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At least 991 records · Page 55Linked to original sources
PubMed1998

Pupillary dilatation and driving in diabetic patients.

Diabetic patients routinely have their pupils dilated for fundoscopy as part of the annual review. To assess the ability of diabetic patients to drive after pupillary dilatation we studied 61 diabetic patients (18 IDDM, 43 NIDDM), mean age 54.98 years, before and 1 h after pupillary dilatation with 1% tropicamide. Binocular visual acuity (BVA) and contrast sensitivity were checked without glare, with glare, and with glare and sunglasses. Glare was introduced using a 60 W bulb in all 61 patients and with a 500 W bulb in 37 of these patients. Prior to dilatation all 61 patients had a BVA of 6/9 or better. A significant reduction in BVA was found post-dilatation (p = 0.005) and 4 out of the 61 patients (6.56%) had a post-dilatation BVA of less than 6/9. The 60 W glare source caused a significant reduction in BVA pre-dilatation (p < 0.05), but not the 500 W glare. With glare, post-dilatation BVA reduced further, resulting in 6 and 7 patients having a BVA of less than 6/9 with the 60 W and 500 W glare source, respectively. The addition of sunglasses with glare did not improve the BVA. No patient with a BVA of 6/5 pre-dilatation reduced to less than 6/9 post-dilatation. No significant change in contrast sensitivity was found in any of the test conditions. We conclude that patients who meet the visual legal requirements to drive (BVA < or = 6/9) prior to dilatation may not fulfil them post-dilatation. This has important clinical implications and the time course of the phenomenon requires exploration. Meanwhile, patients need to be warned not to drive after pupillary dilatation when they attend for annual fundoscopic examination, certainly for at least two hours.

Adult↗
PubMed1998

Screening for diabetic retinopathy by general practitioners: ophthalmoscopy or retinal photography as 35 mm colour transparencies?

In order to assess the relative ability of general practitioners (GPs) to detect diabetic retinopathy (DR), especially sight-threatening diabetic retinopathy (STDR) by direct ophthalmoscopy or by examining, on a separate occasion, retinal images as 35 mm colour transparencies, a South and Mid Wales primary care-based study was performed in four general practices (six GPs). The participating GPs were provided with standardized training and equipment. Both methods were compared to the 'reference' grade of DR provided by the Diabetic Retinopathy Reading Centre (London), based on the same retinal images. Ophthalmoscopy and retinal photography (Canon CR4 45NM) with mydriasis were all practice based. The clinical assessments were based on a protocol developed for screening for DR in Europe. A total of 996 people with diabetes were identified, representing a prevalence of known diabetes of 2.1%. After exclusions on medical grounds, 897 patients were available for screening, of whom 605 (68%) were photographed. Based on the retinal images, the reference centre identified DR in 43% and STDR in 14.4%. In total, 597 valid comparisons between GPs and the reference centre were obtained; of these, 462 (77%) were high quality photographs which were used in subsequent analysis. The sensitivity for detecting any DR increased from 62.6% (95% CI 55.9-69.4) with ophthalmoscopy to 79.2% (95% CI 73.6-84.9) using retinal photographs, specificity remaining essentially unchanged at 75.0 (95% CI 69.5-80.5) and 73.5% (95% CI 68.0-79.1) with the positive predictive value (PPV) increasing from 67.2 (95% CI 60.4-74.0) to 71.0% (95% CI 65.0-77.0), respectively. The detection of STDR sensitivity increased from 65.7 (95% CI 54.4-77.1) with ophthalmoscopy alone to 87.3% (95% CI 79.4-95.2) based on retinal photographs with specificity falling from 93.8 (95% CI 91.4-96.3) to 84.8% (95% CI 81.2-88.5) and PPV from 65.7 (95% CI 54.4-77.1) to 51.2% (95% CI 42.1-60.3), respectively. We conclude that the use of standardized 35 mm colour transparency retinal photographs for screening by trained GPs in a primary care setting achieves an acceptable detection rate (>87%) for STDR, contrasting with ophthalmoscopy alone (66%), which was below the proposed UK standard of 80%.

Diabetes Mellitus, Type 1↗
PubMed2000

Residuals analysis of the generalized linear models for longitudinal data.

The generalized estimation equation (GEE) method, one of the generalized linear models for longitudinal data, has been used widely in medical research. However, the related sensitivity analysis problem has not been explored intensively. One of the possible reasons for this was due to the correlated structure within the same subject. We showed that the conventional residuals plots for model diagnosis in longitudinal data could mislead a researcher into trusting the fitted model. A non-parametric method, named the Wald-Wolfowitz run test, was proposed to check the residuals plots both quantitatively and graphically. The rationale proposedin this paper is well illustrated with two real clinical studies in Taiwan.

Adult↗
PubMed2000

High-performance liquid chromatographic determination of phenylephrine and tropicamide in human aqueous humor.

A high-performance liquid chromatographic method for the simultaneous determination of phenylephrine and tropicamide in human aqueous humor was developed. After centrifugation, an aliquot of the supernatant was injected onto the column and the eluent was monitored at 280 nm then 254 nm after 5 min. Separation was performed on a CN column with 0.01 M Pic B8 (octane sulfonic acid)-acetonitrile (65:35, v/v) as mobile phase. The standard curves were linear in the detection range. The precision of the method (expressed by relative standard deviation) and the accuracy (mean error in per cent) were <5% for both intra- and interassays.

Aqueous Humor↗
PubMed1998

Determination of atropine in biological fluids by micellar electrokinetic capillary chromatography in the presence of strychnine and tetracaine.

The identification and quantitation of atropine, in whole blood and gastric contents in the presence of strychnine and tetracaine is described. This method uses liquid-liquid extraction and micellar electrokinetic chromatography (MECC). Separations are made using a 50 cm long capillary and a borate/phosphate buffer at pH 9.2 with 50 mM sodium dodecyl sulfate (SDS). Linearity was established for the three compounds between 1.0 and 100 microg/mL, using scopolamine as internal standard. The limit of detection for atropine was estimated at 0.06 microg/mL and the limit of quantitation at 0.2 microg/mL. The run time is less than 30 min. Alternate parameters are proposed to reduce the run time to under 10 min. The method was applied to a forensic post-mortem case.

Anesthetics, Local↗
PubMed1975

Central versus peripheral anticholinergic activity as assessed by two in vivo procedures in mice.

The activity of tertiary and quaternary anticholinergic drugs was compared in two different test procedures designed to measure cholinolytic activity in mice. The four drugs utilized were atropine sulfate, atropine methylnitrate, scopolamine hydrobromide, and scopolamine methylnitrate. The results led to the conclusion that one of these test procedures, the induction of mydriasis (increase in pupil size), primarily measures peripheral anticholinergic activity whereas the other procedure, inhibition of physostigmine lethality, primarily measures anticholinergic activity in the CNS. These two test procedures can be utilized to characterize the nature of the cholinolytic properties of prospective therapeutic drug candidates.

Animals↗
PubMed2005

Inference of nested variance components in a longitudinal myopia intervention trial.

This paper was motivated by a double-blind randomized clinical trial of myopia intervention. In addition to the primary goal of comparing treatment effects, we are concerned with the modelling of correlation that may come from two possible sources, one among the longitudinal observations and the other between measurements taken from both eyes per subject. The data are nested repeated measurements. We suggest three models for analysis. Each one expresses the correlation differently in various covariance structures. We articulate their differences and describe the implementations in estimation using commercial statistical software. The computer output can be further utilized to perform model selection with Schwarz criterion. Simulation studies are conducted to evaluate the performance under each model. Data of the myopia intervention trial are reanalysed with these models for illustration. The results indicate that atropine is more effective in reducing the progression rate, the rates are homogeneous across subjects, and, among the suggested models, the one with independent random effects of two eyes fits best. We conclude that model selection is a crucial step before making inference with estimates; otherwise the correlation may be attributed incorrectly to a different mechanism. The same conclusion applies to other variance components as well.

Analysis of Variance↗
PubMed1998

The analysis of aqueous humor constituents using capillary zone electrophoresis.

One of the difficulties encountered in the study of aqueous humor is the relatively small volume generally available for analysis. The purpose of this study was to investigate the potential use of capillary zone electrophoresis (CE) for the analysis of nanolitre quantities of this fluid. Twelve samples of aqueous humor were obtained from patients undergoing cataract surgery and a further three samples were from non cataract post mortem subjects within 6 hr of death. CE was carried out in an uncoated fused silica glass capillary, 75 mu internal diameter and 100 cm long using a run buffer of 40 mM borate pH 9.4 containing 0.4 g l-1 methylcellulose. Detection of the separated zones was by ultra violet absorption at 200 nm. Preliminary identification of peaks was achieved by enzymatic hydrolysis and spiking with purified analytes. A number of very well resolved peaks were obtained from both cataract and post mortem samples using nanolitre quantities of unmodified fluid. Additional peaks were noted in the post mortem samples, most of which were likely to be due to a partial breakdown of the blood aqueous humor barrier. The profiles obtained were not significantly affected by various drugs routinely administered during cataract surgery. This preliminary study has demonstrated the potential value of CE in the analysis of aqueous humor in health and disease.

Aged↗
PubMed1997

Pupillary response to tropicamide in Japanese patients with alcoholic dementia, Alzheimer's disease, and vascular dementia.

The anticholinergic agent tropicamide causes a significantly greater change in the pupil diameter of patients with Alzheimer's disease (AD) than in that of patients with alcoholic or vascular dementia or in normal controls. Although the response increases with the severity of AD, the overlap of response with normal controls in milder cases and the difficulty of obtaining results in severe cases limit its use as a diagnostic tool.

Aged↗