No7 Contact Lenses: Student Support website
Our Quasar Plus lens cleverly utilises the tear layer to provide precise vision at distance, intermediate and near. Clinical trials using empirical fitting have delivered an outstanding success rate of 86%.
– Quasar Plus
The innovative Quasar Plus design cleverly uses the eyes’ own tears to deliver precise vision at distance, intermediate and near. Clinical trials conducted using empirical fitting have shown impressive results – a success rate of 86%.
The Quasar Plus is a distance centre multifocal with a graduated annulus of near vision where the progressive power is incorporated into the optics of the back surface of the lens. The aspheric design of the optical zone is based upon the patient’s degree of ametropia and the reading addition required, so the higher the myopia and the higher the add, the greater the asphericity. By incorporating the asphericity into the back surface, the profile of the tear film will be altered, so when assessing the fit of the Multifocal, it is important to understand that the resulting fluorescein pattern will be different from that obtained with a single vision lens.
– Quasar Plus
No7 recommends the Optimum rage of materials. Other materials available on request.
|Radii||7.00 to 9.00mm in 0.05 steps|
|Max Difference Flat/Steep||0.20mm|
|Total Diameters||9.50mm to 10.50|
|B.V. Power Range||-10.00 to +12.00D|
|Add Powers||0.75 to 2.50D (up to 3.50 on certain B.O.Z.R. and distance power combinations)|
– Quasar Plus
The Multifocal is designed to mimic the tear profile of a single vision lens with the exception of the variable central aspheric back surface. This alters the tear layer thickness and generates the reading addition. Quasar Plus is best fitted empirically, from K’s and Spec RX.
The lens ordered will have required altered fluorescein pattern and the patient will notice an increased depth of focus, improving their ability to read and perform close work. For some this improvement is instant, but for others, a longer adaptation period is required. Assuming satisfactory acuity for distance and near, the patient should trial the lens for up to two weeks before making any change to the lens power from resultant over-refractions.
If the fit of the lens is poor then correct the fit before making power changes. When ordering a change in prescription we will need to know the original lens order so that the required alterations can be incorporated.
If you originally ordered:
7.80 9.60 -4.50 Add +2.00
and you find an over-refraction of -0.50 distance and no extra add is required (i.e. plano over-refraction in front of patient for near vision) then you will need 7.80 9.60 -5.00 Add +2.50, inform the laboratory you need an extra -0.50 in the distance and no extra power for near.
If you originally ordered:
7.80 9.60 -4.50 Add +1.50
and you find an over-refraction of -0.50 distance and an extra add of +0.50 is required (i.e. +0.50 over-refraction in front of patient for near vision) then you will need 7.80 9.60 -5.00 Add +2.50, inform the laboratory you will need an extra -0.50 in the distance and an extra +0.50 for near. Remember: This lens needs at least 15 to 20 minutes to settle for the tear film to stabilise and provide the reading addition.
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. The Quasar Plus 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.
Astigmatism greater than 2.00D. A stable freely moving lens design is needed; high degrees of corneal astigmatism will result in a compromised fit and will disrupt the visual performance. Using a spherical lens design to correct high degrees of astigmatism creates variable fluctuating tear film. Such fluctuations interrupt the back surface optics of the Multifocal; therefore these situations should be avoided.
Cannot establish a satisfactory single vision 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.
Quick Fitting Guide
- Order from K’s and Spec RX
- For more information on fitting Quasar Plus, click here and watch our ‘Multifocal RGP lenses’ course
Then order the lens providing the following information:
- B.O.Z.R. (from the single vision lens used in the trial)
- Total Diameter (from the single vision lens used in the trial)
- B.V.P. (power of the diagnostic lens plus over-refraction)
- Required reading addition.
- Poor centration with a single vision lens
- Astigmatism greater than 2.00D
- You could not establish a satisfactory single vision lens fit
- Any corneal pathology present, i.e. keratoconus
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