With the computer-assisted technique OPTIMA, the edge and centre thickness visible in the frame can be reduced to a minimum. Often, the lens can be produced much more thinly than the smallest possible uncut lens diameter allows.
The thickness of plus lenses is heavily dependent on the diameter ordered.
The possibility of choosing a lens material and surface geometry (sphere, asphere or atorus) allows the eyecare professional to influence the edge and centre thickness of a lens. He or she can also influence the edge and centre thickness visible in the frame by selecting an appropriate frame shape and size.
The general rule is: the smaller the frame selected, the thinner the lens can be. While in minus lenses only the frame eye size influences the edge thickness, the centre thickness of plus lenses is heavily dependent on the ordered diameter of the uncut lens. The smaller the uncut diameter, the thinner the plus lens becomes.
Since the mid-1980s, ZEISS has offered a new technology which allows a further reduction in lens thickness in many cases. With our OPTIMA thickness reduction system, it is possible to reduce the thickness and weight not only of single vision plus lenses with an astigmatic power in particular, but also of progressive and prismatic lenses, in some cases by over 50%.
In the past few years considerable progress has been made in the production of thin, lightweight lenses. This has also resulted in a considerable enhancement in wearing comfort. The development of high index lens materials and the computation and production of aspheric and atoric lenses have both played key roles in achieving these advances.
In the OPTIMA technique the entire back surface of the lens is ground more thinly without changing the dioptric or prismatic power. This results not only in decreased thickness, but also in a smaller finished lens. The lens is not produced with a round shape, but its form approximates that of the finished lens. The lens is just large enough for glazing. The typical uncut shape of ZEISS OPTIMA lenses is the result.
|Power in principal meridian 0°:||+ 2.0 D|
|Power in principal meridian 90°:||+ 4.0 D|
Like every lens with an astigmatic power, the lens in this example displays a different thickness in the two principal meridians. This is attributable to the different back surface radii which produce the astigmatic power (inner toric). The maximum edge thickness (ET max) of a lens always lies in the plus cylinder axis. In this example, this means that ET max lies at 0°.
If OPTIMA thickness reduction is used for this example, the lens becomes thinner in the thick areas (0° and 180°) and smaller in the thin areas (90° and 270°) during grinding.
In this way, an OPTIMA lens is produced which is longer in the mathematically weaker principal meridian, is no longer round in shape and is very thin.
OPTIMA is recommended if a thickness reduction of at least approx. 0.5 mm can be achieved for the given frame and centration data. For every OPTIMA order, our customer service team checks whether this value is feasible or not.
The following factors determine the thickness reduction achieved:
There is no rule of thumb to assess the suitability of lenses for OPTIMA. However, the following table shows for what lens types OPTIMA thickness reduction is sensible, depending on the dioptric and prismatic power.
A worthwhile reduction in thickness can frequently be achieved with OPTIMA.
Attention: Minus Lenses with spherical power can never be reduced in thickness with OPTIMA.
|Lens type||Plus lens with sph. power||Lens with astig. power (1st prin. mer. positive)||Lens with prismatic power|
Depending on combination
of power and base
for predecentred bifoclas
Depending on combination of power and base
Depending on combination of power and base
As there is a large number of possible power combinations, especially for lenses with prismatic power, no really accurate information can be given concerning the thickness reduction possible with OPTIMA without an exact specification of the lens values.
You can perform an OPTIMA computation when advising patients by using the Infral/Winfral lens recommendation program from ZEISS. Immediate information is given on the extent of the thickness reduction possible with OPTIMA. All influences are taken into account and can be ideally incorporated in your consultations with patients.
Tips for eye care professionals
Specify the centration data (fitting height and centration distance):
Specify the lens shape
For spectacle frames from ZEISS, an indication of the model number and frame dimensions is sufficient. Otherwise, a drawing of the lens shape is required, showing the centration data.
If technically possible, a requested minimum edge and centre thickness (e. g. for Supra frames or rimless frames with screw connections) can be taken into account.