contact lens case reports
Multifocal Technology with Exciting New Results
Today, most practitioners agree that a translating GP design often provides the best option for optimum distance and near correction for presbyopia. This is especially true for astigmatic presbyopes. However, one of the major obstacles with most translating/alternating vision designs is the prism ballast, which orients the near segment inferiorly to facilitate lower lid interaction and lens translation.
In the evolution of presbyopic rigid lenses, manufacturers often improve designs from the '60s and '70s and reintroduce them. One is the ContinuVu multifocal lens (Essilor), a De Carle lens design with a 3.5mm distance center surrounded by 360 degrees of near add power (Figure 1). It's a translating vision design that eliminates many problems associated with traditional ballasted lenses. With the near portion of the lens surrounding the center distance, patients need only to gaze slightly down to find the add portion of the lens.
Patient SK is a 52-year-old female struggling with near vision through her current aspheric multifocal GP lenses. We decided that we might enhance her visual performance by switching to a translating lens design.
ContinuVu lens fitting begins by obtaining central keratometric readings; SK's were OD 42.75 @ 175/44.50 @ 85, OS 43.00 @ 10/ 44.75 @ 100 with a manifest refraction of OD –3.00 –1.50 x180, OS –3.25 –1.50 x005. We design initial lenses on or near flat K and order empirically as diagnostic lenses. We apply the initial lenses and evaluate the lens-to-cornea fitting relationship. Optimum fit should demonstrate centration over the pupil with moderate movement with the blink. The fluorescein pattern should show pooling in the lens center surrounded by a wide band of fluorescein thinning indicating midperipheral lens alignment.
A major advantage of the ContinuVu design is the ease you can interpret the fluorescein patterns (Figure 2). A flat lens will exhibit minimal apical clearance with nasal or temporal decentration due to a loss of lens alignment in the midperiphery, while a steep lens will exhibit excessive apical clearance and/or a bubble beneath the lens center.
Perform an out-of-phoropter refraction over the initial diagnostic lenses (at both distance and near) to verify lens powers.
In our hands the ContinuVu design combines the comfort of a traditional, non-ballasted GP design with the optics of a translating bifocal. We find the lens extremely beneficial in managing astigmatic presbyopes interested in optimum binocular distance and near corrections.
Patrick Caroline is an associate professor of optometry at Pacific University and is an assistant professor of ophthalmology at the Oregon Health Sciences University. He is also a consultant to Paragon Vision Sciences and SynergEyes, Inc. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for Alcon Labs, CooperVision and SynergEyes, Inc.