Thicknesses: We recommend a minimum center thickness of 1.5mm, or 1.6mm if AR coated

Abrasion Resistance Coatings:
The front surface of the 1.56 EvoClear Lenses includes the superior protection of RLXPlus non-tintable coating. The uncoated rear surface of the lens provides adequate durability for normal use. Therefore, a backside coating is not required, although backside coating is recommended if the lens will be worn in a highly abrasive environment. Applying a backside coating after surfacing is always recommended when the lens will be anti-reflective coated. However, be sure to verify that impact resistance is maintained, particularly when using a non-tintable coating. Please call Technical Services for the latest test results with various backside coatings.

AR Coating:
Multi-layer AR coatings can be applied to 1.56 EvoClear Lenses. Because AR coatings reduce lens impact resistance, we recommend a 1.6mm minimum center thickness and a backside coating that will enhance the impact resistance capability. Be sure that your AR coating is compatible with your backside coating. Include impact testing for lenses AR coated and sold by your lab. It may be necessary to increase the minimum center thickness in order to meet impact resistance requirements. Please call Technical Services at (800) 759-0075 for additional information about coatings and impact resistance.

Impact Resistance:
As a component, lenses of this design have been shown by testing to be capable of being processed to meet applicable impact resistance requirements of FDA regulation 21 CFR 801.410 and ANSI Z80.1. Conformance to this standard is the responsibility of all subsequent processors. Impact resistant lenses are not unbreakable. Lenses with obvious damage should be replaced immediately.

Tinting:
If you decide to tint the lens, test a sample lens first. When using a tintable backside coating, the tinting performance and compatibility with specific neutralizers are coating dependent. We caution against tinting prior to using a non-tintable coating. Coating applications can change the color or density of tinted surfaces. After tinting, clean the lenses with alcohol or acetone to remove excess dye from surfaces.

Special care must be taken when clamping EvoClear lenses. The combination of edge pressure and high temperatures will cause warpage. You should position the clamp with only enough pressure to keep the lens from falling out. If the lens does warp during the tinting process, remove the warpage by baking the lens on a flat tray in a 175-200°F oven for 5 minutes.

Thermal Stability:
The 1.56 EvoClear Lens material has a similar level of heat sensitivity as other high index materials. The lens can flex if heated under pressure. To prevent warpage, avoid heating the lens over 130° F while it is under pressure from frame or clamping. Warpage can cause a plastic lens to fit loosely in the frame. If the lens should become warped, heat without pressure to allow the lens to return to its original shape.

Fitting and Frame selection:
Our minimum segment height guideline is 17mm, based on the 12mm corridor length. The measurement includes 2mm above the reference dot where the fitting cross is marked, as well as 3mm of clear area below the full addition location. Minimum segment height values are completely Rx and frame dependent. The frame shape and patientís monocular PDs will affect this minimum segment height, which is measured from the lowest point of the frame and not the lowest point of the frame where the reading area falls. Illustration 1.0 shows that the near zone may not fall inside the frame for certain frame and monocular PD requirements.

The simplest and most accurate way to ensure that an adequate distance & near area will be enclosed within the frame is to use Signet Armorlite's center/sizing chart for Navigator Short Lenses. Mark each fit point on the demonstration lenses in the frame and lay it over the center/sizing chart to verify the critical optical zones fall within the eye wire.