THE BUSINESS OF CONTACT LENSES
GOOD BUSINESS REQUIRES PRACTICE
CLARKE D. NEWMAN, OD, FAAO
A significant part of running a successful contact lens business is finding ways to optimize the bottom line. For the GP portion of your contact lens business, this involves honing skills that both improve efficiencies and that reduce chair time, errors/orders, and follow-up visits, among many others.
In my last column, I discussed three things that can affect the accuracy of GP scleral lens assessment at the slit lamp. This month, I will discuss a few more things that raise the bar in GP practice.
Base Toric Optics
First, don’t be afraid of the base toric optic in corneal GP lenses. Just as the GP scleral lens has forced all of us to familiarize ourselves once again with the front-toric lens, we need to remember the value of the base toric for the geometric alignment of corneal GP lenses. One of the best ways to prescribe these lenses efficiently is to have a 2.00D and a 4.00D spherical power effect (SPE) diagnostic lens set.
My set goes from 40.00D/42.00D to 50.00D/52.00D in 1.00D increments for the 2.00D set and in the same range (40.00D/44.00D to 50.00D/54.00D) for the 4.00D set. That is a 20-lens diagnostic set, with each lens having a –3.00D power in the flatter meridian. I also have the base curve radii and the flat meridians laser marked on my diagnostic lenses.
For all corneas that have more than 2.00D of anterior corneal toricity, I try to use a toric base optic whenever possible. The beauty of using a diagnostic lens to assess alignment is that you know what you are getting before you order. Also, the really cool thing about having an SPE trial set is that you can easily figure out the powers through a sphero-cylindrical over-refraction. Remember, an SPE lens does not induce a cylinder, so any cylinder in the over-refraction goes on the lens’ front surface. By marking the flat meridian, you can also make sure that the lens is aligning with the corneal cylinder.
When Rotation Matters One of the biggest problems with low-toric lenses is lid-induced lens rotation. If the lens is a cylinder power effect (CPE) or a cross-cylinder effect (CCE) bitoric lens, rotation will cause power problems and affect vision. Because SPE lenses do not induce a cylinder, rotation is irrelevant to the power, but you can still see whether the lens is rotating. When you add additional cylinder to the front, it is no longer an SPE lens, and rotation then matters.
The CCE lens is a little known bitoric variant that can be a real problem solver. This lens is needed when the meridians of corneal toricity and the corrected cylinder axis are misaligned by 20º or more. Again, the SPE trial lens really helps you sort out this problem.
Let’s say that the flat corneal meridian is at 180°, and the SPE diagnostic lens aligns along 180°, but the sphero-cylindrical over-refraction is –2.00 –3.00 X 025: then a CCE lens would be indicated. With a computer numerical control (CNC) lathe, rotating the meridians on the front to a different axis from the back should be relatively easy. The hard part is verifying the powers of the created cross-cylinder.
A Final Time-Saving Tip
Another way to reduce chair time when using GP lenses is to have every lens plasma treated to improve initial wettability. This surface treatment uses a plasma field to create oxygen radicals that super clean the lens surface. It also realigns the surface molecules to ionize the lens surface such that it binds aqueous to increase surface lubricity.
This process all but eliminates surface-bound paraffins and oils left over from the manufacturing process that render GP lens surfaces non-wettable. Older practitioners like me remember the days when it was a battle to get GP contact lenses to wet at the dispensing visit.
Practice Makes Perfect
So use plasma coatings and base toric options to improve your GP practice. CLS
Dr. Newman has been in private practice in Dallas since 1986 specializing in vision rehabilitation through contact lenses as well as corneal disease management, optometric medicine, and refractive surgery. He is a Diplomate in the AAO and a consultant or advisor to Alcon, Allergan, AMO, B+L, EyePrintPro, GPLI, Johnson & Johnson Vision Care, SynergEyes, TruForm Optics, and Zeiss Optics. Contact him at firstname.lastname@example.org.