What is a contact lens prescription?
Both spectacle and contact lens prescriptions have details of the lens power required to help you see better.
A contact lens prescription is more detailed than a spectacle prescription. It includes the size, shape and optical power of the lenses and specifies the material from which the lens is made and the brand name.
It may also include the colour of the lens and edge profile details if more customised.
A contact lens prescription also has an expiry date, because the wearer’s vision could change and because lenses may impact on the condition of the wearer’s eye surface. A typically review period would be yearly.
How do I get contact lenses for the first time?
Contact lenses must be prescribed by a person who is qualified to do so – an optometrist or ophthalmologist (eye specialist). You’ll find a list of New Zealand contact lens experts here.
Arriving at a prescription is a multi-step process, which may require several consultations and trial fittings. Initial steps include an assessment of your vision and your eye shape and a detailed examination of your eye surface, eyelids and tear film. There’ll be a discussion about which lens is most suitable for you and the advantages and disadvantages of different types of lenses, and the costs associated with each type.
During the fitting process, you will have lenses placed on your eye, which will be assessed for the vision they provide and for their physical fit. You’ll be taught how to get your lenses in and out and how to look after them. After you have worn lenses for a period of time, further examination will assess the lenses in terms of vision, comfort and physical performance. Changes may be made and further assessment will take place. Once both the practitioner and the client are satisfied with the result a prescription will be issued.
I already wear contact lenses...
Most people in New Zealand buy their lenses from an optometrist or from a website.
Websites may be run by an individual (optometrist or otherwise), an optometry chain or a big corporation.
You must have a current contact lens prescription to purchase contact lenses, although some vendors are more rigorous about this than others.
Should I buy contact lenses from a website?
There’s no right answer to this question! A company that only sells online and doesn’t have a physical store or consulting rooms usually has lower overheads and may have bigger buying power than its competitors, which can mean cheaper lenses. However, the online supplier doesn’t have the same duty of care as your optometrist or ophthalmologist to ensure that the lenses being supplied are an appropriate prescription for you, or safe for your eyes.
There’s always some risk that lenses may be counterfeit. You should consider where the company is based and where your lenses are coming from and how long they’ll take to arrive. If you wear specially made lenses, buying them from your optometrist or eye specialist usually includes them checking the lenses both on and off your eye to make sure they meet their specifications and perform as expected.
Can I purchase a different brand from the one I was prescribed?
This is unwise, because different lens materials have different physical properties. Properties that vary between lenses include the modulus (stiffness), thickness, water content and oxygen transmission. Varying these properties may alter your comfort and how healthy the lenses are for your eyes.
Should I have an exam before buying more lenses?
Even though you may have been wearing the same contact lens prescription for some time, changes in vision can be so gradual that you might not notice the shift and eye health issues can arise without any significant signs.
Having an exam ensures that you are still seeing well and that your eye surface is healthy. An exam can also detect any early signs of difficulty with future contact lens use and ensures that you are wearing the right lenses for your needs.
Optometrists and eye specialists have a duty of care to ensure the ongoing health of your eyes that continued contact lens wear remains safe.
What are the risks of wearing contact lenses?
Modern contact lenses are designed for safe healthy wear, however, they require appropriate care and handling to maintain vision clarity and to minimse the risk of eye infections, ocular inflammation and allergic reactions. Regular review with an optometrist, typically annually, is the best way to avoid these complications of contact lens wear.