Rodenstock’s Nicola Peaper discusses why dispensers should take the opportunity to educate patients on tint colours and their applications while accounting for their preferred colour choice.
When we talk about ‘dispensing a tint’ we usually think along the lines of tints for medical purposes such as migraine relief or improving vision for macular degeneration sufferers. As practitioners, however, we should always take the opportunity to discuss the benefits of different tint colours and intensities even if the spectacles are simple sunglasses.
Nicola Peaper.
“Red, orange and yellow tints may not be aesthetically pleasing but may be far safer for certain sports such as skiing or mountain biking.”
Most tints supplied in Australia – be they photochromic, polarised or simple plastic lens tints – are grey. Whilst this may often give the best colour rendering as it removes wavelengths across the visual light spectrum, it may not always be the most suitable for specific tasks and hobbies. The opportunity should be taken to discuss different colours and their usage whilst still taking into account the patient’s idea of their preferred colour.
The ideal sunglass lens should provide protection from glare whilst improving contrast. Scattered light increases glare and, due to its short wavelength, a large share of scattered light is in the blue part of the spectrum.
As scattered light carries no useful visual information it can be said that blue light reduces visual sharpness affecting both contrast and depth of vision. To absorb blue light, a complementary colour is necessary. Complementary colours to blue are yellow, orange, and red. However, whilst these colours will give the best levels of contrast, they are not aesthetically appealing and for this reason brown and amber tints tend to be used for good contrast in a fashion frame.
As it is often difficult to explain the difference between individual lens colours, and why one colour should be chosen over another, a colour contrast index (Figure 1) is useful. This is from Rodenstock Lambda Lens Technology which has been used to develop a scale with values describing the level of contrast provided by the different lens colours of the Rodenstock tint portfolio.
Figure 1: A colour contrast index can be useful to explain the difference between individual lens colours.
These calculated values are based on, among other aspects, the ratio between the amount of red light and the amount of blue light let through the lens. This method is used, rather than percentages, to give an intuitive order to the colours. If purely percentages were used, the grey, green and brown lenses would be clustered together and the amber lens would be much further up the index. Using the index and general tint samples is a discussion that can be had to highlight two simple criteria for the spectacle wearer to consider:
1. What contrast level feels right?
2. What colour feel is right for me?
Colour feel is important as, whilst understanding levels of contrast, patients may still have a fixed view on what tint colour is ‘comfortable’ for them. Talking about the implications to vision of each colour allows the patient to at least make an informed choice.
If sunglasses are going to be worn during sports and hobbies, a more detailed conversation needs to take place. As mentioned, the red, orange and yellow tints may not be aesthetically pleasing but may be far safer for certain sports such as skiing or mountain biking where good contrast and depth perception are essential.
Rodenstock, within its Lambda Technology, has three contrast tints. These tints are in specific colours and transmissions, making them suitable for certain sports and weather conditions.
• Dynamic Yellow. This yellow tint will only block about 15% of light but all of that will be of the blue wavelengths. Effectively it brightens the surroundings making contours and details in the landscape more visible to the wearer. This tint is highly suitable for skiing or mountain biking in foggy or cloudy conditions.
• Dynamic Orange. This 40% tint is a suitable choice for bright conditions, such as a reflective snow field, but with an overcast sky or little direct sunlight.
• Dynamic Red. This lens increases contrast whilst significantly reducing glare as it is an 80% absorption tint. Suitable for changing but mostly sunny conditions.
With its introduction of a colour contrast index and contrast tints, Rodenstock has created a clear way to explain and highlight the benefits of various tint solutions.
ABOUT THE AUTHOR: Nicola Peaper is the National Professional Services Manager for Rodenstock Australia. She spent 20 years working as an optometrist in the UK, and for the past 17 years she has worked within the lens manufacturing industry.
