Should have gone to physics class? Specsavers may be blinding you with bad science

A physics lecturer questions an in-store demonstration the company uses

“The shop assistant showed me a device she said showed the efficacy of polarising layers over nonpolarising ones”

Has Specsavers been blinding its customers with bad science and a test that cannot be replicated in the real world in order to sell high-priced lenses to the unsuspecting? That is the question a reader called John Houlihan posed in a mail he sent to Pricewatch last week.

It just so happens that Houlihan is a physics lecturer at Waterford Institute of Technology and has a research specialism in optics. He went to a Specsavers branch in Midleton, Co Cork, and quickly found himself using his expertise to question a test the retailer was using to help sell polarised lenses.

“This morning I called to inquire about getting prescription sunglasses,” his mail begins. “As part of the discussion I was asked whether I would like to have polarising or nonpolarising intensity reduction layers.”

There is a fairly substantial price difference between the two options, with the nonpolarising lenses costing €39 and the alternative costing €79.


“I wasn’t sure,” he continues, “so to help me make my decision the shop assistant showed me a device that she claimed demonstrated the efficacy of polarising layers over nonpolarising ones.”

So far, so good, you might think. Here was a helpful staff member with a test that would show Houlihan the difference between the two options. But that is not what he thought. He quickly decided the device was “basically a trick one which projected two spatially offset images to the observer, each of which is orthogonally polarised”, he says.

We’re not going to lie, he was starting to lose us at this point.

He then made his point clearer by saying that when the images were viewed through nonpolarising glasses, “the observed image is a sum of the two and so appears blurred due to the intentional spatial offset. When viewed through the polarising glasses, one of the images is blocked and the observer sees only one image so it appears much sharper.”

Now Pricewatch is not a physics lecturer with a speciality in optics but even we can see that something sounds iffy about this.

Houlihan says this situation “does not occur naturally when driving or otherwise so the device cannot be said to replicate any natural environment. Rather, it is designed to ‘prove’ that polarising layers give sharper images than nonpolarising ones (less than half the price)”.

This test appears troubling on many levels. First, it is using “science” to create an impression among consumers – many of whom would have as little a grasp of optics and light as Pricewatch – that the polarised lenses are going to do something that they don’t really do. That is misleading at best. It is made worse because of the substantial price discrepancy between the two options.

Given that Specsavers operates a franchise model and has branches across the State and the UK, we were also concerned that such devices might be utilised across all of its stores to show mainly nonphysicists the so-called difference between the options.

The response

We asked Specsavers if it accepted the view of a physics lecturer with a research speciality in optics that its test is flawed, and in a way that clearly disadvantages consumers?

We also asked how widespread the use of this “test” was. How long has it been used? And how many customers have been encouraged to spend significantly more on lenses as a result of doing this test?

And we wondered if the “test” been approved by the Irish College of Ophthalmologists or any equivalent in the UK? And finally we asked what proof Specsavers could offer that this “test” works.

In response, Specsavers sent us a statement from Russell Peake, the head of ophthalmic lenses and dispensing. This is it in full:

“There are clear and demonstrative benefits to using polarising lenses over conventional sunglasses, which enhance the quality of vision for outdoor glasses wearers.

“Polarising lenses are more effective in blocking glare, helping to effectively eliminate the problems associated with unwanted reflections. Specsavers’ polarising lenses are manufactured with a microfilm polarising filter which is moulded into the lens. This filter acts like a Venetian blind, eliminating glare from flat or horizontal surfaces, only allowing vertical light to travel through the lens, which results in improved vision and comfort for the wearer.

“The in-store technology used by Specsavers in Midleton is produced by a specialist manufacturer and is designed to demonstrate a specific benefit of polarising lenses: reduction of horizontal glare, which often appears on the windscreens of cars. While it is not always apparent, it appears quite frequently during the daytime. The intensity of the reflection depends on a variety of conditions such as direction of the sunlight and its brightness, colour of the dashboard material and a few others. Nevertheless, this reflection is almost always present and, in some cases, it can create a serious visual obstruction for the driver.

“In order to demonstrate this phenomenon, the manufacturer created a display using a special reflective film, which reflects horizontally polarised light on the picture installed in the display producing glare which creates visual obstruction. If a customer looks at the picture through polarising lenses with horizontal absorption axis, the obstruction is virtually eliminated, resulting in higher clarity of image. This simulates what happens when a driver uses polarising lenses in the car. The glare on the windscreen is eliminated, resulting in better visibility, which can improve driver safety.

“Specsavers has used the technology for a number of years and it is one of the most commonly used demonstrators in high-street opticians. Most businesses use very similar technology.

“The demonstrator is used as a tool to help our customers make an informed decision about polarising lenses. We apologise if the benefits of the lenses were not properly explained in this case. The store staff will be undergoing more training to make sure they demonstrate and explain our lens options clearly to customers.”