Biomedical subjects

W J Feuer

Publications and source records attributed to W J Feuer.

At least 55 records · Page 3Linked to original sources

PubMed1996

Automated suprathreshold static perimetry screening for detecting neuro-ophthalmologic disease.

PURPOSE: To devise and evaluate a rapid, accurate, and cost-effective method of detecting neuro-ophthalmologic visual field defects. METHODS: One hundred fifty-nine consecutive patients were evaluated with 76-point, central 30 degree automated static threshold perimetry on the Humphrey Visual Field Analyzer, as well as by a 76-point, central 30 degree suprathreshold examination with the central reference levels set at 2 or 4 dB lower than the estimated normal median central reference level adjusted for age. Six masked readers reviewed the fields. Their readings were compared with those of the other observers, as well as with the final diagnoses as determined from all available clinical information. RESULTS: In detecting abnormality, the full-threshold 30 degree test had a sensitivity (percent of eyes with true field defects identified by the field test) of 93 percent or 99 percent (depending on whether borderline results were counted as a positive or negative test) and a specificity (percent of cases without true field defects appropriately identified by the field test) of 71 percent or 91 percent. In comparison, the 4-dB offset suprathreshold test had a sensitivity (averaged over all reviewers) of 79 percent or 87 percent and a specificity of 81 percent or 89 percent, whereas the 2-dB test had a sensitivity of 87 percent or 94 percent and a specificity of 73 percent or 85 percent. The mean duration of the suprathreshold tests was 3.5 +/- 1.0 minute, compared with 14.8 +/- 2.8 minutes for the full-threshold technique. CONCLUSION: The central 30 degree, 76-point, 2-dB offset suprathreshold automated perimetry is more rapid and nearly as effective as the full-threshold test in detecting visual field abnormalities due to neuro-ophthalmologic disease. More quantitative, full-threshold perimetric strategies should be used in all equivocal cases and to follow progression of established disease.

Adult↗

PubMed1996

Effects of treatment with pentoxifylline on the cardiovascular manifestations of group B streptococcal sepsis in the piglet.

Pentoxifylline (PTXF) is a methylxanthine derivative which modifies leukocyte function and inhibits tumor necrosis factor (TNF)-alpha release. As TNF-alpha is considered a proximal mediator in the cascade leading to septic shock, we evaluated the ability of PTXF to attenuate the cardiovascular manifestations of sepsis secondary to an infusion of group B beta-hemolytic streptococci (GBS). Fifteen anesthetized, mechanically ventilated piglets (weight, 2815 +/- 552 g) were randomly assigned to a treatment group which received a continuous infusion of PTXF (5 mg/kg/h) beginning 30 min after GBS (7.5 x 10(8) colony-forming units/kg/min) administration was started or to a control group which received GBS plus saline as placebo. Comparison of the hemodynamic measurements and arterial blood gases over the first 120 min of bacterial infusion for treatment and control groups revealed the following statistically significant differences (120-min values presented): cardiac output was significantly higher in the PTXF group (0.159 +/- 0.035 versus 0.09 +/- 0.026 L/kg/min; p < 0.05) as was stroke volume (0.54 +/- 0.11 versus 0.27 +/- 0.126 mL/kg/beat; p < 0.01). Pulmonary and systemic vascular resistances remained lower in the PTXF-treated animals (167 +/- 45 versus 233 +/- 69 mm Hg/L/kg/min; p < 0.03) and (427 +/- 162 versus 828 +/- 426 mm Hg/L/kg/min; p < 0.03, respectively). Median survival time was significantly longer in the PTXF group (180 versus 120 min; p < 0.05). In an additional group of animals, PTXF administration before GBS infusion revealed no attenuation in the rise of TNF-alpha, accompanying sepsis. These data demonstrate that treatment with PTXF may ameliorate some of the deleterious hemodynamic manifestations of GBS sepsis and result in improved survival in a young animal model without significantly modifying plasma TNF-alpha levels.

Animals↗

PubMed1995

Pattern of retinal dysfunction in acute zonal occult outer retinopathy.

PURPOSE: To elucidate the pathophysiology of the diseases recently grouped under the name of acute zonal occult outer retinopathy (AZOOR). METHODS: Twenty-four patients with the diagnosis of multiple evanescent white dot syndrome, acute idiopathic blind-spot enlargement syndrome, acute macular neuroretinopathy, multifocal choroiditis, or pseudo-presumed ocular histoplasmosis syndrome, or a combination of these diagnoses, were evaluated on one or more visits with full-field electroretinograms (ERGs) and kinetic and static perimetry. Sera and IgG fractions were tested using immunofluorescence on cryostat sections of fixed and unfixed human and rat retina. RESULTS: Patients with AZOOR as a group showed abnormal results for all eight ERGs and two visual field parameters measured. Interocular asymmetry was a prominent feature of the patients' test results. Logistic regression indicated that interocular differences in ERG parameters significantly increased the efficacy of identifying patients with AZOOR beyond that of the parameter values alone. Visual field area correlated well with ERG a-wave amplitude. Serial visual function tests in a subset of patients showed that there could be short-term partial recovery or progressive loss of function. Autoantibodies to a specific retinal cell type were not detected. CONCLUSIONS: All patients with AZOOR showed a pattern of visual dysfunction that was photoreceptor in origin, patchy in its distribution across the retina, and asymmetric in the two eyes. There was considerable variability in the severity and the natural history of retinal dysfunction in the patients studied. The full-field ERG was found to be a valuable adjunct in diagnosing AZOOR, especially when the expected interocular variation in measured parameters was known for control subjects. No evidence was obtained for autoantibodies to any retinal cell type in the patients with AZOOR who were tested.

Acute Disease↗

PubMed1995

5-Fluorouracil filtering surgery and neovascular glaucoma. Long-term follow-up of the original pilot study.

BACKGROUND: The long-term efficacy and safety of filtering surgery with 5-fluorouracil (5-FU) in eyes with neovascular glaucoma are unknown. METHODS: Kaplan-Meier survival curve analysis of surgical outcome was performed on all 34 patients (34 eyes) enrolled from May 1982 through April 1986 in the original pilot study of filtering surgery with 5-FU. RESULTS: Success rates at the 1-, 2-, 3-, 4-, and 5-year intervals were 71%, 67%, 61%, 41%, and 28%, respectively. The median filter survival time was 38.7 months (95% confidence interval: 32-45 months). Twelve (35%) of 34 patients lost light perception vision, and phthisis bulbi developed in 8 (24%) of 34 patients. Age of 50 years or younger (P < 0.0001) and type 1 diabetes (P = 0.0004) were significant risk factors for surgical failure. The 1-year success rate for patients no older than 50 years of age was 23% compared with a 95% success rate in patients older than 50 years of age. After adjustment for age, type 1 diabetes was a borderline risk factor (P = 0.06). CONCLUSION: There is a high risk of long-term failure of filtering surgery with 5-FU in neovascular glaucoma. Patients 50 years of age or younger have an extremely poor prognosis. Patients older than 50 years of age have initial short-term success with an accelerated failure rate after 3 years.

Adolescent↗

PubMed1995

One-year follow-up results of combined mitomycin C trabeculectomy and extracapsular cataract extraction.

PURPOSE: When patients with glaucoma require cataract surgery, combined procedures offer important advantages over cataract surgery alone. Because mitomycin C has improved the success rate of a trabeculectomy in patients at high risk for filtration failure, the authors investigated whether it also would increase the survival rate of functioning filters in combined procedures. METHODS: Patients with both cataract and glaucoma underwent combined mitomycin C trabeculectomy, extracapsular cataract extraction, and intraocular lens implantation. Mitomycin C (0.5 mg/ml) was applied topically to the trabeculectomy site for 5 minutes before the cataract extraction. Intraocular pressure (IOP), visual acuity, and astigmatism were measured preoperatively and postoperatively. One-year results are available for 74 patients. RESULTS: At 1 year, 54 (73%) of 74 patients had IOPs of 15 mmHg or less without glaucoma medications. Visual acuity was 20/40 or better in 44 (60%) of 74 patients. Ten (15%) patients had a shift of more than 2 diopters of astigmatism against the rule compared with preoperative values. No notable corneal epithelial toxicity was present. Postoperative symptomatic hypotony with the wound construction occurred in 3 (4%) of 74 patients, with 1 patient requiring surgical revision. Other potential complications of mitomycin C include endothelial toxicity (1 patient had decreased vision due to endothelial folds) and wound stability (1 patient had wound rupture after direct ocular trauma). CONCLUSION: The 1-year survival rate of a functioning trabeculectomy using mitomycin C in combined glaucoma and cataract surgery is encouraging. The longer-term benefits and possible adverse effects of mitomycin C in combined procedures are unknown and continue to be investigated.

Adult↗

PubMed1994

Clinical and echographic findings in idiopathic orbital myositis.

We performed a retrospective chart review of 100 patients with idiopathic orbital myositis, who were of ages 9 to 84 years. Data from 75 patients gave the following results. Females were affected more than twice as often as males. Fifty-one patients (68%) had single muscle involvement, with the lateral and medial recti affected most frequently (38 cases [33%] and 33 cases [29%] of muscles, respectively). In 34 patients (45%), affected muscles functioned normally; the remaining 55% (63 muscles) were fairly equally distributed between paretic (20%), restrictive (20%), or combined paretic and restrictive (15%) myopathies. Analysis of muscle function, echographic findings, and duration of symptoms indicates that within days of onset of symptoms, the affected muscle is initially enlarged but retains normal function. Within the first two weeks, continued enlargement results in muscle paresis. The muscle may then enter a partially or completely restrictive phase, which may become permanent. Fifty-one patients (68%) responded well to systemic corticosteroids, although 11 patients (15%) had further recurrences of the disease. Seven patients (9%) later developed thyroid eye disease after initially having unimuscular orbital myositis. We advocate early institution of corticosteroids in order to avoid permanent restrictive myopathies.

Adolescent↗

PubMed1994

Potential bacterial contamination of eyedrops used for tonometry.

We compared the potential for bacterial contamination of a proparacaine hydrochloride solution preserved with benzalkonium chloride, which is used with fluorescein paper for tonometry, to that of a fluorescein-benoxinate hydrochloride combination solution preserved with chlorobutanol. We contaminated bottles of each solution with Pseudomonas aeruginosa or Staphylococcus aureus (10(7) organisms per milliliter of eyedrop solution). From the fluorescein-benoxinate hydrochloride solution, Staphylococcus organisms were cultured in declining numbers over time, with a half-life of nine seconds, and no Staphylococcus organisms were recovered after five minutes. Pseudomonas organisms disappeared from this solution within 15 seconds. Neither species was viable after 15 seconds in the proparacaine hydrochloride solution. Additionally, we cultured 12 bottles of fluorescein-benoxinate hydrochloride and 15 bottles of proparacaine hydrochloride that had been in use in the clinic for one month. No organisms were recovered from a drop dispensed from any bottle or from the tips, caps, rims, or solution from within any bottle, except that five colonies of Staphylococcus grew from the external rim of one bottle. We conclude that both solutions sterilize themselves rapidly and effectively. Either may be used safely for tonometry.

Bacteriological Techniques↗

PubMed1994

Peripapillary vasoconstriction in the glaucomas and the anterior ischemic optic neuropathies.

Proximal constriction (retinal arteries narrower near the disk than further down the stream in the retina) was present in 96 of 226 eyes (42%) with classic glaucoma or normal-tension glaucoma, but it was present in only 11 of 206 eyes (5%) that were normal, had ocular hypertension, or had retinal disease not affecting the optic nerve. In cases of glaucoma with proximal constriction over only part of the disk circumference, its location corresponded to the sector with the greatest cupping in 60 of 66 cases (91%) and likewise corresponded to the sector in which the peripapillary zone of absent retinal pigment epithelium was widest in 48 of 55 cases (87%). Proximal constriction was also present in 16 of 45 eyes (36%) with nonischemic types of non-glaucomatous optic atrophy. The nonarteritic form of anterior ischemic optic neuropathy had proximal constriction in 19 of 28 eyes (68%), which was more frequent than in those with glaucoma (P = .017). Only one of nine eyes with the arteritic form of anterior ischemic optic neuropathy had proximal constriction, which was lower prevalence than in those with glaucoma (P = .066). General arterial narrowing (throughout the retinal course) was present in 111 of 204 (54%) of those with moderate optic nerve damage and 100 of 128 (78%) of those with severe optic nerve damage in all categories, compared with 29 of 208 (14%) of the controls with no optic nerve damage. Unlike proximal constriction, the generalized narrowing was related to severity of optic nerve damage and not to the disease category.

Aged↗

PubMed1994

Use of the potential acuity meter and laser interferometer to predict visual acuity after macular hole surgery.

PURPOSE: As reported anatomic success rates for macular hole surgery increase, a method of accurately predicting postoperative visual acuity has increased clinical utility. METHODS: A series of 18 patients undergoing vitrectomy for idiopathic macular holes was evaluated prospectively for best refracted preoperative visual acuity, potential acuity meter (PAM) reading, and laser interferometer (LI) reading. Best refracted visual acuity after surgery was recorded and analyzed to assess the predictive value of the PAM and LI readings. RESULTS: The LI correctly predicted the final visual result in 6 of the 10 patients who achieved a final visual acuity of 20/50 or better (P = < 0.011). The PAM did not accurately predict postoperative visual acuity for any of the eyes with a final visual acuity of 20/50 or better. Both correctly predicted outcome in the 7 patients with final visual acuity worse than 20/50. The LI prediction was within 2 lines of final visual acuity in 12 (70%) of 17 anatomically successful cases, and the PAM was within 2 lines of final visual acuity in 11 (64%) of 17 cases. CONCLUSION: Both the LI and PAM were modestly accurate in predicting final visual acuity after macular hole surgery, but the LI was more accurate in predicting a visual acuity of 20/50 or better.

Aged↗

PubMed1994

Low glutathione reductase and peroxidase activity in age-related macular degeneration.

Age-related macular degeneration (ARMD) may result from events initiated by reactive oxygen species. Blood samples from 18 patients with ARMD and 18 similarly aged controls were analysed for activities of important antioxidants. Blood glutathione reductase activity was lower in patients with ARMD compared with controls (p = 0.035). The activities of glutathione peroxidase (p = 0.18) and erythrocyte superoxide dismutase (p = 0.29) were similar between the two groups by a Student's two sample t test. Logistic regression was used to determine which enzyme activities were associated with ARMD after adjusting for possible confounding variables: smoking history, age, multivitamin use, and cardiovascular disease. Glutathione reductase activity (p = 0.05) and glutathione peroxidase activity (p = 0.065) were significantly associated with ARMD by this analysis. The relation of glutathione reductase and glutathione peroxidase activity to ARMD merits further study.

Aged↗

PubMed1994

Analysis of HLA DQ alpha allele and genotype frequencies in populations from Florida.

HLA DQ alpha allele and genotype frequencies for Caucasian, African American, Haitian, and Hispanic populations in Florida have been estimated. The Florida laboratories involved in these studies collected donor samples from a variety of sites including clinical laboratories, victim and suspect standards, blood banks, county jail detainees, and laboratory personnel. We have determined that the Caucasian and African American DQ alpha genotype frequencies do not deviate significantly from Hardy-Weinberg expectations and as a result of this heterogeneity analyses, data from the four Florida Caucasian populations may be combined and data from the four Florida African American populations may be combined to form two large HLA DQ alpha genotype frequency databanks. Further, data from the Florida Haitian population may be combined with the Florida African American population. Comparison of the combined Florida Caucasian populations, combined Florida African American populations, the Palm Beach Sheriff's Office (PBSO) Hispanic, and PBSO Haitian population with other databases does not support combination because allele frequency distributions are heterogeneous.

Alleles↗

PubMed1993

Evaluation of baseline-related suprathreshold testing for quick determination of visual field nonprogression.

OBJECTIVE: To evaluate a commercially available means of baseline-related suprathreshold examination designed to detect visual field worsening. DESIGN: Patients for whom results of a baseline series of static-threshold visual field examinations were available underwent both a second static-threshold examination (full-threshold strategy; average time, 15 minutes) and a baseline-related suprathreshold examination ("fast-threshold" strategy; average time, 5 minutes). RESULTS: Most of the 1702 points examined were apparently unchanged from baseline, showing with either method only the degree of variation expected from the measurement inconsistency (short-term fluctuation). For points that did show a change, the changes shown by the two methods were correlated. Change in the field as a whole, represented by a cluster of locations showing deterioration, was evident more frequently with the standard testing strategy: 11 of 37 field examinations showed deterioration by both methods and an additional 11 examinations showed deterioration by the full-threshold method only. CONCLUSIONS: Each examination method identified pointwise changes not detected by the other, the combined effect of false-positive errors (imperfect specificity) and false-negative errors (imperfect sensitivity) with each of the two methods. The findings relating to clusters could represent a better sensitivity of the full-threshold method in detecting visual field deterioration, a better specificity of the suprathreshold method, or both.

Evaluation Studies as Topic↗

PubMed1993

Serum antibody production to botulinum A toxin.

PURPOSE: Conflicting data have been reported regarding development of serum antibodies to botulinum A toxin. The purpose of this study is to determine conclusively whether antibody production to this toxin occurs in humans, and, if so, to determine its relationship, if any, to length of treatment, total cumulative dose, and clinical response to treatment. METHODS: Sixty-five sera samples from 42 adults treated with botulinum A toxin for essential blepharospasm, hemifacial spasm, or spasmodic torticollis were analyzed via a sphere-linked immunodiagnostic assay for antibody production. Results were plotted against length of treatment, number of injections, cumulative dose, and treatment effect produced. RESULTS: Twenty-four (57%) of the 42 patients produced antibodies in all three diagnostic groups. No significant differences were found between antibody producers and nonproducers with respect to age (P = 0.216), length of treatment (P = 0.586), number of injections (P = 0.619), or total cumulative dose (P = 0.286). Within the antibody-producing group, there was no significant correlation between amount of antibody and length of treatment (P = 0.081), number of injections (P = 0.134), or cumulative dose (P = 0.250). The presence of demonstrable antibodies in serum did not affect the clinical responsiveness to injection. CONCLUSION: Antibody production is present in a majority of patients treated with botulinum A toxin. The sphere-linked immunodiagnostic assay is a reliable and reproducible method for detecting and quantifying these antibodies. When antibody production occurs, it is likely due to variations in individual immune responsiveness and appears to have no direct effect on the patient's clinical response to treatment.

Adult↗

PubMed1993

The effect of simulated cataract on the glaucomatous visual field.

PURPOSE: The current study is designed to determine the effect of light scattering (simulated cataract) on glaucomatous visual fields. METHODS: Twelve patients with relative scotomas caused by glaucoma underwent the 30-2 threshold test with the Humphrey Visual Field Analyzer twice: once with and once without having a light-diffusing piece of ground glass in front of the eye, which, in previous experiments, has been shown to decrease perimetric threshold by 4.4 decibels (dB) in normal eyes. As controls, 12 patients underwent the same examination with and without a piece of clear glass in front of the eye. In each pair of fields, five points were analyzed within the relative scotoma and compared with five points in a normal area of the opposite hemifield. RESULTS: The diffusing ground glass produced a mean decrease of perimetric threshold of 5.7 dB (standard deviation [SD] = 3.3 dB) within the area of relative scotoma compared with 6.1 dB (SD = 2.4 dB) within the normal area and 4.4 dB (SD = 2.25 dB) at the fovea. The differences between means were not statistically significant. In addition, the diffusing glass did not affect the corrected pattern SD (CPSD) index (6.5 dB with the diffuser and 6.5 dB without). CONCLUSION: Light scattering depresses the glaucomatous visual field diffusely. Relative glaucomatous scotomas and normal areas are depressed equally, expressed as change in decibel of sensitivity. Therefore, in following patients with cataracts and glaucoma, depression of threshold sensitivity in glaucomatous areas out of proportion to normal areas should not be attributed to the light-scattering effect of the cataract, but rather to possible worsening of glaucomatous damage.

Aged↗

PubMed1992

Effectiveness of a gentamicin dosing protocol based on postconceptional age: comparison to published neonatal guidelines.

OBJECTIVE: To evaluate the effectiveness of a gentamicin dosing protocol based on postconceptional age in producing therapeutic serum concentrations and to compare the protocol with commonly used gentamicin dosing guidelines. DESIGN: During the initial three months of this study infants were dosed according to physician discretion (group I). In the subsequent three-month period patients were dosed according to a postconceptional age dosing schedule (group II). SETTING: Infants were enrolled after being admitted to the Newborn Intensive Care Unit at the University of Miami/Jackson Memorial Medical Center. PATIENTS: Infants less than 37 weeks gestational age with normal renal function, not receiving indomethacin, and requiring gentamicin treatment were enrolled. Fifty-nine infants were enrolled into group I (median weight 1300 g [range 720-3300]), postconceptional age 29 weeks [26-37]); and 68 infants were enrolled into group II (weight 970 g [530-3000], postconceptional age 29 weeks [24-36]). INTERVENTION: Patients in group II were dosed according to the following protocol: postconceptional age less than 30 weeks, 3.0 mg/kg q24h, and postconceptional age 30-37 weeks, 2.5 mg/kg q18h. Peak and trough serum gentamicin concentrations were obtained in all study patients. Pharmacokinetic parameters were calculated from measured serum concentrations. Using the calculated pharmacokinetic data, peak and trough serum concentrations were simulated for five published neonatal dosing guidelines and the proposed postconceptional age protocol. MAIN OUTCOME MEASURES: The number of therapeutic serum gentamicin concentrations resulting from the dosing guidelines studied were compared. RESULTS: Measured trough concentrations differed significantly between the two groups with 35 percent of patients in group I and 90 percent of patients in group II having trough values less than 2 mg/L (p less than 0.001). There was no significant difference in measured peak concentrations between groups. Simulated trough concentrations were significantly different when postconceptional age dosing was compared with commonly used protocols (p less than 0.0001) with the highest percentage of concentrations less than 2 mg/L (89 percent) resulting from the proposed postconceptional age guidelines. CONCLUSIONS: These data suggest that the proposed postconceptional age protocol is reproducible and reliable in achieving therapeutic gentamicin serum concentrations in neonates.

Drug Administration Schedule↗

PubMed1992

Effects of pentoxifylline on the cardiovascular manifestations of group B streptococcal sepsis in the piglet.

Pentoxifylline (PTXF) is a methylxanthine that modifies leukocyte function and inhibits cytokine release. To evaluate its effects on the cardiovascular manifestations of sepsis secondary to group B streptococci, 14 anesthetized, mechanically ventilated piglets were studied over a 240-min period. Animals were randomly assigned to a treatment group that received a PTXF bolus (20 mg/kg) followed by a continuous infusion of 5 mg/kg/h before and during group B streptococci (1 x 10(8) colony forming units/kg/min) administration and a control group that received saline as a placebo. Comparison of the hemodynamic measurements and arterial blood gases during the first 90 min of PTXF treatment with those of the control group resulted in the following 90 min values: systemic arterial blood pressure was significantly higher in the PTXF group (89 +/- 10 versus 56 +/- 30 mm Hg; p less than 0.005) as was cardiac output (0.18 +/- 0.04 versus 0.10 +/- 0.07 L/kg/min; p less than 0.005). Pulmonary vascular resistance remained lower in the PTXF-treated animals (135 +/- 117 versus 248 +/- 119 mm Hg/L/min/kg; p less than 0.001), and these animals were less acidotic as measured by pH (7.07 +/- 0.2 versus 7.31 +/- 0.1; p less than 0.05) and base deficit (-15 +/- 9 versus -5 +/- 2 mmol/L; p less than 0.05). Median survival time was significantly longer in the PTXF group (210 versus 90 min; p less than 0.002). These data demonstrate that PTXF can ameliorate some of the deleterious hemodynamic manifestations of group B streptococci sepsis and result in improved survival in a young animal model.

Acid-Base Equilibrium↗

PubMed1991

Statpac 2 glaucoma change probability.

We compared the traditional intuitive criterion (fixed at 5 dB) with the variable Statpac 2 criterion of the Humphrey Field Analyzer for identifying visual deterioration at individual points within a visual field. The separation of depressed from stable points in 123 follow-up fields of 17 patients, when all points within a field were considered, was reasonably equivalent between the two methods (kappa = 0.55 +/- 0.027 [+/- SE]). Centrally located points within the field demonstrated a stronger agreement (kappa = 0.68 +/- 0.028), because the fixed criterion more often labeled the edge points as having progressed than did the Statpac 2 algorithm. The glaucoma change probability printout is more simply obtained than the manual comparison required for intuitive interpretation with a fixed criterion, and it is potentially more accurate because of its reliance on a database that permits a variable criterion to be applied.

Aged↗

PubMed1991

Beta-adrenergic responsiveness of choroidal vasculature.

Using in vitro binding methods and autoradiographs, the authors showed that choroidal vessels specifically bind iodine 125 cyanopindolol, a nonselective blocker of beta-adrenergic receptors, in albino rabbits. In humans, the presence of beta-adrenergic receptors in choroidal vessels was confirmed by showing an increased choroidal vascular tone after systemic administration of timolol maleate, a nonselective beta-adrenergic blocker. Topically administered timolol maleate lowered the intraocular pressure but did not reach the choroidal receptors in sufficient quantity to produce a measurable effect on vascular tone.

Administration, Topical↗