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Defocus Incorporated Soft Contact (DISC) lens to combat childhood myopia

Defocus Incorporated Soft Contact (DISC) lens to combat childhood myopia


Profs. To Chi-ho and Carly Lam from the Centre for Myopia Research under PolyU’s School of Optometry have developed the novel Defocus Incorporated Soft Contact (DISC) lens. Recently, this invention won a Gold Award with the Congratulations of the Jury and the Grand Prize of the Technical University of Cluj-Napoca, Romania at the 39th International Exhibition of Geneva in Switzerland.

The method behind the multi-zone bifocal lens works on equalizing the physical and optical lengths of affected eyes. When a child has myopia, the light that enters the eye focuses in front of the retina rather than on it. The new method involves producing first an image on the retina and then a second image to generate a defocus. In doing so the DISC lens makes use the natural homeostatic mechanism known as ‘emmetropization’, whereby the eye tends toward a shape that allows it to receive focused images as it would do with normal vision, i.e. the size and shape of the eye is regulated by optical inputs from the environment. The lens improves visual acuity, clearing the wearer’s vision, and provides constant myopic defocus (“STOP” signal to myopia) at all viewing distances. The defocus method is so effective that it can be incorporated into various commonly used forms of contact lens.

Spanning two years with a sample of 80 myopes, the trial of the invention showed that DISC lenses retarded the progression of myopia by approximately 50 per cent in Hong Kong school children aged 8 to 13. More importantly, the children found the lenses comfortable to wear. The new lenses also provided clarity that was comparable to conventional single vision lenses, which deliver the same optical focal point over their entire area. This new technology has already been patented in Australia, the Chinese mainland, the US and various European countries.

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