Our patients are so happy when their bothersome double vision is improved, or even resolved with a Fresnel Prism fitted by a member of our orthoptic team. They fit onto your own glasses, or if you don’t need glasses for vision we use a pair of ‘plano’ glasses with no strength in the lenses.
In difficult to treat double vision cases, or cases that have potential to resolve, Fresnel Prisms are a great option for temporary correction (up to 2 years) prior to incorporating into your glasses. With good care we have seen one Fresnel last for 4 years before it required replacement! So just know that its worth taking the time to keep it clean to ensure its longevity.
However they have a few downsides that you need to know about:
Reduced Contrast Sensitivity – the stronger the prism, the more blur the patient will experience. This is why we fit Fresnel Prisms onto only one side of the glasses, to keep your vision in tact. In most cases the benefit of the prismatic correction outweighs the blur, but this is something that we check with every individual patient to make sure it is tolerable.
Rainbows and Halo’s – due to the design of Fresnel Prisms, they will catch the light in certain positions and cause aberrations.
Tricky to keep clean – the ridges in the prism will trap dust, dirt and skin cells which are not removed with standard spray glasses cleaners or cloths.
Eventually all patients whose double vision won’t resolve will be given a prescription to take to an optometrist of their choice to incorporate the prism into their glasses. The timeline for this is based on the underlying cause of their condition, and how stable their prism has been.
Incorporated prisms (‘ground in’) stop all of the downsides listed above, but there is a higher cost associated as you will require new glasses.
To keep your prism working as well as possible, here are some of our tips and tricks to keep it sparkling and working its best:
Purchase a soft baby tooth brush, this can help as it cleans away the dust which collects in the ridges without damaging the prism
Use a soft glasses cleaning cloth, it is important to use a lint free cloth as otherwise fibres can collect in the ridges of the prism and reduce the clarity of your prism. Gently wipe the prism as you would your glasses lens
Use glasses lens cleaner, this can remove any dust, make up etc from the prism and allow for a clearer prism
A combination of all 3 can keep your prism looking clean and improve clarity and with this prolong its longevity.
Ready-made Cleaning Kits
At Adelaide Orthoptics we offer tailored Fresnel Prism cleaning kits which can help you with the maintenance of your prism.
You can purchase these at our online store, or pick one up at your next appointment.