📬 This is Mindset Mailbag, our series where we answer questions sent in by our supporters. Got one? Drop it in the comments.
If you’ve ever stared at an ortho-K lens design and thought, “okay, but why does it work?” — this one’s for you.
Welcome to Mindset Mailbag — our new series where we answer questions sent in by you, our subscribers. You write in, we bring in the right expert, and we talk it through. For our very first one, our guest is Dr. Carson Wong of Sylvan Family Eye Care, who has a real passion for myopia control in kids and getting involved early. He reached out after our “What Fitters Often Overlook” episode with a question about reverse-engineering orthokeratology — and honestly, it turned into one of our favorite conversations.
Carson’s instinct is one a lot of great ortho-K practitioners share: he likes to take things apart, look inside, and put them back together to see how they work. He’s fitting across several philosophies right now — doctor’s own design, iSpace, Paragon, and he’s been dabbling with RGP Designer — and he wanted to understand what each design is actually doing under the hood so he can modify it for his own patients.
So Cary Herzberg — 40-plus years in myopia management and one of the pioneers of this field — did what Cary does best: he pulled up the software, built a patient on the spot, and walked Carson through it live.
What Cary covered
Cary built a sample patient in RGP Designer (a –5.00 to start, then up to –10 and beyond) and used it to show how you reason about a design rather than just trust the defaults. A few of the ideas that stood out:
You should be able to fit any patient who walks through your door — regardless of the design they’re already in. Cary has corrected –8.00 patients, even fit a CRT lens on one eye and a different design on the other, successfully. The skill isn’t memorizing one brand; it’s understanding where each design is coming from and being able to evaluate and adjust from what you see on the cornea.
The 80-micron rule. This was the heart of it. When you look at the reverse curve and the tear film in a good myopia-control fit, you want roughly 80 microns of elevation — at minimum…
