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70 Ophthalmic Lenses

Red: Red filter gets its colour characteristics because of higher concentration
of selenium. Red filter strongly blocks the transmission of blue and blue –
green wavelengths, resulting in very sharply defined contrast. It allows
excellent depth perception in low light, and is good for skiing and hunting.
Red tint can be helpful for hue discrimination in colour deficiency. This
effect might be enhanced by relating the tint to the anomaly, a red tint for
protanopes and a green for deuteranopes. It is also possible that the choice
will not be as simple as this or the reverse or that the greatest effect is
achieved by another colour or different colour in each eye.
Pink: Pink is an example of unsaturated red. Cerium is added to the batch
mix to give rise to pinkish tint. Psychologically pink has been judged as the
“sweetest” colour. They are prescribed mainly to attenuate the light in a
pleasing way. They have the absorption properties in the UV and blue
light region. Pink may be the colour of choice when there is some
neurological problem.

Amber: Amber is fluorescent that increases the contrast of the objects so
that every cracks and curbs stand out in our field of vision. Non-metallic
element sulphur is used with iron to produce amber glass, the colour of
which can vary from very light straw to deep reddish brown. Night vision
with amber tint brightens the darkness in front of a vehicle so that the
subject can see more details. In addition, the amber tint also reduces the
glare from front headlights. Amber is more of a selective filter. It also offers
excellent light management properties on cloudy or rainy days. Therefore,
it is great for lower light conditions like – golf, shooting, fishing, skiing etc.
This “light enhancing effect” reduces the eye strain. It also improves visual
acuity and depth perception.
Brown: Brown tints are good general purpose filters. They have added
benefit of reducing glare and molecules that mainly absorbs total UV light
below 400nm. In the visible region of spectrum, transmission is controlled
with high peaks in the blue, green and red region, resulting in a colour
enhancing effect. It is an excellent contrast enhancing filter and is very
much suitable for sun protection. Brown is an ideal tint for drivers for day
time driving as it has three effects - eliminates the “blue blur” substantially,
increases the contrast and gives the wearer an impression of higher light
transmission.

Orange: In normal use, orange is the essence of brown, so a tint diagnosis
of orange would transmit to a brown tint. Orange filter allows transmission
of light that is the same colour as the filter and promote tonal separation in
that colour. They tend to reduce the transmission of blue and green
wavelength, thus increasing the contrast. So the image appears sharper. It
is an ideal support for cycling, mountain tours, skiing and a lot more.