Regulation of retinal oxygen metabolism in humans during graded hypoxia.

Animal experiments indicate that the inner retina keeps its oxygen extraction constant despite systemic hypoxia. For the human retina no such data exist. In the present study we hypothesized that systemic hypoxia does not alter inner retinal oxygen extraction.

Retinal oxygen metabolism during normoxia and hyperoxia in healthy subjects.

Purpose: To characterize retinal metabolism during normoxia and hyperoxia in healthy subjects.

Methods: Forty-six healthy subjects were included in the present study, and data of 41 subjects could be evaluated. Retinal vessel diameters, as well as oxygen saturation in arteries and veins, were measured using the Dynamic Vessel Analyzer.

Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects.

Purpose: The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele.

Retinal hemodynamic effects of antioxidant supplementation in an endotoxin-induced model of oxidative stress in humans.

Purpose: The Age-Related Eye Disease Study 1 (AREDS 1) has shown that nutritional supplementation with antioxidants and zinc modifies the natural course of AMD. It is presumed that the supplements exert their beneficial effects by ameliorating oxidative stress due to the scavenging of reactive oxygen species (ROS). We have shown in a human model that under oxidative stress induced by administration of lipopolysaccharide (LPS) the vasoconstrictor response of retinal vessels to oxygen breathing is diminished.

Optic nerve head blood flow autoregulation during changes in arterial blood pressure in healthy young subjects.

Aim: In the present study the response of optic nerve head blood flow to an increase in ocular perfusion pressure during isometric exercise was studied. Based on our previous studies we hypothesized that subjects with an abnormal blood flow response, defined as a decrease in blood flow of more than 10% during or after isometric exercise, could be identified.

Methods: A total of 40 healthy subjects were included in this study.

Role of nitric oxide in optic nerve head blood flow regulation during an experimental increase in intraocular pressure in healthy humans.

The present study set out to investigate whether nitric oxide, a potent vasodilator, is involved in the regulatory processes in optic nerve head blood flow during an experimental increase in intraocular pressure (IOP). The study was conducted in a randomized, double-masked, placebo-controlled, three way cross-over design. 12 healthy subjects were scheduled to receive either L-NMMA (an unspecific nitric oxide synthase inhibitor), phenylephrine (an α-adrenoceptor agonist) or placebo on three different study days.

Regulation of optic nerve head blood flow during combined changes in intraocular pressure and arterial blood pressure.

In the choroid, there is evidence that blood flow does not only depend on ocular perfusion pressure (OPP), but also on absolute mean arterial pressure (MAP) and intraocular pressure (IOP). The present study included 40 healthy subjects to investigate whether such behavior is also found in the optic nerve head (ONH). The ONH blood flow (ONHBF) was studied using laser Doppler flowmetry during a separate increase in IOP and MAP as well as during a combined elevation.

[Clinical characteristics of penetrating ocular injuries with intraocular foreign body. Part II. Diagnostics and treatment].

Ocular trauma remains a major cause of blindness, particularly in the working-age population. Intraocular foreign bodies (IOFBs ), frequently accompany penetrating ocular injuries and can lead to increased ocular morbidity. In this paper, based on published reports and their authors clinical experience, we discuss questions of advantages and disadvantages of three imaging methods (radiology, ultrasound and tomography), and evaluate the value of these methods in the diagnosis of IOFBs.

[Clinical characteristics of penetrating ocular injuries with intraocular foreign body. Part I. Pathogenesis and clinical features].

Intraocular foreign bodies (IOFBs), are the major cause of penetrating ocular trauma and the most serious problem is the resulting impairment of visual function. In this paper, based on published reports and their clinical experience, authors discuss questions of pathogenesis, epidemiology and clinical features of IOFB injuries. Special attention was paid on primary and secondary complications, which include mechanical lesions of the ocular tissues, metallosis and endophthalmitis.

[Late complications after penetrating ocular injuries caused by intraocular and intraorbital foreign bodies].

Purpose: To evaluate late complications in patients with penetrating ocular injuries caused by intraocular or intraorbital foreign bodies (IOFBs).

Material And Methods: We reviewed 58 posttraumatic patients with IOFBs removed by external electromagnet or intraocular forceps. The patients underwent a follow-up examinations at 1 to 7 years after trauma.

[Intraocular and intraorbital foreign bodies characteristics in patients with penetrating ocular injury].

Purpose: To determine clinical features of intraocular and intraorbital foreign body (IOFB) injuries.

Material And Methods: 62 patients with IOFB injury were retrospectively reviewed. Data on age, sex, activity at the time of injury, initial visual acuity and presenting clinical features were recorded.

[Modern neurosurgical techniques to remove intraorbital foreign bodies--report of two cases].

To indicate the usefulness of modern neurosurgical techniques to remove intraorbital foreign bodies, not removed during primary ophthalmological surgical intervention. PATIENT 1: A 29-year-old man, struck with a bottle, with a piece of glass located at the top of the right orbit. During the primary ophthalmological intervention--orbitotomy accessed through the conjunctiva of the fornix of the upper eyelid and the second cut through the wound in the eyelid--the foreign body was not removed.

[The influence of the pseudoexfoliation syndrome on cataract development].

Pseudoexfoliation syndrome (PEX) is a chronic, systemic, connective tissue disease. Its hallmark is the accumulation of an abnormal, amyloid-like material in the anterior segment tissues of the eye. PEX is one of the risk factors in the development of lens opacification.

[Giant cell arteritis--case report].

Giant cell arteritis is a systemic disease of unknown origin. Vasculitis involves large and medium-sized vessels. Frequent clinical manifestations include characteristic headache in the temporal area, jaw or tongue claudication, apathy, fatigue, weight loss.