Lenses are manufactured in compliance with ISO14889:2003
Optical tolerance are conform with EN ISO8980 Ophthalmic optics- Uncut finished spectacle lenses.
In a zone of 30 mm diameter, centered around the reference point and also over the whole area of the segment if the segment is not more than 30 mm in diameter, the lens should not exhibit any defect either internally or on the surfaces which may impair vision. For segments over 30 mm in diameter, the inspection area should also include a 30 mm diameter zone centered around the near design reference point. Out- side this zone, small isolated material and/or surface defects are acceptable.
Carry Out the lens inspection at a light/dark boundary and without the aid of magnifying optics. The recommended system is shown in figure A.1. Inspect the lens within a room with ambient lighting of abou200 lx Use a source of at least 400 Im as an inspection lamp, for example a fluorescent tube of 15W or an open shade 40W incandescent clear lamp.
NOTE 1 This observation method is subjective and requires some experience.