In this
column we've discussed many types of contact lens products for
correcting presbyopia, from GP designs to soft lens multifocals to
monovision. All of these options work, especially when we select
appropriate candidates for each type and employ the proper fitting
techniques.
We've
documented that we often select GPs when we want to provide sharp
acuity, while soft lens multifocals are easy to fit with a short
adaptation period.
There's
now an option that may provide the best of both - the recently
introduced (with only limited availability at the time of this
writing) SynergEyes Multifocal (SynergEyes, Inc.) hybrid contact
lens.
Bringing Soft and GP Together
Hybrid
lens technology (GP center surrounded by a soft lens skirt) isn't
new in itself; in fact, we've seen two previous attempts with the
Saturn Lens, then later the SoftPerm (CIBA Vision). These designs
had some inherent problems such as a low-Dk center, hypoxia-related
corneal neovascularization, frequent separation at the rigid-soft
skirt border and limited parameter availability, especially relating
to the radius of the soft lens skirt.
The
SynergEyes lens system appears to have overcome these issues with a
GP center fabricated from the HDS 100 (Paragon Vision Sciences)
material, various radii of the soft lens portion to fit a greater
number of ocular curvatures and a formulation process that holds the
two materials together.
The
SynergEyes Multifocal is a true simultaneous design in that the
reading portion is a small 1.9mm or 2.2mm central segment (Figure
1). Such a design normally isn't possible with GP lenses due to
blink-induced movement, but it's a common strategy with soft
multifocals. Three reading powers are presently available in 0.50D
steps from +1.25D to +2.25D. It has a diameter of 14.5mm and a wide
range of distance power.
Lens Fitting
Fit the
SynergEyes Multifocal lens using a single vision lens from the
SynergEyes A diagnostic set to determine the basic parameters.
The base
curve is usually 1.00D to 1.50D steeper than the flat keratometry
reading. Select one of the two available skirt radii to ensure good
centration without edge fluting or impingement. As with most
simultaneous vision concepts, choose the distance power by
over-refraction to the least amount of minus (or most plus) power
required to achieve the best distance VA.
Evaluate
for reading with a +1.25D lens over the best-corrected distance
power, increasing only if necessary to provide improved reading for
objects closer to the patient.
In some
cases, disparate add powers can provide a better range for near
vision and should be evaluated on an individual basis.
Promising Addition
Reports
indicate that the SynergEyes Multifocal is being well-received by
those practitioners using the lens at this time.
It may
prove to be a welcome addition to the many options we have available
to increase success in such an important part of today's eyecare
practice.