Presbyopia is the age-related loss of the ability to dynamically focus near and far and it is usually corrected with an additional positive power (near addition). The near addition is conventionally provided in the form of spectacles providing alternating vision at far and near.
Recently, presbyopia is increasingly corrected with Simultaneous Vision, Monovision and Modified Monovision corrections, usually delivered in the form of contact lenses, intraocular lenses, or corneal surgery such as presbyLASIK or corneal implants.
Unlike alternating vision corrections (as progressive spectacle lenses), these solutions are not gaze-dependent and aim at providing clear vision at all distances simultaneously.
Multifocal corrections result in retinal images with superimposed blurred and sharp image components at all viewing distances, yet they provide a reasonable visual quality at all distances, while introducing mild degradations at all distances, compared to a single focus.
The patients and their expectations on the implantation of multifocal intraocular lenses get better perspectives with a visual simulator.
Simultaneous Vision (SimVisGekko, 2EyesVision) is a visual simulator that provides 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. Despite the availability of mIOLs, only 7% of patients opt for this correction modality after cataract surgery.
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 visualise 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, which would ease their decisionmaking process. Visual simulators will help to sell more premium lenses and screen out prospective unhappy patients.
This technology would be valuable for patients, clinicians and IOL manufacturers. 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 and provides a 20° field of view. Additionally, it 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.
The device contains 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.
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-offocus lens types and different energy distributions. A comparison of the performance of an actual commercial IOL with the simulation showed how well the images of the two matched.
When the SimVisGekko was taken into the clinic, it performed well and the researchers have found that the device replicates mIOLs. They performed the test with a trifocal IOL in the SimVis preoperatively, and the patient was ultimately implanted with the lens.
They found that, in patients with clear lenses and those with cataracts, the preoperative (with SimVis) and postoperative (with the implanted mIOL) defocus curves 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.
This technology is also useful for patients opting for multifocal contact lenses. An excellent replication of the contact lens performance on the eye was achieved with the SimVisGekko simulation for different lens designs with different power additions.
The device was also 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.
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. 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. Over and above monitoring the use of the SimVis, different patient lens preferences, the rates of actual implantations of those IOLs, and the conversion rate to multifocality can be monitored.
This information is useful and it is enabled by the fact that the preoperative clinical testing can be performed before surgery.
SimVisGekko represents a new paradigm in presbyopia correction; it provides patient education, aids in lens selection, reduces uncertainty preoperatively, allows for virtual clinical trials and testing of multiple lenses, and provides large data sets of patient preferences and usage.