Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow

Kanakamedala, Priyanka; Harris, Alon; Siesky, Brent; Tyring, Ariel J.; Muchnik, Michael; Eckert, George J.; Tobe, Leslie

doi:10.1136/bjophthalmol-2013-304393

Cited by 25 publications

(20 citation statements)

References 21 publications

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“…Our finding may also explain why certain races have a greater predisposition to OAG. 18 For instance, people of African descent have been shown to exhibit significantly larger optic discs 48 and poorer vascular components compared with those of European descent. 18 Not surprisingly, arterial and venous blood pressures were the other two most significant parameters that affected oxygen concentration and flow velocity.…”

Section: Discussionmentioning

confidence: 99%

“…18 For instance, people of African descent have been shown to exhibit significantly larger optic discs 48 and poorer vascular components compared with those of European descent. 18 Not surprisingly, arterial and venous blood pressures were the other two most significant parameters that affected oxygen concentration and flow velocity. A decrease in arterial pressure and an increase in venous pressure both resulted in lower average oxygen concentration and flow velocity.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have reported a correlation between poor ocular hemodynamics and glaucoma [15][16][17] ; for instance, Kanakamedal et al 18 have suggested that people of African descent had a much higher prevalence of OAG compared with those of European descent due to their relatively weaker vascular components. The study also revealed a significant correlation between changes in blood flow and ONH morphology.…”

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confidence: 99%

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Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Chuangsuwanich

Birgersson

Thiéry

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To identify and rank the lamina cribrosa (LC) morphologic factors that influence LC microcapillary hemodynamics and oxygen concentrations using computational fluid dynamics (CFD).METHODS. We generated 12,000 'artificial' LC microcapillary networks and predicted blood flow velocities and oxygen concentrations within the microcapillaries using CFD. Across models, we varied the average pore size of the LC (5500 6 2400 lm 2 ), the microcapillary arrangement (radial, isotropic, or circumferential), the LC diameter (1.9 6 0.3 mm), the inferior-superior curvature (340 6 116 m À1 ), and the nasal-temporal curvature (À78 6 130 m À1 ). We assumed that blood flow originated from the Circle of Zinn-Haller, fed the LC uniformly at its periphery, and was drained into the central retinal vein. Arterial (50 6 6 mm Hg) and venous (17.7 6 6 mm Hg) pressures were applied as boundary conditions and were also varied within our simulations. Finally, we performed linear regression analysis to rank the influence of each factor on LC hemodynamics and oxygen concentrations. RESULTS.The factors influencing LC hemodynamics and oxygen concentrations the most were: LC diameter, arterial pressure, and venous pressure, and to a lesser extent: the microcapillary arrangement (anisotropy) and nasal-temporal curvature. Lamina cribrosa pore size and superior-inferior curvature had almost no impact. Specifically, we found that LCs with a smaller diameter, a radial arrangement of the microcapillaries, an elevated arterial pressure and a decreased venous pressure had higher oxygen concentrations across their networks.CONCLUSION. This study described LC hemodynamics using a computational modeling approach. Our study may provide clinically relevant information for the understanding of ischemia-induced neuronal cell death in optic neuropathies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Chuangsuwanich

Birgersson

Thiéry

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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“…63 Candidate pathophysiological theories for the earlier and more severe presentation of glaucoma in patients of African ancestry include: larger optic disc size (which mechanically increases posterior bowing of the lamina cribrosa at any given IOP), lower posterior scleral compliance (which reduces deformability of the optic nerve at its exit point at the lamina cribrosa), lower corneal hysteresis (which reflects reduced corneal energy-dampening capacity and may correlate with reduced overall distensibility of glaucomatous eyes), shorter trabecular meshwork height (which may anatomically contribute to reduced aqueous outflow particularly in conjunction with aging-related changes in the trabecular meshwork and anterior chamber angle), and lower retinal blood flow (which increases susceptibility to ischemia-related etiologies of retinal ganglion cell loss). [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80] In concert with these parameters, elevated IOP is a welldocumented risk factor for progressive VF field loss or presentation with advanced glaucoma among patients of many ancestries. [81][82][83][84][85] The association of AT6 with elevated current IOP in our study may reflect some combination of physiological barriers to IOP control and socioeconomic barriers to glaucoma treatment adherence.…”

Section: Section 32 Visual Field Characteristicsmentioning

confidence: 99%

Clinical Correlates of Computationally Derived Visual Field Defect Archetypes in Patients from a Glaucoma Clinic

Cai

Elze

Bex

et al. 2016

Current Eye Research

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Purpose: To assess the clinical validity of visual field (VF) archetypal analysis, a previously developed machine learning method for decomposing any Humphrey VF (24‒2) into a weighted sum of clinically recognizable VF loss patterns. Materials and Methods: For each of 16 previously identified VF loss patterns (“archetypes,” denoted AT1 through AT16), we screened 30,995 reliable VFs to select 10–20 representative patients whose VFs had the highest decomposition coefficients for each archetype. VF global indices and patient ocular and demographic features were extracted retrospectively. Based on resemblances between VF archetypes and clinically observed VF patterns, hypotheses were generated for associations between certain VF archetypes and clinical features, such as an association between AT6 (central island, representing severe VF loss) and large cup-to-disk ratio (CDR). Distributions of the selected clinical features were compared between representative eyes of certain archetypes and all other eyes using the two-tailed t-test or Fisher exact test. Results: 243 eyes from 243 patients were included, representative of AT1 through AT16. CDR was more often ≥ 0.7 among eyes representative of AT6 (central island; p = 0.002), AT10 (inferior arcuate defect; p = 0.048), AT14 (superior paracentral defect; p = 0.016), and AT16 (inferior paracentral defect; p = 0.016) than other eyes. CDR was more often < 0.7 among eyes representative of AT1 (no focal defect; p < 0.001) and AT2 (superior defect; p = 0.027), which was also associated with ptosis (p < 0.001). AT12 (temporal hemianopia) was associated with history of stroke (p = 0.022). AT11 (concentric peripheral defect) trended toward association with trial lens correction > 6D (p = 0.069). Conclusions: Shared clinical features between computationally derived VF archetypes and clinically observed VF patterns support the clinical validity of VF archetypal analysis.

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“…32 To the best of our knowledge, racial differences in ocular blood flow have not been assessed in healthy eyes. The purpose of this study was to determine whether differences in ocular blood flow exist between AD and ED individuals with healthy eyes.…”

Section: Introductionmentioning

confidence: 99%

Differences in Ocular Blood Flow Between People of African and European Descent With Healthy Eyes

Kaskan

Ramezani

Harris

et al. 2016

Journal of Glaucoma

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Purpose: To investigate differences in ocular blood flow between people of African (AD) and European descent (ED) with healthy eyes.Methods: Retrobulbar and retinal capillary blood flow was assessed in one eye of 58 participants (24 AD, 34 ED) with healthy eyes with systemic blood pressure lower than 140/90. Retrobulbar blood flow was measured in the ophthalmic artery (OA), central retinal artery (CRA), nasal (NPCA) and temporal posterior ciliary arteries (TPCA). Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) were assessed. Retinal capillary blood flow was assessed using mean retinal flow and avascular space defined as the percent of area measured with no blood flow. Groups were compared using t-tests and Pearson correlations were compared using Fisher r-toz transformation.Results: Compared to people of ED, people of AD had significantly lower EDV in the NPCA (p=0.01), and higher RI in the CRA (p=0.04) and TPCA (p=0.01). No significant differences were observed in mean retinal capillary flow or avascular area. In the CRA, a significant positive correlation was observed between pattern standard deviation (PSD) and PSV (p=0.02) and this correlation was significantly different from that observed in the ED group (p=0.01). A significant correlation was also observed between PSD and EDV (0.04) in the AD group. Conclusion:This study suggests that retrobulbar blood flow is lower in healthy eyes in persons of AD compared to ED. This may provide a mechanism through which people of AD are at increased risk for ophthalmic diseases such as glaucoma.

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Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow

Cited by 25 publications

References 21 publications

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Clinical Correlates of Computationally Derived Visual Field Defect Archetypes in Patients from a Glaucoma Clinic

Differences in Ocular Blood Flow Between People of African and European Descent With Healthy Eyes

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