prescribing for presbyopia
A Hybrid Lens Option for Correcting Presbyopia
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.
Figure 1. SynergEyes Multifocal lens -
note central reading segment providing
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.
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.
Craig Norman is director of the Contact Lens Section at the South Bend Clinic in South Bend, Indiana. He is a fellow of the Contact Lens Society of America and is an advisor to the GP Lens Institute. He is also a consultant to B&L.