TIPS NO: 231
	Revision:
	Date: July 2003

Purpose:
The following is provided for fitting and processing Navigator Progressive Polycarbonate Lenses.

General:
Processing of the Navigator polycarbonate lens is similar to that of standard resin with a few exceptions. Generator and edger wheels designed for polycarbonate material and fining pads designed for polycarbonate must be used. If you have questions on processing the Navigator polycarbonate lenses, please contact our Technical Services department at 800 759-4630.

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 Navigator 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 180° line. We recommend that you block the lens on the prism reference point even though the corridor is decentered 2.5mm. 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 approximately 0.3mm to the temporal side of 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 Coburn Step One System, and if you are blocking on the cross be sure to use a segment placement of -2mm down and 2.2mm in.

Semi-Visible Markings:
Navigator Lens markings have a "+" at the nasal and temporal sides along the 180° axis line. Approximately 3mm below the nasal "+" you will find the 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/Remarking the Temporary Reference Marks:
The Navigator Lens markings may be removed by wiping the surface with alcohol. If AR coating the lens, wipe the area a second time to make sure all residue is removed. Never use acetone on polycarbonate lenses.

Fining and Polishing:
Processing the Navigator Polycarbonate Lens is the same as processing other polycarbonate lenses. 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. Perform a stock removal test, using your process to most accurately establish the correct surfacing thickness allowance. We strongly recommend fining pads with eight or more petals be used for curves over 9.00 diopters. This can prevent aberrations and score lines.

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 of FDA Regulations 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 damage lenses should be replaced immediately.

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:
Multi-layer AR coatings can be applied to Navigator Lenses. Be sure that your AR coating is compatible with your backside coating. Include impact testing for lenses AR coated and sold by your lab. Please call Technical Services at 800-759-0075 for additional information about coatings and impact resistance.

Tinting:
Polycarbonate material will not absorb tint. Therefore, in order to tint, a tintable backside coating must be applied. Conventional hard resin tints are acceptable. Neutralize by dipping the lens in a non-citrus liquid detergent and water. Standard neutralizers will damage the lens.

Fitting and Frame selection:
Position the fitting cross either at the center or bottom of the pupil.