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At least 973 records · Page 54Linked to original sources
PubMed1975

Effects of drug vehicles on ocular contact time.

Radioactive sodium pentechnetate Tc 99m was added to commonly used ophthalmic drug vehicles of saline, 1% methyicellulose, 1.4% polyvinyl alcohol, and a 6:4 mixture of white petrolatum-mineral oil ointment. These drug vehicles containing 99m Tc were placed on both rabbit and human eyes and the rate of disappearance of the radioactivity determined. The ocular retention of 99m Tc by the eye was much longer in the nonblinking eye regardless of the vehicle used. The rate of loss of 99m Tc from the eye was fastest with saline and slowest with the ointment, with methylcellulose and polyvinyl alcohol in between. The longest contact time of the drug vehicle with the eye is afforded by the use of the ointment vehicle and the covering of both eyes.

Absorption↗
PubMed1976

Sympathetic pupillary tone in old age.

In an attempt to determine whether autonomic neural factors might be involved in senile miosis, we tested pupillary responses to agents acting on the ocular sympathetic system in old subjects and compared them to responses in young adults. Our results suggest that sympathetic tone is decreased in the elderly. The dilator pupillae muscle does not lose its sensitivity to norepinephrine with age.

Adolescent↗
PubMed1978

Evaluation of drugs in ointment for mydriasis and cycloplegia.

Ointment preparations of cyclopentolate hydrochloride and tropicamide were compared with aqueous drops of these medications for the production of mydriasis and/or cycloplegia in clinic patients. Mydriasis and/or cycloplegia could be accomplished by the single application of a minute volume (around 0.005 ml) of ointment containing these drugs. With the use of ointment preparation, ocular irritation was minimal, and there was no interference with subsequent ocular examination. A delivery system was devised with a piece of silicone-rubber tubing that was filled with an ointment preparation. By squeezing the tubing, a minute volume (about 0.005 ml) of ointment preparation was expressed.

Accommodation, Ocular↗
PubMed1980

Cytotoxicity of pivalylphenylephrine and pivalic acid to corneal endothelium.

We examined the effects of topically applied pivalylphenylephrine (PPE) and pivalic acid (PA) on the corneal endothelium of rabbits and the direct effects of PPE and PA on monolayer cultures of bovine corneal endothelium. The PPE-treated corneas without epithelium significantly increased in thickness, whereas no change in thickness was observed in corneas with epithelium intact. The PA did not alter the thickness of corneas with or without epithelium. Although 0.001% PE had no noticeable effect in two hours, 0.01% PPE caused breakdown of intercellular junctions in cultured cells in five minutes. Higher concentrations of PPE caused the cells to detach from the culture dishes within 30 minutes of treatment. Only 1% PA caused cell elongation and loss of intercellular contact after 60 to 90 minutes of exposure; lower concentrations did not effect cultured cells.

Administration, Topical↗
PubMed1980

Is phenylephrine pivalate a prodrug?

Phenylephrine pivalate has been assumed to be a prodrug devoid of important intrinsic activity because of its structural similarity to dipivefrin (dipivaly epinephrine). However, unlike dipivefrin, the pharmacologic activity of phenylephrine pivalate was not prevented by prior administration of echothiophate iodide. Rabbits pretreated bilaterally with 0.25% echothiophate for two and seven days had similar mydriasis, both in quantity and duration, after receiving 10% phenylephrine hydrochloride to one eye and 1% phenylephrine pivalate to the other eye. This as consistent with the hypothesis that the phenylephrine pivalate molecule has important alpha-adrenergic activity regardless of whether it is converted to phenylephrine.

Animals↗
PubMed1984

Clinical evaluation of the Humphrey automatic refractor.

A new automatic objective refractor was used on healthy adults. In the absence of cycloplegic drugs, spherocylindrical objective refractions performed with the instrument provided 20/20 acuity 96% as often as with standard subjective techniques. No instrument-induced accommodations effects were seen. One hundred percent of instrument spherical findings were repeatable within 0.50 diopters; all cylindrical findings were repeatable within 0.37 D. This result represents a higher level of repeatability than that reported for standard subjective refraction under clinical conditions. In the absence of cycloplegic drugs, the correlation coefficient between the instrument's findings and standard subjective spherical findings was .97 v .98 between two practitioners' subjective refractions. The average difference between cylindrical findings of the instrument and those of an experienced practitioner was 0.04 D larger than the average difference seen between two practitioners using subjective techniques.

Accommodation, Ocular↗
PubMed1988

Effects of routine pupillary dilation on functional daylight vision.

The visual acuity of 100 patients between the ages of 16 and 66 years, seen for routine ophthalmologic examination, was measured before and after dilation. All patients had a predilation visual acuity of 20/40 or better. Postdilation binocular visual acuity using the patients' usual correction was measured first in the office and then outdoors, both with the patient's back to and the patient facing the sun, with and without the aid of postmydriatic sunglasses. Twelve percent experienced disabling photophobia even with the use of postmydriatic sunglasses, with 3% having significant objective visual loss defined as 20/50 or worse. No objective visual loss was found in 30 controls examined outdoors before dilation, without sunglasses. We recommend that patients who have experienced significant photophobia with dilation in the past, or who have never before undergone dilation, make arrangements for transportation after a dilated examination.

Adolescent↗
PubMed1990

Time course of thymoxamine reversal of phenylephrine-induced mydriasis.

We conducted a randomized, double-masked, paired comparison of 0.1% thymoxamine vs placebo for the reversal of phenylephrine-induced mydriasis. Mydriasis was induced with 2.5% phenylephrine in each eye of 74 subjects (148 eyes). Each subject then received 0.1% thymoxamine in one eye and placebo in the other eye. Pupillary measurements were obtained at regular intervals during the ensuing 8 hours. At all intervals, a greater percentage of thymoxamine-treated eyes returned to baseline pupillary diameters compared with placebo-treated eyes (P less than or equal to .01). For subjects in whom both pupils returned to baseline, thymoxamine-treated eyes returned to baseline in a mean of 2.2 hours, vs 5.2 hours for placebo (P less than .0001). Among thymoxamine-treated eyes, those with light irides responded more rapidly than those with dark irides, returning to baseline in 1.6 vs 2.8 hours, respectively (P = .0046). After constriction to baseline pupillary diameter had been achieved, no patients experienced a rebound dilation.

Adolescent↗