Biomedical subjects

L A Spitzberg

Publications and source records attributed to L A Spitzberg.

5 recordsLinked to original sources

PubMed1995

New ergonomic stand magnifiers.

BACKGROUND: Stand magnifiers are not satisfactory for reading and other near visual requirements for many low vision patients. METHODS: Four new stand magnifiers have been developed with ergonomic advantages such as a comfortable viewing angle, the capacity for both reading and writing, better illumination, a wider field of view, variable power and magnification, and a longer working distance. The four new stand magnifiers are a spherical mirror magnifier, a cylindrical mirror magnifier, a reflecting prism magnifier, and a zoom magnifier. These magnifiers were tested on 39 subjects from five low vision clinics and compared to a commercial stand magnifier. The study determined reading speed and subject preference for these magnifiers. RESULTS: The reading speed of subjects with the new magnifiers increased over time and there was a significant change in preference over time. Results showed that 29 out of the 39 subjects on the final day of testing picked one of the new magnifiers as their device of choice. Reading speeds were comparable overall on all devices except for the cylindrical magnifier which was somewhat less. CONCLUSIONS: These four new ergonomically designed magnifiers were preferred by low vision patients compared to a commercial stand magnifier.

Equipment Design↗

PubMed1994

Depth of field of plus lenses and reading telescopes.

Using simple optical equations we solved for the depth of field (or range of movement for clear viewing) of plus lenses and near telescopes of the same equivalent power and then compared them. The prevalent clinical wisdom states that reading telescopes have a smaller depth of field than plus lenses. Our results show depth of field to be equal for both and inversely proportional to the square of the equivalent power. A simple nomograph of depth of field vs. power has been prepared for clinicians to use.

Eyeglasses↗

PubMed1994

The design of a zoom stand magnifier--a new low vision device.

A new stand magnifier has been designed for low vision patients and developed into a working instrument. This zoom magnifier has two ergonomic advantages over the currently available single lens magnifiers: it stays in focus (zooms) as the power is changed and it has a longer working space to allow both reading and writing with the same magnifier. This two-lens zoom magnifier contains a stationary plus lens and a movable minus lens. Using a symmetry condition, first order equations are presented and solved for the two lens powers. A family of three zoom magnifiers was designed--low, medium, and high power--each with a conveniently positioned sharp image with a 2-fold range of power and magnification. The equivalent viewing powers of the units (for a +2.50 D add) range from 6 to 23 D. The working spaces are approximately double that of comparable power single lens stand magnifiers.

Equipment Design↗

PubMed1993

Testing the FOCOMETER--A new refractometer.

The FOCOMETER, an optometer which measures spherical refractive errors, is intended to provide rural or economically disadvantaged populations spherical prescriptions without the need for complicated protocols, expensive equipment, or electricity. FOCOMETER readings were compared with the spherical equivalent determined from autorefraction and subjective trial lens refractions in children, and with retinoscopy in adults. Over the range of refractive errors tested (-4 to +5 D) reasonably close readings, within one-half a diopter, were found for comparisons with autorefraction and retinoscopy and about one-tenth of a diopter difference was found between subjective refractions and the FOCOMETER.

Adolescent↗

PubMed1989

Behind the lens telescope: a new concept in bioptics.

A new concept in bioptic prescriptions is presented. The new Behind-The-Lens (BTL) telescope provides the advantages of the typical bioptic with the additional advantage of providing a more acceptable appearance.

Adolescent↗