Evaluation of the anterior chamber angle in pseudoexfoliation syndrome

BACKGROUND

Pseudoexfoliation syndrome (PEX) is the most frequently identifiable cause of secondary open-angle glaucoma, known as pseudoexfoliation glaucoma. The exact pathophysiology and etiology of PEX and associated glaucoma remains obscure.

OBJECTIVES

The purpose of this study was to determine the differences in the morphology of the anterior chamber angle in people with pseudoexfoliation syndrome and pseudoexfoliation glaucoma compared to a control group. We also evaluated the correlation between intraocular pressure (IOP) and pigmentation of the angle with the amount of exfoliated material in the anterior segment.

MATERIAL AND METHODS

The study group was composed of 155 eyes from 103 patients aged between 43 and 86 years. Each patient underwent a complete ophthalmological examination.

RESULTS

Some difference was found in intraocular pressure between the PEX group and the control group and between the pseudoexfoliation glaucoma group and the control group, but no significant difference was found between the 2 study groups. There was a significant difference in the incidence of some degree of pigmentation in the anterior chamber angle and no difference in the widths of the angle between each group. A significant positive relationship was observed between intraocular pressure and the degree of pigmentation of the anterior chamber angle in both the PEX group and the pseudoexfoliation glaucoma group.

CONCLUSIONS

The results of this study indicate that the amount of pigmentation and exfoliation material in the anterior segment significantly correlates with the level of IOP and possibly with the degree of trabecular dysfunction. It seems that for clear identification of PEX and pseudoexfoliation glaucoma factors, clinical assessment appears to be insufficient.

Glaucomatous changes in lamina pores shape within the lamina cribrosa using wide bandwidth, femtosecond mode-locked laser OCT

PURPOSE

The lamina cribrosa (LC) is known to play a critical role in the pathogenesis of glaucoma. Although it has been reported that striae-shaped or slit-shaped lamina pores are more frequent in eyes with primary open angle glaucoma (POAG), this observation is based only on fundus photography. The primary object of this study is to perform layer-by-layer comparisons of the shape of lamina pores within the LC in vivo.

DESIGN

Cross-sectional study.

METHODS

Optic nerve head B-scans were obtained using custom-made broad-wavelength optical coherence tomography with a mode-locked laser. A total of 300 single B-scans per eye were obtained and three-dimensional images were rendered from these image sequences to obtain 2-μm thin-slice en face images of the LC. Elongation indices (EIs) of the lamina pores were measured from the anterior surface (AS) of the LC to the deeper layers in 40-μm increments.

RESULTS

Thirteen eyes from 10 primary open angle glaucoma (POAG) patients of mean deviation -15.2 (-16.5, -12.9) (median [25,75 percentile]) dB and 10 eyes from 7 normal controls were studied. Although the EI value was not significantly different between the superior, temporal and inferior regions of the LC at any depth level in either group, it was greater at the AS than at the 40 μm and 80 μm depth levels (P < .001) in both groups, and was greater in the POAG group only at the AS and 40 μm depth level (P ≤ .05). After adjustment for age and refraction, the effects of depth and presence of POAG on the EI value remained significant. Also, the severity of glaucoma and depth were significant factors associated with EI in multivariate analysis.

CONCLUSIONS

Elongation of lamina pores was significantly more evident at the anterior surface and the 40-μm depth level of the LC in POAG eyes than in normal eyes, suggesting that nerve fiber bundles passing through the LC were under greater stress in the anterior layers of the LC.

σ-1 receptor stimulation protects against pressure-induced damage through InsR-MAPK signaling in human trabecular meshwork cells

The purpose of the present study was to investigate the protective effect of the σ-1 receptor (Sig-1R) agonist (+)‑pentazocin (PTZ) on pressure-induced apoptosis and death of human trabecular meshwork cells (hTMCs). The expression levels of Sig‑1R and insulin receptor (InsR) were examined in hTMCs. Cells were cultured under a pressure of 0, 20, 40, 60 and 80 mmHg for 48 h, and under 80 mmHg for 44 h, after which the cells were treated with (+)‑PTZ (20 µM), N-(2-(3,4-dichlorophenyl)ethyl)-N‑methyl-2‑(dimethylamino) ethylamine (BD‑1063; 20 µM) administered 30 min prior to (+)‑PTZ, or BD‑1063 (20 µM) and then exposed to 80 mmHg again until the 48 h time‑point. The changes of the cells were observed by optical and electron microscopy, the apoptosis and death of hTMCs were detected by ethidium bromide/acridine orange dual staining assay and the expression of Sig‑1R and InsR by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. The phosphorylation of extracellular signal‑regulated kinase (ERK), an important downstream protein of the InsR‑mitogen‑activated protein kinases (MAPK) signaling pathway, was also detected by western blot analysis when (+)‑PTZ and BD‑1063 were added to the 80 mmHg‑treated cells. Sig‑1Rs and InsRs were expressed in hTMCs. The apoptosis and death of hTMCs increased from 40 mmHg with 50% cell death when the pressure was at 80 mmHg and the structure of the cells noticeably changed. The expression of Sig‑1R and InsR increased along with the elevation of pressure. (+)‑PTZ decreased the apoptosis and death of hTMCs and increased the expression of Sig‑1R and InsR, and the phosphorylation of ERK. Such effects were blocked by BD‑1063. The present study suggested that Sig‑1R agonist (+)‑PTZ can protect hTMCs from pressure‑induced apoptosis and death by activating InsR and the MAPK signal pathway.

Relationship between anthropometric parameters and open angle glaucoma: The Korea National Health and Nutrition Examination Survey

AIMS

To evaluate the relationships between open-angle glaucoma (OAG) and various anthropometric measurements.

DESIGN

Korea National Health and Nutrition Examination Survey (KNHANES), a population-based cross-sectional study using a complex, stratified, multistage, probability-cluster survey.

METHODS

A total of 5,255 participants including 247 glaucoma patients, aged ≥ 19 years were included from the KNHANES V database. Glaucoma diagnosis was based on International Society of Geographical and Epidemiological Ophthalmology criteria. Various anthropometric data regarding obesity were analyzed including body mass index (BMI), total body fat mass, total body muscle mass (lean body mass, non-bone lean body mass, and appendicular skeletal muscle (ASM) mass), and waist circumference (WC). The differences in OAG prevalence with respect to anthropometric parameter quartiles were examined.

RESULTS

In males, the multivariate general linear model adjusted for age, alcohol, smoking, exercise, systemic hypertension, diabetes, and intraocular pressure (IOP) showed the quartiles for the anthropometric parameters BMI, fat mass/weight ratio and fat mass/muscle mass ratio were negatively associated with OAG. However, muscle mass parameter/BMI ratio was significantly positively associated with OAG (P for trend<0.05). In females, height and fat mass/BMI showed a significant relationship with the risk of OAG. (P value<0.05).

CONCLUSIONS

In the present study, high fat mass was associated with low OAG risk. Body composition seemed to affect the prevalence of OAG, but further evaluation is needed.

Measurements of the parapapillary atrophy zones in en face optical coherence tomography images

OBJECTIVE

To measure the parapapillary atrophy (PPA) area in en face images obtained with swept-source optical coherence tomography (SS-OCT), and to evaluate its relationship to glaucoma, myopia, and age in non-highly myopic subjects.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Fifty eyes of 30 subjects with open-angle glaucoma (G group) and forty-three eyes of 26 healthy control subjects (C group). Eyes with high myopia (spherical equivalent refractive error ≤ -8 diopters or axial length ≥ 26.5 mm) were excluded.

METHODS

Mean age ± standard deviation was 59.9 ± 12.4 years. The beta zone and the gamma zone PPA areas were measured in en face images reconstructed from three-dimensional SS-OCT images. Relationship between the PPA areas and patient characteristics such as glaucoma, axial length, and age was statistically evaluated using multivariate mixed-effects models.

MAIN OUTCOME MEASURES

Areas of the beta zone and the gamma zone PPA measured on en face OCT images.

RESULTS

Average ± standard deviation area of the beta and the gamma zone was 0.64 ± 0.79 and 0.16 ± 0.30 mm2, respectively. In multivariate models, the gamma zone significantly correlated with axial length (P = 0.001) but not with glaucoma (P = 0.944). In contrast, the beta zone significantly correlated with age (P = 0.0249) and glaucoma (P = 0.014).

CONCLUSIONS

En face images reconstructed from 3D SS-OCT data facilitated measurements of the beta and the gamma PPA zones even in eyes with optic disc distortion. The OCT-defined beta zone is associated with glaucoma and age, whereas the gamma zone correlated with myopia but not with glaucoma. This study confirmed the clinical usefulness of OCT-based classification of the PPA zones in distinguishing glaucomatous damage of the optic nerve from myopic damage in non-highly myopic eyes.

Influence of the lamina cribrosa on the rate of global and localized retinal nerve fiber layer thinning in open-angle glaucoma

The advent of optical coherence tomography (OCT) imaging allows identification of the structural contribution of the lamina cribrosa (LC) to glaucoma progression. This study aimed to determine the role of various LC features, such as the LC depth (LCD), LC thickness (LCT), and focal LC defects, on the future rate of progressive retinal nerve fiber layer (RNFL) thinning in patients with glaucoma. One hundred eighteen patients with glaucoma who had undergone at least 4 OCT examinations were included. Features of LC, including the LCD, LCT, and presence of focal LC defects, from serial scan of the optic disc using the enhanced depth imaging of Spectralis OCT; were analyzed at baseline. Eyes were classified as those with or without progressive RNFL thinning using the guided progression analysis of Cirrus OCT. Factors associated with the rate of RNFL thinning (linear regression analysis against time for global average, inferior, and superior RNFL thicknesses, μm/year) were evaluated using a general linear model. Greater baseline LCD and thinner baseline LCT were significantly associated with the rate of superior RNFL thinning. Focal LC defects were significantly more frequent in eyes with progressive inferior RNFL thinning (93.8%) and the location of the focal LC defect was only related to the location of progression RNFL thinning in the inferior region (P < 0.001). A deeper and thinner LC was related to the rate of superior RNFL thinning, and the presence of focal LC defects was related to the rate of inferior RNFL thinning.

Structural and functional brain changes in early- and mid-stage primary open-angle glaucoma using voxel-based morphometry and functional magnetic resonance imaging

To investigate structural and functional brain changes in patients with primary open-angle glaucoma (POAG) by using voxel-based morphometry based on diffeomorphic anatomical registration through exponentiated Lie algebra (VBM-DARTEL) and blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI), respectively.Thirteen patients diagnosed with POAG and 13 age- and sex-matched healthy controls were enrolled in the study. For each participant, high-resolution structural brain imaging and blood flow imaging were acquired on a 3.0-Tesla magnetic resonance imaging (MRI) scanner. Structural and functional changes between the POAG and control groups were analyzed. An analysis was carried out to identify correlations between structural and functional changes acquired in the previous analysis and the retinal nerve fiber layer (RNFL).Patients in the POAG group showed a significant (P < 0.001) volume increase in the midbrain, left brainstem, frontal gyrus, cerebellar vermis, left inferior parietal lobule, caudate nucleus, thalamus, precuneus, and Brodmann areas 7, 18, and 46. Moreover, significant (P < 0.001) BOLD signal changes were observed in the right supramarginal gyrus, frontal gyrus, superior frontal gyrus, left inferior parietal lobule, left cuneus, and left midcingulate area; many of these regions had high correlations with the RNFL.Patients with POAG undergo widespread and complex changes in cortical brain structure and blood flow. (ClinicalTrials.gov number: NCT02570867).

New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics

Primary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increased risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We conducted a genome-wide association meta-analysis of IOP and optic disc parameters and validated our findings in multiple sets of POAG cases and controls. Using imputation to the 1000 genomes (1000G) reference set, we identified 9 new genomic regions associated with vertical cup-disc ratio (VCDR) and 1 new region associated with IOP. Additionally, we found 5 novel loci for optic nerve cup area and 6 for disc area. Previously it was assumed that genetic variation influenced POAG either through IOP or via changes to the optic nerve head; here we present evidence that some genomic regions affect both IOP and the disc parameters. We characterized the effect of the novel loci through pathway analysis and found that pathways involved are not entirely distinct as assumed so far. Further, we identified a novel association between CDKN1A and POAG. Using a zebrafish model we show that six6b (associated with POAG and optic nerve head variation) alters the expression of cdkn1a. In summary, we have identified several novel genes influencing the major clinical risk predictors of POAG and showed that genetic variation in CDKN1A is important in POAG risk.

Oxidative and Anti-Oxidative Stress Markers in Chronic Glaucoma: A Systematic Review and Meta-Analysis

Chronic glaucoma is a multifactorial disease among which oxidative stress may play a major pathophysiological role. We conducted a systematic review and meta-analysis to evaluate the levels of oxidative and antioxidative stress markers in chronic glaucoma compared with a control group. The PubMed, Cochrane Library, Embase and Science Direct databases were searched for studies reporting oxidative and antioxidative stress markers in chronic glaucoma and in healthy controls using the following keywords: “oxidative stress” or “oxidant stress” or “nitrative stress” or “oxidative damage” or “nitrative damage” or “antioxidative stress” or “antioxidant stress” or “antinitrative stress” and “glaucoma”. We stratified our meta-analysis on the type of biomarkers, the type of glaucoma, and the origin of the sample (serum or aqueous humor). We included 22 case-control studies with a total of 2913 patients: 1614 with glaucoma and 1319 healthy controls. We included 12 studies in the meta-analysis on oxidative stress markers and 19 on antioxidative stress markers. We demonstrated an overall increase in oxidative stress markers in glaucoma (effect size = 1.64; 95%CI 1.20–2.09), ranging from an effect size of 1.29 in serum (95%CI 0.84–1.74) to 2.62 in aqueous humor (95%CI 1.60–3.65). Despite a decrease in antioxidative stress marker in serum (effect size = –0.41; 95%CI –0.72 to –0.11), some increased in aqueous humor (superoxide dismutase, effect size = 3.53; 95%CI 1.20–5.85 and glutathione peroxidase, effect size = 6.60; 95%CI 3.88–9.31). The differences in the serum levels of oxidative stress markers between glaucoma patients and controls were significantly higher in primary open angle glaucoma vs primary angle closed glaucoma (effect size = 12.7; 95%CI 8.78–16.6, P < 0.001), and higher in pseudo-exfoliative glaucoma vs primary angle closed glaucoma (effect size = 12.2; 95%CI 8.96–15.5, P < 0.001). In conclusion, oxidative stress increased in glaucoma, both in serum and aqueous humor. Malonyldialdehyde seemed the best biomarkers of oxidative stress in serum. The increase of some antioxidant markers could be a protective response of the eye against oxidative stress.

The analysis of macular thickness asymmetry in primary open angle glaucoma using Spectral- -Domain Optical Coherence Tomography

PURPOSE

To analyze central retinal thickness asymmetry in patients with known and suspected primary open angle glaucoma.

MATERIAL AND METHODS

A prospective analysis of 21 patients with known glaucoma and 53 patients with suspected glaucoma. A control group consisted of 25 healthy volunteers. Each enrolled patient had a spectral domain optical coherence tomography performed including a circumpapillary retinal nerve fiber layer and central retinal thickness measurements. A central 20 degree area was divided into 64 3⁰ x 3⁰ areas. The mean retinal thickness was measured in each small square and the value obtained in the upper half of every square was compared to the corresponding value in the lower half. A correlation between the mean circumpapillary retinal nerve fiber layer thickness and the central retinal thickness was assessed.

RESULTS

The mean thickness of circumpapillary retinal nerve fiber layer was significantly lower in patients with known and suspected glaucoma (92.15 ±12.85 μm; 93.84 ± 11.45 μm vs. 97.82 ± 7.48 μm; P<0.05). The mean central retinal thickness did not differ significantly between the groups (291.05 ± 15.86 μm; 290.46 ± 13.60 μm vs. 293.94 ± 11.07 μm; P>0.05). Macular asymmetry was detected significantly more frequently in glaucomatous and glaucoma suspected eyes (78%; 66% vs. 32%; P<0.05). An association between the measured values was observed.

CONCLUSIONS

The macular thickness measurements and macular asymmetry analysis may represent a novel strategy in glaucoma diagnosis.

The Relationship between Corvis ST Tonometry and Ocular Response Analyzer Measurements in Eyes with Glaucoma

It is important to compare the results of Corneal Visualization Scheimpflug Technology instrument (CST) measurements and Reichert Ocular Response Analyzer (ORA) parameters. The purpose of the study was to investigate the association between CST measurements and ORA parameters in ninety-five patients with primary open-angle glaucoma. Measurements of CST, ORA, axial length (AL), average corneal curvature (CC), central corneal thickness (CCT) and intraocular pressure (IOP) with Goldmann applanation tonometry (GAT) were carried out. The association between CST and ORA parameters was assessed using linear regression analysis, with model selection based on the second order bias corrected Akaike Information Criterion index. Measurements from ORA (corneal hysteresis [CH] and corneal response factor [CRF]) had high intraclass correlation coefficients (ICC) and low coefficients of variation, but some CST parameters showed much lower reproducibility, namely: A1 length, A2 length, highest concavity time and peak distance. Of 12 CST parameters tested, 8 were significantly correlated with CH and 10 were significantly correlated with CRF, however, the magnitude of the correlation coefficients were weak to moderate at best. The optimal model to explain CH using CST measurements was given by: CH = -76.3 + 4.6*A1 time + 1.9*A2 time + 3.1 * highest concavity deformation amplitude + 0.016*CCT (R² = 0.67, p <0.001). Similarly, the optimal model for CRF was given by: CRF = -53.5 + 4.2*A1 time + 1.9*A1 length + 20.8*A1 deformation amplitude + 0.8*A2 time + 0.017*CCT (R² = 0.73, p <0.001). ORA parameters show higher reproducibility than CST measurements. Although many CST parameters are significantly related to ORA parameters, the strengths of these relationships are weak to moderate.

Contrast sensitivity assessment in primary open angle glaucoma and ocular hypertension

INTRODUCTION

Contrast sensitivity assessment is an important additional examination, which enables the full insight into the patient's quality of vision, and early diagnosis of visual disturbances.

MATERIAL AND METHODS

Forty six patients (92 eyes) with primary open angle glaucoma or ocular hypertension were enrolled in the study. The enrolment criteria were full or almost full visual acuity and the patients with visual field defects or any other ocular disease were excluded. Contrast sensitivity was assessed both under photopic and mesopic conditions (with and without glare) using the Functional Vision Analyzer separately for each eye. Furthermore, the retinal nerve fiber layer (RNFL) thickness was measured using scanning laser polarimetry (GDx).

RESULTS

Contrast sensitivity was significantly reduced under both mesopic and photopic conditions in patients with primary open angle glaucoma or ocular hypertension.

CONCLUSIONS

Evaluation of contrast sensitivity is a valuable diagnostic test, which enables the assessment of visual dysfunction in patients with primary open angle glaucoma or ocular hypertension persisting despite good visual acuity.

Macular microvasculature alterations in patients with primary open-angle glaucoma: A cross-sectional study

To evaluate and compare macular microvasculature changes in eyes with primary open-angle glaucoma (POAG) to normal eyes, and to assess associations among the retinal microvasculature, neural structural damage, and visual field loss.Ninety-nine eyes (68 patients with POAG and 31 normal subjects) were enrolled in this study. Thirty-five eyes with early-stage glaucoma (EG), 33 eyes with advanced-stage glaucoma (AG), and 31 normal eyes were included. An optical coherence tomography system with a split-spectrum amplitude-decorrelation angiography algorithm was used to measure the macular capillary vessel area density and retinal thickness. Visual field testing (30-2 and 10-2 programs) was performed using a Humphrey field analyzer. Correlations between the capillary vessel area density, retinal thickness, and visual field parameters were analyzed.Compared to normal eyes, those with EG and AG had a lower macular capillary vessel area density and lesser retinal thickness (P < 0.001, all). Results of multivariate linear regression analyses showed that each standard deviation (SD) decrease in the vessel area density was associated with a 1.5% and 4.2% thinning of the full retinal thickness and inner retinal layer thickness, respectively. Each SD decrease in the vessel area density was also associated with a 12.9% decrease in the mean sensitivity and a 33.6% increase in the pattern standard deviation (P < 0.001, both). The Pearson partial regression analysis model showed that the vessel area density was most strongly associated with the inner retinal layer thickness and inferior hemimacular thickness. Furthermore, a lower vessel area density was strongly associated with a more severe hemimacular visual field defect and the corresponding hemimacular retinal thickness.The macular capillary vessel area density and retinal thickness were significantly lower in eyes with POAG than in normal eyes. A diminished macular microvasculature network is closely associated with visual field defects, which are dependent on structural damage due to POAG.

Assessment of Open-Angle Glaucoma Peripapillary and Macular Choroidal Thickness Using Swept-Source Optical Coherence Tomography (SS-OCT)

OBJECTIVE

To compare peripapillary and macular choroidal thickness (PCT and MCT) between open-angle glaucoma (OAG) and normal controls using swept-source optical coherence tomography (SS-OCT), and to evaluate global and localized relationships between choroidal thickness and various factors in OAG, also using SS-OCT.

METHODS

In this cross-sectional comparative study, 134 OAG patients and 73 normal controls were examined. PCT (global, 12 clock-hour sectors), MCT (global, six sectors) were measured by SS-OCT. The difference in choroidal thickness between the OAG patients and the normal controls was analyzed. The relationships between choroidal thickness and various factors including age, sex, spherical equivalent (SE), axial length (AXL), central corneal thickness (CCT), intraocular pressure (IOP), peripapillary retinal nerve fiber layer thickness (pRNFLT), visual field mean deviation (MD), ganglion cell-inner plexiform layer thickness (GCIPLT), and disc area were analyzed by univariate and multivariate linear regression. Global and regional analyses were performed in 12 segments of the peripapillary circle and in six sectors of the macula.

RESULTS

There were significant differences in global PCT and MCT between the OAG patients and the normal controls (115.22±41.17 vs. 138.89±44.70, P<0.001), (184.36±57.15 vs. 209.25±61.11, P = 0.004). The difference in global PCT remained, both after adjusting for age, AXL (117.08±3.45 vs. 135.47±4.70, P = 0.002) and also after adjusting for age, AXL, disc area (117.46±3.46 vs. 135.67±4.67, P = 0.002). But the difference in global MCT did not remain after adjusting for age, AXL, SE (188.18±4.46 vs. 202.25±6.08, P = 0.066). PCT showed significant differences between the groups in all of the 12 clock-hour sectors. These differences remained after adjusting for age, AXL and for age, AXL, disc area, with the exception of the 10 o'clock (o/c) sector. MCT in six sectors showed differences between the two groups, but they did not remain after adjusting for age, AXL, SE. In a multivariate regression analysis of the OAG patients, global PCT showed correlations with age (β = -1.18, P = 0.001), AXL (β = -14.01, P<0.001), and disc area (β = -16.67, P = 0.026). Global MCT, meanwhile, showed a significant correlation with age (β = -1.92, P<0.001), AXL. (β = -21.97, P<0.001). Choroidal thickness did not show any global or localized relationship with glaucoma severity in the OAG patients.

CONCLUSIONS

The global and all 12 clock-hour PCT, with the exception of the 10 o/c sector, were thinner in OAG; however, they did not show any correlation with glaucoma severity. Possible roles of PCT in glaucoma pathogenesis should be investigated further.

Working your SOCS off: The role of ASB10 and protein degradation pathways in glaucoma

Evidence is accumulating to suggest that mutations in the Ankyrin and SOCS Box-containing protein-10 (ASB10) gene are associated with glaucoma. Since its identification in a large Oregon family with primary open-angle glaucoma (POAG), ASB10 variants have been associated with disease in US, German and Pakistani cohorts. ASB10 is a member of the ASB family of proteins, which have a common structure including a unique N-terminus, a variable number of central ankyrin (ANK) repeat domains and a suppressor of cytokine signaling (SOCS) box at the C-terminus. Mutations in ASB10 are distributed throughout the entire length of the gene including the two alternatively spliced variants of exon 1. A homozygous mutation in a Pakistani individual with POAG, which lies in the center of the SOCS box, is associated with a particularly severe form of the disease. Like other SOCS box-containing proteins, ASB10 functions in ubiquitin-mediated degradation pathways. The ANK repeats bind to proteins destined for degradation. The SOCS box recruits ubiquitin ligase proteins to form a complex to transfer ubiquitin to a substrate bound to the ANK repeats. The ubiquitin-tagged protein then enters either the proteasomal degradation pathway or the autophagic-lysosomal pathway. The choice of pathway appears to be dependent on which lysine residues are used to build polyubiquitin chains. However, these reciprocal pathways work in tandem to degrade proteins because inhibition of one pathway increases degradation via the other pathway. In this publication, we will review the literature that supports identification of ASB10 as a glaucoma-associated gene and the current knowledge of the function of the ASB10 protein. In addition, we present new data that indicates ASB10 expression is up-regulated by the inflammatory cytokines tumor necrosis factor-α and interleukin-1α. Finally, we will describe the emerging role of other SOCS box-containing proteins in protein degradation pathways in ocular cells.

Rho GTPase signaling promotes constitutive expression and release of TGF-β2 by human trabecular meshwork cells

Elevated intraocular pressure (IOP) is causally implicated in the pathophysiology of primary open-angle glaucoma (POAG). The molecular mechanisms responsible for elevated IOP remain elusive, but may involve aberrant expression and signaling of transforming growth factor (TGF)-β2 within the trabecular meshwork (TM). Consistent with previously published studies, we show here that exogenous addition of TGF-β2 to cultured porcine anterior segments significantly attenuates outflow facility in a time-dependent manner. By comparison, perfusing segments with a TGFβRI/ALK-5 antagonist (SB-431542) unexpectedly elicited a significant and sustained increase in outflow facility, implicating a role for TM-localized constitutive expression and release of TGF-β2. Consistent with this thesis, cultured primary or transformed (GTM3) quiescent human TM cells were found to constitutively express and secrete measurable amounts of biologically-active TGF-β2. Disrupting monomeric GTPase post-translational prenylation and activation with lovastatin or GGTI-298 markedly reduced constitutive TGF-β2 expression and release. Specifically, inhibiting the Rho subfamily of GTPases with C3 exoenzyme similarly reduced constitutive expression and secretion of TGF-β2. These findings suggest that Rho GTPase signaling, in part, regulates constitutive expression and release of biologically-active TGF-β2 from human TM cells. Localized constitutive expression and release of TGF-β2 by TM cells may promote or exacerbate elevation of IOP in POAG.

Macular Ganglion Cell-Inner Plexiform Layer and Retinal Nerve Fiber Layer Thickness in Eyes With Primary Open-Angle Glaucoma Compared With Healthy Saudi Eyes: A Cross-Sectional Study

PURPOSE

We compared the thickness of the ganglion cell-inner plexiform layer at the macula (mGCIPL) and the thickness of the retinal nerve fiber layer (RNFL) in different regions of the retina in eyes with primary open-angle glaucoma (POAG group) and normal eyes (control group).

DESIGN

This was a cross-sectional study performed in 2014.

METHODS

Spectral domain optical coherence tomography (SD-OCT) was used to measure mGCIPL and RNFL thickness. Age-adjusted means and standard deviation were calculated. Age, sex, refractive status, corneal thickness, and stage/severity of glaucoma (defined by vertical cup-to-disc ratio and visual field changes) were associated to outcomes. Statistical significance was indicated by P < 0.05.

RESULTS

There were 50 eyes in the POAG group and 52 eyes in the control group. The difference in age between patients in both groups was statistically significant (P < 0.001). The age-adjusted measurements were thinner for POAG with a mean difference (DF) of 11.1 μm for mGCIPL and 8 μm for mRNFL. The mGCIPL to mRFNL ratio was 2.1 in the POAG group and 1.9 in the control group (degrees of freedom = 0.2, P = 0.001). The mGCIPL and RNFL thickness decreased as the severity of glaucoma increased. The mGCIPL to mRNFL ratio was a predictor of the severity of field defects in POAG (AUROC = 0.66, P = 0.0002). Age and myopia were confounders to the association of OCT findings and the visual field changes in POAG (P = 0.07).

CONCLUSIONS

There was generalized thinning of retinal layers in eyes of nondiabetic Arab patients with POAG. OCT parameters can be important for detecting and monitoring glaucoma cases.

Intraeye retinal nerve fiber layer and macular thickness asymmetry measurements for the discrimination of primary open-angle glaucoma and normal tension glaucoma

PURPOSE

The aim of this study was to evaluate the diagnostic capability of intraeye retinal nerve fiber layer (RNFL) thickness and macular thickness (MT) asymmetry measurements for the discrimination of normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) using spectral domain optical coherence tomography (SD-OCT).

METHODS

A total of 90 subjects were enrolled including 30 consecutive healthy subjects, 30 consecutive subjects with POAG, and 30 consecutive subjects with NTG. RNFL thicknesses around the optic disc as well as MT measurements were taken with circular and radial SD-OCT scans. Intraeye retinal and MT asymmetry were calculated as the absolute difference between superior and inferior hemispheres of the eye using posterior pole asymmetry analysis protocol. Analysis of variance was used for comparison and areas under the receiver operating characteristic (AROC) were obtained for different parameters among the three diagnostic groups.

RESULTS

There was a significant difference in MT asymmetry for all comparison groups (normal-NTG, p<0.05; normal-POAG, p<0.001; and NTG-POAG, p<0.001). Intraeye retinal nerve fiber thickness asymmetry measurements were not different between the groups (normal-NTG, p<0.187; normal-POAG, p<0.056; and NTG-POAG, p<0.837). The area under ROC curves exceeded 0.800 for all the studied parameters, including the MT asymmetry except for intraeye RNFL thickness asymmetry which had the lowest AROC as well as the least sensitivity for identifying subjects with NTG from normal (AROC=0.626, sensitivity=30%); POAG from normal (AROC=0.644, sensitivity=37%) and NTG from POAG (AROC=0.533, sensitivity=13%).

CONCLUSION

The intraeye MT asymmetry holds significant potential as a distinguishing parameter for NTG and POAG.

Establishing Age-Adjusted Reference Ranges for Iris-Related Parameters in Open Angle Eyes with Anterior Segment Optical Coherence Tomography

Purpose

Define criteria for iris-related parameters in an adult open angle population as measured with swept source Fourier domain anterior segment optical coherence tomography (ASOCT).

Methods

Ninety-eight eyes of 98 participants with open angles were included and stratified into 5 age groups (18–35, 36–45, 46–55, 56–65, and 66–79 years). ASOCT scans with 3D mode angle analysis were taken with the CASIA SS-1000 (Tomey Corporation, Nagoya, Japan) and analyzed using the Anterior Chamber Analysis and Interpretation software. Anterior iris surface length (AISL), length of scleral spur landmark (SSL) to pupillary margin (SSL-to-PM), iris contour ratio (ICR = AISL/SSL-to-PM), pupil radius, radius of iris centroid (RICe), and iris volume were measured. Outcome variables were summarized for all eyes and age groups, and mean values among age groups were compared using one-way analysis of variance. Stepwise regression analysis was used to investigate demographic and ocular characteristic factors that affected each iris-related parameter.

Results

Mean (±SD) values were 2.24 mm (±0.46), 4.06 mm (±0.27), 3.65 mm (±0.48), 4.16 mm (±0.47), 1.14 (±0.04), 1.51 mm² (±0.23), and 38.42 μL (±4.91) for pupillary radius, RICe, SSL-to-PM, AISL, ICR, iris cross-sectional area, and iris volume, respectively. Both pupillary radius (P = 0.002) and RICe (P = 0.027) decreased with age, while SSL-to-PM (P = 0.002) and AISL increased with age (P = 0.001). ICR (P = 0.54) and iris volume (P = 0.49) were not affected by age.

Conclusion

This study establishes reference values for iris-related parameters in an adult open angle population, which will be useful for future studies examining the role of iris changes in pathologic states.

[Corrrelation between blood pressure levels in patients with glaucoma (Literature review)]

The problem of correlation between blood pressure levels and intraocular pressure is one of the most talked about. Both, Russian and foreign literature, reflects the heterogeneity of views on the impact of blood pressure changes into the level of intraocular. pressure. At the same time it underestimated the role of systemic cardiovascular changes in the deterioration of visual function in case of primary open-angle glaucoma. Numerous data demonstrate the role of additional factors than average blood pressure levels in advance of glaucoma. More and more researchers tend to assess not only intraocular pressure, but also perfusion pressure as a risk predictor of advance of glaucoma. Correlation between blood pressure level and intraocular pressure has a particular relevance due to the significant improvement of the range of cardiovascular drugs that can affect on intraocular pressure indictors. A number of literature data confirm the need to research variations in blood pressure levels during the day and types of therapy that patients receive.

A Case of Open-Angle Glaucoma Successfully Treated Using Canaloplasty

OBJECTIVE

We report the case of a patient with open-angle glaucoma who underwent canaloplasty and subsequently maintained good intraocular pressure (IOP) control for the entire duration of the 4-year follow-up.

SUBJECTS

The patient was a 68-year-old man who was diagnosed with open-angle glaucoma and uncontrollable IOP at the Tokai University Hachioji Hospital in January 2011. Visual field examination revealed an arcuate visual field defect in the left eye, but no visual field defect in the right eye. In order to lower the IOP, canaloplasty was performed on his left eye.

RESULTS

There were no complications either during or after the surgery. The IOP values at 2 weeks, 1 month, 6 months, 1 year, 2 years, 3 years, and 4 years were, 13, 14, 18, 12, 10, 12, and 8 mmHg, respectively. No deteriorations in visual field or reductions in visual acuity were detected during this follow-up.There were no long-term complications such as cataract formation or exposure of the suture. Spectral domain optical coherence tomography showed that the trabecular meshwork was inwardly distended because of the intracanalicular suture in the affected eye.

CONCLUSION

Canaloplasty can be a safe and effective surgical method for lowering the IOP in glaucoma patients.

TIMP1, TIMP2, and TIMP4 are increased in aqueous humor from primary open angle glaucoma patients

PURPOSE

Elevated intraocular pressure (IOP) is the only known modifiable risk factor for primary open angle glaucoma (POAG), and it can be caused by reduced aqueous humor outflow from the anterior chamber. Outflow is predominantly regulated by the trabecular meshwork, consisting of specialized cells within a complex extracellular matrix (ECM). An imbalance between ECM-degrading matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) within the trabecular meshwork is thought to contribute to POAG. This study aimed to quantify levels of TIMPs and MMPs in aqueous humor samples from glaucomatous and non-glaucomatous eyes, analyze MMP/TIMP ratios, and correlate results with age, IOP, and Humphrey's visual field pattern standard deviation (PSD).

METHODS

Aqueous humor samples were collected from 26 non-glaucomatous control subjects before cataract surgery and 23 POAG patients undergoing trabeculectomy or cataract surgery. Analyte concentrations were measured using multiplexed immunoassays. Statistical significance was assessed with Mann-Whitney U tests, and Spearman's method was used to assess correlations with age, IOP, and PSD.

RESULTS

Concentrations of TIMP1 (p = 0.0008), TIMP2 (p = 0.002), TIMP4 (p = 0.002), and MMP2 (p = 0.020) were significantly increased in aqueous humor samples from POAG versus cataract samples. For the majority of MMP/TIMP molar ratios calculated for the cataract group, TIMPs outweighed MMPs. In POAG, molar ratios of MMP2/TIMP1 (p = 0.007) and MMP9/TIMP1 (p = 0.005) showed a significant decrease, corresponding to an elevated excess of TIMPs over MMPs in POAG compared to cataract samples. Conversely, MMP2/TIMP3 (p = 0.045) and MMP3/TIMP3 (p = 0.032) molar ratios increased. Several MMP/TIMP molar ratios correlated with IOP (r = 0.476-0.609, p = 0.007-0.034) and PSD (r = -0.482 to -0.655, p = 0.005-0.046) in POAG samples and with age in cataract control samples.

CONCLUSIONS

An imbalance among MMPs and TIMPs was found in glaucomatous aqueous humor samples, with a shift toward raised TIMP levels. This may result in the inhibition of MMP activity, leading to an altered ECM composition in the TM and thereby contributing to increased outflow resistance.

Amplitude of low frequency fluctuation in primary open angle glaucoma: a resting state fMRI study

Primary open angle glaucoma (POAG) is a kind of progressive neuropathy with no clear cause. In the present fMRI study, a data-driven approach was employed to map the alteration of regional spontaneous activity in POAG patients by measuring the amplitude of low-frequency fluctuation (ALFF) of the blood oxygen level-dependent (BOLD) signal. Twenty one POAG patients and 22 age and gender matched healthy subjects participated in this study. We found that the abnormal ALFF values in the POAG patients compared with healthy controls were not only detected in the visual regions but also across the whole brain. We also found the correlations between ALFF values and the POAG stages for POAG patients. We concluded that the abnormality of spontaneous brain activity in patients with POAG existed in visual cortex as well as in distal brain regions associated with sensation, motion, emotion and psychology. And the abnormal spontaneous neural activity in different brain regions could be better detected by specific frequency bands. These findings might contribute to a better understanding of the pathophysiology of POAG.

Axial Myopia Is Associated with Visual Field Prognosis of Primary Open-Angle Glaucoma

Purpose

To identify whether myopia was associated with the visual field (VF) progression of primary open-angle glaucoma (POAG).

Methods

A total of 270 eyes of 270 POAG followed up for more than 3 years with ≥9 reliable VFs by Octopus perimetry were retrospectively reviewed. Myopia was divided into: mild myopia (-2.99 diopter [D], 0), moderate myopia (-5.99, 3.00 D), marked myopia (-9.00, -6.00 D) and non-myopia (0 D or more). An annual change in the mean defect (MD) slope >0.22 dB/y and 0.30 dB/y was defined as fast progression, respectively. Logistic regression was performed to determine prognostic factors for VF progression.

Results

For the cutoff threshold at 0.22 dB/y, logistic regression showed that vertical cup-to-disk ratio (VCDR; p = 0.004) and the extent of myopia (p = 0.002) were statistically significant. When logistic regression was repeated after excluding the extent of myopia, axial length (AL; p = 0.008, odds ratio [OR] = 0.796) reached significance, as did VCDR (p = 0.001). Compared to eyes with AL≤23 mm, the OR values were 0.334 (p = 0.059), 0.309 (p = 0.044), 0.266 (p = 0.019), 0.260 (p = 0.018), respectively, for 23 <AL≤24 mm, 24 <AL≤25 mm, 25 <AL ≤26 mm, and AL>26 mm. The significance of vertical cup-to-disk ratio of (p = 0.004) and the extent of myopia (p = 0.008) did not change for the cutoff threshold at 0.30dB/y.

Conclusions

VCDR and myopia were associated with VF prognosis of POAG. Axial myopia may be a protective factor against VF progression.

[Foveal choroidal thickness assessment with SD-OCT in high myopic glaucoma]

PURPOSE

To measure macular choroidal thickness (CT) using spectral domain optical coherence tomography (OCT) in high myopic eyes with primary angle-open glaucoma (POAG), and to investigate whether the choroid is thinner in these eyes compared to high myopic eyes without glaucoma.

PATIENTS AND METHODS

We conducted a cross-sectional study of forty-eight eyes with high myopic glaucoma matched with 48 highly myopic eyes without glaucoma by age, central corneal thickness and axial length (AL). OCT scans were performed with the spectral domain OCT (Topcon 2000). The subfoveal CT was measured between the Bruch membrane and the internal aspect of the sclera.

RESULTS

In the subgroup without glaucoma, matched with the subgroup with glaucoma (P=0.57), by age, central corneal thickness (P=0.33) and AL (P=0.10), the mean subfoveal CT was 96.32 μm ± 39.56 μm. In the subgroup with glaucoma, the mean subfoveal CT was 50.44 μm ± 16.36 μm. The comparison between the two subgroups found a statistically significant difference in subfoveal CT (P<10(-4)).

CONCLUSIONS

Foveal choroidal thickness is reduced in highly myopic eyes with glaucoma. The choroidal thinning can be a useful parameter for the diagnosis and the follow-up of highly myopic patients with glaucoma.