Ordering contact lenses online? You could save 20% by NOT buying direct

We've checked the prices of products sold by eight online contact-lens retailers. Four – Alensa, FeelGoodContacts, Lenstore and Vision Direct – often offered a discount to shoppers who came via a comparison site such as Google Shopping, PriceRunner or PriceSpy rather than going direct to the retailer's website.

Some of the retailers have admitted they offer these extra discounts as they want to feature at the top of comparison sites' search results.

For full help on how to slash the cost of lenses, see our guide.

How much can this trick save?

The exact saving you can make depends on what you're buying and where you're shopping, but our checks show it's possible to cut the cost of lenses by up to 24%. For instance, a pack of 30 Acuvue Moist lenses bought direct from Vision Direct cost £15.99 – yet clicking to the same site via Google Shopping made exactly the same item £3.84 cheaper.

While lenses were usually shown on the retailers' sites as discounted, it was not made clear on the comparison sites or retailers' sites that customers were paying less simply because they'd clicked through from a comparison site.

We looked at the prices of five packs of contact lenses in total. With FeelGoodContacts, 5/5 were cheaper via comparison sites. For Alensa it was 4/5 and Lenstore 3/5. With Vision Direct, we were only able to find one of the packs listed on a comparison site, and it was cheaper via Google Shopping.

The discounts varied between different price-comparison sites though – here's what we found for one of the products:

Variation in prices of 30 Acuvue Moist lenses

Even with these sites, going via a comparison site wasn't ALWAYS cheaper though – in some cases going direct got the best price.

It's worth noting that if you go to a retailer via a comparison site you'll miss out on any cashback you could get by going to the retailer direct – right now, for example, Topcashback offers between 4.2% and 10.5% for the four sites. But some of these cashback offers are for new customers only, or require a minimum spend.

How to make sure you get the cheapest price

Our research shows that you should check the price of contact lenses going via all the main comparison sites if you can – then see if you can beat it going direct, which in some cases will still win.

This isn't the only trick you can use to save on the cost of contacts. Our Cheap Contact Lenses guide has 12 other tips, including:

• How to find own-brand lenses cheaper online. A lot of high-street optician chains sell manufacturers' contact lenses 'disguised' under their own branding.

• Swap to monthly lenses – they can be cheaper than dailies. Always check with your optician whether they're suitable first.

• Reclaim the costs on a healthcare cash plan. Healthcare cash plans allow you to reclaim the cost of dental, optical and other forms of healthcare, whether you get these via the NHS or not.

• How to check online sellers are legit. Ask the seller who its registered optician is, then check the name against the General Optical Council's register.

What do the retailers say?

A spokesperson for Alensa admitted that the company offered a "deliberate discount" to shoppers using Google Shopping, and said: "Because our regular prices are not in sync with Google Shopping, clicking through the Google Shopping link is automatically a discount as a way to help guarantee lowest market price."

He added: "For customers who come to us directly and find a better price on another website, we are always more than happy to manually adjust our prices in accordance with our lowest-price guarantee."

A FeelGoodContacts spokesperson said: "We acknowledge the key role that Google Shopping plays in the world of e-commerce, and strive to accommodate for that customer group with a reduction on our already-competitive prices."

Lenstore told us: "Whilst offering reduced prices via Google shopping has become common practice for online contact lens retailers, we pride ourselves on our level of ongoing care and service... If any of our customers have questions regarding our prices, we'd like to reassure them that our team will happily match the prices we display on Google."

We've also contacted Vision Direct, and will update this story when they respond.

Seen this trick work elsewhere?

This trick doesn't work with all online contact-lens retailers. With four others we tried – ContactLenses.co.uk, Lenssaver, Lentiamo and Mister Spex – there was no difference in price between going via a comparison site and going direct.

We also couldn't find cheaper prices via comparison sites for other types of retailer, such as Amazon, Feel Unique, John Lewis and Sports Direct. If you've spotted any other online retailers which offer comparison site discounts, please let us know in the comments below or by emailing news@moneysavingexpert.com.