Eyewear Inspection Processes

    InTouch   Optics

Enormous volumes of eyewear products such as spectacle lenses, frames, and sunglasses are outsourced from China each year. While outsourcing has been profitable for most optical distributors, a number fell into unwanted complications such as product recalls. These problems could have been easily averted if only appropriate inspection protocols were utilized.

The following are some of the inspection processes InTouch uses in dealing with eyewear products:

Material Inspection Processes

  • Plastic Resin and Additives – Verify that the manufacturer uses the right type of resins and additives in creating plastic lenses. It is important that these materials possess the right specific gravity, refractive index, Abbe value, etc.
  • Glass – Verify the use of the specified raw materials and additives in the production of spectacle glass lenses.
  • Coating – Verify the use of approved coating and finishing materials to provide or enhance a variety of desirable properties such as hardness, color, anti-reflectance, water resistance , abrasion resistance, static resistance, and UV protection.
  • Frames – Verify the use of specified materials for the production of spectacle frames. These materials may include carbon fiber, plastic, rubber, and light metal alloy.

Lens Inspection

  • Impact Resistance Test – Verify impact resistance of lens using the procedures provided in 21 CFR Part 801.410 or superior test method. This standard test method, commonly referred to as the “Drop Ball Test”, deals with dropping a 5/8 inch steel ball that weighs no less than 16 grams from a height of 50 inches. This testing protocol is required for sunglasses and eyeglasses sold in the USA, including the issuance of certification statement of impact resistance from supplier or manufacturer. An alternative and derivative of this method is the Variable Height Impact Test.
  • Refractive Index Check – Verify that the product possesses the refractive index specific to its type. BS 7394: Part 2 specifies the different refractive indices for spectacle lens.
  • Abbe Value Test – Determine the Abbe value by using appropriate lab tests to evaluate dispersion rating of lens. Higher Abbe value means lower dispersion and better vision quality for the users.
  • Density Check – Measure the specific gravity of lens, finished and semi-finished, and compare with approved samples or contractual specifications for compliance. This is essential as this may help reveal potential problems associated with issues like quality of materials and proper production techniques and protocols.
  • Reflective Index Check – Evaluate the anti-glare property of the lens so that users are not affected by glaring light.
  • Abrasion Resistance Check – Evaluate the propensity of product to resist abrasion using test procedures appropriate to the materials and coating used. A common test is to forcefully rub the lens with a clean cotton cloth by hand and check for scratches or transfer of color.
  • Transition Lens Check – Verify the time it requires for the lens to change from dark to clear and clear to dark under pre-determined lighting conditions.
  • Transmittance Rating Check – Verify the transmittance rating of sunglasses. Transmittance ratings are different in Europe, in New Zealand and Australia, and in the USA. Transmittance ratings must be in adherence with applicable standards including EN 1836:2005, AS/NZS 1067:2003, and ANSI Z80.3-2001.
  • UV Protection Check – Measure the UV Protection level of sunglasses using UV meter. UV Protection level should also be conveyed through a product marking.
  • Lens Dimensional Check – Verify the various dimensional measurements of lens including center thickness, edge thickness, roundness, base curve, and diameter.

Frame Inspection

  • Frame Style Check – Compare frame with approved samples to check any deviations on style, rimmed or rimless, model, number, etc.
  • Frame color – Compare color with approved samples or specified values in the Pantone color chart.
  • Eye Size and Dimensions – Verify that the eye size and related dimensions are according to specifications and/or are the same with approved samples.
  • Bridge Check – Check that the bridge of the frame is the same in thickness, shape, material, and color with contractual specifications or approved samples.
  • Temple Check – Verify that eyewear temples do not have noticeable deviations from that in approved samples or specifications including style, material, thickness, color, and length.
  • Attachments – Inspect frame attachments, if any, for compliance with specifications and that there are no signs of damage or defect such as scratches, imperfections, and chips.

Assembled Eyewear Inspection

  • Lens Tightness of Fit – Verify that lenses are fitted into the frame with appropriate tightness so that they do not fall off under normal use. Conduct laboratory testing to determine the force necessary cause detachment of lens from the frame, if necessary. This is recommended for high-end sunglasses and industrial eyewear.
  • Cosmetic Defects Check – Inspect eyewear for any sign of manufacturing defects and handling damage including scratches, chips, coating pits, drips, and blemishes.
  • Drilled Lenses Check – Verify the drilled lenses are secured and that there are no visible cracks, chips, and deformities in the drill holes.
  • Labeling – Verify that the labels used in the product comply with relevant standards as well as with the specifications provided for by the importer including brand name, model, UV rating, etc.
  • Packaging – Check that retail and shipper’s packaging are in accordance with existing regulations and contractual specifications.
  • Flammability – Check that eyewear is made from non-combustible materials including its attachments, if any. Sunglasses to be imported to the USA must comply with 15 USC 1261~1, 1263 and 16 CFR 1500.44 to address this flammability requirement.
  • Biocompatibility – Verify that product are made from materials that are non-toxic, non-irritating, and may cause significant allergic reaction to wearer under normal use.

The regulations on eyewear are ever evolving, as well as the materials and techniques used in their production. It is important that buyers are able to adjust to these changes as well. For a more detailed and complete list of the inspection protocols applicable to your spectacles, please contact InTouch.

service guide download

Leave a Reply

Be the First to Comment!