The Role of the Ciliary Body in Aqueous Humor Dynamics Structural Aspects

2010 ◽  
pp. 179-186 ◽  
Author(s):  
E.R. Tamm
2015 ◽  
Vol 8 (1) ◽  
pp. 46
Author(s):  
Syed Shoeb Ahmad ◽  
Syed Zia-ur-Rahman ◽  
Norlina Ramli ◽  
Shuaibah Abdul Ghani ◽  
◽  
...  

“Pharmacologic trabeculectomy” is a term used to describe the modulation of aqueous outflow by the biochemical manipulation of the trabecular meshwork. Most of the medications currently in use either reduce aqueous production or increase its outflow through the ciliary body. However, there is a new group of agents being investigated, which can increase the facility of aqueous humor outflow through the trabecular meshwork. Thus, these agents will be able to provide a more physiologic means to control aqueous humor dynamics. This review sheds light on this concept of “medical trabeculectomy.”


Author(s):  
Satish Kumar ◽  
Sumanta Acharya ◽  
Roger Beuerman ◽  
Arto Palkama

Numerical calculations of the aqueous humor dynamics in the anterior chamber of a rabbit’s eye are presented to delineate the basic flow mechanisms. The calculations are based on a geometrical model of the eye, which represents the Trabecular mesh (TM) as a multi-layered porous zone of specified pore sizes and void fraction. The outer surface of the cornea is assumed to be at a fixed temperature (corresponding to the ambient temperature), while the iris surface is assumed to be at the core body temperature. Results are obtained for both the horizontal upward-facing orientation of the eye, and the vertical orientation of the eye. Parameters varied include: the pore size in the TM to understand how TM blockage influences the flow pattern and the intra-ocular pressure (IOP) distribution; the temperature difference between the iris and the cornea to underscore the important role of buoyancy in driving the aqueous humor flow; and, the pupil size reflecting different levels of ambient light. Buoyancy is observed to be the dominant driving mechanism for the convective motion in both orientations of the eye. Reducing the TM pore size does not appear to have a significant influence on the IOP until the pore size drops below 1 micron beyond which a significant increase in IOP is observed. Variations in the pupil size appears to have little influence on the IOP or flow distributions in view of the dominant role of buoyancy in controlling the flow motion.


2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Nicola Pescosolido ◽  
Francesco Parisi ◽  
Paola Russo ◽  
Giuseppe Buomprisco ◽  
Marcella Nebbioso

Both studies on animals and humans suggest the presence of dopamine (DA) receptors in the anterior segment of the eye. Their role in the dynamics of intraocular pressure (IOP) is not yet clear. DA2and DA3receptors are mainly located on postganglionic sympathetic nerve endings. Their stimulation reduces the release of norepinephrine and suppresses the production of aqueous humor. DA1receptors seem to be more expressed by the ciliary body and the outflow pathway of aqueous humor. The administration of DA1-selective agonists stimulates the production of aqueous humor, increasing IOP, whereas DA2- and DA3-selective agonists could reduce IOP and, therefore, the risk to develop a glaucoma (GL). GL is a broad spectrum of eye diseases which have in common the damage to the optic nerve and the progressive loss of the visual field. Further studies are desirable to clarify the role of the dopaminergic system and the usefulness of DA2and DA3agonists in reducing IOP.


Author(s):  
Margaret Morrison

After reviewing some of the recent literature on non-causal and mathematical explanation, this chapter develops an argument as to why renormalization group (RG) methods should be seen as providing non-causal, yet physical, information about certain kinds of systems/phenomena. The argument centres on the structural character of RG explanations and the relationship between RG and probability theory. These features are crucial for the claim that the non-causal status of RG explanations involves something different from simply ignoring or “averaging over” microphysical details—the kind of explanations common to statistical mechanics. The chapter concludes with a discussion of the role of RG in treating dynamical systems and how that role exemplifies the structural aspects of RG explanations which in turn exemplifies the non-causal features.


2020 ◽  
Vol 55 (1) ◽  
pp. 83-99
Author(s):  
Lukas Hermann

AbstractIn its peritext, Thomas Mann’s Entstehung des Doktor Faustus is described as a “Roman eines Romans”. The essay reasons that this description of its genre as well as structural aspects of its composition mark it as an autobiographical text. Instead of following most studies on the Doktor Faustus, which regard the Entstehung simply as a documentary source for exposing autobiographical intricacies of Mann’s novel, textual evidence for the Entstehung’s autonomy is given. The analysis focuses first on the structural frame of the Entstehung in order to show Mann’s central techniques of autobiographical self-stylization. In this context auto-fictional elements can also be identified. Exemplary passages from two longer sections are taken into account based on these findings. While the Doktor Faustus is a recurrent topic in these passages, it is not, by any means, the only one. Combined with varying autobiographical writing techniques, the Entstehung is thus displaying continuous independence from the Faustus. Based on these insights, future Mann studies on both works may reevaluate the role of the Entstehung for the reception of the Faustus and the status of autobiographical literature in the works of Thomas Mann.


1988 ◽  
Vol 106 (3) ◽  
pp. 396-403 ◽  
Author(s):  
E. J. Higginbotham ◽  
D. A. Lee ◽  
S. P. Bartels ◽  
T. Richardson ◽  
M. Miller

2010 ◽  
Vol 91 (6) ◽  
pp. 860-865 ◽  
Author(s):  
Carol B. Toris ◽  
Justin M. Risma ◽  
Janis Gonzales-Martinez ◽  
Marsha A. McLaughlin ◽  
William W. Dawson

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