Biomedical subjects

E J Seibel

Publications and source records attributed to E J Seibel.

4 recordsLinked to original sources

PubMed1997

Imaging 'intact' myofibrils with a near-field scanning optical microscope.

Fluorescently labelled myofibrils were imaged in physiological salt solution by near-field scanning optical microscopy and shear-force microscopy. These myofibrils were imaged in vitro, naturally adhering to glass while retaining their ability to contract. The Z-line protein structure of the myofibrils was antibody labelled and easily identified in the near-field fluorescence images. The distinctive protein banding structure of the myofibril was also seen clearly in the shear-force images without any labelling requirement. With the microscope in the transmission mode, resolution of the fluorescence images was degraded significantly by excessive specimen thickness (> 1 micron), whereas the shear-force images were less affected by specimen thickness and more affected by poor adherence to the substrate. Although the exact mechanism generating contrast in the shear-force images is still unknown, shear-force imaging appears to be a promising new imaging modality.

Animals↗

PubMed1989

Validation of a method for measuring small color differences in pigmented contact lenses.

A method for measuring and quantifying color variability of soft contact lenses is presented in this paper. The lenses studied are opaquely pigmented, varying in color intensity in each of four hues. The instrument selected for color measurement is the HunterLab ColorQUEST reflectance spectrophotometer using integrating sphere geometry and a customized contact lens support. Total color difference is measured using the Commission International de l'Eclairage (CIE), 1976 L* a* b* color space in delta-E* units. The correlation between the instrumental measurement and human estimation of color intensity difference is presented graphically for each hue. Trained inspectors ranked the eight lenses per hue from lightest to darkest on a linear scale which was converted to the instrumental delta-E* units. The instrument validation is based upon (1) maximum average differences of less than 1.1 delta-E* between the instrument and inspectors, and (2) overall repeatability (SD) of +/- 0.1 for the instrument vs. +/- 0.3 for the inspectors.

Calibration↗

PubMed1988

Evaluating soft contact lens quality: a manufacturer's perspective.

This study was designed to compare quality control between six aphakic contact lens brands. The methodology eliminates the sampling and experimental variables of previous studies. The lenses were all purchased new at +13.00 D power, with the same number of lenses and distribution of manufacturing batch/lots per brand. We measured or assessed 120 study lenses (20 per brand) for diameter, front sagittal height, power and image quality, center thickness, surface and edge quality, and edge design. The base curve radius was calculated accurately using lens cross-sectioning techniques. The reproducibility of measured lens parameters (precision) and conformance to label claims (accuracy) were tabulated separately and the lens brands were ranked and grouped statistically. The tabulated results are represented graphically in one spread sheet where selected American National Standards Institute (ANSI) tolerances were used as a standard to which all lens brands were compared. Lens brands coded as Brand A and Brand B rated the highest using our criterion for ranking overall quality control.

Calibration↗

PubMedDate not supplied

The virtual retinal display as a low-vision computer interface: a pilot study.

This pilot study examined the performance of an alternative computer visual interface, the Virtual Retinal Display (VRD), for low-vision use. The VRD scans laser light directly onto the retina, creating a virtual image. Since visually impaired individuals can have difficulty using computer displays, a matched comparison study was done between the VRD and the standard cathode ray tube (CRT) monitor. Reading speed and acuity tests were collected from 13 low-vision volunteers selected to represent the broad range of partially sighted individuals actively involved in the work force. Forty-six percent of subjects had highest visual acuity while viewing the VRD; 30% of subjects had highest acuity viewing the CRT; and 24% of subjects had equal acuity across the two displays. Although mean reading speed across all 13 subjects indicated no significant difference between displays, individual subjects with predominantly optical causes of low vision exhibited clinically important increases in reading speed versus the CRT. However, most subjects with predominantly retinal damage showed a slight disadvantage using the VRD. We give theoretical explanation to the bifurcated results and conclude that for a subset of low-vision users, the VRD technology is very promising as a basis for future low-vision aids.

Adult↗