Blended Bifocal design with a 24–28 mm round segment and DuraBase calculations for defined distance and near needs.
Application and design rationale
Two viewing zones, a round segment
The model specifies a 24–28 mm segment width and an 8 mm near-reference position. This differs from DoubleMax's wider segment.
| Design identifier | Description |
|---|---|
| Category | Blended freeform bifocal with a round segment |
| Design type | Blended Bifocal |
Technical specifications
Orderable options depend on prescription, material and current product availability.
| Technical parameter | Value / status |
|---|---|
| Product classMarket Segment | Legacy Product |
| Computational technologyCalculation Technology | DuraBase (Nominal Power) |
| Design typeType | Blended Bifocal |
| Available materialsAllowed Materials | All materials |
| Pre-calibrationPrecalibration | Yes |
| PersonalisationPersonalization | No |
| Prism reference pointPrism Reference Point (PRP) | Geometrical centre |
| Distance reference pointDistance Reference Point (DRP) | Equal to PRP |
| Segment shapeSegment Style | Round |
| Segment widthSegment Width | 24–28 mm |
| Segment vertical dropSegment Vertical Offset | 5 mm |
| Fitting reference pointLayout Reference Point (LRP) | Equal to PRP |
| InsetInset | 2.5 mm |
| Near reference pointNear Reference Point (NRP) | 8 mm |
| Addition rangeAddition Range | +0.50 to +4.00 D |
| PRP decentration range | 0 to 10 mm |
| Specified indices and options | Refractive indices 1.50, 1.53, 1.60, 1.67 and 1.74 (clear, photochromic and polarised); confirm final availability when ordering. |
| Addition step | 0.25 D |
Design mechanism and features
Round segment with a blended surface
DualMax is a freeform bifocal with a round segment. The document describes digital rear-surface machining and a blended rather than raised segment junction. It has distinct distance/near zones, not a continuous intermediate corridor.
Difference from DoubleMax
DualMax specifies segment width 24–28 mm and NRP 8 mm. DoubleMax has a 40–45 mm Round Ultex segment and 10 mm NRP. These differences inform near-field selection and frame fit.
Technologies in this design
- DuraBase
- Nominal-power calculations; also described as Nominal Power in the sources.
Measure before manufacture
Required parameters vary by design and must be recorded by a professional.
- Monocular PD
- Each eye's pupillary distance is recorded separately to align horizontal lens positioning with the visual axis.
- Fitting Height
- Fitting height is recorded on the adjusted frame in the natural position of wear; the required near zone must also fit within the frame.
- Box A
- Horizontal width of the frame opening in the boxing system.
- Box B
- Vertical height of the frame opening in the boxing system.
- DBL
- Distance between the two lens boxes at the frame bridge.
- ED
- Effective diameter: twice the greatest distance from the boxing centre to the lens-shape edge, used for blank selection and edging calculations.
Design-specific inputs
- Segment Width: choose a standard round-segment dimension of 24 or 28 mm according to the wearer's movement habits.
- Inset (near-vision shift): fixed at 2.5 mm inward to match natural eye convergence during reading.
Monocular pupillary distance
For aligning the lens centre with each eye's visual axis.
Fitting height
Vertical pupil position relative to the frame in the position of wear.
Back vertex distance
One of the inputs describing the actual position of wear.
These are basic fitting parameters; additional inputs and the level of personalisation are specified for each model.
Complete parameter guide ↖View the original catalogue page
