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Biomedical subjects

H T Lewis

Publications and source records attributed to H T Lewis.

5 recordsLinked to original sources
PubMed1993

Use of spectacle mounted telescope systems by the visually impaired.

BACKGROUND: Spectacle mounted telescope low vision aids are designed to magnify objects Spectacle telescopes are often rejected by the visually impaired because of their unusual cosmetic appearance which may call attention to their disability. METHODS: Fifty-six subjects were recruited at four independent low vision clinics and divided into two categories: 24 were current wearers of expanded field spectacle mounted telescope systems, and 32 were new wearers. New wearers underwent a randomized cross-over trial, comparing the experimental device (Ocutech VES) to one of two controls (DFV Expanded Field or Walter's Keplarian Close-focus Telescope). RESULTS: Our data show that previous telescope wearers increased their use of telescopes after introduction of the experimental device (Ocutech VES) and there was an equivalent utilization rate for new wearers. CONCLUSIONS: Visual activity patterns are not a sensitive measure of telescope benefit, but frequency of use patterns do change and appear to demonstrate a valid benefit of spectacle mounted telescopes for the visually impaired.

Adolescent↗
PubMed1991

The Ocutech Vision Enhancing System (VES): utilization and preference study.

An NIH-sponsored user and prescriber preference trial was conducted comparing a new low vision telescope system, the Ocutech Vision Enhancing System (VES) to two conventional Keplarian spectacle telescope systems in a controlled cross-over clinical study performed at four independent low vision clinics. Fifty-five visually impaired individuals, 18-81 years of age, with both previous and no telescope experience, were followed for 8-16 weeks. The experimental and control devices were compared on a series of subject-selected visual tasks using a standardized clinical protocol. Subjects were trained in the use of the systems with standardized clinical methods. The data shows a statistically significant preference of the new design by both patient and clinician with the overriding factors relating to appearance, weight, adjustability and the fit of the frame.

Adolescent↗
PubMed1986

Parameters of contact lens-spectacle telescopic systems and considerations in prescribing.

Contact lens-spectacle telescopic systems provide an alternative to conventional spectacle-mounted telescopes. There is a need to describe the parameters of such systems, the interrelations between them, and the use of such relations in selecting values for prescribing. Graphical representation of ocular (contact) lens power, objective (spectacle) lens power, separation (vertex distance), and magnification are presented. Skillful prescribing involves selection of the best set of parameters to achieve the desired visual goal in spite of the practical limitations imposed by facial features, lens availability, and appearance. Additional factors (not graphically represented) are induced vergence amplification, altered depth perception, and apparent motion, all unique to telescopic systems. One patient is described and selection of appropriate parameters is discussed. General application of the selection process is described.

Accommodation, Ocular↗