging System 2. A group of 18 healthy subjects, homogeneous for age and sex with glaucoma patients, was used as a control. The following parameters were considered-latency and duration of contraction and dilatation; initial, minimum, maximum, and mean pupil diameter; amplitude of contraction; contraction and dilatation speed; and percent pupil contraction (PPC). PPC and pupil contraction speed and minimum diameter showed covariate correlation with the stages of glaucoma. The control group significantly differed from the stage 3 group in terms of PPC and from the stage 4 group in terms of minimum diameter. There were significant differences between the stage 5 group and stage 1, 2, 3 and control groups. Ordinal logistic regression showed a correlation between pupil contraction speed, minimum diameter, PPC, initial diameter and the stage of glaucoma. The study showed that glaucoma damage is associated with altered values of pupillary response to light. This event may be the consequence of the progressive loss of retinal ganglion cells and their axons induced by glaucoma.

Chêneau brace for adolescent idiopathic scoliosis: long-term results. Can it prevent surgery?

OBJECTIVE

The aim of this study was to evaluate the effectiveness of Chêneau brace in the management of idiopathic scoliosis.

METHODS

This is a retrospective observational study according to SOSORT and SRS (Scoliosis Research Society) recommendations involving 48 girls with documented progressive idiopathic scoliosis, treated with Chêneau brace. A statistical analysis was performed with STATA MP11.2 to validate the obtained results.

RESULTS

No patient needed surgery. The average curve angle measured in Cobb degrees passed from 27° ± 6.7° at the beginning (T0), to 7.6° ± 7.4° in brace (T1) (72 % of correction), to 8.5° ± 8.6° (69 % of correction) at the end of treatment (T2), to 11.0° ± 7.4° (59.3 % of correction) at final follow-up (mean 5 years and 5 months) (T3).

CONCLUSION

Conservative treatment with Chêneau brace and physiotherapy was effective in our hands for halting scoliosis progression in 100 % of patients.

Short and long range surface plasmon polariton waveguides for xylene sensing

Nanostructured plasmonic sensors are fabricated as sinusoidal surface plasmon metallic gratings (SPGs) embedded in a functional and porous hybrid sol-gel material, phenyl-bridged polysilsesquioxane (ph-PSQ). The metal layer is in contact with the environment through the sol-gel film, which works as sensitive element, changing its dielectric properties upon interaction with aromatic hydrocarbons. The combination of sensitivity, transparency and patternability offered by ph-PSQs gives the exceptional possibility to fabricate innovative optical sensors with straightforward processes. An embedded SPG is a thin metal slab waveguide, in which the surface plasmon polaritons (SPPs) at the two metal-dielectric interfaces superpose, resulting in two physical coupled modes: the long range SPPs (LRSPPs) and the short range SPPs (SRSPPs). An extended experimental and theoretical characterization of the optical properties of the plasmonic device was performed. The sensor performance was tested against the detection of 30 ppm xylene, monitoring the influence of the target gas on the SPPs modes. A reversible red-shift of the reflectance dips of both LRSPP and SRSPP resonances in the 1.9-2.9 nm range was observed and correlated to the interaction with the analyte. An enhancement in sensitivity associated with the rotation of the grating grooves with respect to the scattering plane (azimuthal rotation) was verified within the experimental errors. Collected data are compatible with theoretical predictions assuming a variation of the film refractive index of 0.011 ± 0.005.

Brain involvement in glaucoma: advanced neuroimaging for understanding and monitoring a new target for therapy

On the basis of a large body of experimental data the notion that glaucoma damages retinal ganglion cells and central areas of the visual system has been put forward. The mechanisms underlying glaucomatous involvement of the central areas are not known: the most likely hypothesis is that this event is the result of an anterograde transynaptic neurodegeneration triggered by ganglion cells' death. However, it is possible that in some cases it may be the consequence of a neurodegenerative disease of the central nervous system. In any event, novel mechanisms leading to cell demise might be implicated. The development of powerful neuroimaging techniques in conjunction with sophisticated analysis has recently provided compelling support to the involvement of central stations of the visual pathway in patients suffering of glaucoma. Diffusion Tensor-MRI allows the central damage associated with glaucoma to be assessed and therapeutic efficacy of novel neuroprotective interventions to be quantified.

Compressibility of microporous materials with CHA topology: 2. ALPO-34

The HP behavior of ALPO-34 as-synthesized was investigated by means of in-situ synchrotron X-ray powder diffraction, in the frame of a wider project aimed at understanding the role of the framework/extraframework content in the P-induced deformation mechanisms of natural and synthetic microporous materials with CHA framework topology. ALPO-34 compressibility under non-penetrating P-transmitting medium was determined up to 6.0 GPa and upon decompression to P amb. After an initial large structure deformation at P < 0.4 GPa, a regular volume reduction was observed up to about 3 GPa. Above 3.1 GPa, an abrupt change in the behavior of all cell parameters was observed, accompanied by an evident decrease in compressibility. The isothermal Equation of State (EoS), refined with a II-order Birch–Murnaghan EoS from 0.4 to 3.1 GPa, yielded the following parameters: V 0 = 755(1) Å3, K 0 = 54(3) GPa. No complete X-ray amorphization was achieved up to the highest investigated P value. A complete reversibility of the unit cell parameters was observed upon P release. The compressibility behavior of ALPO-34 was compared with that of the other CHA-type zeolites. The volume reduction observed for natural chabazite, and for SAPO-34 and ALPO-34 as-synthesized, was 6.2%, 9.4%, and 6.0%, respectively. Notwithstanding the presence of morpholine molecules, as a structure directing agent, in the two as-synthesized phases, they exhibited significantly different compressibility. This can be interpreted as due to the octahedral coordination of part of the ALPO-34 framework aluminum, leading to a more rigid framework compared to that of SAPO-34, which contains only tetrahedral aluminum.

Differences between proximal versus distal intraorbital optic nerve diffusion tensor magnetic resonance imaging properties in glaucoma patients

PURPOSE

To analyze in vivo the diffusion tensor magnetic resonance imaging (DT-MRI) properties of the intraorbital optic nerve at two different levels: Proximal to the optic nerve head (ONH) and distal to the ONH at the level of the orbital apex in glaucoma patients.

METHODS

Twenty-four patients with primary open-angle glaucoma were examined. The categorization into early and severe glaucoma was performed by Hodapp's classification. Fifteen healthy individuals served as controls. DT-MRI was performed with a 3T-MR unit.

RESULTS

At early stage mean diffusivity (MD) values were higher at the proximal site with respect to the distal site. On the contrary, a decrease in fractional anisotropy (FA) was observed only relative to patient stage, independent of optic nerve site. Moreover, at early disease stage an increase in overall diffusivities, was evident at the proximal site, whereas at the distal site a decrease of the largest diffusivity and an increase in both the intermediate and smallest diffusivities were observed. FA and MD measured at the proximal site, had, respectively, the highest sensitivity and specificity in discriminating between healthy and glaucomatous eyes.

CONCLUSIONS

Our study represents the first attempt to evaluate in vivo fiber integrity changes along the optic nerve with DT-MRI. Optic nerve degeneration appears to be a process that affects differently the proximal and the distal segments of the optic nerve. The complementary high sensitivity of FA with the high specificity of MD at the proximal site may provide reliable indexes for the identification of glaucomatous patients at early stages.

3-T Diffusion tensor imaging of the optic nerve in subjects with glaucoma: correlation with GDx-VCC, HRT-III and Stratus optical coherence tomography findings

OBJECTIVES

To correlate diffusion-tensor imaging (DTI) of the optic nerve with morphological indices obtained by scanning laser polarimetry (GDx-VCC); confocal scanning laser ophthalmoscopy (Heidelberg III retinal tomograph; HRT-III) and optical coherence tomography (Stratus OCT).

METHODS

Thirty-six subjects (12 with no eye disease and 24 with perimetrically diagnosed glaucoma) were examined. One eye for each participant was studied with 3-Tesla DTI (with automatic generation of mean diffusivity (MD) and fractional anisotropy (FA) values); GDx-VCC, HRT-III and OCT. Single and multiple regression analyses of all variables studied were performed.

RESULTS

MD displayed the strongest correlation with linear cup/disc ratio (LCDR) from HTR-III (r=0.662), retinal nerve fibre layer (RNFL) thickness (avThickn) from OCT (r=-0.644), and nerve fibre index (NFI) from GDx (r=0.642); FA was strongly correlated with the LCDR (r=-0.499). In multiple regression analyses, MD correlated with LCDR (p=0.02) when all variables were considered; with avThickn (p<0.01) (analysis of all RNFL parameters); with NFI (p<0.01) (analysis of all GDx parameters); with avThickn (p<0.01) (analysis of OCT parameters); with LCDR (p=0.01) (analysis of HRT-III morphometric parameters) and with linear discriminant function (RB) (p=0.02) (analysis of HRT-III indices). As for FA, it correlated with avThickn (p=0.02) when we analysed the OCT parameters and with RB (p=0.01) (analysis of HRT-III indices).

CONCLUSIONS

DTI parameters of the axonal architecture of the optic nerve show good correlation with morphological features of the optic nerve head and RNFL documented with GDx-VCC, HRT-III and OCT.

Au and NiO nanocrystals doped into porous sol-gel SiO(2) films and the effect on optical CO detection

Thin-film composites comprised of NiO and NiO/Au nanoparticles in a porous SiO(2) matrix have been prepared using the sol-gel technique. When at elevated temperatures (200 °C< T<350 °C) and exposed to carbon monoxide, the films undergo reversible changes in optical transmittance at wavelengths in the visible-near IR region. For NiO composite films heated at 330 °C and exposed to 1% CO in air, there is an increase in transmittance which approaches 2-4% over most of the visible range. For NiO/Au composite films the transmittance increase exhibits a wavelength dependence, with a maximum change which is close to 6% at λ≈630 nm and which is close to zero in the Au plasmon resonance range (λ≈550 nm).