Incidence of severe rise in intraocular pressure after intravitreous injection of aflibercept with prefilled syringes.

Our aim was to analyze the intraocular pressure (IOP) changes following different intravitreous injection (IVI) procedures with or without prefilled syringes (PFS) and to elaborate their possible causes. Clinical study and laboratory assessment. 173 eyes of 141 patients. The IOP was prospectively measured pre- and postoperatively in three groups of patients receiving IVI either with ranibizumab (RP), aflibercept PFS (AP) or aflibercept vials (AV). The AP emptying volume (EV) was assessed using 40 aflibercept PFS vials: the plunger was aligned precisely (normal volume, NV) or right below the indication line (high volume, HV) and the drug was ejected with (wP) or without forced pressure (nP). Primary outcome was post-treatment IOP with type of IVI and pre-treatment IOP as fixed factors. Secondary outcome was identification of possibly confounding factors (age, sex, pathology, presence of pseudophakia, spherical error, and number of injections) and IOP > 30 mmHg post-treatment. An IOP rise above 30 mmHg was observed in 8/38 (22%), 16/51 (31%) and 35/86 (41%) cases in the RP, AV and AP groups, respectively (p = 0.129). Pre-treatment IOP was the only predictive variable for IOP rise (p < 0.001). The EV values in the NVnP, NVwP, HVnP and HVwP groups were 56.06 ± 10.32, 70.69 ± 4.56, 74.22 ± 7.41 and 81.63 ± 3.67 µl, respectively (p < 0.001). We observed a marked, although not significantly higher incidence of IOP elevations with the aflibercept PFS. One possible reason may be the error-proneness of administering the correct volume with the AP. Caution should be taken when using the aflibercept PFS in order to prevent potential optic nerve damage in cases with marked elevation in IOP.

Cell Types of the Human Retina and Its Organoids at Single-Cell Resolution.

Human organoids recapitulating the cell-type diversity and function of their target organ are valuable for basic and translational research. We developed light-sensitive human retinal organoids with multiple nuclear and synaptic layers and functional synapses. We sequenced the RNA of 285,441 single cells from these organoids at seven developmental time points and from the periphery, fovea, pigment epithelium and choroid of light-responsive adult human retinas, and performed histochemistry. Cell types in organoids matured in vitro to a stable "developed" state at a rate similar to human retina development in vivo. Transcriptomes of organoid cell types converged toward the transcriptomes of adult peripheral retinal cell types. Expression of disease-associated genes was cell-type-specific in adult retina, and cell-type specificity was retained in organoids. We implicate unexpected cell types in diseases such as macular degeneration. This resource identifies cellular targets for studying disease mechanisms in organoids and for targeted repair in human retinas.

Venous blood flow alterations in glaucoma patients.

PURPOSE: To evaluate the correlation between retinal venous blood flow parameters and glaucomatous visual field damage in a retrospective analysis. METHODS: Fifty-five (24 male, 31 female) glaucoma patients, under intraocular pressure (IOP) reducing treatment, aged (mean ± SD) 69 ± 10 years, 29 with primary open-angle and 26 with normal-tension glaucoma, were evaluated with regard to the correlation between IOP, color Doppler retinal venous blood flow velocity and glaucomatous damage. RESULTS: Univariate regression analysis disclosed statistically significant correlations of the visual field index MD with age, IOP and venous blood flow (p ≤ 0.026 for each parameter). A mixed linear effects model disclosed a significant correlation of MD with age, IOP and venous blood flow (p ≤ 0.002 for each parameter), but not with sex, side (right eye versus left eye) and diagnosis (primary open-angle glaucoma versus normal-tension glaucoma). Finally, interocular difference (right eye vs. left eye of the same patient) in MD correlated with interocular differences in venous blood flow velocities (p < 0.001), but not with interocular differences in IOP. CONCLUSIONS: Glaucomatous damage correlated negatively with retinal venous blood flow velocity, be it between subjects or between eyes within individuals. This study is limited by its cross-sectional design, and it is not possible to draw any conclusion with regard to the origin of the correlations.

Statistical framework for validation without ground truth of choroidal thickness changes detection.

Monitoring subtle choroidal thickness changes in the human eye delivers insight into the pathogenesis of various ocular diseases such as myopia and helps planning their treatment. However, a thorough evaluation of detection-performance is challenging as a ground truth for comparison is not available. Alternatively, an artificial ground truth can be generated by averaging the manual expert segmentations. This makes the ground truth very sensitive to ambiguities due to different interpretations by the experts. In order to circumvent this limitation, we present a novel validation approach that operates independently from a ground truth and is uniquely based on the common agreement between algorithm and experts. Utilizing an appropriate index, we compare the joint agreement of several raters with the algorithm and validate it against manual expert segmentation. To illustrate this, we conduct an observational study and evaluate the results obtained using our previously published registration-based method. In addition, we present an adapted state-of-the-art evaluation method, where a paired t-test is carried out after leaving out the results of one expert at the time. Automated and manual detection were performed on a dataset of 90 OCT 3D-volume stack pairs of healthy subjects between 8 and 18 years of age from Asian urban regions with a high prevalence of myopia.

Optical coherence tomography angiography (OCTA) as a new diagnostic tool in uveitis.

BACKGROUND: The broad spectrum of uveitis disorders requires a multimodal imaging approach in the daily practice of an ophthalmologist. As inflammatory conditions, they have in common an alteration in leukocyte migration. In this context, optical coherence tomography angiography (OCTA) might be of great value for diagnosing or following up patients with these disorders. To date, OCTA has rather been used as an additional tool besides the well-established diagnostic imaging tools, but its complementary diagnostic features become increasingly relevant, to follow disease activity and treatment response and for the understanding of pathomechanisms of various uveitis types. This review summarizes the possible applications of OCTA and its advantages and disadvantages as opposed to dye-based angiographies in uveitic diseases. MAIN BODY: Hitherto gold standards in the diagnostic workup of posterior or intermediate uveitis have been angiography on a dye-based method, which is fluorescein or indocyanine green. It gives information about the status of the blood-retinal barrier and the retinal and choroidal vasculature by visualizing diffuse leakage as a state of inflammation or complications as an ischemia or choroidal neovascularization. As noninvasive methods, fundus autofluorescence depicts the status of metabolic activity of the retinal pigment epithelium and OCT or enhanced depth imaging OCT, respectively, as a depth-resolving imaging method can supply additional information. OCTA as a non-invasive, depth-resolution imaging tool of retinal and choroidal vessels adds detailed qualitative and quantitative information of the status of retinal and choroidal vessels and bridges the gap between the mentioned conventional diagnostic tools used in uveitis. It is important, though, to be aware of its limitations, such as its susceptibility to motion artifacts, limited comparability among different devices, and restricted contribution of information regarding the grade of disease activity. CONCLUSION: OCTA as a non-invasive, depth-resolution imaging tool can give qualitative and quantitative information about the status of retinal and choroidal vessels, but also has certain limitations. Employing OCTA as a complementary rather than exclusive tool, it can give important additional information about the macro- and microvasculature under inflammatory circumstances. Thereby, it also contributes to the understanding of the pathophysiology of various uveitis entities.

The prognostic value of retinal vessel analysis in primary open-angle glaucoma.

PURPOSE: To analyse a prognostic value of initial retinal vessel flicker response for the 3-year development of functional (visual field) and morphological (nerve fibre layer thickness) damage progression in primary open-angle glaucoma patients. PATIENTS AND METHODS: Initially, 70 patients were recruited, and flicker response was measured by standardized procedure with the retinal vessel analyser (RVA). Ocular coherence tomography of retinal nerve fibre layer (OCT RNFL) and a visual field testing were performed at beginning and every 6 months for 3 years; 56 patients completed the study. RESULTS: No correlation was found between the progression of visual field (VF) mean defect and retinal nerve fibre layer (RNFL) thinning over 3 years on one and the maximal flicker reaction in arteries and veins on the other side (all p > 0.1). However, the calculated difference of examined parameters in the superior versus inferior retinal halves correlated significantly between the RNFL thinning and the initial maximal flicker response for arteries (p = 0.01) and veins (p = 0.003). CONCLUSION: This longitudinal study did not find a general correlation between initial retinal vessel response to flicker light and the glaucoma damage progression measured by OCT and VF, hence limiting the relevance of the RVA device as a predictor of future glaucomatous damage.

Daytime variation in ambient temperature affects skin temperatures and blood pressure: Ambulatory winter/summer comparison in healthy young women.

It is widely accepted that cold exposure increases peripheral vascular resistance and arterial blood pressure (BP) and, hence, increases cardiovascular risk primarily in the elderly. However, there is a lack of concomitantly longitudinal recordings at personal level of environmental temperature (PET) and cardiophysiological variables together with skin temperatures (STs, the "interface-variable" between the body core and ambient temperature). To investigate the intra-individual temporal relationships between PET, STs and BP 60 healthy young women (52 completed the entire study) were prospectively studied in a winter/summer design for 26 h under real life conditions. The main hypothesis was tested whether distal ST (Tdist)mediates the effect of PET-changes on mean arterial BP (MAP). Diurnal profiles of cardiophysiological variables (including BP), STs and PET were ambulatory recorded. Daytime variations between 0930 and 2030 h were analyzed in detail by intra-individual longitudinal path analysis. Additionally, time segments before, during and after outdoor exposure were separately analyzed. In both seasons short-term variations in PET were positively associated with short-term changes in Tdist (not proximal ST, Tprox) and negatively with those in MAP. However, long-term seasonal differences in daytime mean levels were observed in STs but not in BP leading to non-significant inter-individual correlation between STs and BP. Additionally, higher individual body mass index (BMI) was significantly associated with lower daytime mean levels of Tprox and higher MAP suggesting Tprox as potential mediator variable for the association of BMI with MAP. In healthy young women the thermoregulatory and BP-regulatory systems are closely linked with respect to short-term, but not long-term changes in PET. One hypothetical explanation could serve recent findings that thermogenesis in brown adipose tissue is activated in a cool environment, which could be responsible for the counter-regulation of cold induced increase of BP in winter leading to no seasonal differences in MAP. Our findings suggest that the assessment of diurnal patterns of STs and PET, in addition to the conventional ambulatory BP monitoring, might improve individual cardiovascular risk prediction.

Peripapillary retinal vessel diameter correlates with mfERG alterations in retinitis pigmentosa.

PURPOSE: To investigate relationship between the peripapillary retinal vessel diameter and the residual retinal function, measured by mfERG, in patients with retinitis pigmentosa (RP). PATIENTS AND METHODS: A cross-sectional study based on 23 patients with RP (43 eyes) and 20 controls (40 eyes) was performed. Retinal vessel diameters were measured using a computer-based program of the retinal vessel analyser (RVA; IMEDOS Systems UG, Jena, Germany). We evaluated the mean diameter in all four major retinal arterioles (D-A) and venules (D-V) within 1.0-1.5 optic disc diameters from the disc margin. The data were compared with the N1 amplitudes (measured from the baseline to the trough of the first negative wave), with the N1P1 amplitudes (measured from the trough of the first negative wave to the peak of the first positive wave) of the mfERG overall response and with the mfERG responses averaged in zones [zone 1 (0°-3°), zone 2 (3°-8°), zone 3 (8°-15°) and zone 4 (15°-24°)]. RESULTS: Mean (±SD) D-A and D-V were narrower in patients with RP [84.86 µm (±13.37 µm) and 103.35 µm (±13.65 µm), respectively] when compared to controls [92.81 µm (±11.49 µm) and 117.67 µm (±11.93 µm), respectively; the p-values between groups were p = 0.003 for D-A and p < 0.001 for D-V, linear mixed-effects model]. The RP group revealed clear differences compared to the controls: D-A and D-V became narrower with reduced mfERG responses. D-V correlated significantly with the overall mfERG N1 amplitudes (p = 0.013) and with N1P1 amplitudes (p = 0.016). D-V correlated with the mfERG amplitudes averaged in zones: (zone 2, 3 and 4; p ≤ 0.040) and N1P1 mfERG amplitudes (zones 1, 2, 3 and 4; p ≤ 0.013). CONCLUSIONS: Peripapillary retinal vessel diameter is reduced in RP proportionally to functional alterations.

Reproducibility of retinal oximetry measurements in healthy and diseased retinas.

PURPOSE: Retinal oximetry (RO) has been established as a non-invasive method to analyse oxygen saturation in retinal vessels. The aim of our study was to determine the reproducibility of RO images in healthy and in diseased retinas. METHODS: A total of 61 right eyes (244 RO images) in 61 subjects (35♀, 26♂) were examined: 22 controls, 18 patients with glaucoma and 21 patients with inherited retinal diseases (IRDs). Four test-retest RO images were obtained in each subject. Oxygen saturation was measured with the oxygen saturation measurement tool of the Retinal Vessel Analyser (RVA; IMEDOS Systems UG, Jena, Germany). The test-retest standard deviation within the subject's (±SDw ) measurements (the mean vessel oxygen saturation in retinal venules and arterioles), its coefficient of variation (CoV) and the intraclass correlation coefficients (ICC) were analysed. RESULTS: The average test-retest SDw in venules was ±2.52% (CoV = 4.35%) and in arterioles was ±1.67% (CoV = 1.76%). Among controls, glaucoma eyes and eyes with IRDs, the test-retest SDw in venules were ±2.33% (CoV = 4.48%), ±2.85% (CoV = 4.71%) and ±2.43% (CoV = 3.90%) (SDw p = 0.366 (CoV p = 0.452); one-way anova). The test-retest SDw in arterioles were ±1.65% (CoV = 1.80%), ±1.83% (CoV = 1.92%) and ±1.54% (CoV = 1.56%), respectively [SDw p = 0.762 (CoV p = 0.686)]. The ICCs in venules were 0.76 in controls, 0.69 in patients with glaucoma and 0.82 in patients with IRD. The ICCs in arterioles were, respectively, 0.92, 0.70 and 0.93. CONCLUSION: The reproducibility of RO in healthy, as well as in diseased retinas, is excellent. In the glaucoma group, the lower standard deviation between subjects (SDb ) for arterioles contributes to the lower ICCs. Nevertheless, the measurements of oxygen saturation in arterioles seem more reliable when compared to venules.

Retinal vessel oxygen saturation and its correlation with structural changes in retinitis pigmentosa.

PURPOSE: To study the influence of retinal structural changes on oxygen saturation in retinitis pigmentosa (RP) patients. METHODS: Oximetry measurements were performed on 21 eyes of 11 RP patients and compared to 24 eyes of 12 controls. Retinal oxygen saturation was measured in all major retinal arterioles (A-SO2) and venules (V-SO2) with an oximetry unit of the retinal vessel analyser (IMEDOS Systems UG, Jena, Germany). Oximetry data were compared with morphological changes measured by Cirrus optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA, USA, macular thickness protocol). RESULTS: In RP patients, the retinal A-SO2 and V-SO2 levels were higher at 99.3% (p = 0.001, anova based on mixed-effects model) and 66.8% (p < 0.001), respectively, and the difference between the two (A-V SO2) was lower at 32.5% (p < 0.001), when compared to the control group (92.4%; 54.0%; 38.4%, respectively). With the RP group, the A-V SO2 correlated positively, not only with central macular thickness, but also with retinal thickness, in zones 2 and 3 (p = 0.006, p = 0.007, p = 0.014). CONCLUSION: These data indicate that oxygen metabolism was altered in RP patients. Based on our preliminary results, retinal vessel saturation correlated with structural alterations in RP. This method could be valuable in monitoring disease progression and evaluating a potential therapeutic response.

Differences in gene expression in lymphocytes of patients with high-tension, PEX, and normal-tension glaucoma and in healthy subjects.

PURPOSE: Purpose Differences in the gene expression of leukocytes between patients with normal-tension glaucoma (NTG) and controls have been described. This study was performed in order to detect the differences in gene expression in peripheral lymphocytes in patients with primary open-angle glaucoma (POAG), patients with pseudoexfoliation glaucoma (PEX), and patients with NTG, and in healthy subjects. METHODS: Ten patients with POAG, 11 patients with PEX, 10 patients with NTG, and 42 sex- and age-matched healthy persons were recruited. All study subjects were Caucasian. Twenty-two preselected genes were chosen and their expression in blood lymphocytes was quantified by real-time PCR. First, a univariate comparison among all groups was performed using the nonparametric Friedman test. Second, an L1 penalized logistic regression was performed. RESULTS: Using the Friedman test to compare the 4 groups, 9 genes showed a different expression (p<0.05). Comparing the controls vs patients with POAG, 8 genes were differently expressed (p<0.05). Comparing patients with PEX vs controls, 9 genes were significantly different (p≤0.05). The statistical analysis of patients with NTG vs controls showed a difference in gene expression of 7 genes (p≤0.05). All these genes were upregulated in the glaucoma groups compared with the controls. The genes RhoGDI and RAR showed the most significant statistical difference in the L1-penalized logistic regression. The genes overexpressed in POAG/PEX differed from the ones in NTG. CONCLUSIONS: In this masked study among the preselected 22 genes, several genes are overexpressed in the blood lymphocytes of Caucasian patients with glaucoma compared with the controls. The genes upregulated in POAG/PEX differed from the ones in NTG.

Effect of ageing on the retinal vascular responsiveness to flicker light in glaucoma patients and in ocular hypertension.

AIM: To evaluate the effect of ageing on the retinal vascular responsiveness to flicker light in glaucoma and ocular hypertension (OHT). METHODS: Retinal vascular response to flicker was measured with the retinal vessel analyser in 56 healthy subjects (59 ± 9 years), 50 primary open-angle glaucoma (POAG) (60 ± 10 years) and 46 OHT patients (62 ± 9 years). In the glaucoma group, the less damaged eye; in the OHT group, the eye with the higher intraocular pressure; and in healthy controls, one randomly selected eye was considered. Parametric and non-parametric linear regression analysis, as well as a model of covariance analysis (ANCOVA) was used to evaluate the effect of age on the vascular response. RESULTS: In all three groups (N=152) absolute (Pearson R: -0.19, p<0.019; Spearman R: -0.22, p<0.006) and relative change (Pearson R: -0.18, p<0.027; Spearman R: -0.21, p<0.010) were statistically associated with age. The ANCOVA showed no difference between the three groups in this regard (absolute change: p=0.43; relative change: p=0.51). CONCLUSIONS: Vascular responsiveness to flicker light decreases with age in healthy individuals, in glaucoma patients and in OHT patients. This effect seems to be comparable between the tested groups, and age-related change in vascular responsiveness to flicker light seems an unlikely risk factor for glaucoma.

Postoperative microhyphema as a positive prognostic indicator in canaloplasty.

PURPOSE: To assess risk factors for failure in canaloplasty. METHODS: Nonrandomized prospective study involving 51 eyes of 51 patients with medically uncontrolled primary open-angle glaucoma undergoing canaloplasty. Visual acuity, intraocular pressure (IOP) and slit-lamp examinations were performed before and after surgery at 1 and 7 days, and at 1 month and every 3 months thereafter. Factors like age, gender, preoperative IOP and microhyphema on day 1 were evaluated. RESULTS: The mean follow-up was 20.6 (SD 8.3) months. The mean preoperative IOP was 26.8 (SD 5.2) mmHg; the mean postoperative IOP was 8.4 (4.2) mmHg at day 1 and 12.7 (1.7) mmHg at month 24. Microhyphema was found in 40 patients (85.1%) on day 1 after surgery. The height of microhyphema was 1.8 mm ± 0.4 (SD) (range 1-2.5), and the time of resorption was 6.6 days ± 2.8 (SD) (range 3-14) on average. No recurrence of hyphema has been observed. IOP < 16 mmHg without medications depended significantly on the presence of microhyphema (hazard ratios, HR 0.03, 95% CI 0.01-0.25, p < 0.001), but not on age (HR 1.00, 95% CI 0.91-1.09, p = 0.32), preoperative IOP (HR 0.98, 95% CI 0.85-1.12, p = 0.80), cup-to-disc ratio (HR 0.15, 95% CI 0.00-20.01, p = 0.45) and gender (HR 0.24, 95% CI 0.05-1.12, p = 0.07). Factors like preoperative IOP, age, gender, cup-to-disc ratio were not associated with microhyphema. There were no significant differences between patients with versus without microhyphema in regard to age, preoperative IOP, morphological and functional glaucomatous damage, number of medications and postoperative day 1 IOP. However, patients with microhyphema had significantly fewer Nd:YAG goniopunctures after surgery than patients without microhyphema (p < 0.001). CONCLUSION: Microhyphema the first postoperative day seems to be a significant positive prognostic indicator in uneventful canaloplasty in regard to IOP reduction, possibly representing a restored and patent physiologic aqueous outflow system.

Association between risk factors and glaucomatous damage in untreated primary open-angle glaucoma.

PURPOSE: To analyze an association between the presumed risk factors for glaucoma and the actual extent of glaucomatous damage in untreated primary open-angle glaucoma. PATIENTS AND METHODS: In 50 untreated open-angle glaucoma patients, we analyzed an association between the level of glaucomatous damage and presumed glaucoma risk factors: mean untreated intraocular pressure (IOP) and short-term IOP variability, ocular pulse amplitude, corneal thickness, acral and corneal temperature, retinal arterial diameter and retinal venous diameter, choroidal blood flow (laser Doppler flowmetry flow, velocity, volume), heart rate, and ocular perfusion pressure. Morphologic damage (mean retinal nerve fiber layer thickness, measured by ocular coherence tomography) and functional damage (visual field mean defect) were evaluated separately in 2 forward-stepwise multiple regression models. RESULTS: The mean retinal nerve fiber layer thickness was significantly (P<0.05) associated with IOP (r=-0.35), retinal arterial diameter (r=0.36), and choroidal blood flow (r=0.30); mean defect was associated with ocular perfusion pressure (r=-0.30), laser Doppler flowmetry volume (r=-0.33), and IOP variability (0.36). CONCLUSIONS: Despite small differences between the morphologic and functional glaucomatous damage, IOP and perfusion parameters seem to contribute, at least in part, independently to both.

Diurnal blood pressure variations are associated with changes in distal-proximal skin temperature gradient.

It is generally assumed that skin vascular resistance contributes only to a small extent to total peripheral resistance and hence to blood pressure (BP). However, little is known about the impact of skin blood flow (SBF) changes on the diurnal variations of BP under ambulatory conditions. The main aim of the study was to determine whether diurnal patterns of distal SBF are related to mean arterial BP (MAP). Twenty-four-hour ambulatory measurements of BP, heart rate (HR) and distal (mean of hands and feet) as well as proximal (mean of sternum and infraclavicular region) skin temperatures were carried out in 51 patients (men/women = 18/33) during a 2-d eye hospital investigation. The standardized ambulatory protocol allowed measurements with minimal interference from uncontrolled parameters and, hence, some conclusive interpretations. The distal minus proximal skin temperature gradient (DPG) provided a measure for distal SBF. Individual cross-correlation analyses revealed that the diurnal pattern of MAP was nearly a mirror image of DPG and hence of distal SBF. Scheduled lunch and dinner induced an increase in DPG and a decline in MAP, while HR increased. Low daytime DPG (i.e. low distal SBF) levels significantly predicted sleep-induced BP dipping (r = -.436, p = .0014). Preliminary path analysis suggested that outdoor air temperature and atmospheric pressure may act on MAP via changed distal SBF. Changes in distal SBF may contribute to diurnal variation in MAP, including sleep-induced BP dipping and changes related to food intake. This finding might have an impact on individual cardiovascular risk prediction with respect to diurnal, seasonal and weather variations; however, the underlying mechanisms remain to be discovered.

Inactivation of MARCH5 prevents mitochondrial fragmentation and interferes with cell death in a neuronal cell model.

PURPOSE: To study the impact of the mitochondrial ubiquitin ligase MARCH5 on mitochondrial morphology and induction of apoptosis using an in vitro model of neuronal precursor cells exposed to glaucoma-relevant stress conditions. METHODS: RGC5 cells transfected with expression constructs for MARCH5, MARCH5(H43W), Dpr1(K38A) or vector control were exposed to either elevated pressure of 30 mmHg, oxidative stress caused by mitochondrial electron transport chain (ETC) inhibition, or hypoxia-reoxygenation conditions. Mitochondrial morphology of RGC5 cells was analyzed following staining of the mitochondrial marker cytochrome c and photoactivatable GFP (PAGFP) diffusion assay. Induction of apoptotic cell death in these cells was determined by analyzing the release of cytochrome c from mitochondria into the cytosol and flow cytometry. RESULTS: Exposure of RGC5 cells to oxidative stress conditions as well as to elevated pressure resulted in the fragmentation of the mitochondrial network in control cells as well as in cells expressing MARCH5. In cells expressing inactive MARCH5(H43W) or inactive Drp(K38A), mitochondrial fragmentation was significantly blocked and mitochondrial morphology was comparable to that of control cells under normal conditions. Exposure of RGC5 cells to elevated pressure or oxidative stress conditions induced apoptotic cell death as assessed by cytochrome c release and DNA staining, while expression of dominant-negative MARCH5(H43W) or Drp1(K38A) did significantly delay cell death. CONCLUSION: Preventing mitochondrial fragmentation through interference with the mitochondrial fission machinery protects neuronal cells from programmed cell death following exposure to stressors physiologically relevant to the pathogenesis of glaucoma.

Use of colour Doppler imaging in ocular blood flow research.

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

Plasma citrate levels as a potential biomarker for glaucoma.

PURPOSE: To determine the possibility of plasma citrate as a biomarker in patients with glaucoma. METHODS: Twenty-one consecutive Caucasian patients with glaucoma and 21 sex- and age-matched controls were investigated. Plasma citrate, plasma creatinine, urine citrate, and urine creatinine were analyzed by ion chromatography. Mean (±standard deviation) concentrations and the calculated fractional citrate excretions were compared using the Mann-Whitney test. Sensitivity and specificity to detect glaucoma using plasma citrate levels were calculated. RESULTS: The mean plasma citrate (104.8±23.2 vs. 128.2±31.1 µmol/L; P=0.01) concentrations were significantly lower among the patients with glaucoma, whereas the mean urine citrate concentrations (1.7±0.9 vs. 2.8±1.9 µmol/L; P=0.07) were slightly lower. Mean plasma and mean urine creatinine concentrations showed no significant differences (plasma creatinine: 63.0±16.7 vs. 63.4±15.5 µmol/L; P=0.72; urine creatinine: 9.6±5.1 vs. 11.5±8.4 µmol/L; P=0.67). The calculated fractional citrate excretions were also not different with 12.1% versus 13.6% (P=0.37). Setting the cut-off limit at 110 µmol/L, the plasma citrate level evaluation would have a sensitivity of 66.7% and a specificity of 71.4% to detect glaucoma. CONCLUSION: In this masked study, plasma citrate levels were significantly decreased in Caucasian patients with glaucoma giving the possibility to use them eventually as a biomarker. The kidney function was normal in both groups, leaving the etiology of this hypocitraemia yet unexplained.