Scientists in Israel have made a brand-new type of contact lens that can fix a type of red-green colour blindness called deuteranomaly. By including plasmonic meta-surfaces right into standard contact lenses, the scientists had the ability to restore lost colour contrast and also enhance colour understanding by approximately a factor of 10.
Humans can generally distinguish more than a million colours, but for some, colour understanding is restricted in particular series of the electro-magnetic range. In these people, the reaction of the light-sensitive cone photoreceptor cells at the rear of the eye is undermined when excited with a specific wavelength of light.
In deuteranomaly, for example, signals from the cells that are sensitive to green-yellow light (known as medium-type cone photoreceptors) are dulled, in other words these cells perceive these wavelengths very weakly. This means that the brain gets too many signals from longer wavelengths connected with yellow-red light. The result is that people with this type of colour blindness struggle to tell red as well as green wavelengths apart. Although unique glasses that reduce assumption of yellow-red light are available, they are large as well as awkward to put on.
Artificially-engineered thin metallic films
Scientists have currently transferred meta-surfaces – which are basically artificially-engineered thin metallic films that can be fine-tuned to interact with light in very detailed ways – onto the surface of commercially-available contact lenses to achieve the same filtering system capacity as the glasses mentioned above can provide.
The meta-surfaces function by manipulating the physics of plasmons, which are quasiparticles that emerge when light communicates with the electrons in a metal as well as makes them oscillate. The shape, dimension as well as arrangement of the nanoscale frameworks – in this situation, a 40-nm-thin film of nanosized gold ellipses which are then put onto the surface of the contact lens – within plasmonic materials makes it feasible to sustain plasmons at specific frequencies, providing a handle on particular wavelengths and frequencies. By therefore adjusting these structural specifications, the scientists can regulate which frequencies of light the material will absorb and also spread.
From flat to bent surfaces
Because meta-surfaces are generally produced on flat surfaces, the scientists were required to create a technique to transfer them onto the bent surface of a contact lens. Their new manufacturing procedure unlocks the door for installing these products right into various other non-flat sub-stratums too, they say.
By examining the optical action of the meta-surface at every phase of the new construction method and imaging its structure, the researchers validated that its light manipulation properties did not change after transfer to the curved surface.
Multiple of 10 improvement in colour perception
They then simulated exactly how a wearer of their brand-new nanostructured contact lens would certainly perceive colour using standard tests based upon Compensation International de l’Eclairage (CIE) colour spaces as well as conventional designs of human colour-sensitive photoreceptors, in order to find out if their modified contact lenses really had any impact on improving colour blindness of this sort. They discovered that the device can shift incorrectly-recognized colours closer to the initial hues and lost visual contrast in red-green colour blindness might basically be restored, which is a big step but it’s still early days for commercial adoption of these lenses. Indeed, they gauged an improvement of up to a factor of 10 in colour perception, which is really big. An Ishihara-based colour blindness test (a specific type of test which is the most well-known colour perception examination for red-green colour deficiencies or the colour deficiencies which are targeted to be restored with these contact lenses) also validated comparison restoration with these nano-structured lenses.
While the new lens still requires to pass clinical-stage examinations, the scientists state that manufacturers could potentially install the meta-surfaces during the moulding phase of contact lens manufacture or thermally fuse them to an inflexible lens. They plan to proceed improving their meta-surface transfer process and also test it for various other applications as well.