General:
Processes used for surfacing CR-39® lenses can be applied to the Kodak Precise SunSensors Lenses. Please note that SunSensors Lenses have a refractive index of 1.555

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 Progressive Lens design data. If yours does not include 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 180º 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 above the prism reference point dot. 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 Progressive Lens markings have a "+" at the nasal and temporal sides along the 180º axis line. Located approximately 3mm below the nasal "+" are the letters "K₊ I." Located approximately 3mm below the temporal "+" is the add power of the lens. These marks can be located by visually inspecting the lens. Position the lens at armís length, preferably in front of an overhead fluorescent light. While moving the lens slowly, look through the lens for the semi-visible marks located along the surface of the lens. The marks will become visible at a given angle of light and be most visible as the lens nears the edge of the light fixture.

Removal/Remarking the Temporary Reference Marks:
The Kodak Precise Progressive Lens markings may be removed by wiping the surface with alcohol or standard lens mark removing solvents. To re-mark the Kodak Precise Progressive 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 Progressive Lens verification mask or the progressive lens center/sizing chart. Use the fitting cross to accurately optimize optics during final fitting of Kodak Precise Progressive Lens.

Cribbing:
Aggressive cribbing during generating SunSensors Lenses may increase breakage. Cribbing may create hairline fractures in the new edge of the lens which could cause this lens to break during post-generating processes. We recommend you evaluate your processes for this potential cause of breakage.

Fining and Polishing:
Processing the SunSensors Lens material is similar to the CR-39 lens material with two exceptions: The stock removal during the fining can be greater, and SunSensors Lenses can be polished in 2-4 minutes. See the following tables for our test results at 19 PSI.

Abrasion Resistance Coatings:
The front surface of the SunSensors 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.

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. Obviously damaged lenses should be replaced immediately.

AR Coating:
Multi-layer AR coatings can be applied to SunSensors Lenses but a backside coating must also be applied if doing so. Because lens impact resistance is reduced by AR coatings, we recommend a 1.8mm 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. We recommend HT-1000 by Gerber-Coburn, UVNV or UVNVS by Ultra Optics. Include impact testing for lenses AR coated and sold by your lab. Confirm your samples with backside and AR coatings meet the FDA impact regulation before you begin selling AR coated SunSensors lenses. It may be necessary to increase the minimum center thickness in order to meet impact resistance requirements. We recommend a minimum center thickness at 1.7mm and 1.8mm if AR coated. Please call Technical Services at 800-759-0075 for additional information about coatings and impact resistance.

Tinting:
SunSensors Lens material is tintable. However, we recommend against tinting since it reduces the reaction of the photochromic dyes and may result in a too dark lens. Additionally, it is important to use caution when tinting, as SunSensors Lenses absorb tints much faster than most other plastic lens materials. If you decide to tint the lens, test a sample lens first. Note: Many tint neutralizer products will damage the lens. Call Technical Services at 800-759-0075 for recommended tinting procedures or for additional information.

CAUTION
Dispensing Note: At cooler temperatures, 53º F (12º C) and below, photochromic plastic lenses may become very dark on bright sunny days and may be too dark for driving any type of open-air vehicle. At colder temperatures, particular caution should be used when going from sunny to shady areas.

Drilling:
SunSensors lenses can be successfully drilled and mounted into a three-piece rimless frame. However, we discourage the use of three-piece frames with other than polycarbonate plastic lenses as it may result in higher warranty returns. The pressure on a screw mount when subjected to excessive bending force is often sufficient to crack the lens. For the strongest drilled plastic lens we recommend the following:

Use a bur-type bit (vs. a twist drill bit) and grind slowly through the material. CNC drilling machines should be set on the polycarbonate mode or the slowest feed rate. Chamfer the holes on the front and back of the lens with a cone-shaped stone Dremel tool. Use nylon top hat bushings in the holes for cushioning. Do not over-tighten the screws.

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.

The frame shape, frame PD and patient's PD affect how much of the full addition reading area falls inside the frame. To insure these variables will not limit near vision, lay the frame (with the fit point marked) onto the KODAK Lens Dispensing Aid (part number K763-578.) Check to see if the blue shaded area is contained within each eye of the frame. This chart also references a recommended minimum distance up from the fitting point to the frame edge. We advise a minimum distance viewing area of approximately 12mm for patient comfort.