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Biomedical subjects

B Becker

Publications and source records attributed to B Becker.

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

Filtering valve implant surgery for eyes wtih neovascular glaucoma.

We performed filtration surgery with a unidirectional, pressure-sensitive valve implant in 40 eyes with neovascular glaucoma. The device consisted of an open Supramid tube (outside diameter 0.58 mm, inside diameter 0.38 mm) sealed to a Silastic tube with a slit valve. The Supramid tube was inserted at the corneoscleral limbus 1 to 4 mm into the anterior chamber and the Silastic portion was located under a lamellar scleral flap. Twenty-seven of 40 eyes (68%) had a postoperative IOP less than or equal to 24 mm Hg with a mean follow-up of 13.8 months. Ten of these 27 eyes required postoperative medical therapy to achieve this level of IOP control. The glaucoma valve implant failed to return IOP to normal in 13 of the 40 eyes (32%), 11 of these as a consequence of scarring of the external bleb.

Adult↗
PubMed1980

Prognostic significance of optic disk cupping in ocular hypertensive patients.

The stereoscopic photographs of 102 patients with increased intraocular pressure (IOP) and normal visual fields were graded for cup:disk ratio. All patients were followed up for a five-year period, during which time 27 patients developed glaucomatous visual field loss and 75 patients did not. The patients who subsequently developed glaucomatous visual field loss had significantly larger cup:disk ratios than did the patients who did not develop glaucomatous visual field loss. Patients with a mean IOP greater than or equal to 28 mm Hg and a vertical contour cup:disk ratio greater than or equal to 0.6 had a 100% incidence of the development of glaucomatous visual field loss as compared to a 2% incidence in those with a mean IOP less than 28 mm Hg and a vertical cup:disk ratio less than 0.6. Disk:cup asymmetry and progressive increase in the area of the disk occupied by the cup was more common in the group that developed glaucomatous visual field loss.

Aged↗
PubMed1980

The effect of H1-blocking antihistamines on intraocular pressure in rabbits.

H1-blocking antihistamines were administered topically to rabbits to determine their effects on intraocular pressure. Chlorcyclizine which is in the piperazine class of H1-inhibitors was found to elevate intraocular pressure. This effect was prevented by the systemic administration of indomethacin and is probably a prostaglandin induced change. Of the other agents tested, antazoline which is in the ethylenediamine class, was the only drug found to lower intraocular pressure. The antazoline-induced lowering of intraocular pressure was associated with no changes in outflow facility, episcleral venous pressure, systemic blood pressure, or ocular blood flow. Tonographic and aqueous humor ascorbate humor ascorbate data suggested a decreased (41% and 33% respectively) rate of aqueous flow as the mechanism for the decrease in intraocular pressure. The systemic administration of the alpha-adrenergic blocker phentolamine prevented the decrease in intraocular pressure but systemically administered blockers of cholinergic (atropine) or beta-adrenergic (propranolol) activity had no effect.

Animals↗
PubMed1980

Dipivefrin: current concepts.

Pro-drugs are agents that require biotransformation prior to exhibiting pharmacologic activity. Dipivefrin (dipivalyl epinephrine or DPE) is an epinephrine pro-drug produced by the addition of two pivalic acid groups to the parent compound. This creates a more lipophilic molecule which penetrates the cornea more readily than epinephrine. Enzymes in ocular tissues convert dipivefrin into its active form, epinephrine. In concentrations approximately one-tenth that of epinephrine, topically applied dipivefrin therefore produces: (1) similar intra-ocular concentrations of epinephrine; (2) similar reductions in intra-ocular pressure (IOP); (3) similar degrees of mydriasis; and (4) fewer extraocular and systemic side effects. For reasons that are discussed, dipivefrin should probably not be used in conjunction with anticholinesterases. Dipivefrin offers the same risk of cystoid macular oedema as does epinephrine. Dipivefrin is a safe, effective, and well-tolerated alternative to epinephrine in the treatment of elevated IOP. It is particularly useful for patients who cannot tolerate epinephrine.

Absorption↗
PubMed1980

Vanadate and aqueous humor dynamics. Proctor Lecture.

Topical administration of 0.5% vanadate lowers intraocular pressure in monkey and rabbit eyes. This appears to be a consequence of a reduction in the rate of aqueous humor secretion, probably resulting from the inhibition of ciliary epithelium membrane. NaK ATPase. The ubiquitous vanadate and its interactions with catecholamines and ascorbate may play a role in regulating the sodium pump of the ciliary epithelium. Adrenergic blocking agents may also lower intraocular pressure by inhibiting the NaK ATPase of the ciliary epithelium.

Adrenergic beta-Antagonists↗
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

Halothane anesthesia and aqueous humor dynamics in laboratory animals.

Halothane anesthesia decreased intraocular pressure (IOP) by approximately 4 mm Hg in both normal rabbits and monkeys. The administration of nitrous oxide or 100% oxygen had no effect on IOP. Although PO2 and PCO2 increased following halothane administration in rabbits, similar blood changes occurred without IOP reduction in control rabbits receiving 100% oxygen. Outflow facility in both species as measured by tonography remained unchanged by halothane administration. Aqueous humor flow as estimated by tonography decreased by about 39% in rabbits and 31% in monkeys. Posterior chamber aqueous humor ascorbate was significantly elevated 90 min after halothane administration in rabbits. The ratio of the aqueous humor flow coefficient to diffusion coefficient for ascorbate (kfa/kdpa) was reduced approximately 47% following the administration of halothane. Halothane did not alter the in vitro accumulation of 131I-hippuran or 86Rb by rabbit ciliary body--iris preparations.

Anesthesia, Inhalation↗
PubMed1979

Timolol maleate: efficacy and safety.

A randomized, double-masked trial of various concentrations of timolol maleate ophthalmic solution (0.1%, 0.25%, 0.5%, and 1.0%) vs placebo demonstrated that all concentrations of timolol effectively lowered intraocular pressure (IOP). A 0.5% solution of timolol was as effective in reducing IOP as the 1.0% concentration. Blood pressure, visual acuity, and pupillary diameter were not altered significantly by any concentration of timolol tested during this study. There was a dose-dependent decrease in resting pulse rate with increasing concentrations of timolol. No objective signs of drug intolerance were found on external ocular examination, nor were any subjective symptoms elicited on questioning the subjects. Timolol applied topically twice daily in concentrations of 0.1% to 0.5% appeared to be an effective and safe ocular hypotensive agent.

Adult↗
PubMed1979

Multivariate analysis of the risk of glaucomatous visual field loss.

In a retrospective study, 92 patients with ocular hypertension, ie, intraocular pressure of 21 mm Hg or higher, and no evidence of glaucomatous visual field defects, were observed for five years. Visual field defects developed in one or both eyes of 33 patients during the five-year follow-up period, while none were detected in the remaining 59. Values for suspected risk factors, determined at the outset of the follow-up period, were subjected to a multivariate analysis with use of linear discriminant analysis and a multiple logistic function. Models of risk providing maximum separation of the two patient groups (visual field loss vs no visual field loss) found that the risk factors having the greatest significance for prediction of visual field loss included vertical estimates of cup/disc ratio, mean IOP during the period of observation, a positive family history of glaucoma, and age. Factors having the lowest predictive values included IOP response to topical dexamethasone, plasma cortisol suppression, and a history of systemic hypertension.

Glaucoma↗
PubMed1979

Dipivefrin and epinephrine treatment of elevated intraocular pressure: a comparative study.

Every 12 hours 0.1% dipivefrin was administered to one eye and 2% epinephrine hydrochloride was administered to the fellow eye of 42 patients with primary open-angle glaucoma or ocular hypertension in a randomized, double-masked study lasting three months. Dipivefrin produced similar percent reductions in intraocular pressure (18.6%) to epinephrine (21.0%), as well as similar increases in outflow facility and pupil diameter. A significantly lower incidence of burning and stinging after drug instillation was noted with dipivefrin therapy. This study supported the contention that dipivefrin is an effective and safe alternative to epinephrine therapy for the reduction of elevated intraocular pressure.

Adult↗
PubMed1979

Recurrent orbital and metastatic melanoma in a patient undergoing previous glaucoma surgery.

A 61-year-old woman had unilateral acute angle-closure glaucoma and subsequently underwent a Scheie filtering operation. After a two-week interval, a large choroidal and ciliary body melanoma in the glaucomatous eye was found. No evidence of metastatic disease was found and the eye was enucleated. Histopathologic sections did not show extrascleral extension. Two and one-half years later the patient developed local orbital recurrence of the melanoma and fatal metastatic disease. We hypothesized a possible causal relationship between the filtering surgery and the local and systemic recurrence of the tumor.

Choroid Neoplasms↗
PubMed1979

Efficacy and patient acceptance of pilocarpine gel.

Fifteen patients with symmetrically increased intraocular pressure (IOP) participated in a single-masked random 30-day clinical trial comparing 4% pilocarpine hydrochloride gel applied at bedtime to one eye with 4% pilocarpine hydrochloride drops instilled four times daily in the fellow eye. Both forms of pilocarpine reduced IOP significantly at 8 A.M., 12 noon, and 4 P.M. (P less than .01). At these times there was no significant difference in effect between the two forms of pilocarpine (P greater than .05). The mean IOP of eyes treated with gel showed no significant difference from the pretreatment value at 10 P.M. (P = .37), whereas at this time eyes treated with drops did maintain a significant IOP reduction (P = .02). At 10 P.M. pilocarpine drops reduced IOP significantly more than did pilocarpine gel (P = .002). Pupil diameter was affected by the gel and drops in a similar pattern to that of IOP. Patients tolerated the gel with few side effects and were pleased by the convenience of administration once daily.

Administration, Topical↗