Moderate to high myopia that requires -5.0 diopters or more for lens correction is related to increased risk for serious eye diseases. Thus, it is essential to keep myopic progression under control, especially among developing children.
Prof. Carly LAM and Prof. Chi-ho TO from the School of Optometry have invented a new way to retard myopia progression for children by working on the natural homeostatic mechanism of the eye.
An eye naturally tends to adjust its shape so that it sees focused images on the retina. By focusing the images slightly in front of the retina, or so-called myopic defocus, the eyeball tends to shorten itself to receive the images. The principle of the new method is to produce a clear image on the retina and a defocused or blurred image in front of the retina simultaneously. In this way, the wearer can enjoy a clear and comfortable vision while myopia progression is being controlled.
This technology has been applied to Defocus Incorporated Soft Contact (DISC) lens and Defocus Incorporated Multiple Segments (DIMS) Spectacle Lens. Our clinical trial shown that DISC lens and DIMS lens retarded the progression of myopia by approximately 60% in Hong Kong school children aged 8 to 13.
Defocus Incorporated Soft Contact (DISC) lens
The DISC lens is a multi-zone bifocal soft contact lens which comprises optical zones for correcting refractive error and “positive” defocus zones for myopia control. It won a Grand Prize and a Special Gold Medal at the 39th International Exhibition of Inventions of Geneva in 2011. A PolyU supported start-up, VST, has been licensed for the production of DISC lens, which is available on the market. PolyU also prescribes DISC lens at its Optometry Clinic and provides training in ﬁtting the DISC lens on the eyes for optometrists.
Defocus Incorporated Multiple Segments (DIMS) Spectacle Lens
Jointly developed by PolyU and its research collaborator Hoya Corporation, the DIMS lens is divided into zones – the central zone is a regular concave lens for corrected vision at the centre of the retina, while the rest of the lens is made up of numerous tiny lenses that focus light slightly in front of the retina to create peripheral myopic defocus. The DIMS lens won the Grand Prize (overall championship), a Grand Award and a Gold Medal with the Congratulations of Jury at the 46th International Exhibition of Inventions Geneva in 2018. It is available on the market and in PolyU Optometry Clinic.