Contrast and Low Vision Moorfields Eye Hospital, UCL & Kingston University London Rubin, Dalke, Corso and Riaz Research funded by Special Trustees of Moorfields Eye Hospital Trustees Fund

Work on contrast has been ongoing since 2003 Dalke, Corso, Riaz

UCL/Moorfields Trust Project Rubin, Dalke, Corso, Riaz Research had the main aim of informing designers and architects about the importance of contrast Since 2012 with Professor Rubin at UCL

CONTRAST We don’t need to tell you all how important this is for people with low vision! Contrast helps people to navigate the environment with added confidence

Whether it is a cup on a cafe table……

...or a wc against a wall

Contrast is needed for VIPs to see these things which can be dangerous obstacles

Several things are important to understand on this subject first of all: 1 Surfaces have light reflectance values from 0% BLACK (None), to 100% which is WHITE 2 Contrast is the difference between two adjacent surfaces’/objects’ light reflectance values – E.G HANDRAIL ON WALL 3The light reflectance value % of a surface has to be measured to calculate if the difference is contrasting enough FACTS ABOUT CONTRAST

LIGHT REFLECTANCE VALUE But what makes contrast? Light reflectance value difference % between two adjacent surfaces is simple to gauge Taking one number away from another – it’s not rocket science!

WALL Background LRV Object/element LRV This is how it works Contrast difference 10% Light Reflectance Value (LRV ) 60% LRV Contrast = ( ) 50 points of contrast difference WALL DOOR Adjacent edges

INTRODUCTION Results from previous studies on contrast in the environment needed further investigation – Rubin & Dalke expertise We needed to find out about the contrast levels effective for people with very low vision An aim was to arrive at some empirical data to inform future accessibility policy and guidance

INTRODUCTION Quantifying the contrast needed has been the subject of this current investigation But involving a large group from the low vision community was most important Accessed expertise from the three bases – UCL, Moorfields and Kingston University London

PARTICIPANTS 105 volunteers, 35 in each of 3 vision groups (Dalke, et al 2011, Grundy et al 1999) V3 Cannot recognise a friend if close to his/her face V4 Cannot recognise a friend who is at arm’s length away V5 Cannot read a newspaper headline Age Able to walk unassisted

Snellen Visual Acuity Mars Letter Contrast Sensitivity VISION ASSESSMENTS

FACILITY The lab was 7 metres in length, floor marked at half metres on a line towards the end wall The testing was conducted in this controlled environment A daylight-proof laboratory at UCL, Institute of Ophthalmology, Bath Street, London

GREYSCALE PATCHES 10 sets of painted LRV greyscale paper square patches Greys measured with spectrophotometer to get the right LRV greyscale patches painted for tests 50mm, 150mm, 300mm, 750mm square patches

METHOD One patch at a time placed in a random location on a black wall 0% LRV in a dimly lit room (100 lux) Participant positioned 7 meters from patch Instructed to walk towards wall until they could see the patch Distance at which the patch was correctly identified was recorded Experiment took about 90 minutes to complete

RF THE TESTS This shows RF Alessio Corso working with participant volunteers The volunteer approaches the wall to see at what distance he can identify the patches

RESULTS Participants were female 61/male 44 Similar numbers in V3, V4, V5 groups 31%, 33%, 36% respectively 36%31% 33%

RESULTS Average distance of 3+ meters that 68% participants saw patches

Results Increasing the dimension of a patch has a greater effect on the distance the patch is seen.

Results While increasing contrast does not have as much of an effect on the distance the patch is seen.

RESULTS Objects of 450mm in size were seen on average by at least 80% of the Participants Arithmetic Mean over all 105 Participants Contrast Average Critical Dimension rounded up to nearest 25 (mm)

There is a rise in visibility of small objects when contrast difference is increased to a critical level of 40+ RESULTS

People achieved better results than in previous ‘Real-World’ tests The laboratory did not have the busy visual noise and distractions of a ‘real world’ site The low lux level was definitely preferred by many of our participants - no glare from daylight CONCLUSIONS

From all the analysis 50 points of contrast difference is needed for low vision groups This is higher than current recommendations of 30 or even 20 Contrast is important but we found that size of object is more effective in ensuring visibility CONCLUSIONS

50 points of contrast difference Each pair is a contrast difference of 50

RECOMMENDATIONS A dimension of 450mm should be used where possible for objects that are potential hazards A minimum of 50 points of contrast difference is advised to make objects visible to 80% of visually impaired people (V3+) Dangerous objects should be visible from at least 3m away

RECOMMENDATIONS Examples - advertising boards on pavements Paving slabs manufactured from pale to dark for contrast at curbs, street furniture etc. Ensure that local councils throughout the country are aware of contrast infringements We need to inform policy and guidance on these contrast outcomes

Booklet will be a ‘Ready Reckoner’ For architects, designers, access consultants Support from AATi & GRADUS for the publication British Standard BS8493: 2008 Updated OUTCOMES

Thank you all and please do comment and offer feedback