Researchers reaching for the stars to cure presbyopia

A visual simulator can provide patients with the experience of vision with multifocal intraocular lenses before actual implantation, helping to manage patients' expectations. 

This article was reviewed by Susana Marcos, PhD

Simultaneous Vision (SimVisGekko, 2EyesVision) is a visual simulator that provide patients with the experience of vision with multifocal intraocular lenses (mIOLs) before actual implantation, helping to manage patients’ expectations.

This innovation arose out of the scaling down of technologies that originated in astronomy, such as adaptive optics, into a system useful to ophthalmologists for prescribing correction for presbyopia and simulating multifocal lenses, according to Susana Marcos, PhD.

Related: Simulator helps patients 'see' with multifocal IOLs before implantation

Despite the availability of mIOLs, she pointed out, only 7% of patients opt for this correction modality after cataract surgery. 

Prof. Marcos, a research professor at the Instituto de Optica Daza de Valdés, Consejo Superior de Investigaciones Científicas, Madrid, said she believes that the key may be the difficulty explaining multifocality to patients.

In addition, it is difficult for patients to make a decision about mIOL implantation if they cannot visualize what their vision will be preoperatively, a scenario that leaves them with a great deal of uncertainty about both their expectations and the actual surgical results. 

A solution to this may be use of the mobile SimVisGekko that would ease their decision-making process. 

“Visual simulators will help to sell more premium lenses and screen out prospective unhappy patients,” Prof. Marcos explained. “This technology would be valuable for patients, clinicians, and IOL manufacturers.”

Related: Improving outcomes of cataract surgery

The device provides practical utility in the clinic, in that it improves patient satisfaction, facilitates comparison of corrective solutions, and saves time by providing an easy explanation of multifocality.

It also provides business advantages by reducing patient complaints and refunds, provides a competitive advantage to doctors who adopt the device early, and increases the number of mIOL prescriptions. 

SimVisGekko is wearable, binocular, see-through, provides a 20-degree field of view, is programmable on a tablet and simulates multifocal and extended-depth-of focus corrections and provides monovision or modified monovision correction. 

“This facilitates testing a range of preoperative corrections,” she pointed out. 

Related: Striving for perfection: Creating the perfect IOL

How technology works
The device contains an optotunable lenses. Using a custom high-speed electronic driver, the lenses can change focus rapidly by a process called temporal multiplexing. 

“With periodic variations of the optical power at high speed, above 50 Hertz, static appearance of multifocal retinal images are provided by mapping spatial distribution in a lens into temporal distribution in the optotunable lens,” Prof. Marcos described.

Dr. Marcos demonstrated this in a trifocal FineVision IOL. The map in the IOL is defined with a set of coefficients; the data show how much time the lens spends at the different power additions.

With a trifocal lens the coefficients are at three different foci. This process can be performed with different coefficients and simulate extended-depth-of-focus lens types and different energy distributions.

Related: Performance of trifocal toric IOL highlighted in tests 

“We also control for dynamic effects in the lens so that we can really map the true focus performance of the lens,” she said. A comparison of the performance of an actual commercial IOL with the simulation showed how well the images of the two matched.

Practical application
When the SimVisGekko was taken into the clinic, it performed well. Prof. Marcos said researchers have found that the device replicates mIOLs. 

“We performed the test with a trifocal IOL in the SimVis preoperatively and the patient was ultimately implanted with the lens,” she said. “We found that in patients with clear lenses and those with cataracts, the pre-operative (with SimVis) and post-operative (with the implanted mIOL) defocus curved matched.

In the presence of a cataract, there is a shift down because of the light distribution caused by the cataract, but the shape of the defocus focus curve is well captured.”

Related: Precise alignment helps surgeons focus on best toric IOL post-op results

Multiple uses
This technology is also useful for patients opting for multifocal contact lenses. An excellence replication of the contact lens performance on eye  was achieved with the SimVis simulation. For different lens designs with different power additions.

The device also was tested using different natural images at far and near distances under conditions during the day and at night. When tested in a patient with, for example, corrected binocular far vision, the scores at the far distance were high and the scores for near were low.

Related: Surgeon finds new monofocal IOL lands in a visual 'sweet spot'

When bilateral bifocal correction was provided the far vision decreased slightly and the near vision improved. This also can be applied to monovision and modified monovision. 

Prof. Marcos noted that when the patient is tested with different corrective options, surgery can proceed with much more certainty regarding the postoperative vision. 

The physician can choose the desired lenses and control the test on an iPad. The management of the mobile device allows connection of every iPad to the cloud, remote management of the devices, security management, remote app updates, monitoring and tracking, and remote troubleshooting. In addition, when new IOL designs become available the software is updated. 

“This technology provides a powerful back-end,” she explained. “Over and above monitoring the use of the SimVis, we can monitor different patient lens preferences, the rates of actual implantations of those IOLs, and the conversion rate to multifocality.”

Related: Excellent visual outcomes achieved with novel trifocal design

Prof. Marcos explained that the information is useful and is enabled by the fact that the preoperative clinical testing can be performed before surgery.

Conclusion
“We believe that SimVis represents a new paradigm in presbyopia correction that provides patient education, aid in lens selection, reduced uncertainty preoperatively, virtual clinical trials, the ability to test multiple lenses, and large data sets of patient preferences and usage,” she concluded.

Read more by Lynda Charters

Susana Marcos, PhD
E:susana@io.cfmac.csic.es
Prof. Marcos is a coinventor of SimVis Technology and co-founder and shareholder in 2EyesVision.