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Optical characteristics of Alvarez variable-power spectacles.

Hema Radhakrishnan1, W Neil Charman1

  • 1Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.

Ophthalmic & Physiological Optics : the Journal of the British College of Ophthalmic Opticians (Optometrists)
|February 18, 2017
PubMed
Summary

Variable-power spectacles offer adequate optical performance for correcting vision in ametropes and presbyopes. These Alvarez spectacles demonstrate stable power across the lens aperture, suitable for distance and near vision needs.

Keywords:
Alvarez lensesfocimetryinterferometrypresbyopiavariable-power spectacles

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Area of Science:

  • Optics
  • Ophthalmology
  • Vision Science

Background:

  • Alvarez variable-power spectacles offer adjustable lens power.
  • Their utility for ametropes and presbyopes requires optical performance evaluation.

Purpose of the Study:

  • To assess the optical performance of commercial Alvarez variable-power spectacles.
  • To determine their suitability for correcting refractive errors in ametropes and presbyopes.

Main Methods:

  • Evaluated two commercial variable-power spectacle designs (FocusSpecs, Adlens Adjustables).
  • Measured lens power and prism using focimetry across the aperture.
  • Assessed local optical quality with interferometry at multiple power settings.

Main Results:

  • Equivalent sphere power remained stable within a central 20 mm lens aperture.
  • Prism changes adhered to Prentice's rule.
  • Minor astigmatism and higher-order aberrations were detected, increasing towards the lens periphery.

Conclusions:

  • Currently available Alvarez variable-power spectacles exhibit adequate optical performance.
  • They are suitable for correcting distance and near vision in spherical ametropes within their designed power ranges.