The Conjunctiva in Normal Tension Glaucoma Patients is Thinner Than in Primary Open-Angle Glaucoma Patients: A Comparative Histologic Study

PURPOSE: To compare histologically the thickness of conjunctival specimens of normal tension glaucoma (NTG) patients with primary open-angle glaucoma (POAG) patients. MATERIALS AND METHODS: In this prospective study, 54 patients scheduled for trabeculectomy were categorized into NTG and POAG based on their maximum untreated intraocular pressure at any time (IOPmax) as measured by Goldmann applanation tonometry. Sixteen patients with NTG (IOPmax≤21 mm Hg) and 36 patients with high tension POAG (IOPmax>21 mm Hg) were included in the study. Biopsies were taken from the superior bulbar conjunctiva during trabeculectomy. The specimens were fixed in formalin, embedded in methacrylate, histologically sectioned, stained with toluidine blue, and analyzed with a light microscope. The stromal conjunctival thickness (CT) was measured in a standardized way and compared between the 2 groups. Intergroup comparisons were performed using the Mann-Whitney U test for continuous variables and the Fisher exact test for categorical variables. The correlation between the central cornea thickness (CCT) and the CT was investigated by the Spearman test. RESULTS: The stromal CT was significantly thinner in NTG compared with POAG (64±31 vs. 103±44 µm, respectively; P=0.002). Stromal CT of the whole group was positively correlated with IOPmax (r=0.41; P=0.002; 95% confidence interval, 0.15-0.62) but not with central cornea thickness (r=-0.005; P=0.97; 95% confidence interval, -0.28 to 0.27). CONCLUSIONS: The conjunctiva in patients with NTG was thinner than in POAG patients. This finding is an additional feature in the pattern of thinner ocular structures in patients with NTG.status: publishe

Choroidal Thickness of the Papillomacular Region in Young Healthy Individuals

PURPOSE: To characterize the choroidal thickness of the papillomacular region in young healthy individuals using spectral-domain optical coherence tomography (SD-OCT). METHODS: Papillary and macular SD-OCT scans were obtained using an enhanced depth imaging mode. Digital retinography was used to assess any overlapping areas and to determine the papillomacular region. Spearman's correlations were used to explore the relationship between the different regional choroidal thicknesses. RESULTS: Sixty-three volunteers aged 21.6 ± 1.1 years were included. There was a significant asymmetry in choroidal thickness throughout the 10-mm length model (p < 0.001). While the choroid was shown to thicken as the distance from the optic disc increased (p < 0.001), each of the 500-µm blocks of the papillomacular region were significantly thinner than their nasal counterparts (p < 0.02 in all pairwise comparisons). CONCLUSION: In young healthy individuals, the choroid under the papillomacular region appears to be thinner than in other areas. These differences could relate to specificities of the retina overlying this region.status: publishe

Quantitative automated circumpapillary microvascular density measurements: a new angioOCT-based methodology

PURPOSE: To develop a new methodology to detect glaucoma damage based on circumpapillary microvascular density (cpmVD) as measured by optical coherence tomography angiography (angioOCT). METHODS: AngioOCT scans from a random eye of 40 healthy subjects (aged 63 ± 14 years) and 82 glaucoma patients (aged 66 ± 9 years with an average visual field loss of -7.8 ± 6.5 dB) were used to develop a new angioOCT evaluation methodology. Optic disc-centred 3 × 3 mm images were collected (Angioplex®, Zeiss Cirrus 5000 HD-OCT). An annular area with an inner radius of 1.16 mm and outer radius of 1.44 mm was chosen as the region of interest (ROI), with cpmVD calculated through lower envelope modulation avoiding the influence of the major retinal vessels. Additionally, the cpmVD and the microvascular density (mVD), stratified by sectors, were compared with the respective retinal nerve fibre layer (RNFL) thickness. RESULTS: A significantly lower cpmVD was observed in the glaucoma group, for all visual field sectors (p  0.05). CONCLUSIONS: The presented open-source methodology provides a robust quantitative analysis of the 360˚ mVD. It shows that cpmVD, and mVD sectors measured by angioOCT, can be used in everyday glaucoma practice.status: publishe

Trends in Glaucoma Surgical Procedures in Portugal: A 16-Year Nationwide Study (2000-2015)

PURPOSE: Glaucoma leads as the first cause of irreversible blindness. The number of patients will greatly increase in upcoming years and changes will have to be accomplished to cope with those numbers. As such, data are important to understand the effect of new policies introduced in glaucoma management. Only few countries have described their glaucoma surgical profile and, in Europe, only the United Kingdom described the last 15 years. The aim of this study is to assess the glaucoma surgical profile and its changes in mainland Portugal from 2000 to 2015. METHODS: Retrospective database analysis of inpatient and surgical outpatients' episodes of all public hospitals in mainland Portugal was performed. The annual absolute numbers of ophthalmic procedures, as well as their surgical rate (per 100,000 inhabitants) were calculated. RESULTS: Glaucoma patients undergoing glaucoma procedures were 67±14 years old and 50% were female. During the study period there was an increase in the number and surgical rate of glaucoma procedures. Trabeculectomy showed a stable surgical rate (7 per 100,000 inhabitants) despite a reduction in terms of relative weight among glaucoma procedures. At the same time, the surgical rate of glaucoma drainage devices and cyclophotoablation increased, while remaining stable for cyclocryoablation. CONCLUSIONS: In Portugal, trabeculectomy had a stable surgical rate throughout the study period, being the most performed glaucoma surgical procedure. Other surgeries, like glaucoma drainage devices and cyclophotoablation are gaining ground among glaucoma specialists. Our results match what has been published by other countries worldwide and can be used to achieve a better health planning.status: publishe

Heterogeneity in arterial hypertension and ocular perfusion pressure definitions: Towards a consensus on blood pressure-related parameters for glaucoma studies

PURPOSE: Glaucoma studies have long taken into account the blood pressure (BP) status of patients. This study summarizes and evaluates the impact of the different criteria that have been used for BP-related variables in glaucoma research. METHODS: Studies included in two meta-analyses that reviewed the role of BP in glaucoma were analyzed. Additional studies published after the search periods of the meta-analyses were also included. Criteria for the definition of arterial hypertension and other BP-related variables, such as mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP), were retrieved. RESULTS: Sixty-four studies were evaluated. One-third used 140 mmHg as a systolic BP cut-off to define hypertension, 20% used 160 mmHg and the remaining half used various other criteria. Less than 20% of studies reported MAP and/or MOPP. While eight of the ten studies reporting MAP used a correct formula that only happened for five of the eleven studies reporting MOPP. Using as an example average blood pressure values, incorrectly used formulas could have led to an overestimation of more than 100% of the expected values. CONCLUSION: Considerable heterogeneity exists in BP-related variables in glaucoma research and different definitions can lead to large disparities. Glaucoma research would benefit from a consensus regarding blood pressure parameters.status: publishe

Retinal oxygen saturation as a non-invasive estimate for mixed venous oxygen saturation and cardiac output

PURPOSE: To investigate the correlation between retinal vessel oxygen saturation and mixed venous oxygen saturation (SvO2-mixed ) and cardiac output (CO). METHODS: Retinal arterial (SaO2-retinal ) and venous (SvO2-retinal ) oxygen saturation were measured non-invasively with dual-wavelength retinal oximetry in subjects receiving invasive measurements of SvO2-mixed and CO through right heart catheterization. Correlations were analysed using Spearman's rank correlation coefficients and linear regression models. RESULTS: Fourteen patients (median age 62.7 years, range: 21-77) were included in the analysis. When adjusted for age, SvO2-retinal showed a positive correlation with SvO2-mixed (β = 0.80, p = 0.003). Retinal arteriovenous oxygen saturation difference was significantly correlated with the inverse of CO (Spearman's ρ = 0.59, p = 0.026). CONCLUSION: This pilot study provides proof of concept for the use of retinal oximetry as a non-invasive tool to assess systemic cardiovascular function.status: publishe

The effect of glaucoma treatment using high-intensity focused ultrasound on total and corneal astigmatism: a prospective multicentre study

PURPOSE: Ultrasound cycloplasty (UCP) acts through the selective coagulation of the ciliary body using high-intensity focused ultrasound (HIFU) technology. The aim of this study was to investigate whether the application of ultrasound beams targeting the ciliary body using an external probe influences astigmatism. METHODS: Multicentre, prospective, single-arm, open-label study in adult patients with primary open-angle glaucoma and moderately uncontrolled intraocular pressure (IOP) under glaucoma medication. The primary outcome was induced corneal astigmatism, calculated from topography, and assessed statistically through vector analysis. Secondary outcomes included induced total astigmatism and mean changes from baseline in best-corrected visual acuity (logMAR) and IOP. Subgroup analysis was performed to assess the impact of device centring on corneal and total induced astigmatism. RESULTS: Fifty eyes were enrolled. Mean age was 69.6 ± 11.3 years. At 1, 3 and 6 months postprocedure, HIFU-induced corneal astigmatism was 0.88 D × 93°, 0.87 D × 106° and 1.16 D × 97°, respectively, while induced total astigmatism was 0.62 D × 103°, 0.42 × 106° and 0.39 × 107°. By the last follow-up, the percentage of patients with <0.50, <1.00, <1.50 and <2.00 D of induced corneal versus total astigmatism was 8.3% versus 46%, 29% versus 66%, 62.5% versus 88% and 79% versus 94%. Visual acuity was statistically significantly impaired at 1 month, but no difference remained by 3 and 6 months postprocedure. CONCLUSION: Ultrasound cycloplasty procedure is associated with increased corneal astigmatism. However, its impact on total refractive astigmatism is less pronounced.status: publishe

The effect of glaucoma treatment using high-intensity focused ultrasound on total and corneal astigmatism: a prospective multicentre study

Ultrasound cycloplasty (UCP) acts through the selective coagulation of the ciliary body using high-intensity focused ultrasound (HIFU) technology. The aim of this study was to investigate whether the application of ultrasound beams targeting the ciliary body using an external probe influences astigmatism

Improved discrimination between normal-tension and primary open-angle glaucoma with advanced vascular examinations - the Leuven Eye Study

PURPOSE: Vascular factors have been suggested to influence the development and progression of glaucoma. They are thought to be especially relevant for normal-tension glaucoma (NTG) patients. We aim to investigate which vascular factors, including advanced vascular examinations, better describe patients with NTG comparing to those with primary open-angle glaucoma (POAG). METHODS: The Leuven Eye Study database (182 NTG and 202 POAG patients; similar structural and functional damage) was used to compute three multivariate logistic regression models: a conventional model (conventional parameters only, including vascular-related self-reported phenomena, such as migraine or peripheral vasospasm); an advanced vascular model (advanced vascular parameters only: colour Doppler imaging (CDI), retinal oximetry, ocular pulse amplitude and choroidal thickness); and a global model, in which both types of parameters were allowed. Receiver operating characteristic (ROC) curves and corresponding areas under the curve (AUC) were calculated and compared between models. RESULTS: Patients with NTG had a higher resistive index and lower early systolic acceleration (ESA) in their retrobulbar vessels and a smaller arteriovenous retinal oxygen saturation difference. The global model (AUC 0.743) showed a significantly better discriminative ability when compared to either the conventional (AUC 0.687, p = 0.049) or the advanced vascular (AUC 0.677, p = 0.005) models. Also, the conventional and the advanced vascular models showed a similar discriminative ability (p = 0.823). CONCLUSION: Patients with NTG have more signs of vascular dysfunction. Clinical conventional parameters, such as asking simple vascular-related questions, combined with advanced vascular examinations provide information to better understand the value that non-IOP-related factors play in NTG.status: publishe

Retinal oxygen metabolism in healthy subjects and glaucoma patients

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