The Optometrist Perspective by Harvey Yamamoto, OD

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Harvey Yamamoto, ODHappy Thanksgiving to all. Happy Holidays to all my readers from our entire staff at C&E. May your Holidays be filled with happy moments. This year is fast closing in on each of us.

Last month, I promised to touch upon one of my favorite topics. Specialty contact lens fitting. I can honestly tell you that fitting specialty contact lenses is an art but not impossible to achieve. First, one should have a good corneal topographer. Then one must have some fitting sets. i.e.: We have many such fitting sets. Some are sitting on the shelf forever. Some are used daily. My favorite is our Scleral fitting set. My second favorite in our Ortho-K fitting set.

Between the two fitting sets, our practice is staying above water. Yes, you heard correctly. Our practice thrives today because of our contact lens fitting expertise. We have all the modern equipment to make that happen. We have incorporated this year, the new 5000 OCT unit which gives us a 15mm scan of the cornea with the scleral lens in place. Our lenses are 16.4mm but the 15mm scan provides us with priceless information on how well the lenses are resting on the sclera.

Yes, the lenses must come to a rest beyond the limbal zone. Stem Cells reside in the limbal zone so we don’t want to cause any damage to these important cells. Thus our favorite size to fit is 16.4mm. We began experimenting with 13.5mm some 8 years ago. We found that the 13.5mm would initially work quite well.

However, after 30 days of wear, our patients would return with impingement on the limbal zone. We quickly learned that we needed to increase the size of our scleral lens by a couple of mm. We then turned our attention to 15.0mm.

The 15.0mm lens was larger and gave better clearance over the limbal zone. Shortly after fitting a few dozen patients, we quickly learned that we were dealing with complaints of lens fogging. This was very troubling.

Patients would leave our office extremely happy and then only to return a few weeks later with an upside down frown on their faces. Acuity had diminished as well as foggy vision.

We upsized our lenses to 16.4mm and bingo, we hit paydirt with the 16.4mm diameter. There was enough landing zone on the larger lenses and yet the new size provided us with enough room to provide our patients with a nice edge lift. Edge lift has always been important topic of discussion when it came to hard lenses. Sclerals lenses are glorified hard lenses made out of high-DK materials. We had to learn how to prepare the lenses due to the high DK. The learning curve was very difficult for us initially to master.

Once our patients saw the size of the trial lenses, they would freak out. So we have to train ourselves to handle the 16.4mm lenses with dignity and calmness. We panic, the patients panic. Once we mastered lubricating the large diameter lenses, the insertion became much easier with a more relaxed patient to work with.

It’s like the domino theory. We want to avoid any tension filled exam room. Once I mastered being relaxed, the patient became relaxed. I recommend choosing one member of your staff to become your assistant during the fitting process.

A note to those who have been shy to begin fitting Scleral lenses. First, purchase a fitting set. We get ours from GP Specialists. Our practice was the beta testing site for the I-Sight Scleral lenses. We incorporate what we had learned from manufacturing Scleral lenses in our practice during 1990. We began with PMMA buttons. Once the higher DK buttons became available then the Sclerals lenses exploded on the scene.

Nearly every GP lab in the country began to manufacture their version of Sclerals. We went through many trials and errors trying to unlock the secrets to the perfect parameters that comprise the I-Sight Sclerals today.

We tried mini-sclerals, mid-range sclerals, regular diameter sclerals and then super sized sclerals. Each step uncovered pricess information that went into today’s I-Sight lenses.

We also learned that the sclera was not round as we had original thought. The sclera takes on many different contours. Once again, this led to ‘back to the drawing board’ to establish the average contour of each sclera.

We also learned that the corneal toricity can affect the sclera toricity as well. Once we had digested that information then we began to conduct serious R&D on various parameters until we finally began to understand the nature of the sclera. Each stage was labor intensive but all the hard work eventually began to pay off with multiple successful fits in our practice.

Patients began to spread the word to their friends and family members. Our practice soon became flooded with patients from around the globe wanting to be fitted with these magical lenses.

Once a novice fitter experience his/her first successful patient then the next one becomes easier and easier until you become an expert. Today, we can quickly pick out the correct base curve on the first try. Many years ago when we first began to fit sclerals, it was a labor of love. Each patient would take 4 hrs to fit. We stayed many hours after work fitting just one patient. That was short-lived once we understood which base curve was the ideal base curve to begin with.

We have learned through trial and error that the ideal B.C. to begin with is based on the steepest B.C. Select the trial lens that is closest to the steepest K reading and that usually is the ideal B.C. The lenses must be lubricated with a gas perm wetting solution using a liberal amount of solution. The lenses made out of high DK materials tend to be dry and thus it is very important to lubricate the lenses well. The next step is equally important. Place 2-3 drops of non-preserved saline into the bowl of the lens prior to insertion. The lids must be propped open as wide as possible. Once this technique is mastered, the process of insertion becomes very routine.

Removal is done with a small 45 degree angle DMV remover suction cup. Place the suction cup on the lower portion of the lens and just twist you wrist and the lens should pop right off the cornea. This may take a couple of tries but it is easy to master.

Have Fun.


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