IV.B. Oxygen in Vitreoretinal Physiology and Pathology

Holekamp, Nancy M.; Beebe, David C.; Shui, Ying-Bo

doi:10.1007/978-1-4939-1086-1_26

Cited by 5 publications

(6 citation statements)

References 51 publications

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“…It is now clear that the vitreous has many roles in protecting the structure and providing the means for the functions of the eye (Foulds, 2014). In addition, vitreous humor supports the lens (Jin et al, 2019) and regulates the intraocular oxygen (Holekamp et al, 2014). The vitreous gel is attached to the retina which results in a direct connection between the changes in its network and the pathology of many vitreoretinal diseases (Sebag, 2008;Sharif-Kashani et al, 2 2011).…”

Section: Introductionmentioning

confidence: 99%

Time dependent degradation of vitreous gel under enzymatic reaction: Polymeric network role in fluid properties

Rangchian

Hubschman

Kavehpour

2020

Journal of Biomechanics

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The viscoelastic behavior of vitreous gel is due to the presence of biopolymers in its structure. Fluid properties of the vitreous is mainly the result of interactions between the characteristics of collagen type II and Hyaluronic Acid networks. Having a better understanding of the structure of each component and their changes during aging and various diseases such as diabetes can lead to better monitoring and treatment options. We study the effects of collagenase type II on 44 samples of porcine vitreous using an in situ rheological experiment in comparison with 18 eyes in a control group injected with Phosphate Buffered Saline Solution. We analyze the behavior of each component over time in both groups. We focus on the changes of viscosity and elasticity of the collagen network within the vitreous. The results of the

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Section: Introductionmentioning

confidence: 99%

Time dependent degradation of vitreous gel under enzymatic reaction: Polymeric network role in fluid properties

Rangchian

Hubschman

Kavehpour

2020

Journal of Biomechanics

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“…It is probable that the solution present in the eye at the end of vitrectomy surgery is replaced by the body within a relatively short period of time (weeks to months). In contrast, some effects of vitrectomy on oxygen metabolism and transport within the eye are not transient, and numerous studies have shown how altered oxygen metabolism following vitrectomy can promote cataract formation . Indeed, surgical strategies that are based upon these principles have been designed to lower the incidence of cataract surgery following vitrectomy .…”

mentioning

confidence: 99%

“…In contrast, some effects of vitrectomy on oxygen metabolism and transport within the eye are not transient, and numerous studies have shown how altered oxygen metabolism following vitrectomy can promote cataract formation. 13 Indeed, surgical strategies that are based upon these principles have been designed to lower the incidence of cataract surgery following vitrectomy. 14,15 Experience to date has shown that in spite of infusing BSS Plus ™ during surgery, not inducing surgical posterior vitreous detachment (PVD) and preserving intact retrolental vitreous is associated with a lower incidence of cataract surgery than extensive vitrectomy with surgical PVD induction.…”

mentioning

confidence: 99%

Vitreous: Not just through it

Sebag¹

2016

Clinical Exper Ophthalmology

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“…The VH also protects the retina from UV radiation with antioxidants, such as ascorbate. 43,44 It is possible that the regional changes in the HA-collagen network may serve other functions yet to be elucidated. The VH serves as a repository for the surrounding ocular regions.…”

Section: Vh Functionsmentioning

confidence: 99%

“…However, when the VH is liquefied it no longer consumes the oxygen and therefore the oxygen reaches the lens causing oxidative stress that contributes to cataractogenesis. 44 The opacity of cataracts cause vision problems.…”

Section: Diseases Associated With Liquefactionmentioning

confidence: 99%

The regional distribution and molecular interactions of phospholipids and glucose in mammalian vitreous humors.

Schnepf¹

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The vitreous humor (VH) is located in between the lens and the retina. It is composed of 98% water, hyaluronan (HA), collagen, proteins, phospholipids (PLs), and other metabolites. With aging, the VH undergoes liquefaction, a process that causes the gel-like structure of the VH to turn into a liquid and can lead to serious ocular diseases, including retinal detachment, vitreal detachment, and macular hole formation. The liquefaction process is expedited in diabetic VHs. This project focuses on understanding the molecular changes that lead to liquefaction and the reasons for which this process is accelerated with diabetes. Matrix-assisted laser desorption ionization/mass spectrometry (MALDI/MS) and nuclear magnetic resonance (NMR) spectroscopy were applied for in vitro, ex situ, and model studies of VHs to identify and quantify several components of the VH network and explore their interactions. In-vitro and ex-situ methods were optimized and conducted on porcine and human VHs. The mammalian species produced similar compositional trends. MALDI/MS showed that PLs were most abundant in the posterior region (closest to the retina) followed by the anterior (closest to the lens) and then the central regions. Diabetic and non-diabetic VHs regional distribution of glucose was compared. Glucose was vi present in significant higher levels (three-fold) in diabetic VHs compared to non-diabetic ones of similar age. The levels of glucose in the diabetic VH were highest in the posterior followed by the anterior and central regions. This trend follows that observed for the PLs. Model studies were performed to explore the interaction(s) of vitreal components and hyaluronan (HA) using MALDI/MS and NMR. The studies indicate interactions between both the headgroups of PLs and the carboxylate groups of HA as well as that between the acyl tails on PC with the hydrophobic regions of HA. Such interactions are proposed to disrupt the H-bonding network of HA and contribute to liquefaction of the VH. Future studies will focus on age-dependent studies of human VHs as well as the analysis of fresh human VHs following vitrectomy surgery. vii

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IV.B. Oxygen in Vitreoretinal Physiology and Pathology

Cited by 5 publications

References 51 publications

Time dependent degradation of vitreous gel under enzymatic reaction: Polymeric network role in fluid properties

Time dependent degradation of vitreous gel under enzymatic reaction: Polymeric network role in fluid properties

Vitreous: Not just through it

The regional distribution and molecular interactions of phospholipids and glucose in mammalian vitreous humors.

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