Clinical assessment of a customized free-form progressive add lens spectacle

Optom Vis Sci. 2011 Feb;88(2):234-43. doi: 10.1097/OPX.0b013e31820846ac.


Purpose: To determine whether there are significant differences in standard clinical measures of vision, progressive addition lens (PAL)-specific vision tests, or subjective ratings and preferences between customized free-form and standard non-free-form PALs in an experienced wearing population. In addition, we aim to determine whether subjective or objective clinical outcomes depend on demographic, PAL usage, spectacle prescription, or frame fitting characteristics.

Methods: In a randomized, double-masked cross-over trial, 95 experienced wearers wore Zeiss Individual customized free-form PAL spectacles (test) and standard non-free-form PAL spectacles (control) for 1 week each. At dispensing and after 1 week of wear, subjects were tested for distance and near visual acuity under both high and low contrast; in addition, 30° off-axis visual acuity was measured using a novel apparatus, as was the horizontal extent of clear, undistorted vision at reading distance. Subjects also completed a set of questionnaires detailing their satisfaction levels, adaptation times, and preferences for test or control spectacles for different visual tasks.

Results: The test spectacles were preferred overall and for distance, midrange, transitional and active vision, and rated higher in overall satisfaction (p = 0.006). There were no clinically important differences between test and control spectacles in standard clinical vision assessments. In the PAL-specific assessments, however, the horizontal extent of clear vision at reading distance was significantly greater with the test spectacles (p = 0.004).

Conclusions: There were statistically significant preferences for the optically customized free-form lenses over the non-free-form lenses. Subjects also reported a wider field of undistorted vision when looking through the reading zone of the test spectacles. Although standard clinical vision assessments are not sufficiently refined to detect important objective differences between the spectacle types, customization taking into account back vertex distance, segment height, pantoscopic tilt, and wrap angle can result in a superior subjective wearing experience for many PAL patients.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological
  • Adult
  • Aged
  • Aged, 80 and over
  • Contrast Sensitivity
  • Cross-Over Studies
  • Double-Blind Method
  • Equipment Design
  • Eyeglasses*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Optics and Photonics*
  • Patient Preference
  • Patient Satisfaction
  • Presbyopia / physiopathology
  • Presbyopia / rehabilitation*
  • Surveys and Questionnaires
  • Time Factors
  • Treatment Outcome
  • Visual Acuity