, who observed reduced performance on the VMI in uncorrected ametropic
(hyperopic and/or astigmatic) preschoolers compared to an emmetropic control group, but comparable performance in corrected ametropes (tested after 6 weeks of spectacle wear) and emmetropes.
When an ametropic
patient uses a device without his or her spectacles there will be a change in the level of magnification achieved:
For the ametropic
presbyope, all spectacles must be multifocal.
Largely, this evidence comes from studies which show that moderate artificially-induced dioptric defocus of emmetropic (or corrected ametropic
) individuals has less of a negative impact on performance than might be expected.
With an ageing population, the multifocal IOL market is set for growth and is being targeted by the major surgical providers--not only for those with cataract but also as a viable option for ametropic
and presbyopic vision correction using a clear lens extraction procedure.
(10) Some researchers have suggested that although a homeostatic mechanism may be in operation, in ametropic
individuals growth may be regulated to a specific dioptric value (other than zero) predetermined by genetics or otherwise.