Color vision deficiency can be either inherited or acquired. If acquired by life events such as head trauma, stroke or eye disease, there is often a good possibility of treatment improving or eliminating color defects.

Take cataracts, for example. As the crystalline lens of the eye hardens and yellows with age, short-wavelength light (blues and greens) is absorbed selectively. Over time discrimination in this part of the light spectrum becomes increasingly difficult. Surgical treatment, increasingly by the implantation of intraocular lenses, offers sufferers a complete cure.

But, unfortunately, this isn't the case with inherited color vision deficiency. Those born with color defects have an incurable, faulty mechanism in the retina of the eye. The cone-like cells in the retina, which enable us to see colors in daylight, contain three different chemicals. Each cone reacts to red, green or blue light, and most people with color deficiency have a problem with one set of chemicals, usually those responsible for red or green colors.

Having said that there is no cure for inherited color defects, this does not mean that it is all doom and gloom. Color vision deficiency should be seen as a continuum, depending on the amount of chemical alteration within the cones.

For many with mild color defects, life can sometimes be frustrating. Learning compensation techniques, however, often results in these individuals committing fewer color-naming errors than those with acquired color vision deficiency. Life-long experience with defective color perception enables mildly affected individuals to overcome most everyday and work problems. Self-help and occasional help from others is the best "treatment".

One in three people with color vision problems, though, have a more severe form leaving them unable to discriminate strong colors. This group encounters more problems in daily life and the workplace, in particular, and they are likely to ask: "Is there a treatment for color deficiency?"

While acknowledging there is no way of restoring the lost sensation of color, they have heard of colored filters which they hope will help them to pass employment-critical color tests. Red-tinted monocular contact lenses for color deficiency (which help color recognition) have indeed been around for a long time.

Recently, tinted glass lenses, reportedly for colorblindness, have been actively promoted as a "treatment" for red/green color deficiency which will allow the wearer to pass the more exacting Ishihara test. Color-defective would-be pilots and applicants for the armed forces are often among the keenest to believe that these color lenses will help them pass the pre-employment tests, especially since regulations are getting increasingly strict.

Unfortunately, these colored lenses are not a panacea for all color deficient ills:

They will help you pass some color vision tests, but equally so would a piece of red cellophane.

Promoted as an optical aid for red/green color vision deficiencies, they offer very little which sets them apart from normal prescription lens sunglasses and should not be seen as a special class of device.

The Federal Aviation Administration, for example, would be most unlikely to allow these lenses to be used to take their color vision test. They would be rightly sceptical that wearers would subsequently able to identify correctly the red and green lights on an airplane at night.

These filters can cause problems with binocular vision and co-ordination.

These lenses only emphasise the dark/light differences between the colors being confused, and do not help wearers perceive colors as people with normal vision do. They simply shift the color defect to another area of the spectrum and, as a result, impair the discrimination of some other colors.

It seems, then, that these colored filters are not a "treatment" which can guarantee success in pre-employment tests. A better bet would be to accept that some positions (pilot, line officer) carry a disqualification for those with color defects. Qualification for other positions, health care provider or lawyer in the Navy, for instance, is not precluded by failure in the color vision tests.

Instead of looking to color corrected lenses, try color corrected fluorescent tubes, as opposed to tungsten filament lamps, as an aid to color recognition. However, natural indirect light is best providing optimum illumination levels to help color discrimination. As ever, though, if in doubt ask advice from a relative or colleague with good color vision.

Of course, the demand for a treatment to cure color vision deficiency would be obviated if every child underwent a color deficiency test. Many years of study and several thousands of dollars preparing for a career where color deficiency was not acceptable, would not, then, be wasted and huge disappointment would be avoided.

On the other hand, many individuals classified as mild, low-grade color deficient feel discriminated against when applying for jobs. The requirement for normal color vision, they feel, is often a recent introduction and overplayed. Without the possibility of a viable treatment, many would like to see reasonable guidelines set for job qualifications.

Drivers who wear bioptic lenses for driving feel similarly aggrieved at the wide variation in licensing requirements from state to state. Many, like color deficient individuals, advocate challenging rulings, applying for less stringent testing and lobbying for standardised licensures.

Although there is no treatment for color vision deficiency, many sufferers find methods other than color to get round their problems, e.g. texture, shape or position of objects. Unfortunately, rigidly-enforced restrictions in color-critical occupations will bar many from following their preferred career. This is why early testing for color defects is such a good idea allowing the individual to plan a career in middle school.

For the majority, treatment implies handicap and, despite some color-related frustrations, their lives are little different from normal color-sighted people's.