An investigation of the effects of benzodiazepine receptor ligands and of scopolamine on conceptual priming.

Scopolamine and lorazepam both produce anterograde impairments of explicit memory but only lorazepam impairs implicit memory as assessed by perceptual priming tasks. The main aim of the two experiments reported in this article was to determine the effects of these drugs on conceptual priming. Experiment 1 compared the effects of lorazepam (1,2 mg PO) with scopolamine (0.3,0.6 mg SC) and placebo in a study with 60 healthy volunteers. Experiment 2 compared the separate and combined effects of lorazepam (2 mg PO) and flumazenil (2 mg IV) with placebo in a study with 48 healthy volunteers. We found that conceptual priming in category generation tasks was intact following lorazepam in both studies. This preservation of conceptual priming contrasted with lorazepam-induced impairments on explicit memory tasks. In conjunction with previous findings, these results are interpreted as providing further support for the notion that conceptual and perceptual priming are subserved by distinct memory systems, one based on the operations of semantic memory, the other possibly based on a perceptual representation system. That lorazepam impairs perceptual but not conceptual priming suggests that the neurochemical substrates of the two kinds of priming are distinct.

Psychopharmacological analysis of implicit and explicit memory: a study with lorazepam and the benzodiazepine antagonist flumazenil.

Recent studies have suggested that the benzodiazepine (BZ) lorazepam (LZ) differs from other BZs in its impairing effects on implicit memory tasks. The present study was designed to assess whether this atypical effect withstood the experimental rigour of Schacter's retrieval intentionality criterion and further, whether it could be reversed by the BZ antagonist, flumazenil (FL). The separate and combined effects of LZ, FL and placebo (PL) were assessed on indices of memory, sedation, and attention in 48 healthy volunteers. LZ disrupted performance on both explicit and implicit memory tasks, induced motor sedation and impaired focussed attention. Fl attenuated LZ-induced attentional deficits but did not affect motor sedation. FL also attenuated LZ-induced impairment on the implicit retrieval task. On the explicit retrieval task FL attenuated LZ-induced impairment for words which had been deeply processed at study but not words which had been shallowly processed. A subsequent recognition test showed LZ impaired recognition memory only when accompanied by recollective experience and flumazenil again attenuated this effect. FL itself lowered performance on several measures, reflecting intrinsic activity of this "antagonist". Assessment of the relationship between the mnestic and other effects of the drugs suggested that attentional effects contribute to, but do not explain, effects on implicit memory tasks. These results imply that the apparent atypical effects of LZ on implicit memory tasks are mediated by the same BZ receptor complex as mediates LZ's other effects.

Bilateral argon laser trabeculoplasty in primary open-angle glaucoma.

We performed bilateral argon laser trabeculoplasty on 34 patients with medically uncontrolled open-angle glaucoma. Preoperative intraocular pressure was greater than 21 mm Hg, with a less than 3-mm Hg difference between the two eyes. Laser treatment (360 degrees) was performed on both eyes within a three-month interval. Mean (+/- S. D.) baseline intraocular pressure was similar in the first- (26.9 +/- 3.7 mm Hg) and second- (26.5 +/- 3.3 mm Hg) treated eyes. One hour after treatment, four first- and four second-treated eyes had a greater than 30% increase in intraocular pressure. The one-hour change in pressure was highly correlated between the two eyes (r = .794, P less than .0001). Intraocular pressure was reduced (P less than .0001) one, two, and three years after treatment in both the first and second-treated eyes. The percentages of first- and second-treated eyes with a pressure of less than or equal to 21 mm Hg were similar at one, two, and three years. Pressure response between the two eyes was correlated (P less than .0001) at year 1 (r = .815), 2 (r = .757), and 3 (r = .886) after laser therapy.

Variability of automated visual fields in clinically stable glaucoma patients.

The total variability of the visual field was measured in 20 patients with open-angle glaucoma who appeared to be clinically stable and well controlled on medical therapy. All patients had at least four visual fields performed on the Octopus 201 perimeter with at least 12 months follow-up since their first visual field. The four most recently performed visual fields were analyzed. Two different methods for calculating total variability were used. One was based on the variance of the threshold determinations and the other was based on the range. The average total variability per subject was 2.8 decibels (db) using the variance-based calculation and 5.1 db using the range-based calculation. Ninety-five percent of the test locations had a variability of less than 6 db by the variance-based calculation method and 13 db by the range-based calculation method. We discuss the possibility of using this type of data to develop criteria for detection of progressive visual field loss in glaucoma.

Postoperative intraocular pressure rise in open-angle glaucoma patients after cataract or combined cataract-filtration surgery.

Postoperative intraocular pressure (IOP) was measured in patients with open-angle glaucoma undergoing extracapsular cataract extraction with a posterior chamber lens implant (ECCE-PC IOL). Patients considered to be under adequate medical glaucoma control had cataract surgery alone or combined with a posterior lip sclerectomy. Patients with medically uncontrolled glaucoma had cataract surgery combined with either a posterior lip sclerectomy or a trabeculectomy. Cataract surgery alone (n = 26) was associated with a significantly (P less than 0.001) increased IOP on postoperative day 1: preoperative IOP, 18.9 +/- 3.6 mmHg; postoperative IOP, 34.2 +/- 12 mmHg. An IOP rise of 10 mmHg or more occurred in 69% of the eyes, whereas 77% of the eyes had an absolute IOP over 25 mmHg. Eyes undergoing combined surgery (n = 42) had a preoperative IOP of 21.3 +/- 4.8 mmHg. On postoperative day 1, the mean IOP was 14.9 +/- 12.0 mmHg. An IOP rise of 10 mmHg or more was observed in 14%, and an IOP over 25 mmHg in 21% of combined surgery eyes. Cataract surgery in eyes with open-angle glaucoma requires careful monitoring and therapy for early postoperative increases in IOP. Combined surgery reduces the frequency and magnitude of, but does not eliminate, this complication.

Variability and reproducibility of optic disk topographic measurements with the Rodenstock Optic Nerve Head Analyzer.

Variability of optic disk topographic measurements obtained with the Rodenstock Optic Nerve Head Analyzer was determined by obtaining three separate images on one eye of ten normal subjects and nine subjects without glaucoma. Marking of the disk margin was performed in a random and masked fashion on each image three times by three independent observers. The overall variabilities of the measurements of the subjects with glaucoma were not statistically different from those of the normal subjects. Overall variability was about 0.2 mm2 for total disk area, 0.08 for cup/disk ratio, 0.2 mm2 for disk rim area, and 0.07 mm3 for cup volume. The largest component of the variability was the result of acquisition of separate images of the optic disk at different times. Observer inconsistency in marking the disk edge was relatively small. Based on the expected amount of random variability of the measurements, we proposed criteria for detecting significant change in the optic disk over time.

A comparison of experienced clinical observers and statistical tests in detection of progressive visual field loss in glaucoma using automated perimetry.

The visual fields of 30 patients (subjects) with glaucoma were sent to six experienced clinicians (observers). Each subject had at least four visual field examinations on the OCTOPUS 201 automated perimeter spanning at least one year. Each observer was asked to review the visual field data of each subject and determine whether the visual fields were stable, improved, or worse over time. The visual field data were then analyzed using six different statistical models. In only 15 of the 30 subjects did at least five of the six human observers agree on the behavior of the visual field. Agreement among the statistical models was better, with at least five of the six models agreeing on 22 of the 30 subjects. It was concluded that there is, at present, no validated technique for detecting progressive visual field loss in glaucoma using automated perimetry when relatively few visual fields are available for analysis.

Intraocular pressure and visual field defects after argon laser trabeculoplasty in chronic open-angle glaucoma.

Nineteen patients undergoing argon laser trabeculoplasty for open-angle glaucoma were studied prospectively. All patients had glaucomatous visual field defects with inadequate medical control of intraocular pressure (IOP) before laser treatment. All patients had two automated visual fields immediately before laser treatment. They also had follow-up automated perimetry at 1, 4, 8, and 12 months posttreatment. The serial visual fields were compared using a one-way analysis of variance and trend analysis. After the laser trabeculoplasty, six patients showed visual field improvement, eight showed no change, and five showed progressive visual field deterioration. Patients with little fluctuation of IOP measurements after laser treatment had a better prognosis for visual field retention. The mean IOP level, however, was a poor predictor of visual field progression. Patients with more extensive visual field damage before laser treatment did not do worse than patients with less extensive visual field loss.

Argon laser trabeculoplasty in black and white patients with primary open-angle glaucoma.

The effect of argon laser trabeculoplasty (ALT) on lowering intraocular pressure (IOP) was studied retrospectively in 68 black patients and 42 white patients with uncontrolled primary open-angle glaucoma on maximally tolerated medical therapy. Patients with the diagnosis of pigmentary or pseudoexfoliation glaucoma and those having previous intraocular or laser surgery were excluded. While the mean age of the black patients (66.9 years) was lower than the white patients (72.2 years), the prelaser IOP was similar between the two groups: 26.2 mmHg for the black patients and 25.5 mmHg for the white patients. The mean IOP one year (18.4 mmHg for black patients and 18.4 mmHg for white patients) and two years (19.5 mmHg and 20.3 mmHg, respectively) after ALT was the same between the two groups of patients. A similar percentage of black (85%) and white (83%) patients showed more than a 15% decrease in IOP from their prelaser values one year after treatment. The IOP lowering effect of ALT decreased during the second post-operative year; but the diminished response was identical in patients of both races, with 71% of patients of both groups still showing greater than 15% reduction from their pre-laser IOP. We conclude that ALT is equally effective in lowering IOP for black and white patients with medically uncontrolled primary open-angle glaucoma.