No7, driven by its culture of original thinking and continuous improvement has developed a radical aspheric front surface multifocal, which incorporates wavefront -controlled centre distance optics and also provides intermediate and reading power.
The power characteristics are defined by the front surface geometry alone, so the back surface can be of standard aspheric or spherical design. This makes it easy to fit existing GP wearers with the front surface multifocal.
To download the Quasar FS fitting guide click here
Quasar FS is best fitted empirically using the patient's spec rx, required reading add and K readings. The ideal fit is the same as the single vision Quasar. This can be a toric back surface if required. The fluorescein fit should be alignment in the mid periphery and slight apical clearance. Constant apical and edge clearance are maintained independent of the base curve and total diameter.
It is important that the lens sits central or slightly low on the patient's cornea, this allows correct aligment of the distance prescription and allow optimum near vision with some translation on down gaze
As with all lenses, not every patient is suitable for all designs. To maintain confidence and a high success rate, avoid prescribing this lens to patients who present the following:
- Poor centration with the single vision diagnostic lens. The Quasar FS Multifocal lens will work best when centration is good. A high-riding lens or displaced lens will not allow the optics of the lens design to provide any reading addition.
- Cannot establish a satisfactory single vision diagnostic fit. If a patient cannot wear or use single vision rigid lenses, they are unlikely to be successful with the Multifocal design. The design has been developed to help you with the presbyopic lens population.
- Any corneal pathology present, i.e. keratoconus. A diseased cornea will not provide a stable platform, as a result the patient will complain of variable vision or an unreliable reading add.
