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An increasingly popular correction for presbyopia is simultaneous vision, which can come in the form of contact lenses, intraocular lenses or presbyopic LASIK ablations. Unlike in alternating vision (progressive lenses) simultaneous vision corrections superimpose on the retina a focused image and a defocused image, as some areas of the correction are focused for far, and others for near.
Prescription of bifocal/multifocal correction normally entails a multiple-trial process (contact lenses). Some patients do not tolerate those corrections, and their multifocal IOLs need to be explanted.

Simultaneous Vision Simulations allows experience and testing of a bifocal correction prior to fitting, implantation or manufacture of the correction, and therefore can be used as a screening tool for multifocal correction tolerance. Also, it allows, in a controlled setting, testing of critical parameters in a bifocal correction (i.e. near addition, energy ratio near/far, pupillary distribution for near/far).

The Simultaneous Vision Simulation Instrument is a compact optical bench instrument with two channels (one for far and the other for near) that recombine at the pupil plane, simulating a bifocal pattern, with no magnification artifacts, which allows correcting the patient for far and adjusting the desire near add. A transmission spatial light modulator, in combination with polarizers, allows creating any pupillary distribution for near/far. A psychophysical channel allows testing of visual performance and perceived image quality with these bifocal patterns. Multiple multifocal phase designs and additions and short-term neural adaptation to bifocal corrections have been studied with this instrument.

In order to provide a multifocal experience in the clinic prior to lens fitting or implantation, a new head-mounted binocular Simultaneous Vision (SimVis) instrument is being developed. This device is based on the use of an opto-adjustable lens: by beating the lens at high speed, different focuses can be created and superimposed in the viewer’s retina, simulating multifocal corrections. This principle has already shown its potential as a multifocal correction simulator in a hand-held monocular version of the instrument. SimVis is currently being developed by a spin-off company (2Eyes Vision) that will bring it to the clinical market in 2017.

More info about the project and the company at

 New instruments

  Laser Ray Tracing
  Adaptive Optics
  Simultaneous Vision
  Lens Stretcher
  Ocular microscopy
  Anterior Segment Optical Coherence Tomography
  Ocular aberrations
  Corneal biomechanics

 Selected references

  de Gracia et al. IOVS (2013)
  de Gracia et al. Opt. Lett. (2013)
  Radhakrishnan et el. PloS One (2014)
  Dorronsoro et al. Optica (2016)
  Dorronsoro and Marcos (2009)
  Dorronsoro, Alonso and Marcos (2013)
  SimVis mini media coverage