contact lens management
Silicone hydrogel meets challenging-to-fit patient's needs.
BY STEVEN I. BENNETT, O.D., F.A.A.O.
"Challenging-to-fit" contact-lens patients include those who have astigmatism, presbyopia and extreme myopia or hyperopia. Others in this category have a steep or flat cornea that may fall outside commonly available silicone-hydrogel-lens parameters. In addition, many of these patients complain of discomfort and symptoms of contact-lens-related dryness, such as burning, as a result of wearing a low-Dk/t HEMA lens.
I've found that the O2Optix Custom lens, from CIBA Vision, is a great match for many of these patients for a number of reasons.
First, the lens offers a Dk/t of 117 at -3.00D. This contributes to healthy and comfortable lens wear.
Second, O2Optix Custom lenses contain a biocompatible plasma surface treatment for a smooth, continuous surface that resists deposits. The surface treatment transforms the normally hydrophobic silicone material into a hydrophilic material that allows for comfort and biocompatibility.
Third, these lenses consist of sifilcon A, a silicone-hydrogel formulation that not only promotes wettability, but contains a unique property that facilitates the lathing of the lens into made-to-order powers, diameters and base curves (see sidebar). The result of this lathing: front curve asphericity for aberration control; back surface asphericity, ensuring a comfortable fit; a double-zone lenticular region for relatively consistent peripheral thickness and a smooth edge design throughout the entire range of O2Optix Custom prescriptions. Other features: a light-green handling tint and an inversion mark.
Here are two cases in which I've found success with this lens.
Aphakic night watchman
A 45-year-old night watchman presented frustrated with the quarterly replacement HEMA lens his prior practitioner prescribed. He said the lens provided him with reasonable, yet fluctuating vision. He also reported that the lens was very uncomfortable. Apparently, the lens became coated with protein deposits very quickly, so he couldn't always wear it for the full replacement interval. He further reported that he needed a lens he could wear comfortably during his long work shifts.
Exam results revealed +12.00D with no cylinder with a best-corrected visual acuity (BCVA) of 20/25 OD and plano -0.50 × 025 with a BCVA of 20/20 OS. Slit-lamp revealed Grade 1 conjunctival injection OD with 1+ limbal injection.
I fit this patient in an O2Optix Custom lens for three reasons:
First, I felt that the reason his vision was fluctuating and part of the reason his HEMA lens felt uncomfortable was because his HEMA lens didn't offer him the best parameters for his post-surgical corneas. The O2Optix Custom lens offers numerous parameters.
Material: Sifilcon A
Water Content: 32%
Dk/t: 117 @ -3.00D
Wearing Schedule: Daily wear
Recommended Replacement Schedule: Quarterly
Recommended Lens Care System: Clear Care
Diameters: 13.2mm, 14.0mm, 14.8 mm
Base Curves: 13.2 mm
diameter: 7.4, 7.7, 8.0*, 8.3
14.0 mm diameter: 7.8, 8.1, 8.4*, 8.7, 9.0
14.8 mm diameter: 8.0, 8.3, 8.6*, 8.9, 9.2)
Sphere Powers: +20.00D to -20.00D (0.25D steps)
ECP Cost: $110.00 (4 pack) (excluding volume discounts and level pricing), quarterly replacement, according to "Tyler's Quarterly Soft Contact Lens Parameter Guide," Dec. 2007.
* To simplify the fitting process, CIBA Vision recommends starting with the highlighted base curve in each of the diameters listed above.
Second, I felt that his habitual HEMA lens' lack of oxygen transmissibility was also playing a role in his discomfort. The O2Optix Custom lens offers high-oxygen transmissibility.
Third, because this silicone-hydrogel lens (O2Optix Custom) contains a permanent biocompatible plasma surface treatment that resists deposits, I knew it would be less prone to deposit build-up throughout the day.
The result: After approximately two weeks, the patient said he adjusted to the change from HEMA to silicone-hydrogel lens, which I educated him about, and he presented for a follow-up visit.
At this visit, he said he was ecstatic with the comfort of his new lens. Exam results at this visit revealed no signs of limbal redness and trace conjunctival injection.
Generation X-er requires clarity
A 30-year-old female presented dissatisfied with the two-week replacement HEMA lens her previous practitioner prescribed. Specifically, she said the level of acuity with which the lens provided her (20/30 OU) wasn't clear enough.
Exam results revealed a prescription of -14.00D -0.50D × 015 OD and -16.00D -0.75D × 170 OS. Slit lamp revealed Grade 1 conjunctival injection and moderate limbal redness.
I refit her with an O2Optix Custom lens. I chose this lens for two reasons:
First, I knew it would be able to correct her high myopia (the lens offers several parameters), providing her with the vision she desired.
Second, I was confident in the lens' high-oxygen permeability, which would eliminate her signs of conjunctival injection and limbal redness.
At this patient's first follow-up visit, she nearly cried with joy when we began asking about her vision. Once I fine-tuned her prescription, she was seeing 20/20, which she described as "the best vision I've ever had in my life." Furthermore, examination showed that her conjunctival injection had resolved.
There is no greater reward than being able to turn frustrated contact-lens wearers into satisfied and happy ones. Their excitement is a wonderful reminder as to why I became an O.D. in the first place. And, when these patients tell friends or family members about how I solved their difficult case, my practice revenue is rewarded by the influx of several new referrals. O2Optix Custom has enabled me to achieve these rewards. For more information on this lens, visit www.specialty-lenses.com. OM
DR. BENNETT PRACTICES IN ANN ARBOR, MICH. HE SPECIALIZES IN CUSTOM FITTING CONTACT LENSES AND LOW VISION AND IS THE PRINCIPAL INVESTIGATOR FOR NUMEROUS CONTACT LENS STUDIES. E-MAIL HIM AT SBEN NETT@BENNETTOPTOMETRY.COM.
Optometric Management, Issue: February 2008