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Biomedical subjects

S M Podos

Publications and source records attributed to S M Podos.

At least 127 records · Page 7Linked to original sources
PubMed1980

Interocular comparison of contrast sensitivities in glaucoma patients and suspects.

Glaucoma affected the ability to detect low-contrast, flickering patterns ('DRC' measurement). DRC patterns were foveally viewed, of low spatial frequency, and flickering at 8 hertz. Interocular comparisons were performed in control subjects, in ocular hypertensives, and in glaucoma patients with asymmetric damage. Interocular differences in DRC tended to be of greater magnitude in the glaucoma patients than in the ocular hypertensive patients or control subjects. In the glaucoma patients DRC was consistently lower in the eye with the greater field defect than in the other (more normal) eye. In patients with optic disc asymmetry DRC was lower in the eye with the more abnormal disc. Treatment asymmetries did not appear to play a significant role in these relationships. When examined by interocular comparisons DRC showed no consistent relationship to Snellen visual acuity or to level of intraocular pressure at the time of DRC testing.

Form Perception↗
PubMed1980

Topical vanadate lowers intraocular pressure in rabbits.

In unanesthetized rabbits the topical application of vanadate lowered intraocular pressure. Tonographic outflow facility and episcleral venous pressure were unaltered by topical vanadate. As estimated from the tonographic data, aqueous humor flow was reduced by approximately 30%. Posterior chamber aqueous humor ascorbate increased in the eye receiving topical vanadate, and this was compatible with a decreased rate of aqueous humor flow. Topical vanadate did not alter anterior chamber aqueous humor protein or cyclic AMP. In five monkeys intraocular pressure was also significantly reduced by topical vanadate.

Administration, Topical↗
PubMed1980

Oxygen lowers intraocular pressure.

A significant decrease in intraocular pressure was demonstrated in 14 patients as atmospheric pressure was increased at intervals of 0.5 atmospheric pressure up to 3 atmospheres within a hyperbaric chamber. Nine of these patients had the identical protocol repeated in room air at atmospheric pressure without a significant change in intraocular pressure. Administration of 100% O2 at 15 L/min by partial rebreathing face mask to these patients using the same protocol at atmospheric pressure resulted in a significant decrease in intraocular pressure. The results in the oxygen and hyperbaric groups were not statistically different. While in the hyperbaric chamber, scleral rigidity increased uniformly, outflow facility decreased significantly, and keratometry readings remained unchanged. A significant decrease in intraocular prssure occurred in 20 rabbits that received 100% oxygen by partial rebreathing face mask for 180 minutes. Arterial blood gases were obtained at 0.90, and 180 min in seven rabbits. The pH and pCO2 did not change significantly; however, pO2 was markedly elevated. Increased oxygen concentration was felt to be responsible fot the decrease in intraocular pressure and the changes in other parameters observed in patients and rabbits.

Animals↗
PubMed1979

Ocular effects in normal rabbits of topically applied labetalol: a combined alpha- and beta-adrenergic antagonist.

The ocular effects in rabbits of topically applied labetalol hydrochloride, a new alpha- and beta-adrenergic receptor blocking agent, were studied. A dose-related reduction in intraocular pressure (IOP) followed treatment with 0.01% to 1% solutions. Labetalol at a 1% concentration had no effect on pupil diameter. The same dose blocked an increase in IOP after water loading but did not significantly alter the coefficient of aqueous outflow facility. Mydriasis induced by phenylephrine hydrochloride was competitively inhibited.

Animals↗
PubMed1979

Clinical comparison of dipivalyl epinephrine and epinephrine in the treatment of glaucoma.

Dipivalyl epinephrine, 0.1%, though slightly less effective in decreasing intraocular pressure, showed significantly fewer side effects than epinephrine hydrochloride, 2%. Seventeen patients with symmetrically increased intraocular pressures who completed a six-month double-masked crossover study showed a significant decrease in intraocular pressure averaging 23.7% for dipivalyl epinephrine over the entire study and 27.4% for epinephrine. In the first treatment period, dipivalyl epinephrine was slightly less effective than epinephrine. In the second treatment period, dipivalyl epinephrine was statistically less effective than epinephrine. Two of the original 25 patients were dropped from the study because of epinephrine allergy or intolerance, one had uncontrolled pressures with either drug, and five failed to maintain adequate follow-up. Complaints of side effects such as burning and irritation occurred much more frequently in eyes receiving epinephrine (24%) than dipivalyl epinephrine (3%). Mild mydriasis occurred with each drug, averaging +0.65 mm with dipivalyl epinephrine and +0.55 mm Hg with epinephrine. No effect on blood pressure or pulse rate was found for the two drugs.

Adult↗
PubMed1979

Abnormalities of central contrast sensitivity in glaucoma.

The detectability of foveally presented low-contrast flickering stimuli was determined for glaucoma patients, ocular hypertensives, and normal control subjects. Two types of stimuli, a homogeneous flickering field, and a counterphase flickering grating of low spatial frequency, were presented on a screen subtending 4 degrees of visual angle. The average of the contrast sensitivities to these two simuli (defined as the dynamic response coefficient) was consistently lower in glaucomatous than in normotensive eyes. The dynamic response coefficient was also below normal in half the ocular hypertensive eyes.

Adult↗
PubMed1979

Continuous wave argon laser iridectomy in angle-closure glaucoma.

By using a continuous wave argon laser in a multiburn fashion, successful iridectomies were achieved in 42 out of 45 phakic eyes with either acute or chronic angle-closure glaucoma. Five of the successful procedures required multiple sittings on different days or abandonment of the primary treatment site in favor of an alternate site, or both, to attain patency. Within the immediate postoperative period, ten eyes needed retreatment to eliminate moderate pigment proliferation at the perforation site. The procedure was performed on an outpatient basis under topical anesthesia, usually required less than one-half hour for completion, and resulted in only minimal complications. Therefore, continuous wave argon laser iridectomy appears to present a viable alternative to surgical iridectomy for the definitive treatment of angle-closure glaucoma, although long-term evaluation of this modality of therapy is presently unavailable.

Adult↗
PubMed1979

Transient open-angle glaucoma associated with sickle cell trait: report of 4 cases.

Four black patients, all with sickle trait (SA), developed transient open-angle glaucoma with blood in Schlemm's canal. In 3 patients the condition followed blunt trauma, while in the fourth no antecedent trauma was described. The intraocular pressure became normal in all 4 cases with the resolution of the haemorrhage from the trabecular meshwork and Schlemm's canal.

Adult↗
PubMed1979

Modification by timolol of catecholamine stimulation of chloride transport in isolated corneas.

In the isolated frog cornea, 10(-5)M timolol completely blocked the stimulation of chloride transport by 10(-6)M isoproterenol. In this preraration, timolol inconsistently modified the response to epinephrine. In some experiments, epinephrine added to the bathing medium after timolol caused a smaller than normal increase in chloride transport, but in other instances, epinephrine caused a decrease in chloride transport. In the isolated rabbit cornea, 10(-5)M timolol totally blocked the stimulation of chloride transport by 10(-6)M epinephrine. In vivo, topical treatment of rabbit eyes with 0.5% timolol resulted in corneas from these eyes having an inhibited response to epinephrine when incubated in vitro. This inability to stimulate chloride transport persisted for several days following termination of topical treatment with timolol.

Administration, Topical↗
PubMed1979

Effect of dipyridamole on prostaglandin-induced ocular hypertension in rabbits.

The effect of intraperitoneal injections of dipyridamole on the elevations of intraocular pressure and anterior chamber aqueous humor protein produced by topical application of prostaglandin E2 was studied in rabbits. Pretreatment with 100 mg/kg dipyridamole inhibited the prostaglandin E2--induced ocular hypertension and rise of aqueous humor protein. Systemic administration of dipyridamole did not alter the responses of the eye to instilled nitrogen mustard. Topical instillation of dipyridamole was ineffective. Dipyridamole, a clinically available drug, may be useful in the treatment of ocular inflammatory disease.

Administration, Topical↗
PubMed1979

Continuous wave argon laser iridectomy in angle-closure glaucoma.

Utilizing a continuous wave argon laser in a multiburn fashion, successful iridectomies were achieved in 42 of 45 phakic eyes with either acute or chronic angle-closure glaucoma. Five of the successful procedures required multiple sittings on different days or abandonment of the primary treatment site in favor of an alternate site to attain patency. Within the immediate postoperative period, ten eyes needed further treatment to eliminate moderate pigment proliferation at the perforation site. The procedure was performed on an outpatient basis under topical anesthesia, usually required less than one-half hour for completion, and resulted in only minimal complications. Therefore, CWAL iridectomy appears to present an alternative to surgical iridectomy for the definitive treatment of angle-closure glaucoma, although long-term evaluation of this modality of therapy is presently unavailable.

Adult↗
PubMed1978

Lack of association of histocompatibility antigens with primary open-angle glaucoma.

Eighty-seven patients (35 with primary open-angle glaucoma, 20 with angle-closure glaucoma, and 32 controls) underwent HLA typing of peripheral lymphocytes. Sixteen specificities were detected at the A locus, 19 at the B locus, and four at the C locus. No significant differences were found between patients with either type of glaucoma and control patients.

Ethnicity↗
PubMed1978

A comparison of the effects of timolol and epinephrine on intraocular pressure.

We conducted a double-masked, six-week crossover study comparing bilateral twice-a-day therapy with timolol maleate (0.1%, 0.25%, and 0.5%) and epinephrine hydrochloride (0.5%, 1.0%, 2.0%) in 36 otherwise untreated patients. Increasing concentrations of each drug were administered until an arbitrary level of control was achieved before each of the six-week follow-up periods. Seventeen patients were controlled by both drugs and four patients were controlled by neither drug. Timolol, but not epinephrine, was effective in ten patients, whereas epinephrine, but not timolol, was effective in two patients. Three patients did not complete the study. The mean decrease in intraocular pressure from baseline was significantly greater with timolol than with epinephrine both before crossover and overall at both the lowest and highest concentrations of drug used. Significantly toxicity was produced in four patients during treatment with epinephrine, but in no patients during treatment with timolol.

Adult↗
PubMed1978

The effect of 1.5% timolol maleate on intraocular pressure.

A controlled trial was instituted to compare the effect on intraocular pressure of topical administration of timolol maleate with epinephrine hydrochloride. A bottling error by the manufacturer resulted in the placebo bottles containing 1.5% timolol maleate. This drug given twice a day for two weeks significantly reduced intraocular pressure and produced no side effects.

Administration, Topical↗