Preo planning Toric Lens and LRI

[uxuh]

After I watched Dr. Oyakawa’s video he posted on U tube. I used LRI Calculator to estimate the LRI arc need to correct my right eye without Toric lens to target my right eye vision to Plano. Total LRI arc is 180° which is awful large .My right eye has cataract and astigmatism has not been operated yet. The IOL master data is as follow:

AL: 24.95mm (SD=0.03mm SNR=2.7)
K1:44.23D/7.63mm@5°
K2:47.20D/7.15mm@95°
SE: 45.72D
Cyl: -2.97D@5°
R: 7.39mm (SD=0.00mm)

I used Acrysof IQToric IOL Calculator Online with Spherical equivalent 14 D, SIA 0.4D The Toric calculator recommended SN6AT5 lens for me. What I am interest in is the anticipated residual Astigmatism left after surgery. I found the incision location makes difference. The data is as follow:

Incision location       residual Astigmatism after implant
180°   (Temporal)                  1.3D
225°                                       1.06D
250°                                       0.67D
270°                                       0.52D

I think I can live with 0.52D residue astigmatism after implant.  Is Incision location at 270° difficult for surgeon to operate on?  If Incision location is at 180°, how to calculate the arc for LRI, if I want implant and LRI to be done at the same time? What is the health rick if the LRI arc is too large?

[Ray T Oyakawa, MD]

The answer you got depends on the nomogram used.  You used the DONO.   If you had used the NAPA (Nichamin Age Pachymetry Adjusted);  your eye will need two 70 degree arcs (I put in an age of 65).  However,  this is depth adjusted and a peripheral pachymetry needs to be done.  Most doctors are not comfortable correcting this much astigmatism and do not do depth adjusted LRIs.  This require a micrometer adjusted LRI blade which is much more expensive that a fixed depth blade.  Also,  you need a pachymeter that will measure the cornea in the periphery.

See my latest video-posted last night.

http://www.youtube.com/watch?v=wE6Hrhaal34

If your surgeon implants a T5 there will be an anticipated residual astigmatism of 1.3.  Now if you enter this in the AMO LRI calculator with 43.3 steep at 95 and 42.00 for the flat axis (any ks with 1.3 difference will work since this is refractive- the anticipated post toric astigmatism).  This will require a pair of 45 at 95 degress.  This is much easier to do.  However,  this depends on placing the Toric IOL on the correct axis.

Dr. O.

[John C Hagan III, MD, FACS, FAAO]

You should ask this question to Dr. O.  Repost it tomorrow. He answers questions on even days but will not be answering this coming Wednesday.

JCH MD