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Results for “Refractometry”

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At least 127 records · Page 7Linked to original sources
PubMed1976

Laser meridional refractometry.

Laser meridonal refractions were undertaken on 30 subjects. The results were compared to classical subjective techniques utilizing both correlative statistics and clinical criteria. The laser meridional techniques were highly correlated with the subjective procedures and were accurate when judged by clinical criteria.

Adolescent↗
PubMed1978

Accuracy of evoked potential refractometry using bar gratings.

We recorded cortical potentials evoked by phase-alternating square-wave gratings. Significant effects of varying the refractive power of the eye are obtained only at 5 cycles/degree (cy/deg) and above. The extrapolation to zero amplitude of the evoked response as a function of spatial frequency predicts the psychophysical visual acuity even for the myopic eye. As the sensitivity of meridional refraction using sufficiently fine bar gratings is better than 0.5 D it provides a suitable means for the measurement of astigmatism.

Astigmatism↗
PubMed1988

Instant photographic refractometry in children.

A simple photographic method for detection and measurement of refractive errors in children, using a specially designed camera and electronic flash unit and 'instant' (Polaroid) film, was tested on 64 children, aged 3 to 8 years, and compared with the results from retinoscopy. The refractive errors ranged from -6.5 to +6.5 D. A light reflex in the pupil was observed on the photos of all children with hyperopia greater than = 0.5 and myopia greater than = 2.0 D. A curvilinear relationship was observed (in the range -2 to -4 and +0.5 to +3 D) between the width of the light reflex in the pupil, easily measured on the photos and the degree of refractive error, determined by retinoscopy. The degree of ametropia could be estimated with reasonable accuracy (+/- 0.5 D) in the interval from -2 to -4 D and +0.5 to +3 D. The method can demonstrate the type and, to a limited extent, also the degree of refraction anomaly and may be of value in screening for refractive errors in children.

Child↗
PubMed2003

Multimode reverse-symmetry waveguide sensor for broad-range refractometry.

A sensor design that uses a grating-coupled multimode planar optical waveguide for absolute detection of the refractive indices of liquids or gases is presented. The waveguide consists of a simple 50-microm-thick, free-standing glass plate with air beneath it and the sample to be analyzed on top of it. This design offers a simple alternative to the well-known monomode waveguides, and, owing to its so-called reverse-symmetry configuration, a large detection range can be obtained.

Journal Article↗
PubMed1977

Refractometry as a measure of the immunoglobulin status of the newborn dairy calf: comparison with the zinc sulfate turbidity test and single radial immunodiffusion.

Immunoglobulins were quantitated by single radial immunodiffusion in 34 female Holstein-Friesian calves which had been kept with their dams for the first 24 hours of life. The mean immunoglobulin G1 (IgG1) concentration was 1.063 g/dl; IgG2, 0.093 g/dl; IgM, 0.171 g/dl; and IgA, 0.125 g/dl. Both serum total protein as measured by refractometer and zinc sulfate turbidity measured at 498 nm gave good correlations with total protein, which were significant, P less than 0.001. Plasma total protein had a slightly poorer correlation with total immunoglobulins, presumably due to variable fibrinogen content. Plasma total protein gave a better correlation with total immunoglobulins than did any of the immunoglobulin classes individually. Total protein by refractometer underestimated naturally occurring or added immunoglobulins by one-third.

Animals↗