Once again, this year’s Global Specialty Lens Symposium (GSLS) offered interesting insights regarding presbyopia and how to correct it with contact lenses. From the technology that will bring us the presbyopic lenses of the future to what’s going on in the here and now, following are interesting findings that were shared at the meeting.
Pie in the Sky Presbyopia Correction Possibilities
Dr. Jerry Legerton peered into the future, describing potential “smart contact lenses” for numerous indications including for presbyopia correction. He described two types of accommodating lenses for presbyopia: one using liquid crystal technology and another with the concept of an energized fluid meniscus.
In addition, the University of Manchester is working with eVision to develop an electro-optical flexible contact lens that will dynamically change focus while still correcting for other refractive errors.
Another futuristic, bio-inspired presbyopia design is being developed by a team at the University of Wisconsin-Madison led by Hongrui Jiang, PhD. Under a National Institutes of Health/National Eye Institute grant, they are studying the elephant-nose fish (www.nih.gov/news-events/news-releases/fish-insects-guide-design-future-contact-lenses ). The lens is being designed based on this fish’s retinal structure and can continually adjust its focus working together with humans’ own cornea and crystalline lens.
Back in the Here and Now
Two interesting posters regarding presbyopic contact lenses were presented at GSLS 2017 (www.gslsymposium.com/posters ). “Multifocal Scleral Lenses: A Newer Player for Presbyopic Correction” by Tiffany Chen, OD, and Judith Perrigin, OD, from the University of Houston College of Optometry looked at the possibility of scleral multifocal lenses in an aspheric design masking corneal irregularities and corneal astigmatism, and therefore possibly providing better image quality compared to soft multifocal lenses.
The patient, a 68-year-old male optometrist who desired multifocal contact lenses, wanted flexibility from spectacles and was seeking good vision at all distances without having to change head posture. His history demonstrated experience with the gamut of presbyopic contact lenses options, from monovision to soft lens multifocals to both aspheric and translating GPs. His dissatisfaction with these was a combination of inadequate vision, head positioning, and centration issues.
Although it took multiple fits, good comfort, vision, and fit were ultimately achieved. The scleral multifocal was a simultaneous vision design, yet the image quality was subjectively sharper at all distances compared to soft multifocals.
Frank Spors, EuroOptom, MS, PhD, et al presented a poster titled “Corneal Wavefront Aberrations: Multifocal Soft Lenses compared to Orthokeratology.” Their study compared aberrations induced by center-distance multifocal soft lenses in vivo with those induced by ortho-k on naked corneas post-treatment.
The right eyes of 40 participants who had myopia of up to –6.00D and no greater than –0.75D cylinder were fitted with soft multifocal center-distance lenses, which corrected their distance refractive errors and had four different add power values. Wavefront aberrations were determined over 6mm entrance pupil diameters with corneal topography prior to and following lens fitting. Results were compared to published wavefront aberration data from successful ortho-k treatments.
The authors concluded that the use of soft multifocal center-distance contact lenses leads to a significant increase in higher-order wavefront aberrations. The increase in add power is associated with a reduction of lower-order aberrations (primary astigmatism) and an increase in higher-order aberrations. Compared to ortho-k, the amounts of induced higher-order aberrations with center-distance multifocal soft lenses were less. CLS
For references, please visit www.clspectrum.com/references and click on document #256.