Does the Bursa Pre-Macularis protect the fovea from shear stress? A possible mechanical role

Rossi, Tommaso; Badas, Maria Grazia; Querzoli, Giorgio; Trillo, Carlandrea; Telani, Serena; Landi, Laura; Gattegna, Roberto; Ripandelli, Guido

doi:10.1016/j.exer.2018.06.022

Cited by 9 publications

(6 citation statements)

References 27 publications

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“…6). Such values are significantly higher than vitreous shear stress at the fovea previously published by Rossi et al 11 who calculated approximately 5 Pa in the presence of the bursa premacularis and 10 Pa after complete posterior vitreous detachment.…”

Section: Discussionmentioning

confidence: 50%

“…From the clinical standpoint, shear stress changes have not been overtly linked to detrimental retinal effects, but Muller and retinal ganglion cells 25,26 modulate gene expression in response to shear stress. 27 We observed that the bursa premacularis drastically reduces shear stress at the fovea 11 until aging disrupts the physiologic adhesion resulting in the posterior Figure 8. 3D maps of the pointwise maximum shear stress (PMSS) for a 90% SiO1000 fill during saccadic rotation as indicated in the grey phantoms to the left.…”

Section: Discussionmentioning

confidence: 95%

“…The vitreous chamber was modeled as a spherical mesh (24 mm in diameter), with a spherical cap on the anterior side mimicking the indentation of the lens as described elsewhere. 11,15 A view of the body conformal hex-dominant mesh adopted for the simulations is displayed in Figure 1a.…”

Section: Cfd Modelmentioning

confidence: 99%

“…10 Computational fluid dynamics (CFD) modeling allows the accurate calculation of physical parameters that are impossible to estimate in vivo and can be applied to several fields in medicine, including ophthalmology. 11 A few studies applied CFD to predict the equilibrium shape of the aqueous-tamponade interface. However, none of them analyzed the shear stress distribution and the percentage of retinal surface in contact with SiO.…”

Section: Introductionmentioning

confidence: 99%

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Computational Fluid Dynamics of Intraocular Silicone Oil Tamponade

Rossi

Querzoli

Badas

et al. 2021

Trans. Vis. Sci. Tech.

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To investigate the behavior of silicone oil (SiO) at the steady equilibrium and during saccades and calculate SiO-retina contact, shear stress (SS), and shear rate (SR). Methods:A 24 mm phakic eye mesh model underwent 50°/0.137s saccade. The vitreous chamber compartment was divided into superior and inferior 180°sectors: lens, preequator, postequator, and macula. SiO-retina contact was evaluated as a function of fill percentages between 80% and 90% for a standing patient, 45°upward gaze, and supine. SS and SR for 1000 mPa-s (SiO1000) and 5000 mPa-s (SiO5000) silicon oil were calculated.Results: SiO fill between 80% to 90% allowed 55% to 78% retinal contact. The superior retina always kept better contact with SiO, regardless of the fill percentage (P < 0.01). SiO interface thoroughly contacted the macula only in standing position. SS followed a bimodal behavior and was always significantly higher for SiO5000 compared to SiO1000 (P < 0.01) throughout the saccade. The macula suffered the highest mean SS in standing position, while throughout the saccade the average SS was maximum at the SiO-aqueous interface. SR was significantly higher for SiO1000 compared to SiO5000 (P < 0.001).Conclusions: SS on the retinal surface may instantaneously exceed reported retinal adhesiveness values especially at the SiO-aqueous interface and possibly favor redetachment. Despite 90% SiO fill the inferior retina remains extremely difficult to tamponade.Translational Relevance: Accurate assessment of retina-tamponade interaction may explain recurrent inferior retinal redetachment, silicone oil emulsification, and help to develop better vitreous substitutes.

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Section: Discussionmentioning

confidence: 50%

Section: Discussionmentioning

confidence: 95%

Section: Cfd Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Computational Fluid Dynamics of Intraocular Silicone Oil Tamponade

Rossi

Querzoli

Badas

et al. 2021

Trans. Vis. Sci. Tech.

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“…Thus, fibroblasts and mast cells residing in the BPM might provide a microenvironment for the undifferentiated cells in the foveola. Meanwhiler, Rossi et al proposed via computer simulation that the BPM protected the fovea from shear stress caused by the movement of the vitreous [61], and Worstpostulated that the BPM has a protective function for the macula in hydrodynamic and biochemical senses [12, 62]. Eisner first proposed that intravitreal tracts regulated the intravitreal fluid transports [16].…”

Section: Discussionmentioning

confidence: 99%

Involvement of premacular mast cells in the pathogenesis of macular diseases

et al. 2019

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We previously reported on the elevated intravitreal activities of tryptase and chymase in association with idiopathic epiretinal membrane (ERM) and idiopathic macular hole (MH). In this present study, we investigated the potential intraocular production of these serine proteases, and measured and compared tryptase and chymase activities in the vitreous body and serum in ERM, MH, proliferative diabetic retinopathy (PDR), and rhegmatogenous retinal detachment (RRD) patients. In addition, nuclear staining with hematoxylin and eosin (H&E) and mast-cell staining with toluidine blue were performed on samples of the vitreous core and bursa premacularis (BPM) of MH. We also performed immunostaining on the above two regions of vitreous samples for MH with anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, anti-lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) antibody, and anti-fibroblast antibody. Moreover, we performed immunostaining with anti-tryptase antibody and anti-chymase antibody on ERMs collected intraoperatively. Tryptase activity in the vitreous body was significantly higher in ERM and MH than in PDR. However, no significant differences were observed in the tryptase activity in the serum among these four diseases. Chymase activity in the vitreous body was significantly higher in MH than in the other three diseases, yet chymase activity in the serum was below detection limit in any of the diseases. Nuclear staining with H&E revealed an abundance of nuclei in the BPM region, but few in the surrounding area. Mast-cell staining with toluidine blue revealed that the BPM showed metachromatic staining. In immunostaining with anti-fibroblasts antibody, anti-tryptase antibody, anti-chymase antibody, anti-podoplanin antibody, and anti-LYVE-1 antibody, the BPM stained more strongly than the vitreous core. Tryptase and chymase-positive cells were also observed in ERM. These findings revealed that the presence of mast cells in the BPM potentially represent the source of these serine proteases. Moreover, the BPM, as a lymphatic tissue, may play an important role in the pathogenesis of macular disease.

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Mathematical Models of Vitreous Humour Dynamics and Retinal Detachment

Repetto

Dvoriashyna

2019

Ocular Fluid Dynamics

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Does the Bursa Pre-Macularis protect the fovea from shear stress? A possible mechanical role

Cited by 9 publications

References 27 publications

Computational Fluid Dynamics of Intraocular Silicone Oil Tamponade

Computational Fluid Dynamics of Intraocular Silicone Oil Tamponade

Involvement of premacular mast cells in the pathogenesis of macular diseases

Mathematical Models of Vitreous Humour Dynamics and Retinal Detachment

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