TIPS NO

219

Revision

B

Date:

Apr 2002

 

 

Navigator Short Progressive
with Corning® SunSensors® Lens Material
Product Specifications & Processing Information

Purpose: The following information will assist you in processing the Navigator Short Progressive SunSensors lenses in gray and brown.

Summary of TIPS Version Changes:
This TIPS revision incorporates the stabilized SunSensors material which is identifiable by the letter "S" following the SunSensors name in technical files, includes a cold weather use advisory, and drilling instructions.

Characteristics

Navigator Short SunSensors Lens

Refractive Index

1.555

Dispersion Value (Abbe)

38.0

Density

1.17

Chemical Resistance

Excellent

Machinability

Excellent

Rear Surface Coating

Optional

Scratch Resistant

In-Mold RLXPlus®

 

Navigator Short progressive SunSensors Lens Dimensions
Blank Size:
74mm diameter blanks, decentered 3mm.

Effective diameter is 80mm.

Base Curves: 1.25 (-6.25 to -8.50), 3.25 (-2.00 to -6.25), 5.50 (+1.00 to -2.00), 7.50 (+2.00 to +5.00)

Power Range: -8.50 to +5.00

Add Powers: 1.00 to 3.00 in 0.25 Diopter Steps

Thicknesses: We recommend a minimum center thickness of 1.6mm, or 1.8mm if AR coated

Nominal Curve

True Curve

Radius mm

SAG at 50mm

Nominal Concave

Edge Thickness

Center Thickness

1.25

1.16

3.0

15.4

13.9

3.25

3.25

6.0

11.7

9.0

5.50

5.54

6.0

8.4

8.9

7.50

7.62

6.0

8.5

12.2

General:
Processes used for surfacing CR-39® lenses can be applied to 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 Navigator Short Progressive SunSensors 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 180° 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 approximately 1/3mm 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 Step-One System, and if you are blocking on the cross, be sure to use a segment placement on the lens blank of -2mm down and 2.2mm in.

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

Semi-Visible Markings:
Navigator Short Progressive Lens markings have a "+" at the nasal and temporal sides along the 180† axis line. Located approximately 3mm below the nasal "+" is the Navigator icon and the letters "sI". 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.

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.

 

ONE-STEP Fining Pads

Millimeter Take-Off

Pad Brand & Type

20 sec

40 sec

60 sec

80 sec

PSI P-1000

0.25

0.47

0.69

0.87

DAC Fire (Fine red vinyl)

0.20

0.40

0.60

0.75

Salem 933

0.20

0.40

0.60

0.75

TWO-STEP Fining Pads (DAC Brand)

Pad Type

20 sec

40 sec

60 sec

80 sec

1st Fine: 600 GRIT

.26

.48

.69

.87

Salem 993

.30

.59

.86

.110

2nd Fine: 9 MICRON BLUE

.08

.12

.15

.17

Salem 1128

.13

.19

.23

.27

POLISHING TIME ( 2 - 4 minutes)

Allow 0.1mm Take-Off

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 unless an AR coating is to be used.

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 that sample lenses 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 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 many 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 additional tinting information.

CAUTION:
Dispensing Note: At cooler temperatures, 53 degrees F (12 degrees 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 most plastic lenses. 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. Automated 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 tool. Use nylon top hat bushings in the holes for cushioning. Do not over-tighten the screws.

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 patientís monocular PDs will affect this minimum fitting 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 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.

 

Illustration 1.0

fitting point

Usable full addition point inside frame

Unusable full addition point out of frame

Corning and SunSensors are registered trademarks of Corning Incorporated, Corning, New York.
CR-39 is a registered trademark of PPG.
RLXPlus is a registered trademark and Navigator Short is a trademark of Signet Armorlite, Inc.

Navigator Short Progressive in SunSensor,
1.555 material index Base Curve Selection Chart
SPHERE
POWER
 
CYLINDER POWER
0.00 -0.50 -1.00 -1.50 -2.00 -2.50 -3.00 -3.50 -4.00 -4.50 -5.00
-8.75^                      
-8.50                      
-8.25                      
-8.00                      
-7.75   -7.75           -7.75      
-7.50   -7.50           -7.50      
-7.25     -7.25                
-7.00     -7.00       1.25
base
     
-6.75                  
-6.50       -6.50           -6.50  
-6.25       -6.25           -6.25  
-6.00         -6.00            
-5.75         -5.75           -5.75
-5.50           -5.50         -5.50
-5.25           -5.25          
-5.00             -5.00        
-4.75       3.25
base
  -4.75        
-4.50           -4.50      
-4.25               -4.25      
-4.00                      
-3.75                 -3.75    
-3.50                 -3.50    
-3.25                   -3.25  
-3.00   -3.00               -3.00  
-2.75   -2.75                 -2.75
-2.50     -2.50               -2.50
-2.25     -2.25                
-2.00       -2.00              
-1.75       -1.75              
-1.50         -1.50            
-1.25         -1.25            
-1.00                      
-0.75                      
-0.50   5.50
base
    -0.50          
-0.25       -0.25          
0.00                      
0.25             0.25        
0.50   0.50         0.50        
0.75   0.75 0.75         0.75      
1.00     1.00 1.00     1.00      
1.25       1.25 1.25          
1.50           1.50     1.50    
1.75                 1.75 1.75
2.00             2.00     2.00
2.25             2.25 2.25      
2.50               2.50      
2.75       7.50
base
      2.75    
3.00             3.00 3.00  
3.25                   3.25  
3.50                     3.50
3.75                     3.75
4.00V