Electronic liquid crystal lenses for the correction of presbyopia

Design considerations for liquid crystal contact lenses

“…The simplest technique that is currently available is using lenses of differing focal powers in each eye [2]. Multifocal lenses are also available that focus light from both near and far objects onto the retina simultaneously [6]. Both techniques can be disorientating and it takes the user some time to train their brain to distinguish between the two images being focused simultaneously.…”

“…However, not all wearers are able to adapt to either of these solutions. A contact lens that is automatically able to selectively switch between the different foci when required is beneficial as it would reduce this inconvenience and disorientation [6][7][8].…”

“…This includes lens shaped LC layers, [9,10] flat gradient index lenses [12,13], diffractive lenses [14,15] and flat lenses using inhomogeneous electric fields [16][17][18][19]. Recently, PMMA lens substrates have been used to fabricate switchable contact lenses [6]. The materials and manufacturing techniques used are comparable to those already used in conventional contact lenses [6][7][8]20].…”

“…Recently, PMMA lens substrates have been used to fabricate switchable contact lenses [6]. The materials and manufacturing techniques used are comparable to those already used in conventional contact lenses [6][7][8]20]. A non-uniformly spaced cavity was created within the PMMA lensing substrates, with electrodes and alignment layers deposited onto their surfaces.…”

“…The geometry of the spherical LC cavity illustrated in figure 2 is calculated by the following equation [6]:…”