contact lens practice pearls
When All Else Fails, Follow the Directions
BY JOHN MARK JACKSON, OD, MS, FAAO
Ah, spring. My early lawn care this year has focused on killing weeds. I spread a bag of weedkilling pellets on my yard, but it didn't kill them as promised. Perplexed, I decided to actually read the directions on the bag. I missed an important step: the lawn was supposed to be wet before using the pellets. I wasted $30 by not following the directions! I tried again and now the weeds are (mostly) gone.
Why am I telling you this? For some reason, I've had a wave of patients lately who came to our clinic because their lenses weren't working well for them. In many cases, it appeared the original clinician didn't follow the fitting guide very well for the lenses.
Follow the Guide
Manufacturers spend time and money developing the best practices for products. It should stand to reason that we should follow the directions.
I think we just can't help ourselves. We've fit lots of soft multifocals… how different can a new one be? Reading guides takes time, and in a busy practice it's easier to rely on experience. I'm as guilty as anyone. But new products don't always work like the old ones.
As an example, consider the SynergEyes hybrid GP/soft lens. With standard GPs, we want a lens that aligns well with the cornea. With SynergEyes you need the GP part to be a little steep to prevent lens adherence. For a standard soft lens you would flatten a too-tight fit, but with the SynergEyes lens you would steepen the soft skirt.
I ran into this scenario with a patient who was having a terrible time with her lenses because they were fit close to on-K. Figure 1 shows how the lens should look (well, it's a little too steep). Figure 2 shows it fit incorrectly with alignment in the GP part.
Figure 1. A correct fit of a SynergEyes lens.
Figure 2. A lens with incorrect alignment in the GP section.
Another patient presented wearing the Air Optix Aqua Multifocal (Ciba Vision). Her distance spectacle Rx was −2.00D OD, −1.75D OS, +2.50D add OD and OS. She was having a tough time reading and her eyes felt unbalanced. Her lens boxes showed a low add/high add combination. She said that she tried only one pair of lenses and was told her vision was as good as it could get.
The fitting guide says to use two high adds, which is what we tried. Her near vision improved and she was much happier with the balance. Based on experience with earlier multifocals, the last clinician may have assumed that two high adds would interfere with distance vision and didn't follow the fitting guide. I thought the same thing until recently. But lenses have improved, and you should use the company's recommended first lens and then start troubleshooting.
If you haven't pulled out a fitting guide in a while, start reading. You may be surprised, and lenses that you thought didn't work may turn out to be winners. CLS
Dr. Jackson is an associate professor at Southern College of Optometry where he works in the Advanced Contact Lens Service, teaches courses in contact lenses and performs clinical research.