Apparatus and method for alleviation of symptoms by application of tinted light

Abstract

Apparatus and a corresponding method for the diagnosis and alleviation of symptoms of visually induced physiological defects and/or pathological conditions is provided. A plurality of narrow-band light sources are combined to constitute a colour controllable lamp. A method for adjusting the settings of this lamp permits the optimum illumination for a particular subject to be found, whilst the latter carries out a task such as reading or writing. By use of the lamp to simulate the expected visual stimulus, to which the subject would be exposed if provided with viewing aids such as tinted spectacles and the like, an optimal selection from a database of such aids may be made or a new formulation defined. Inter alia, the symptoms of visual dyslexia, macular degeneration and visually induced migraine may be alleviated.

1 . Apparatus for the assessment of a subject for at least one of a plurality of vision-related physiological defects and pathological conditions comprising a plurality of light sources, each of which is arranged to emit a respective spectral component of the visible spectrum, and control means for selecting a weighted mixture of said spectral components and controlling said light sources to provide illumination having the selected spectral components, wherein a first spectral component has its peak at a wavelength which is located between 510 nm and 540 nm and contributes predominantly to a respective first tristimulus value of the light entering an eye of the subject.  
     
     
         2 . Apparatus as claimed in  claim 1  in which, in use, said illumination is arranged to illuminate a surface for viewing by the subject; said mixture is an additive combination of the spectral components emitted by at least two of said light sources; and the control means varies the amount of illumination from each of said at least two light sources to impinge on said surface whereby, in use, a combination of said spectral components is provided to alleviate the symptoms of at least one of said visually induced physiological defects and pathological conditions.  
     
     
         3 . Apparatus as claimed in  claim 1  in which the first spectral component has its peak at a wavelength located between 520 nm and 530 nm.  
     
     
         4 . Apparatus as claimed in  claim 1  in which a second spectral component has its peak at a wavelength located between 465 nm and 475 nm.  
     
     
         5 . Apparatus as claimed in  claim 1  in which a second spectral component has its peak at a wavelength located between 610 nm and 650 nm.  
     
     
         6 . Apparatus as claimed in  claim 1  in which each of said light sources comprises at least one respective light emitting diode arranged to provide one of said spectral components.  
     
     
         7 . Apparatus as claimed in  claim 1  in which each of the spectral components has a spectral power distribution having a width at half height which does not exceed 50 nm.  
     
     
         8 . Apparatus as claimed in  claim 2  in which the illumination from each of the light sources is diffused prior to impinging on the surface so that the relative intensity of the light impinging at two points spaced on said surface is substantially the same for each of said spectral components.  
     
     
         9 . Apparatus as claimed in  claim 1  further comprising means for computing the combined effect of at least two of the active illumination spectra, the ambient illumination spectrum, the reflectance spectrum of the target or an illuminated surface, the transmission spectrum of at least one filter and the transmission spectrum of a surface coating over the visible spectrum, so that in use, the subject's retinal response may be predicted and the settings of the active light source and/or the formulation of a filter to be used by the subject may be improved.  
     
     
         10 . Apparatus as claimed in  claim 1  in which the control means includes a matrix transformation of desired chromaticity co-ordinates of the illumination whereby, in use, the light sources are controlled to provide the illumination.  
     
     
         11 . Apparatus as claimed in  claim 1  in which the control means includes a light sensor for calibration of the light sources.  
     
     
         12 . Apparatus as claimed in  claim 1  in which the control means includes a temperature sensor whereby the light sources are controlled to provide the illumination substantially without temperature dependence.  
     
     
         13 . A method for assessing a subject for at least one of a plurality of vision related physiological defects and pathological conditions comprising: 
 arranging a plurality of light sources to emit different spectral components within the visible spectrum;    assessing the subject's performance with a series of targets under different levels of each of a plurality of illuminants, including individual spectral components or pre-determined ratios thereof;    recording the level of each of said illuminants corresponding to improved performance by the subject; and    combining the levels of each respective illuminant as recorded in said recording step to provide a resultant additive mix of said illuminants.    
     
     
         14 . The method of  claim 13  including the further step of applying variations to the level of each of the spectral components in small steps whilst combined in order to establish the mix of said illuminants which substantially improves the subject's performance.  
     
     
         15 . A method for the simulation of the use of a filter under expected lighting conditions comprising: 
 defining the tristimulus values of a tint which would be observed under the expected lighting conditions by a subject when said filter is used in transmission for viewing a surface,    providing a colour controllable lamp including narrowband coloured light sources,    selecting the level of illumination provided by each light source and    controlling the colour controllable lamp to illuminate the surface for viewing by the subject so that, in use, the defined tristimulus values are observed by the subject    
     
     
         16 . The method of  claim 15  further comprising the step of simulating a range of pre-formulated filters and lighting conditions, whereby the subject can select one or more of said pre-formulated filters for use under said lighting conditions.  
     
     
         17 . The method of  claim 15  which includes the further step of formulating and/or selecting the filter to improve the subject's performance.  
     
     
         18 . The method of  claim 16  which includes the further step of formulating and/or selecting one of said preformulated filters to improve the subject's performance.  
     
     
         19 . A method as claimed in  claim 15  applied to the formulation of any one of filters and anti-reflection coatings for spectacles, contact lenses, coloured overlays and any other tinted material through which the subject may view the surface a purpose of which is to alleviate problems caused by colour-related disorders of the human visual system.  
     
     
         20 . An article formulated by the method of  claim 19 .  
     
     
         21 . A method for alleviating the symptoms of any one of a plurality of vision related physiological defects and pathological conditions suffered by a subject which comprises: 
 arranging a plurality of light sources to emit different spectral components within the visible spectrum,    controlling the weight of each of said spectral components to provide illumination,    arranging at least two of the light sources to additively illuminate a surface for viewing by the subject;    varying the amount of illumination from each of said at least two light sources to impinge on said surface; and    providing a combination of said spectral components to alleviate the symptoms of at least one of said visually induced physiological defects and pathological conditions.    
     
     
         22 . The method of  claim 21  in which the physiological defect is visual dyslexia.  
     
     
         23 . The method of  claim 21  in which the pathological condition is visually induced migraine.  
     
     
         24 . The method of  claim 21  in which the pathological condition is macular degeneration.