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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ten normal subjects underwent static threshold visual field testing of both eyes with the Humphrey perimeter, with one eye tested twice. The mean sensitivity of the field seemed virtually identical in the two eyes, with the average difference between the right and left eyes (0.65 decibels [dB]) being no greater than the testing error as reflected in the difference between the same eye tested twice (0.7 dB). The authors provide the mathematical basis for recognizing that a right eye-left eye difference in mean sensitivity might be abnormal. Additional information is needed about the variance of the right eye-left eye difference in the population at large, but present information suggests that a 2-dB difference may be meaningful on a single examination. A 1.5-dB difference is statistically significant if confirmed on a second test, and a difference as small as 1 dB may be meaningful if shown consistently in a series of four examinations. In all cases, nonglaucomatous causes of field abnormality needs to be ruled out, and the generalized asymmetry is most meaningful if it is consistent with asymmetry of cupping or intraocular pressure. Several cases are reported in which a mild (1 dB) generalized depression of the visual field is the only recognizable abnormality in the visual field in eyes with early glaucoma.
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PMID:Static threshold asymmetry in early glaucomatous visual field loss. 277 96

A test of suitability of the electroimpression tonometer from Fritz Schwarzer GmbH, Munich, for measuring intraocular pressure in dogs was performed. Intraocular pressure of 63 clinically healthy English beagles was measured in both eyes using the instrument with different plunger weights. Intraocular pressure and volume of corneal depression during measurement were determined as a function of the plunger weight from readings on the tonometer with the aid of Friedenwald's tables (2). Using Friedenwald's law and with knowledge of the rigidity coefficient, an intraocular pressure of 32.7 mmHg was found, with individual variations between 12.8 and 54.2 mmHg. The rigidity coefficient for dogs, which was determined by linear regression, was, on average, 0.0103. Differences between male and female dogs were not significant for either parameter. A conversion table for eyes with a rigidity factor of 0.0103 is attached. Intraocular pressure as a function of plunger weight and the reading of measurement is shown in mmHg. In our measurements the Schwarzer electrotonometer for determination of intraocular pressure provided easily reproducible readings.
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PMID:A contribution to indirect ophthalmotonometry in beagles. 380 68

Recent reports from this laboratory indicate that dopamine (DA2) agonists can lower intraocular pressure (IOP) in rabbits, monkeys and rats. This communication suggests that the cat nictitating membrane (CNM) preparation is a useful model for localizing the site(s) and mechanism(s) of action of dopamine (DA2) agonists and that this model can be used to discriminate between alpha 2 and DA2 activity. This in vivo preparation consists of indirect (neuronal)- and direct (agonist)-induced activation of the CNM by: 1) pre- and postganglionic stimulation of sympathetic nerves and 2) injection of norepinephrine (NEPI) into the external carotid artery (i.a.). A variety of DA2-agonists (ergolines, azepines, aminotetralins, aporphines) can cause dose-dependent depression of neuronally mediated contractions with minimal effects on contractions elicited by NEPI i.a. Characteristically, DA2-agonists depressed contractions elicited by low frequency (2 & 4 Hz) stimulation more than high frequency (6 & 8 Hz) stimulation. For example, the inhibitory effects of an ergoline derivative LY141865 on neuronally mediated contractions of the CNM could be reversed (or prevented) by relatively selective DA2 antagonists, such as sulpiride and domperidone, but not by relatively selective alpha 2-antagonists, such as yohimbine and rauwolscine. Interestingly, alpha 2-adrenoceptor agonists, such as clonidine and xylazine, caused less depression of nerve-stimulated responses than did DA2-agonists at the same dose. This modest suppression by alpha 2-agonists could be inhibited by yohimbine but not by sulpiride or domperidone. These results with the CNM document the presence of DA2 receptors on sympathetic neurons innervating an ocular adnexa and demonstrate a model for dissociating DA2 from alpha 2 activity.
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PMID:An in vivo model for dissociating alpha 2-and DA2-adrenoceptor activity in an ocular adnexa: utility of the cat nictitating membrane preparation. 615 Aug 10

Sclera-laminating goniotrepanation is a modification of the Elliot-Fronimopoulos operation. In this procedure the scleral flap is removed, so that a shallow depression is formed in the sclera; this helps to prevent an ectatic bleb. No cicatrization of the trephine hole was observed in the authors' cases. The modification is only used by them in glaucoma cases with poor prognosis. Forty-six patients, 39 of whom were suffering from neovascular glaucoma associated with occlusion of the central retinal vein or diabetic retinopathy, underwent the operation and the results were followed up. As far as regulation of intraocular pressure and elimination of pain are concerned, the results were encouraging. Severe hemorrhage into the anterior chamber without spontaneous absorption only occurred in 2 cases.
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PMID:[Results of sclera-laminating goniotrephination in neovascular glaucoma]. 619 92

delta-9-Tetrahydrocannabinol (delta 9-THC) or cannabichromene, a structurally diverse naturally occurring cannabinoid, was delivered unilaterally to the corneas of cats either acutely by application of single drops or chronically via osmotic minipumps over a period of nine days. While delta 9-THC only reduced intraocular pressure (IOP) minimally after acute administration, this cannabinoid produced substantial reductions in ocular tension during the entire period of chronic administration. Ocular toxicity during chronic treatment, however, was pronounced; conjunctival chemosis, erythema, and hyperemia were sustained, and corneal opacities approximating the site of drug delivery became evident within three to five days. In contrast, cannabichromene did not significantly alter IOP either acutely or during the nine days of chronic administration, and ocular toxicity was not apparent. After systemic administration of delta 9-THC to rats, a dose-related increase in the appearance of 8-13 Hz polyspike discharges became evident in the electrocorticogram during wakefulness and behavioral depression. These polyspikes subsequently reappeared during rapid eye movement (REM) sleep episodes. Cannabichromene was devoid of this effect. These results indicate that, in contrast with acute administration, chronic delivery of delta 9-THC to cat eyes produces substantial reductions in IOP. The tension lowering effect, however, is accompanied by considerable ocular toxicity and neurotoxicity. As cannabichromene lacked these activities, the terpenoid portion of the cannabinoid structure appears to be important for their mediation.
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PMID:Intraocular pressure, ocular toxicity and neurotoxicity after administration of delta 9-tetrahydrocannabinol or cannabichromene. 632 6

Five pairs of excised human eyes were examined for anatomic correlates of changes in aqueous outflow facility that result from changing the intraocular pressure (IOP) and from placing mechanical tension on the irido-corneal angle (lens depression). An increase in IOP from 0 to 40 mm Hg tended inconsistently to compress trabecular meshwork as a whole and to distend the juxtacanalicular tissue. The most constant and significant effect of increasing IOP, however, was to compress Schlemm's canal, thereby progressively diminishing its volume to its virtual collapse at 40 mm Hg IOP. Lens depression increased Schlemm's canal volume and partially prevented its collapse at high levels of IOP. The mean frequency of endothelial vacuoles was remarkably constant at IOPs from 2.5 to 40.0 mm Hg, with and without lens depression, but was significantly lower when the IOP was reduced to 0 mm Hg. When correlated with existing physiologic data, these anatomic findings suggest that Schlemm's canal collapse, but not vacuole frequency, is an important contributor to pressure-dependent changes in aqueous outflow facility.
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PMID:Anatomic correlates of changing aqueous outflow facility in excised human eyes. 707 8

Introduction of L-timolol maleate into the clinics for glaucoma treatment has been a great success as it produces relatively few side effects, such as miosis, ciliary spasm and headache, which are associated with the use of pilocarpine. Recent reports indicated, however, that L-timolol produces asthmatic attacks, cardiovascular suppression and central depression. D-Timolol was found to be as effective as L-timolol in lowering the intraocular pressure and aqueous humor production. However it was much less potent than L-timolol in inhibiting cardiac contractility and heart rate stimulated by isoproterenol and was less active in blocking beta-adrenergic receptors in tracheal muscle. It is suggested that the D-isomer of timolol could be used to treat glaucoma instead of L-isomer without producing untoward side effects in cardiovascular and bronchial tissues.
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PMID:Effects of D-timolol on intraocular pressure, heart rate, cardiac contractility, and tracheal muscle function. 718 3

The concept of the conventional aqueous outflow pathway (through the trabecular meshwork and other components of the canal's inner wall, along Schlemm's canal to collector channels, and out of the eye through the collector channels) was modeled on tubes with leaky walls and a network of electrical resistances. Analysis of these models suggested experiments to test the models and to assess the magnitude of the resistance of portions of the pathway. We found that the well-known increase in outflow resistance with increased intraocular pressure was, in large measure, the result of blockage of the collector channels, probably by the canal's inner wall. A model of the trabecular meshwork predicted that tension on the scleral spur and trabecular mesh would cause the meshwork to arch over Schlemm's canal. We depressed the lens to generate such tension, and found that the resistance of the inner wall of the canal decreased. In one eye, lens depression also decreased resistance to flow in the collector channels and the canal of Schlemm and prompted the suggestion that when secretory inhibitors are used in glaucoma, cyclo-tonic agents should be used simultaneously to relieve canal collapse and blockage of collector channels by inner canal wall.
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PMID:The conventional outflow resistances. 731 32

The Authors have studied in a homogeneous group of rabbits the variations of intraocular pressure and of aqueous humour pH caused by instillation of timolol maleate at different concentrations. In the animals treated with drug concentration of 0,25% and 0,5% a constant reduction of IOP has been observed in comparison with controls, associated to acidification of aqueous humour: no evidence of this correlation it seems to be at low doses of timolol. Further studies are in course to indicate an eventual action of intermediate substances in the mechanism of IOP depression caused by timolol.
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PMID:[Preliminary study of acidification of the pH of the aqueous humor in rats treated with timolol maleate]. 745 18

Effects of a Russian b-a-adrenoblocker proxodolol on the intraocular pressure, ocular hemodynamics, pupil diameter, ocular functions, arterial pressure, and heart rate were studied in 105 patients (163 eyes) with primary open-angle glaucoma. A manifest hypotensive effect of proxodolol was due to depression of aqueous humor production and improvement of its outflow. Comparative study of the efficacies of proxodolol and timolol maleate by the blind test and randomization demonstrated the identity of these drugs. A synergic effect on intraocular pressure was observed when proxodolol was combined with pilocarpine and/or klofelin.
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PMID:[Proxodolol, a new domestic preparation for lowering intraocular pressure in glaucoma]. 764 80


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