Using Confocal Microscopy for Contact Lenses
Used for research today, this technology will help evaluate contact lens wearers' corneas in the future.
Dr. Potter: Dr. Sindt, you're our resident expert on confocal microscopy. This is a great new technology for evaluating the physiological effects of contact lenses on the cornea, and the eye in general. Could you describe this technology and tell us how it relates to the findings that a clinician may make?
Dr. Sindt: Confocal microscopy provides us with high-resolution, real-time imaging of living human corneal cells, and that's very exciting because it allows us to see what's happening with our patients while they're wearing their contact lenses. There's a lot of information related to the technology and various disease states, but it's a relatively new area of research for contact lenses.
STAINING AND CONFOCAL MICROSCOPY
Dr. Sindt: We first evaluated whether we could see corneal staining with a confocal microscope. Our group and others have learned that we can visualize staining on the cornea with the confocal microscope, and it appears as bright spots, or hyper-reflective cells.
Some researchers speculate that the hyper-reflective cells in the most superficial layer of the cornea are progressing toward cell death. We also evaluated whether or not fluorescein affects confocal imaging. In 2009, at the Academy meeting, a presentation showed that fluorescein does not affect this method (Schneider, 2009). In that study, ConfoScan (Nidek), a confocal microscope that uses white light, was used. I'm using the HRT (Heidelberg) microscope, which uses laser light, and I'm finding the same thing. Adding fluorescein does not affect the images, so we can put the fluorescein in before we use the confocal microscope and assess corneal staining as well as cell morphology.
PUTTING RESEARCH INTO PRACTICE
Dr. Sindt: Confocal microscopy itself gives us another piece of the puzzle for making decisions in practice. When patients are having inflammatory problems, I use the instrument to evaluate the immune state in the cornea. I don't put the patient back into contact lenses until the immune cells have retreated from the cornea. Confocal microscopy is a research tool now, but I believe it will become a tool used in practice to monitor contact lens wearers.
Dr. Brujic: I will welcome that technology. It is needed. It's sometimes difficult to identify why some contact lens wearers have poor results. We had difficulty in our office even figuring out what care solutions people were using and how they were replacing their lenses. As a result, we made a rule that all contact lens wearers have to bring in their lens cases, solutions and any other products they use to care for their lenses. Sometimes it's still difficult to determine why certain responses occur, but it's easier when we know what products patients are actually using.
We've also found that this approach makes patients more responsible about compliance. They listen to the recommendations we make in the exam chair, and they know that they need to show us what they're using and doing the next time they visit. They're often happier, too, because when they do what we ask, they're more likely to succeed with wearing contact lenses.
Dr. Sindt: Common-sense approaches like that and new technologies are great ways to tackle a complex problem.
Confocal microscopy offers one way to show patients the effects of certain combinations of lenses and solutions or of non-compliance with recommended wearing schedules or care regimens, and that illustration of the problem brings the reality home.
Our primary goal is to minimize adverse events and infection, and we need to do whatever it takes to prescribe what's best and make sure patients understand and follow our recommendations. CLS