Contact Lens Design & Materials
Contact Lens Design & Materials
Make the Most of Expanded Material and Design Options
BY RONALD K. WATANABE, OD, FAAO
When I was in school, contact lens material and design selection was easy. We had a few silicone acrylate GP materials, traditional hydrogel materials, three disposable lenses, and a so-so hybrid. We didn’t fit multifocals, sclerals, or orthokeratology lenses. We fit all keratoconus patients with corneal GPs. Our main focus was on getting the fit right and trying to limit corneal changes.
Today’s contact lens world is very different. While we still aim to minimize ocular surface changes, a big challenge for us now is to figure out which of the hundreds of brands and designs is the best choice for each patient. On the upside, today’s options are far superior to the choices we had back in the ’80s, and we can fit more patients with better outcomes.
Options for “Normal” Patients
Most of the patients whom I see have “normal” refractive needs: myopia, astigmatism, presbyopia, etc. For these patients, I try to tailor the lens choice to their individual needs. Daily disposables are great for children, busy professionals, dry eye patients, heavy depositors, athletes, etc. Many recent material breakthroughs have occurred in this category, and most patients are eager to try the latest and greatest if it means better comfort and wearability.
Excellent new monthly options have recently been introduced with high Dk values and good water retention properties; along with biweekly options, these may be a better choice for those who need more oxygen transmission, have higher refractive errors, or are more budget-conscious.
Soft multifocal designs have also improved tremendously, with custom options available for those who don’t succeed with first-line disposable offerings. And corneal GPs remain excellent options for myopic and hyperopic astigmats, especially if they are also presbyopic or have had problems wearing soft lenses. Scleral GPs are also on the rise for patients who do not have corneal irregularities.
A growing area is myopia control in children. I present both orthokeratology and soft multifocals to all parents of children whose myopia is increasing significantly each year. While I can’t guarantee that it will work for each child, and it is currently off-label, many parents are surprised but grateful to learn about these options.
Scleral lenses in hyper-Dk materials can be fit to virtually any shape cornea with great success. There are reverse geometry, toric, quadrant-specific, and even multifocal options available from many labs.
Custom hydrogel options are becoming increasingly common because they can “mask” or correct for high amounts of corneal irregularity with good visual results. Some of these designs are very sophisticated with asymmetric curves and zones, reverse geometry, asphericity, and toricity to drape smoothly over the cornea. With their ease of adaptation, they are desirable to patients who have had to endure discomfort with other options.
Higher-Dk materials and evolving designs are making hybrid lenses more viable and widely used options for mildly to highly irregular corneas.
Finally, corneal GP lenses still have perhaps the best balance of material availability, design options, and ability to fit irregular shapes while delivering the most oxygen and ease of handling.
Today’s contact lens practice can be more daunting than in the past. But with so many great options, practitioners can provide excellent comfort, wearing time, vision, and corneal health. CLS
Contact Lens Spectrum, Volume: 29 , Issue: August 2014, page(s): 17