Progressive Lenses Adaptation Failures

Written by Optician Club on . Posted in Freeform Rx Lenses, Optician News

Progressive Lenses Adaptation Failures

§ The design doesn’t provide the information about the functionality of the lens.
§ Only the user can judge the functionality of a lens (adaptation, fields…) using clinical test under fixed conditions
§ Adaptation: complex area with many aspects.
Acceptance of progressive lenses: between 86% and 99% (mean 93%)
 
Adaptation depends on a great number of different things
– Correct lens mounting    – User experience
– User expectation              – User needs
– Optical properties

Progressive Lenses Adaptation Failures

New PAL user:
New visual situation
•Adaptation needed
•Adaptation is possible thanks to the plasticity of the visual system
Expert user with a new PAL design:
•Change of prescription
Change the spatial perception
•Different fields, different head strategy
•Different profile, new head vertical angles
•New frame: different lens position
Less changes à better adaptation
 
Problems reported Progressive Lenses Adaptation Failures
§Swim (peripheral image distortion, apparent in dynamic situations). Swim is visually disturbing and may cause physical distress.
§Ergonomic issues: the wearer must learn how to position head and eyes to see clearly at any distance
§Static distortion: straight lines appear to be bent.
 
Causes of failure
§Unsuited prescription: High oblique cylinder; anysometropia.
§User expectancy: Unreal wide intermediate field.
§Incorrect user training: Explanations on the required postural changes.
§Optometrist attitude: Confidence on the design.

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