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 Precise 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.

Layout:
All surfacing should be done in relation to the prism reference point located on the ° line. We recommend that you block the lens on the prism reference point even though the corridor is decentered 3 mm. If blocking is done on the geometric center of the blank, you must calculate the amount of decentration prism needed to move the optical center to the prism reference point. The fitting cross is located directly above the prism reference point dot. This improves the accuracy of positioning the patient's pupil to the center of the corridor. If you use an automated lens blocker, such as the Gerber Step-One System, and if you are blocking on the cross, be sure to use a segment placement on the lens blank of 4mm down.

Semi-Visible Markings:
Kodak Precise Lens markings have a "+" at the nasal and temporal sides along the 180° axis line. Approximately 3mm below the nasal "+" you will find the "K₊6" 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 Precise 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. They provide an easy way to verify the edging accuracy and can be removed before or after tinting.

To re-mark the lens, first locate the semi-visible markings, specifically the "+" symbols engraved along the 180° 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 Precise verification chart for the final re-marking.

Special Requirements:
The KODAK Precise 1.6 EvoClear Lens processes much like our 1.56 high index and CR-39 lenses with two exceptions: stock removal during surfacing, (refer to the chart below to establish an allowance), and the KODAK Precise 1.6 EvoClear Lenses can be polished in 1 minute. See the following tables for our test results. You can adjust your surfacing computer to compensate for the stock removal and take advantage of much shorter fining and polishing cycles.

Fining and Polishing:
Processing the 1.6 EvoClear 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.

Abrasion-Resistant Coatings:
The front surface has the superior protection of the RLXPlus non-tintable coating. Signet Armorlite recommends using either a tintable or non-tintable backside coating after surfacing. Verify that the impact resistance is maintained, particularly when using a non-tintable coating.

Impact Resistance:
"Our test results indicate that lenses backside coated with UVX by Ultra Optics, UVNVS by Ultra Optics, or HT1000 by Gerber Coburn exceed the FDA impact-resistance requirements and are 100% compatible with the KODAK Precise 1.6 EvoClear Lens. Contact our Technical Service Department if you are using a different coating.

Edging:
Layout for edging should be done in reference to the fitting cross located 4.0mm above the MRP. The fitting cross is placed at the point of the specified segment height and monocular PD.

AR Coating:
Multi-layer AR coatings can be applied to Kodak Precise Lenses. Because lens impact resistance is reduced by AR coatings, we recommend a 1.7mm 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.

Tinting:
When a tintable backside coating is used, tint performance and compatibility with specific neutralizers are coating dependent. Take special care when loading the KODAK Precise 1.6 EvoClear Lens into the tinting holder. The combination of edge pressure and high temperatures will cause warpage. Position the clamp with virtually no pressure, but restricted enough to secure the lens. If the lens does warp during the tinting process, bake the lens on a flat tray in a oven at 175-200°F for approximately 20 minutes or until the lens is heated all the way through. Reference the following tables for approximate tint absorption rate results.

Neutralizing:
Our test results show the KODAK Precise 1.6 EvoClear Lens can be damaged when using tint neutralizers designed for CR-39. Use a neutralizer designed for polycarbonate or high index materials.

Thermal Stability:
KODAK Precise 1.6 EvoClear Lens material has a similar level of heat sensitivity as other 1.6 high index materials. The lens will flex if heated under pressure. To prevent warpage, avoid heating the lens over 130° F while under pressure. Warpage can cause a plastic lens to become loose in the frame. If the lens should become warped beyond tolerance, place the lens on a flat tray in a oven at 175-200°F for approximately 15-20 minutes or until the lens is heated all the way through.

Removal/Remarking the Temporary Reference Marks:
The KODAK Precise 1.6 EvoClear Lens markings may be removed by wiping the surface with alcohol or standard lens mark removing solvents. To remark lens, locate the semi-visible "+" symbols engraved along the 0-180° axis line. Use a felt pen to mark a spot over the "+" symbols, and trace the progressive markings using the KODAK Precise 1.6 EvoClear Lens Verification Mask or the Center/Sizing chart. Use the fitting cross to accurately optimize optics during final fitting of KODAK Precise 1.6 EvoClear Lenses.

Fitting and Frame selection:
The fitting point (+) has been positioned slightly higher than our other progressives. Therefore, you can fit the lens at the center of the pupil rather than at the bottom of the pupil. Always use monocular PDs and individual fitting heights when they differ more than 1.0 mm.

We recommend a minimum fitting height (sometimes called the segment height) of 20 mm. While a successful fitting of Precise lenses is possible with less than a 20 mm fitting height, we recommend the KODAK Concise™ short corridor lens for smaller fitting height situations.

Kodak is a trademark of Eastman Kodak Company, used under license by Signet Armorlite, Inc.
RLXPlus is a registered trademark and Concise, Precise and EvoClear are trademarks of Signet Armorlite, Inc.
CR-39 is a registered trademark of PPG.