Computer Calculation of Rx:
The easiest, most efficient method to calculate and process values for an Rx is to use an existing computer software package that contains Kodak Concise Lens design data. If your software company has not included this data in its package, our Technical Services group will be happy to provide the necessary specifications. Please forward us the contact name and phone number of your software vendor. If you need a software program for processing lenses, Signet Armorlite has developed a computer program to calculate surfacing data. This program is available through Signet Armorlite's Technical Services Department.

Semi-Visible Markings:
Kodak Concise Lens markings have a "+" at the nasal and temporal sides along the 180º axis line. Approximately 3mm below the nasal "+" you will find the "C7" product code. Approximately 3mm below the temporal "+" you will find the add power of the lens. These marks can be located by visually inspecting the lens. Position the lens at arm's length, preferably in front of an overhead fluorescent light. Slowly move the lens away from the edge of the light fixture while looking at the estimated location of the marks along the surface of the lens. The marks will become visible at a given angle of light.

Removal/Re-marking the Temporary Reference Marks:
The Kodak Concise Lens markings may be removed by wiping the surface with alcohol, acetone, or standard lens mark removing solvents. These marks are designed to withstand all processing procedures and must be removed before tinting.

To re-mark the lens, first locate the semi-visible markings, specifically the "+" symbols engraved along the 180º axis line (see above procedure for locating the semi-visible marks). Once you have located the semi-visible markings, dot them on the lens and use the Kodak Concise verification mask for the final re-marking.

Fining and Polishing:
Processing the 1.67 Kodak Lens is similar to the CR-39 lens material. Safety bevel the lens before fining to alleviate chips and allow the slurry smoother access along the lens surface. Large lap tools (at least 3 inch) should be used and allowance made for approximately 0.3mm of stock removal. We strongly recommend fining pads with eight or more petals be used for curves over 9.00 diopters. This can prevent flares and wrinkles.

Edging:
Layout for edging should be done in reference to the fitting cross located 2.0mm above the MRP. The fitting cross is placed at the point of the specified segment height and monocular PD.

AR Coating:
Since impact strength is reduced when a lens is AR coated, confirm the compatibility of combining the AR coating with backside coating. This should include in-house impact testing for lenses coated in your lab. Signet Armorlite does not recommend AR coating the KODAK Concise Progressive 1.67 lens without using a scratch-resistant backside coating. Our test results showed that all of the lenses processed with commonly used tintable backside scratch-resistant coatings exceeded the FDA impact-resistance requirements when AR coated. Please call Technical Services for additional information about coatings.

Tinting:
The 1.67 index lens material tints similarly to other high index lenses using the normal materials and methods. Prolonged immersion in tint tanks may cause warpage. After tinting, clean the lenses with alcohol or acetone to remove excess dye from surfaces. If you decide to tint the lens, test a sample lens first.

Fitting and Frame selection:
Our minimum fitting height (sometimes called the 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 fitting height values are completely Rx and frame dependent. The frame shape and patient’s monocular PDs will affect this minimum fitting height, which is measured from the lowest point of the lens and not the lowest point of the lens 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 and near area will be enclosed within the frame is to use the Kodak Concise center/sizing chart. 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.

If a small portion of the critical optical area is outside the frame, discuss with the patient the optical compromise that will occur if this frame is used.

Kodak is a trademark of Eastman Kodak Company, used under license by Signet Armorlite, Inc.
Concise is a trademark of Signet Armorlite, Inc.
CR-39 is a registered trademark of PPG.