Addressing the increasing prevalence of myopia and presbyopia
OT speaks to CEO of SynergEyes, Bob Ferrigno, and head of research and development at the Brien Holden Vision Institute, Dr Ravi Bakarju (RB), to find out more about how their new contact lens works
When will the contact lenses launch and how did the partnership come about?
Bob Ferrigno: SynergEyes will be offering the hybrid lenses with extended depth of focus technology during 2019 and plans include the UK.
The Brien Holden Vision Institute (BHVI) is recognised as a worldwide leader in translational research for contact lenses and SynergEyes is the world leader in hybrid contact lenses for conditions like myopia, presbyopia and astigmatism.
The BHVI contact lens designs are based on patented extended depth of focus (EDOF) technology, while SynergEyes has strong distribution in the US, UK and other countries, which is ideal for delivering the EDOF technology.
Both companies recognised that the combination of the EDOF technology and the hybrid platform is a winning combination that will help to address the increasing populations of myopic and presbyopic people around the world.
What is EDOF technology and how does it help patients with myopia?
Dr Ravi Bakarju (RB): Research has found that correction strategies that reduce hyperopic defocus or impose myopic defocus can slow myopia progression. The EDOF contact lenses manipulate higher order aberrations to provide global retinal image quality that degrade in the direction of myopic eye growth, thereby providing a therapeutic effect in treating myopia.
Clinical studies have found that these EDOF contact lenses were able to slow eye growth by between 33% and 35% (axial length) when compared to standard single vision lenses. Importantly, through manipulation of higher order aberrations these lenses are able to minimise visual disturbances that are characteristic of other myopia management contact lenses. The EDOF lenses demonstrated improved visual performance over the traditional bifocal and multifocal alternatives.
How does it benefit patients who are presbyopic?
RB: Many commercial multifocal lenses claim to provide simultaneous vision at various visual distances, but often this comes at the cost of reduced contrast, increased ghosting (a blurred, shadow-like effect), halos (rings around bright points of light) and compromised overall vision satisfaction.
Several factors can lead to variability in visual performance, which can occur at one or more distances including:
- Type of lens design (centre-near, centre-distance multifocal or concentric bifocal)
- Amount of near add power
- Pupil size
- Rate of power change across the optical zone
- Inherent spherical aberrations of the corrected eye
- Contact lens centration on eye.
These shortcomings are often exacerbated with low illumination levels. Such visual compromises have been associated with an increase in patient dropout rate and lack of confidence in fitting by practitioners.
The EDOF contact lens performs relatively independently of patients’ natural aberrations and variation in pupil size. The lens is therefore designed to meet the vision needs of emerging, moderate and advanced presbyopes. In published clinical studies these EDOF designs have compared very favourably over a range of measures with currently available multifocal lenses.
What was considered during research and development?
RB: We did extensive optical modelling to predict how the lens designs would perform. We found that when multiple modes of spherical aberrations (with appropriate magnitude and sign) were introduced, the through-focus retinal image quality was greater than that obtained through individual modes of spherical aberrations. This indicates an extended depth of focus.
We then evaluated several lens prototypes in a series of clinical trials and they compared very favourably over a range of measures with currently available traditional multifocal lenses.
We’re also investigating other approaches to achieving EDOF. One of these is what we call ‘phase-step,’ which uses phase modulation to create a stable through focus distribution of light by means of light interference. We’re currently using this approach in our intraocular lens designs.