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Query: UMLS:C0595921 (intraocular pressure)
 11,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intracapillary haemoglobin oxygenation (oxygen saturation) and haemoglobin concentration (corresponding with blood volume) were measured in different regions of the albino rabbit anterior eye segment using the Erlangen micro-lightguide spectrophotometer (EMPHO I). The tip of the microlightguide (active diameter 210 microns, cover diameter 0.5 mm) was placed in the vitreous by a goniometric mounting and controlled by a micromanipulator. After stepwise elevation of intraocular pressure (IOP) the haemoglobin oxygenation decreased slightly in the iris at an IOP-level of 60 mmHg, whereas in the three regions of the ciliary processes and in the peripheral choroid haemoglobin oxygenation did not decrease until values of 80 mmHg were applied. In contrast, haemoglobin concentration decreases when the IOP increases in all regions except in the pars plana where the haemoglobin concentration increased at 40 and 60 mmHg. The most pronounced reactive hyperaemia was found in the major ciliary processes. Quite passive changes of haemoglobin concentration were seen in the peripheral choroid. Effective regulatory mechanisms must exist which result in IOP-independent (20-60 mmHg) haemoglobin oxygenation, whereas pronounced changes in intracapillary haemoglobin concentration were observed. The decay of both parameters at IOP 80 mmHg is indicative of an exhaustion of their regulatory capacity. Epinephrine topically applied onto the conjunctival sac or injected into the common carotid artery led to a short-term decrease of haemoglobin concentration and, later, a hyperaemic response. A short-term haemoglobin deoxygenation was found especially in the major ciliary processes.
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PMID:Spectrometric measurements in the anterior eye vasculature of the albino rabbit--a study with the EMPHO I. 201 59

Previous studies have shown a reduction in intraocular pressure (IOP) from many forms of exertion, ranging from walking to exhausting exercise. The variability in these results may be due to several factors, such as age, diurnal and seasonal variations, drinking water or coffee before the test, acute hyperglycaemia, and physical fitness. The purpose of the study was to investigate the effects of the common means of exertion on IOP in the same subject, after elimination of above-mentioned factors. The effects of sitting, walking, jogging, and running fast till exhaustion were noted on the IOP of 15 healthy sedentary male volunteers at an interval of 4 days. Intraocular pressures were measured with a Goldmann applanation tonometer at the beginning and at 5th, 20th, 40th, and 60th minutes of the first three tests, but in test 4, only at the beginning and end. Post-exercise measurements were taken after every 10 minutes until IOP returned to pre-exercise levels. The effects of all tests were similar on both eyes. During sitting, walking and jogging, the maximum decreases were (mean +/- SD) 1.20 +/- 0.66, 3.20 +/- 1.19, and 5.07 +/- 1.76 mmHg, and occurred at the 20th, 40th and 60th minutes of the tests respectively. During sitting, walking and jogging, 66.7%, 75% and 68.4% of the maximum decreases occurred after 5 min respectively. After running the mean decrease was 5.7 +/- 1.09 mmHg and the average time of running was 10.53 +/- 2.17 min. In the sitting test, recovery occurred at the end of the test, while in walking, jogging and running tests it occurred after 12.67 +/- 44.48, 30.67 +/- 7.99, and 56.00 +/- 11.21 min, respectively. It is concluded that all forms of exertion decrease IOP. It would seem reasonable, at present, not to discourage patients who have glaucoma from walking; perhaps, on the contrary, it should be encouraged.
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PMID:Effects of mild, moderate and severe exercise on intraocular pressure of sedentary subjects. 881 81

The effects of exercise and water replacement on intraocular pressure (IOP) have not been well established. Furthermore, it is not known whether the temperature of the fluid ingested influences the IOP response. In the present study we determined the effect of water ingestion at three temperatures (10, 24 and 38 degrees C; 600 ml 15 min before and 240 ml 15, 30 and 45 min after the beginning of each experimental session) on the IOP of six healthy male volunteers (age = 24.0 +/- 3.5 years, weight = 67.0 +/- 4.8 kg, peak oxygen uptake (VO2peak) = 47.8 +/- 9.1 ml kg-1 min-1). The subjects exercised until exhaustion on a cycle ergometer at a 60% VO2peak in a thermoneutral environment. IOP was measured before and after exercise and during recovery (15, 30 and 45 min) using the applanation tonometry method. Skin and rectal temperatures, heart rate and oxygen uptake were measured continuously. IOP was similar for the right eye and the left eye and increased post-water ingestion under both exercising and resting conditions (P<0.05) but did not differ between resting and exercising situations, or between the three water temperatures. Time to exhaustion was not affected by the different water temperatures. Rectal temperature, hydration status, heart rate, oxygen uptake, carbon dioxide extraction and lactate concentration were increased by exercise but were not affected by water temperature. We conclude that IOP was not affected by exercise and that water ingestion increased IOP as expected, regardless of water temperature.
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PMID:Effects of submaximal exercise with water ingestion on intraocular pressure in healthy human males. 1174 24

Normal pressure glaucoma (NPG) is a heterogeneous pathology of the optic nerve and retina. Besides, primary open-angle glaucoma (POAG) with high pressure belongs equally to the heterogeneous group. The risk factors and pathogenesis stages of NPG and those of POAG do not coincide completely. A considerable number of the NPG cases can be attributed to the glaucoma of pseudo-normal pressure. The individual norm of the intraocular pressure (IOP) does not coincide with the statistical standards. At the same time, POAG with high pressure has, to a more or less extent, the specific features peculiar to NPG. This is especially characteristic of POAG with moderately high IOP. The NPG specific features peculiar to a majority of the examined patients were related with an insufficient cerebral blood circulation caused by occlusive processes in the great and small vessels of the brain, by the nature of the collateral blood circulation and by a dysfunction of the vascular endothelium due to an exhaustion of the cerebral perfusion reserve. The latter is formed mainly at the cost of the vertrebobasilar basin. The mentioned basin supplies blood to the visual tract, as well as to the cerebral centers of the visual analyzer and of the midbrain. Ischemia of the upper corpus bigeminum and of the optic nucleus of the corpus geniculate laterale reduces the formation and supply of neurotrophines (in particular, of BNDF) with the axonal transport to the retinal ganglionic cells, which leads to their apoptosis. Cavernous dystrophy of the optic nerve is a factor preconditioning the occurrence of excavation of the optic nerve head. The mechanic factor related with excavation cannot be ruled out, either. NPG patients often have a relatively large size of the optic nerve disk (OND), therefore, their disk area is equally large. The pressure exerted on the OND is proportional not only to an IOP value, it is also proportional to a disk area. Consequently, provided the IOPs are identical, the mechanical forces exerted on the OND would differ with direct dependence on a disk area. There is every reason to suggest that a considerable share of NPG cases are preconditioned by the cerebrovascular pathology and, therefore, not only the ophthalmologist but also the neurologist must be involved in the diagnostics and treatment of such patients.
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PMID:[Normal-pressure glaucoma: a hypothesis of pathogenesis]. 1367 95