Understanding Scleral Shape - Dr. Sheila Morrison

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Understanding Scleral Shape
Sheila Morrison, OD, FSLS


[please place all discussion about this lecture in this thread.]

 

[Charles A McBride]

Hi Dr. Morrison. I had time to watch the first half of this lecture on ODWire tonight and paused on your treatment of anterior segment OCT and scleral lenses. What are your thoughts on judging scleral lens shape via OCT given the role that index of refract plays? Are the caliper's accurate?

I listened to a Huang lecture a couple of weeks ago where he pointed out the the posterior "bulge" we see when viewing Intacs via OCT was artifactual due to differences in index of refraction. He hinted that there is a way to correct for index of refraction, but, either he didn't expand, or I wasn't paying attention.

(I use a Spectralis, but I don't think their "caliper" has ever been FDA approved.)

Thanks for your thoughts. -Charlie

Charles McBride
Beaverton, OR

 

[Greg Gemoules]

Hi Dr. Morrison. I had time to watch the first half of this lecture on ODWire tonight and paused on your treatment of anterior segment OCT and scleral lenses. What are your thoughts on judging scleral lens shape via OCT given the role that index of refract plays? Are the caliper's accurate?

I listened to a Huang lecture a couple of weeks ago where he pointed out the the posterior "bulge" we see when viewing Intacs via OCT was artifactual due to differences in index of refraction. He hinted that there is a way to correct for index of refraction, but, either he didn't expand, or I wasn't paying attention.

(I use a Spectralis, but I don't think their "caliper" has ever been FDA approved.)

Thanks for your thoughts. -Charlie

Charles McBride
Beaverton, OR

Dr. Morrison is pretty sharp. I wished that I could see her presentation in Fort Worth later this month, but I'll be out of town. Maybe I can watch it here!

I recently received a few dozen OCT images from an imaging center of a patient in Canada, and I'm pretty sure it was one of the newer spectral/frequency/Fourier domain units. I noticed discontinuities in the images at the edges of the lens. I don't know what instrument was used. It's a small error, but it does illustrate what I have been saying for many years, which is that those images are useful from a qualitative standpoint, i.e. to show the lens position relative to the eye. If I know the corneal thickness and the lens thickness, then it's easy to estimate the vault with enough precision for clinical purposes.

I've probably mentioned this to you in the past, Charlie? I would like to get my hands on a swept-source Tomey SS-1000 CASIA, but they have not received FDA approval, or at least not insofar as I am aware.