Since the first lockdown, there has been increased interest in developing ways of minimising testing time, and therefore patient proximity, while maintaining acceptable levels of accuracy. And as we adapt to the post-pandemic world, the need for minimising pathogen transmission will be with us for good. So, any new instrument capable of undertaking a complete refraction more quickly, one that might easily be operated by suitably trained support staff under supervision but is flexible enough for an ECP to overview and intervene when required, and one that might even be operated remotely has to be of interest.
The new Essilor Vision S-700 (figure 1) is just such an instrument. And when, recently, I got to put it through its paces at the Essilor HQ in Thornbury, there were a couple more surprises in store.
Essilor Vision S-700
The Vision S-700 is a compact unit capable of a complete subjective refraction, either from scratch or starting from data imported from a lens meter or autorefractor. Operation of the unit is from a separate console (figure 2) which controls both the targets seen by the patient and the lenses they look through. During my trial, we sat next to the patient, but the unit could just as easily be controlled from another room or even remotely.
So, here is the first surprise; considering the machine contains the capability of a high specification automated phoropter and has target screens compatible with a 6m chart and virtual views compatible with real life images, the refraction station is remarkably small (see table 1 for specifications). Indeed, with a ‘footfall’ of little more than some automated focimeters, the unit suddenly becomes very attractive as an easily incorporated extra refraction station for a busy practice, or a unit that might be borne in mind by anyone undergoing a refurbishment and wishing to increase refraction capacity in their practice.
How So Small?
The small size has been made possible by two neat innovations. Firstly, the target screens have been designed using a patented ‘ distance simulation technology’ which avoids any near effect, as can often happen with small projection systems that often require some sphere adaptation to the final refraction, and allows the use of real world simulation views alongside all the expected Snellen, logMAR and BV targets (figure 3).
Secondly, the phoropter includes a liquid lens system whereby a single fluid lens is before each eye that is deformable by controlled electrical input to adopt any power profile required; instantly and without significant aberrations. This patented Liquid Lens Optical Module (figure 4) is real state-of-the-art stuff, and does away with any need for mechanical lens tracks. This improves speed of testing and helps size reduction.
Ease of Use
My guinea pig was an anisometropic presbyope with a small degree of amblyopia. I chose her, as she has previously proved to be a challenge to other semi-automated refraction systems. I am pleased to report that she proved no problem at all to the VS-700. Positioning the patient is easy (figure 5) and in-built cameras help to centralise each eye and also to ensure the appropriate back vertex distance is maintained (figure 6), something often forgotten with phoropters in these days of steamed up lenses.
The refraction is may then be carried out in a way familiar to most who already use a phoropter system (figure 7), but there is also the option for a Smart refraction (figure 8). This algorithmic approach allows the operator to run through a sequence of pre-set tasks, where options are offered to the patient to view and, depending on their response, a tick or a cross is clicked on. For a simple refraction, this allows a trained staff member to carry out a full refraction and BV check in just minutes. Where responses are inconclusive, or where there is a problem identified, it is a simple matter then of deferring back to the professional in charge.
Final Thought
In terms of ease of use and accuracy, the VS-700 easily rivals any other automated refraction system. The fact that the refraction routine may be pre-set to walkthrough algorithms and the way it can be controlled remotely also makes it a wise investment both in terms of post-pandemic patient safety, efficient use of delegated staff and in making best use of space in a busy practice.
In my humble view, however, what really makes this unit a cut above is its incorporation of a liquid lens system. It’s almost as if it was possible to improve refraction accuracy to a level way beyond the 0.25DS steps we are all used to. Now why would that be? Look out for a review of the VR-800 system in the coming weeks.
- For further information on the VS-700, go to ecp.essilor.co.uk.
- To access a video of the VS-700, go to vimeo.com/ 546407244.