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Colorimetry and Visual Stress

Visual Stress can contribute to reading difficulties in both children and adults.

Visual stress is due to overstimulation of the visual cortex (the visual processing part of our brains) by certain visual patterns such as lines of black text on a white background.

Symptoms of visual stress include:

  • Letters and words appear as if they are moving
  • Skipping words or lines
  • Blurring of print
  • Re-reading the same line frequently
  • Discomfort when reading
  • Glare from a white page
  • Patterns in the print
  • Moving the reading material around the desk
  • Poor comprehension of reading material

Visual stress largely goes unrecognised in both children and adults. So often we have adults who have never been able to explain why they have struggled with reading tasks throughout their life, and there is a real ‘light bulb’ moment when they see the benefits of treating their visual stress.

Prior to undertaking any formal colorimetry assessment, a full eye examination is carried out to ensure there are no underlying issues such as refractive error, or muscle imbalance between the two eyes.

The colorimetry assessment itself uses a sophisticated machine that measures an individuals response to text that is viewed under varying highly controlled colour light conditions. The coloured tint that best reduces visual stress can then be accurately calculated, and coloured spectacles ordered accordingly.

Related Reading

Colour in the Classroom, an article from

Intuitive Colorimeter

This instrument was developed by Professor Arnold Wilkins and the Medical Research Council and manufactured exclusively by CVT and is fully supported by research studies and peer reviewed controlled trials.

It is used by our Optometrists to logically and sequentially explore colour space to find the optimal Precision Tint for the relief of perceptual distortions in Visual Stress.

The instrument independently changes the 3 parameters of colour, hue, saturation and brightness while the eyes are colour adapted.  This will give a final colour which is extremely precise to each individuals needs. The colour will be different for each person and the precision coming from a choice of over 100,000 colour combinations now available. In its most effective form this prescription will be delivered as Cerium Precision Tinted Lenses.

The tint is selected rapidly and efficiently in an examination lasting about 20-30 minutes.

The optimal colour which will benefit each individual can change over time, especially with children. It is therefore very important that the patient visits the specialised Optometrist regularly for re-evaluations.

The optimal colour can also be available with soft Contact Lenses.


Having previously tried varifocals and not got on with them I was extremely reluctant to try them again, but was becoming increasingly frustrated at constantly swapping between different pairs of spectacles.

Perhaps somewhat naively, I thought all varifocals were the same.

It wasn't until I had an eye examination at Shrewsbury Optometry that I actually had it explained to me that there was a type of varifocal that could give me the extra reading and computer distance focus that I needed.

I was impressed with the digital lens measuring, and the bespoke lens service that I was provided with.

I now happily wear my varifocals for all my day to day office work, and gone are the days of swapping spectacles.

On our Lenses

Wonderful service from very nice people who genuinely care! Nothing like the high street chains at all! Attention to detail and customer care second to none. I can honestly say I have never had a better eye test! I can honestly say I have never had such wonderful help in choosing glasses and lenses! I will never go back to the high street multiples. I discovered today that the glasses I'd had from a now obsolete high street chain about three years ago were far too strong! I hardly wore them at all because they made me feel sick! Now I know why! If you need an eye test and new glasses go to these people! Danielle on the eye tests and Jess on the glasses choice and fitting - both of them are just wonderful in my opinion!

Jeremy Higgins

I was diagnosed as having a corneal disease called kerataconus some five years ago. In that time I tried a number of different opticians who didn't seem to understand my condition, and I ended up with spectacles that simply didn't give me the vision I needed.

It wasn't until I got referred to Gareth Hardcastle by my consultant Ophthalmologist that I found someone who finally understood my eye condition.

Now some five years later, I am happily wearing specialist contact lenses which give me fantastic vision from morning to night.

Simon C

Our daughter Erin has Down's syndrome, and has a number of healthy issues including problems with her visual development.

I first came to hear about Shrewsbury Optometry though the hospital eye service, and was recommended to them, having had trouble finding spectaclesthat fit properly.

We saw Elizabeth who took her time to find the right frame for Erin with a specially adapted bridge that meant she no longer peered over the top of her glasses all the time.

We noticed an almost immediate difference in Erin's behaviour, and she began to take interest in objects around her, that we realised she simply wasn't seeing with standard spectacle frames.

We can't thank you enough for the time and care you took for our beautiful daughter.

On our Children's Glasses

I wouldn't go anywhere else for my optical appointments!

My sight is too important to not use the best!

The staff are all very supportive and will ALWAYS go the extra mile to ensure that you are totally happy with your prescription and frames. When there has been a problem, they rectify it as fast as they are able. I have never been disappointed with the service I have received!

Thank you!

Graham Farmer

Having been to several different opticians over the years I became disillusioned with the quality of service and care I received. I never seemed to see the same optician twice, and always felt like their main priority was to sell me a pair of glasses.

My first examination at Shrewsbury Optometry was like a breath of fresh air. I immediately felt like I was in the hands of a professional team, and the level of examination I received was far beyond anything I had received before.

In the ten years since that first examination I have always seen Jenny Hardcastle, and I never ceased to be amazed at the new equipment used during the examinations, which seems to get more sophisticated every year.

Mrs Catrina B

I hadn't been to see an Optician in about 10 years. I went today and was pleasantly surprised. I was welcomed the moment I walked through the door. All the staff were very helpful and friendly. Mrs Hardcastle was brilliant and explained everything in detail. Nice to know I can still be a fighter pilot! Would recommend this Optometry to anyone.Thank you everyone.

Lorraine Pryce

I hate eye tests, but staff here made me feel so at ease from the moment I walked through the door. I left knowing I made the right choice for change. Thank you.

Carole Markham