A wearer trial of two rear surface progressive addition spectacle lenses

1 February 2002
Volume 03, Issue 1

Until recently, the vast majority of all progressive addition spectacle lenses (PALs) were manufactured with the progressive surface on the front. This paper looks at changes in this field.

Introduction 

Until recently, the vast majority of all progressive addition spectacle lenses (PALs) were manufactured with the progressive surface on the front. The rear surface was then made spherical or toroidal as required by the prescription. The lens production would typically take place in two parts: the front progressive surface only being manufactured initially to give a semi-finished lens, and the prescription being worked on the rear surface at a later date.

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