Swapping one type of contact lens for another

Clinical input is required when contact lenses are substituted

A boy putting in contact lenses

Suppliers of contact lenses sometimes swap or ‘substitute’ a different lens for the one that was originally specified for the patient. To manage the risks involved, the clinical professional who oversees and authorises the supply of lenses must take responsibility for making sure that the decision to substitute lenses is in the patient’s interests. 

Supply and fitting of contact lenses 

Contact lenses vary in size, shape and the material they are made from. When contact lenses are prescribed for a patient, a qualified and registered professional must consider these things and check the lenses to make sure they are well fitted and suitable1

Patients with a valid contact lens specification can then buy lenses from other suppliers, including online. This process must also be overseen by a suitably qualified and registered professional. 

Substituting contact lenses  

The supplier must check the original lens specification, but the wording of the legislation appears not to require them to match it exactly, and so appears to allow the substitution of a different lens. 

Substituting one lens for another can provide patients and optical professionals with useful flexibility where the specified lens isn’t available – for instance, if a patient needs a fresh supply of contact lenses just before going on a holiday, but the specified lens is not in stock, or when a type of lens is discontinued. However, the supplier must be satisfied that the substitute lens will fit properly and will not cause harm.

Risk of harm? 

Substituting one lens for another in other circumstances is more controversial. However, the regulator of the optical sector, the General Optical Council (GOC), has said that in the absence of any clear evidence of harm, it does not intend to take action against a business that substitutes one lens for another. 

There are many different lenses on the market with different features. This in itself means that evidence of harm caused by a certain lens to certain types of patient is hard to identify – the numbers are small. But it is a fact that for some patients, some types of lens are better than others. That is why they must be fitted by a suitably qualified professional, and why the professional overseeing and authorising the supply of contact lenses must take care when substituting one lens for another.

What we think

We advise our members that to manage the risk of harm appropriately and ensure patient safety: 

  • Where a contact lens supplier substitutes one brand or type of lens for another, the registered optical professional who oversees and authorises the substitution will be responsible for ensuring that the change of lens is clinically appropriate and in the interests of the patient, and
  • Any decision to substitute lenses should therefore only be taken with clinical input from an appropriately qualified registered professional

1  “Only registered optometrists, dispensing opticians with a specialist qualification (contact lens opticians) and medical practitioners can fit contact lenses.” - From GOC Patient leaflet Buying Contact lenses p.3 (accessed November 2018)


November 2018

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