Creating Digital Lens Style(s)

Owned by Tony LeBlanc
Last updated: Jan 31, 2023
8 min read

Create Digital Lens Style(s)

Once the interfaces to the digital surfacing calculators have been set up, a lens style must be set up for each different digital surfacing design to be used.  The designs are purchased from the lens vendor(s), and the lens vendor will provide a "design name" for each specific digital surfacing design that the lab is authorized to manufacturer.

Lens styles for digital surfacing are set up exactly as they would be for any new lens style. For example, to set up a new digital surfacing style "CUST14", using the calculation engine specified previously as digital surfacing interface "01", a lens style similar to the following would be set up:

General Tab

 


 Minimum SegHt and Min SegHt Action - specifies the lowest seg height that can be used for this lens design. Setting this, and setting the Action to “E”, prevents the user from requesting a seg height that is invalid for the digital design.

Maximum Add - specifies the highest add power that can be manually entered for this lens style.  This prevents requesting invalid add powers from the digital surfacing calculation engine, which can cause errors with some engines.

Digital Type – this identifies which digital surfacing interface to use for this lens style, if set, it activates the fields on the Digital tab.  This number corresponds to the digital type number discussed in section 1.0.


Digital Tab


Some fields to note for this type of lens, on the Digital tab::

Subs Add For Cyl – For DS designs which do not use BRS requests to determine the best base curve to use, there are two options.

If this option is checked, this causes Rx-Universe to substitute add power for cylinder power in the base curve selection charts.  This option changes the meaning of the top line of the base curve chart to be add instead of cylinder (for example, Shamir uses this method of base curve selection for their freeform designs).  In this scenario, cylinder power has no effect on base curve selection.

If this option is UNchecked, Rx-Universe will use a standard base curve chart, with cylinder across the top, and sphere down the side, but will add the add power to the sphere power if the sphere power is plus (greater than 0).   Thus, an Rx of +2.00 sphere, -1.00 cylinder, with a 2.00 add, would use the entry in the chart for a +4.00 sphere, -1.00 cylinder. 

For an Rx of -2.00 sphere, 1.00 cylinder with a +2.00 add, Rx-Universe will use the chart entry for -2.00 sphere, -1.00 cylinder (the add is not considered because the sphere power is minus).
If “Use BRS to get BC from DS” flag is used to get the base curve selection from the DS engine, then the “Subs Add for Cyl” flag has no effect.

Center Design – if this design is automatically centered to frame center on the blank (as with Shamir designs), or if you wish the design to be centered for frame center on the blank (as with IOT designs), check this box.  When checked, this causes Rx-Universe to assume the design is centered on the frame center when calculating minimum blanksize, and will cause the IOT VCA label “_DECM” to be set to 1, indicating that the design should be centered for the FGC.  Note that Epson-Seiko does not support centered designs (as of this writing).  This optimizes the blank, and results in the smallest possible blanks being used for jobs.

Near Vision Digital – if the design is a near vision digital (lens is to be verified only at the near and not at distance), check this box.  This causes Rx-Universe to print near power (compensated or not) for validation on the work ticket.

Use BRS to get BC from DS – the VCA 3.07 standard added a way for an LMS to request the base curve range to use for an Rx, rather than using a base curve chart.  Checking this box will cause Rx-Universe to request the base curve range for the Rx using a BRS request, created as an LDS file in the outgoing LDS folder.  Rx-Universe will then look for a .BAS file response, and select a lens that falls within the base curve range specified.

LDS selects blanks to use – if the digital calculator will dictate the blanks to use (by OPC), AND Rx-Universe should not select designs or blanks, check this box.  If checked, Rx-Universe will not attempt to do blank selection at all, and will expect the LMS file that is returned from the digital vendor to include the OPC code(s) of the donor blank(s) to be used for the job.

Use OPC from LMS file - checking this box causes Rx-Universe to use the blank specified in the OPC label of the LMS file.  This would be used, in the case of Nikon designs, for example, where Rx-Universe should do blank selection in order to select the best design based on the seg height of the Rx, but still use the blank that is dictated by the digital vendor in the LMS file.

Trace required – if the digital vendor requires a trace to be present for this design, check this box.  Rx-Universe will not allow creation of a job using this design without a trace present.  Remote orders using this design which do not have a trace will be saved Unvalidated.

Use Anti-Fatigue prism – this is enabled only for SignetArmorlite digital designs; if enabled, it sends _ANTIFATIGUE=1 to the SignetArmorlite calculator for jobs using this lens design.

Blend Edges (_LTLVL or CCBLND) -  if checked, it sets _LTLVL=1 in the LDS file to the digital calculators, and allows access to the “Blend Diam / Bowl Size” field on the F12 Surface Options screen in order entry.  For Essilor, Crossbows and A2Vision digital styles, the blend diameter is sent as a value from 0 through 2.  For all other digital vendors, the value sent will be from 0 through 10.  

Use Alt DEO paths – this is enabled only for Essilor, and is used for Varilux S processing.  Designs with this option checked will use the “alternate paths” set up on the Essilor Digital Calculator screen, instead of the normal path for the surfacing and engraving files. If there is no alternate path set on the Essilor Digital Type, then the files will be created in the normal folders.  This is generally used for Varilux S designs, to place the surfacing files into a separate folder for use by the CLBS blocking devices; these devices will then create the actual files to be used in manufacturing, in the normal folders.

Base Curve Seln Not Allowed – some digital designs require blanks with a specific base curve to be used, and do not allow the lab or dispenser to request any different base curve.  Checking this box will dis-allow specifying a specific base curve for an Rx using this design.

Both eyes required in Rx – some designs require that both eyes be entered and manufactured; check this box if this design has such a requirement.

VCA LNAM – this field will be sent as VCA label LNAM to the digital calculator.  (Note that VCA Label Tables can be used instead of setting the LNAM by lens style – for Essilor, it is necessary to use the VCA Label Tables as the LNAM value is based on the material and color of the lens, as well as the lens style).

VCA LDNAM – this field will be sent as VCA label LDNAM to the digital calculator.  Note that most digital calculators use LNAM (above), but some may use LDNAM, or even both LNAM and LDNAM, to specify the particular digital design to be manufactured.

Laser Template Name – this field indicates what engraving template base files should be used for this design.  This field is used if Rx-Universe is creating the .JOB files for the LaserOp engraver (using the LensMarkJobBuilder program), and is used as the base name for the ENGMASK for a laser connected with VCA protocol.  (See the separate section on interfacing laser engravers).

_TKADOC VALUE – this field (used by the IOT calculator), can be specified for specific designs.  The valid values are (these descriptions come from the IOT documentation):

_TKADOC=0. No adjustment is made; the lens will be calculated to respect the minimum center thickness and minimum edge thickness on the frame shape. No control is made of the thickness outside the frame. This optimizes positive lenses with frame shape to the maximum. This option can produce negative thickness in the cribbing region, which means that the cutting tool will remove all material and can even be cutting into the alloy. Consult your free-form machine provider on the risks of this option for the cutting tools and polishing pads.

_TKADOC=1. The surface is considered to be optically valid on the whole cribbing ellipse, and therefore curvatures are continuous on the whole cribbing region. Thickness for positive lenses cannot be optimized to the frame as much as would be desirable because the elliptical cribbing region is restricting the minimum thickness.

_TKADOC=2. Thickness is calculated so it will respect the minimum center thickness and minimum edge thickness on the frame. The surface is propagated outside the frame increasing curvature within the allowed ranges of the free-form machinery, while avoiding that the concave surface cuts the convex surface. Thickness for positive lenses with frame shape is optimized as much as is possible without negative thickness and within the range of the free-form limitations. Improvement of thickness with this option respect to _TKADOC=1 can be between 0.4 and 1.2mm, depending on prescription and frame shape.

Min Thick at Crib Diam – this corresponds to the MINTHKCD field defined in the VCA specification – edge thickness on a plus lens is normally optimized to give the thinnest possible edge, and thus the thinnest possible center, for the best cosmetic result.  Unfortunately, in the case of cut-to-polish equipment, a moderately strong plus lens in a small frame can result in an edge thickness at the crib diameter which is very thin.  On the generator, this can result in cutter crash (where the blade will cut into the alloy), and on the polisher, this can result in the sharp edge of the cribbed lens cutting into the soft polish block. A lab can get around this problem by specifying a minimum thickness at the cribbing diameter – thus, if the lens is so thin/small that it might cut into the polish tool, this parameter would increase the thickness by requiring the edge at the crib diameter to be 0.5mm (for example).  Please note that this will (obviously) increase the overall thickness of the finished lens as well (the finished ET could be greater than is cosmetically optimal).


Optional Fields Tab

Style-specific VCA labels and values can be set up on the “Optional” tab for the lens style.  For example, to always force CORRLEN=14 for a particular style, add the CORRLEN label, with a value of 14, to the label grid as shown above.

Note that the CORRLEN must be configured as one of the labels to be sent to the calculator, in the LDI file for that calculator (see section 1.1 which discusses LDI files).  Generally, setting labels in this section will be done during discussions with your support rep and the digital vendor, during set up of a new design.

For Indo designs, since they use encrypted surface point files for some equipment, three labels should normally be set up for each Indo lens design (again, as shown above):

LDCRYPT and LDTYPE will be sent to equipment which requests it, indicating the surface data is in Indo encrypted format.  The _OPTIM=1 label instructs Indo to optimize thickness for the design.

Fitting Instrument information (VMAP) when checked, will allow access to the VMAP field in the order 'F12 Surface Options" screen.  This field can be used by some digital calculators to get more information regarding the patient's fitting of lenses.  It references a file that contains information provided by the fitting device used by the optometrist when accessing a patient's needs.