Getting Over the Plasma Barrier

GP LENSES

In this interview, Robert Buffington, OD, FAAO, discusses the benefits of plasma-treated GP lenses.

Menicon: Some practitioners are reluctant to try Menicon Z because of the plasma treatment. Please describe your practice and discuss your experience using Menicon Z.

Dr. B: My practice is a specialty lens/difficult fit contact lens practice. We prescribe about 300 GP lenses per month, drawing patients from across the United States and around the world. We have used Menicon Z lenses for more than 13 years, and we prescribe them for more than 90% of our patients. In all this time, we have not had an issue with wettability or the plasma surface treatment.

GP contact lenses undergoing plasma treatment.

Menicon: Please share other experiences that would further demonstrate your comfort level with plasma surface treatment.

Dr. B: The nature of our practice is fitting all types of patients, but we specialize in difficult-to-fit cases, such as post grafts, keratoconus, pellucid marginal degeneration, orthokeratology, post refractive surgery failures and continuous wear. We routinely modify our GP lenses by altering peripheral curves, changing power, adjusting edge lift and so on. We have added as much as +1.00D to – 1.00D of power to Menicon Z lenses without adversely affecting wettability.

Menicon: What is plasma treatment and how does it work?

Dr. B: Many practitioners believe plasma treatment is a coating on the lens. It is not. Basically, plasma treatment is a scientific way for the polymer molecules to orient on the surface of the lens so that the surface is more wettable. In fact, plasma treatment has become part of everyday contact lens fitting as most silicone hydrogel lenses have some sort of plasma treatment.

Plasma treatment is accomplished in two phases. First, the finished lenses are run through an oxygen chamber where they are ionized. The surface polymer molecules orient so that the negative side positions on the surface of the lens, increasing wettability.

The second part of the plasma treatment process is the removal of the ionized oxygen by creating a vacuum. Essentially, this process “super cleans” the surface of the finished lens. The oxygen molecules knock off debris over the surface of the lens at a molecular level. This removes residue, polishing agents and binding agents, anything that might be left on the lens following manufacturing.

Many practitioners have heard of the water drop test, whereby a drop of water is placed on the surface of a lens and the angle of the water droplet indicates wettability. The lower the angle is, the more wettable the surface is. After plasma treating a lens, water simply spreads across the entire surface. There is no water droplet to measure. Isn’t that the type of wettability that our patients need?

Dr. Buffington examines a patient at the slit lamp.

Menicon: Your knowledge of lens manufacturing is impressive. Where and how did you learn so much?

Dr. B: I reached a point in my practice where I had a patent on lens designing and I had mastered customized modification and fitting of specialty lenses. The next area to master was lens material development to ensure the highest quality lenses for my patients. From 1989 to 1992, I developed Transaire GP materials. I was involved in all aspects of GP lens management, from the raw materials and button-making to patient care and customized designs, with the goal of providing cutting-edge care to my patients.

Menicon: What prompted you to end that business venture?

Dr. B: Part of the reason was the fact that I had visited the Menicon facilities in Nagoya, Japan, when the company was launching its business in the United States. I was impressed. The research and production facilities were — and still are — exceptional. Having bought the raw chemicals, worked with the polymer chemists and made my own buttons, I know what is involved. As a material and button manufacturer, I was pleased to see someone in the world doing things in what I considered the right way at a level higher than I could ever afford. There were other reasons challenging our Transaire business as well, but after seeing Menicon Japan, I threw in the towel and started working with the Menicon products.

Menicon: Do lens care solutions and regimens make a difference for vision and comfort?

Dr. B: Yes. Absolutely. Even before I discuss lens care products, I stress that the proper cleaning technique is most important. We thoroughly instruct all patients to clean both sides of their lenses before storage by lightly rubbing the front and back surfaces with a generous amount of the recommended cleaning solution. We explain that excessive pressure is not required, but leaving mucus or oils on the lens surface may cause a host of problems.

Menicon: What would you say to practitioners who are concerned that the plasma treatment will rub off or lose efficacy over time?

Dr. B: I understand that, theoretically, plasma treatment can lose efficacy over time. That is one reason why plasmatreated lenses are shipped wet. There is a possibility that the polymer molecules can rotate back to expose their hydrophobic profile to the surface and reduce wettability. Although that is the scientific theory, I have not experienced that situation in our practice. With proper cleaning and disinfection, and with regular Progent treatment, we have not seen wettability problems with Menicon Z, even after changing the power of the lenses up to one diopter.

Menicon: Practitioners often ask how long plasma treatment lasts. What is your experience?

Dr. B: Scientific study and theory state that plasma treatment slowly dissipates over time. However, in my experience. the lenses and the plasma treatment can last up to 2 years or more.

Menicon: How often do you recommend patients change their GP lenses?

Dr. B: Our policy is to dispense new GP lenses every year. I believe it is the doctor’s responsibility to educate and train patients to replace their lenses every year for health reasons. The days of 3 to 5 year replacement went out with PMMA and low-Dk lenses.

Menicon: What advice would you share with contact lens practitioners?

Dr. B: The goal of our practice is to offer our patients the best care, the best lens materials and the best vision. We have patients coming to my practice for consultation from 49 states and 29 countries. When a patient’s travel and hotel costs exceed the cost of their lenses, it is important that we deliver exceptional care.

Doing the best we can, having confidence in the lens material, and being able to explain to patients how that material will perform is crucial. Knowing I can change the lens power up to one diopter before they return to their home country is also key for me. Even practitioners who do not have such high demand from their patients should appreciate the quality of Menicon Z and realize that plasma treatment is a nonissue when considering this lens.

Dr. Buffington is in private practice in Sacramento, Calif.