No7 Contact Lenses: Student Support website
This brilliantly conceived yet simple-to-fit contact lens is the first choice for many practitioners around the world. Thousands of successful long term wearers confirm this enduring product to be the ultimate in its class.
– Quasar SV
Superbly conceived and easy to fit, it’s the first choice for many practitioners around the world. Plus thousands of successful long term wearers confirm it as the ultimate lens in its class.
Designed by practititoners for practitioners, the Quasar lens is truly aspheric from centre to edge. The central area consists of a modified conic profile, which is designed to flatten at a much slower rate than a fixed elliptical curve. This improves centration characteristics and eliminates any significant positive/astigmatic aberration over the central 7mm. This unique aspheric geometry results in slight apical clearance and close alignment over the mid-peripheral cornea. Edge clearance is achieved by the addition of a second aspheric edge band. Constant apical and edge clearance are maintained independent of base curve and total diameter.
– Quasar SV
No7 recommends the Optimum rage of materials. Other materials available on request.
|Radii||7.00 to 9.00mm in 0.05 steps|
|Total Diameters||8.80, 9.20, 9.60, 10.00mm|
|BV Power Range||+25.00 to -25.00 in 0.25D steps|
– Quasar SV
The Quasar lens has been designed to make the transition from fitting spherical lenses to aspheric lenses as straightforward as possible. The initial trial lens selection is based on the corneal cylinder as follows: –
Initial Trial Lens Selection
|0.00 to 1.50D Cyl||Select lens on flattest K /nearest steeper lens|
|1.50 to 3.00D Cyl||Select 0.10 steeper than the flattest K|
|Over 3.00D Cyl||Consider Quasar Toric|
The trial lens is placed on the eye and an assessment of fit is made. Either a flatter lens is selected if the fluorescein pattern is like Figure 1
or a steeper lens is selected if the fluorescein pattern is like Figure 2
Once an optimal fit has been attained, as demonstrated in Figure 3, an over refraction is carried out. An allowance is then made for effectivity and the final radius and power are determined.
If the total diameter is considered too small and there is insufficient coverage of the pupil or poor centration, the larger diameter should be ordered with NO CHANGE to the radius or power. If the lens is considered too large and there is insufficient vertical movement with the blink, the smaller total diameter should be ordered, again with NO CHANGE to radius or power.
The final fitting lens should give good vertical movement with the blink and move temporally and nasally looking left and right. Vision should remain clear between blinks and there should be no increased flare from a spot light source in a darkened room. Optimal fitting should result in a very comfortable lens.
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