Using multifocal ERG ring ratios to detect and follow Plaquenil retinal toxicity: a review : Review of mfERG ring ratios in Plaquenil toxicity.

Multifocal ERG ring ratios provide a sensitive and objective method to detect ocular toxicity in patients taking hydroxychloroquine (Plaquenil). In order to measure ring ratios, the average mfERG amplitude was calculated for each of five concentric rings of a 61-hexagon mfERG. The age-corrected amplitude of the central hexagon (R(1)) and the ratios of R(1) to each of the successive rings (R(1)/R(2), R(1)/R(3), etc.

Detection of early hydroxychloroquine retinal toxicity enhanced by ring ratio analysis of multifocal electroretinography.

Purpose: To assess decreased retinal function associated with high cumulative doses of hydroxychloroquine using multifocal electroretinography (mfERG).

Design: Retrospective cross-sectional study.

Methods: Sixty-two patients referred for evaluation of hydroxychloroquine retinal toxicity.

Pupillary and visual thresholds in young children as an index of population vitamin A status.

A prototype scotopic sensitivity machine was used to evaluate pupillary and visual thresholds for 295 Indonesian children aged 1-5 y, most of whom were initially vitamin A-deficient. Subjects were tested 6 and 9 mo after receiving a high dose of vitamin A. A group of 136 older children was tested at 6 mo after dosing; all subjects underwent testing at 9 mo.

Methodologic dependence of electroretinogram oscillatory potential amplitudes.

The International Society for Clinical Electrophysiology of Vision (ISCEV) protocol for eliciting oscillatory potentials uses a considerably lower flash intensity and a different preconditioning stimulus than the only oscillatory potential protocol used to predict progression of diabetic retinopathy. To determine if the ISCEV protocol will be useful in predicting progression of diabetic retinopathy, summed oscillatory potential amplitudes were measured by both protocols in a population of diabetics. Summed oscillatory potential amplitudes measured by the ISCEV protocol, although smaller, are highly correlated with the summed oscillatory potential amplitudes measured with the higher-intensity flash.

Predicting outcome in central retinal vein occlusion using the flicker electroretinogram.

Objective: To evaluate the usefulness of the 30-Hz flicker electroretinogram (ERG) in predicting outcome in patients with central retinal vein occlusion using an automated system previously developed to measure parameters of the flicker ERG and using information about the a priori probability of developing neovascularization of the iris in central retinal vein occlusion.

Methods: Amplitude and timing were extracted from 30-Hz flicker ERGs of 76 patients with acute central retinal vein occlusion from a previous study. The ability of the ERG to predict the development of neovascularization of the iris based on derived parameters was measured using the area under the receiver operating characteristic curve.

The variability of the b-wave of the electroretinogram with stimulus luminance.

We measured the variability of the b-wave of the electroretinogram as a function of stimulus luminance in two young normal individuals. We also estimated b-wave variability by examining residuals from Naka-Rushton curves fit to intensity-response data. The change of variability with amplitude was similar with both techniques.

The care and fitting of Naka-Rushton functions to electroretinographic intensity-response data.

We developed an automated system to estimate parameters of the Naka-Rushton function based on a heuristic model of the electroretinogram intensity-response series. Data from a population of patients with central retinal vein occlusion were used to examine the ability of the derived parameters to predict the development of neovascularization of the iris. The predictive performance of this automated system in central retinal vein occlusion is comparable to that of a human expert.

Pattern discrimination perimetry in patients with glaucoma and ocular hypertension.

We compared the results of the pattern discrimination perimeter to the program 30-2 on the Humphrey Field Analyzer (Humphrey, Inc., San Leandro, California) in 93 consecutive patients with ocular hypertension and glaucoma and 30 control patients. In 20 patients with ocular hypertension, a significantly greater number of glaucomatous defects were noted on pattern discrimination perimetry (ten patients) than on the program 30-2 (two patients) (P less than .

Characterization of the electroretinographic scotopic B-wave amplitude in diabetic and normal subjects.

The intensity-response function of the scotopic b-wave of the electroretinogram may be a useful device for monitoring patients with retinal disease. Three models were evaluated that describe this function in 152 patients with diabetic retinopathy of varying severity and in 40 nondiabetic comparison subjects. The models considered were the Naka-Rushton equation fit to all 21 data points collected, the Naka-Rushton equation fit to the data points below the "second limb" of the function, and a log-linear fit only to data at the nine lowest intensities.

Automated estimation of implicit time and amplitude from the flicker electroretinogram.

The electroretinogram (ERG) has been shown to yield sensitive and specific information about the development of neovascularization in ischemic disorders such as diabetic retinopathy and central retinal vein occlusion. However, even though the test is quick, easy to perform, and carries few risks, the ERG is poorly utilized in clinical situations because of the extended training period necessary for test interpretation. We have developed an algorithm that estimates the phase and amplitude of a 30-Hz flicker ERG and that is relatively insensitive to many forms of interference in ERG recordings.

Selective loss of pattern discrimination in early glaucoma.

A new perimetric pattern discrimination test was compared with conventional automated perimetry (Humphrey program 30-2 or Octopus program 32) in glaucoma patients, glaucoma suspects, and control subjects. The new test is based on the rationale that a greater percentage of retinal ganglion cells should be needed to detect a stimulus by its shape, or pattern, than by its brightness. The pattern discrimination stimulus was apatch of nonrandom dots embedded in a surrounding random dot field of the same average density.

Computerized threshold determination for automated ABO/Rh tests.

Automated microplate blood-grouping systems rely on a pair of thresholds to determine whether reactions are positive or negative. The determination of these thresholds is a critical step in the quality control process for automated microplate blood grouping. A simple method has been developed for automatically setting these thresholds.

A one-step Du test in microplates.

A one-step Du test, developed for use in automated microplate systems, uses anti-D with 0.6 percent dextran to potentiate the reaction. Because the washing and reagent-adding steps of the antiglobulin test are not required, the Du test can be performed in the same microplate as the ABO/Rh test.

Considerations in the use of laboratory robots: aspects of safety and accuracy.

A general-purpose laboratory robot was configured to prepare blood samples for the HBsAg and anti-HIV tests. Several issues were studied in order to eliminate problems and optimize the system. These included pipetting accuracy, intersample carryover, reagent interference, splashing and aerosol generation and user-related issues.

The status of automation and data processing in the United States blood banking community.

A survey of the extent of automation and data processing in the blood banking community was conducted by questionnaire. The likelihood that a facility had some type of automation was related to the volume of blood products produced or transfused. Facilitates that collected blood or collected and transfused blood were more likely to have automation for ABO and Rh testing than those that only transfused blood.

Cost analysis of routine laboratory testing in blood centers.

The direct costs of ABO, Rh, Du, syphilis, and antibody screening tests were investigated. Questionnaires from 58 blood centers were analyzed to compare cost-effectiveness among methods of testing and annual collection volume as well as differences in cost of the various methods of testing within the same-size center. We found that "expensive" automated equipment cannot be justified on the basis of direct costs in centers processing less than 100,000 units of blood per year and that there is a wide variation in costs among centers using the same equipment.

Application of robotics in blood banking.

To demonstrate the feasibility of using robots in blood banking applications several prototype systems were developed. Activities associated with sample testing and component preparation were examined. In one project, a general-purpose laboratory robot (Zymate Laboratory Automation System, Zymark, Inc.

A robotic system to prepare samples for HTLV-III testing.

A robotic handling system was adapted to perform the sampling and dilution steps needed in an assay to detect antibodies to the HTLV-III virus, the causative agent of AIDS. The system reduced the labor required to prepare the samples and provided standardization and accuracy in the preparation of the samples.

An avian vocalization detector.

A simple circuit to detect avian vocalizations is described. Adjustments of five different controls (frequency, bandwidth, amplitude, duration and spacing) allow the circuit to accurately detect the vocalizations of different ages and species of birds. Analyses of over 4000 peeps and 500 inter-peep intervals from 40 chicks and 16 ducklings showed that the circuit and an experienced observer agreed closely in the timing and counting of vocalizations.

Estimating medullary chemoreceptor blood flow from ventilatory-CO2 response transients: theory and data from anesthetized dogs.

We examined the tracer wash-in technique for measuring blood flow for a specific experimental model in which medullary chemoreceptor blood flow is estimated using carbon dioxide as the tracer. Using a mathematical model, we calculated the flow values that would be estimated when blood flow is a function of the tracer concentration, CO2. The estimate was compared with three indices of time-varying blood flow: the steady-state blood flow before and after the step change of CO2 and the time-average blood flow.

Automated determination of ABO/Rh in microplates.

A semi-automated system for determining the ABO group and Rh type of blood samples has been developed using a commercially available automated microplate (ELISA) reader and a microcomputer. Optimization of serologic, measurement and interpretation parameters was accomplished without significantly changing an existing manual procedure. The first pass noninterpretation rate of this system in the laboratory prior to field trials is 7.