There is much interest in the prevention and slowing of the progression of myopia. One line that is being pursued is the use of dual focus contact lenses. Multifocal contact lenses and aspheric contact lenses have been around for many years and some have been used in attempts to slow progression of myopia. These were designed and supplied for vision improvement and were used ‘off label’ for myopia treatment. There are currently three soft contact lenses available that have regulatory approval for the treatment of myopia.
These lenses have design differences but the same fundamental principal is used by them all. The optics of these lenses have been constructed to reduce peripheral hyperopic focus. It is this focus ‘behind’ the peripheral retina that is thought to stimulate the increase in axial length.
They allow for different focal points at different eccentricities on the lens as well as correcting for the myopia already present. Refractive (correction) zones on the lens focus light precisely on the fovea, allowing good visual acuity, while other (treatment) zones are over powered for the length of the patient’s eyes and cause a pre-retinal (myopic) peripheral focus.
The pre-retinal peripheral focus is thought to create an intra-ocular environment that is less conducive to axial elongation when compared to that created by the post-retinal (hyperopic) focus of standard contact and spectacle lenses. These dual focus myopia treatment contact lenses are suitable for children as young as 8 years old and are available in powers up to just over 12 dioptres.
An interesting area and I look forward to further developments in the treatment of rampant myopia.