Центр коррекции зрения ASTANA VISION

Ким
И.А. Ремесников
ASTANA
VISION
Astana city
Republic of Kazakhstan

Vision™ in astigmatic situations

– topography-modified refraction
BCDVA – best corrected distance visual acuity
NCDVA –

non corrected distance visual acuity

Financial Disclosure: Author has no financial or proprietary interest in any material or method mentioned

of calculation (V.1)
(A John Kanellopoulos)
Kanellopoulos AJ Topography-modified refraction (TMR): adjustment

of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK // Clinical Ophthalmology, November 2016

Case 1.
AR OS sph -2.75 SD * cyl -0.75 CD * ax 175°

BCDVA = 1.00 (0.00 LogMAR)

SEQ = -3.125 D

TOPO-G) method

required!

upper windows
to sph 0.00 and also cyl 0.00 with

ax 0° (180°)

Max. Ablation depth: it must be never > 15 mkm

Save this preliminary plan

EX500
Open preliminary plan

set C4 ≈ C12 by changing sphere to myopia about

-0.15 ÷ -0.25 SD

Initial Zernike C4 = 0.0000, C12 = 0.2150
After adding -0.15 SD Zernike C4 = 0.2282

so we plan sph -2.35 SD * cyl -1.55 CD,

to keep initial SEQ = -3.125 D

to sphere up to -2.50 SD, to compensate myopic shift

Set cylinder axis to 1°as measured: TRUST TOPO!

-2.75 SD * cyl -0.75 CD * ax 175°

TMR will be: sph -2.50 SD * cyl -1.55 CD * ax 1°

Steps from 11 to 14 slides you can also do in Treatment Planning EX500

BCDVA = 1.00 (0.00 LogMAR) and we see regular symmetrical

topograms, so, in my opinion according to my practice and my experience, we will get 1.00 or better NCDVA not only using Topo-Guided method, but also using standard Custon-Q method
We have very simple planning in Custom-Q, requiring only entering sph -2.75 SD * cyl -0.75 CD * ax 175° and not this difficult steps described above, also with higher risk of committing accidental human errors during planning
Furthermore, after treatment using this variant of Topo-Guided method we can expect undercorrected sphere with overcorrected cylinder and changed axis of astigmatism from WTR to the non-physiological ATR one

PostOp situation like this:
AR sph -0.5 SD * cyl +1.00

CD * ax 180° and resulting
SEQ = 0.00 with NCDVA = 1.00, but it will be “bad ten lines”
“Uniformly-spherical” cornea without normal WTR astigmatism ≈ 0.50 ÷ 0.75 D in corneal plane will cause
lens-induced ATR one, but now in the resulting general clinical refraction

Difference map

of calculation in myopic situations (V.2)
(Igor A Remesnikov)

Purpose:
To get

good functional results
To get entirely corrected sphere
To keep normal WTR astigmatism ≈ 0.50 ÷ 0.75 D in corneal plane


In our practice we use Topo-Guided method mainly in the cases with astigmatism ≥ 2.00 CD, excepting irregular corneas with any values of astigmatism, where we can also apply Topo-Guided method

CD * ax 180°
SEQ = -3.75 D

BCDVA = 1.00 (0.00 LogMAR)
Steps from 5 to 12 slides are similar
Calculate sphere: -1.75 – 0.25 (from the standard nomogram) – 0.15 (to prevent myopic shift) = -2.15 SD

from the amount of measured cylinder. For example: measured cylinder

is -4.02 CD – (-0.80 CD) = -3.25 CD

as measured
Finally, TMR for this case will be:
sph

-2.15 SD * cyl -3.25 CD * ax 178° and it’s no need to calculate SEQ to compare it with initial

PreOp
AR OD sph -1.75 SD * cyl -4.00 CD

* ax180° ΔK = 3.25 D
BCDVA = 1.00 (0.00 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl -1.25 CD * ax 15°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = -0.375 D

Measured cylinder was -4.02 CD – (-0.77 CD) = -3.25 CD
TMR = sph -2.15 SD * cyl -3.25 CD * ax 178° (V.2)
With conventional method of calculation:
TMR = sph -1.90 SD * cyl -4.00 CD * ax 178° (V.1)

Difference Map

SD * cyl -4.00 CD * ax 170°

ΔK = 3.25 D
BCDVA = 1.00 (0.00 LogMAR)

1D PostOp
AR OD sph +0.50 SD * cyl -1.00 CD * ax 120° (you can see slight torque-effect)
NCDVA = 1.00 (0.00 LogMAR)
SEQ = 0.00 D

Measured cylinder was -3.91 CD – (-0.76 CD) = -3.15 CD
TMR = sph -1.90 SD * cyl -3.15 CD * ax 179°

Difference Map

sph -4.25 SD * cyl -4.00 CD * ax 15°

ΔK = 3.75 D
BCDVA = 0.80 (0.10 LogMAR)

1D PostOp
AR OD sph +0.50 SD * cyl -1.25 CD * ax 40°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = -0.125 D

Measured cylinder was -4.38 CD – (-0.83 CD) = -3.55 CD
TMR = sph -4.40 SD * cyl -3.55 CD * ax 12°

Difference Map

SD * cyl -4.00 CD * ax 170°

ΔK = 3.25 D
BCDVA = 1.00 (0.00 LogMAR)

1D PostOp
AR OD sph +0.50 SD * cyl -1.00 CD * ax 120° (you can see slight torque-effect)
NCDVA = 1.00 (0.00 LogMAR)
SEQ = 0.00 D

Measured cylinder was -5.64 CD – (-2.64 CD) = -3.00 CD. The values of cylinders and ΔK measured by AR on the both eyes (see previous Case 4) are almost the same, so we significantly reduced amount of cylinder for entering in TMR.
TMR = sph -3.15 SD * cyl -3.00 CD * ax 170°

Difference Map

sph -1.75 SD * cyl -5.75 CD * ax160°

ΔK = 4.75 D
BCDVA = 0.70 (0.15 LogMAR)

PostOp
AR OD sph 0.00 SD * cyl 0.00 CD * ax 0°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = 0.00 D

Measured cylinder was -6.16 CD – (-0.86 CD) = -5.30 CD
TMR = sph -2.10 SD * cyl -5.30 CD * ax 168°

Difference Map

SD * cyl -6.75 CD * ax 15°

ΔK = 5.50 D
BCDVA = 0.8 (0.10 LogMAR)

1D PostOp
AR OD sph -0.50 SD * cyl -1.00 CD * ax 45° (you can see slight torque-effect)
NCDVA = 1.00 (0.00 LogMAR)
SEQ = -0.75 D

Measured cylinder was -7.27 CD – (-1.27 CD) = -6.00 CD. We can’t enter the value of cylinder more than +/- 6.00 CD, so we significantly reduced amount of measured cylinder for entering in TMR.
TMR = sph -0.35 SD * cyl -6.00 CD * ax 14°

Difference Map

sph -8.75 SD * cyl -4.25 CD * ax 5°

ΔK = 3.00 D
BCDVA = 0.10 (1.00 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl -0.75 CD * ax 0°
NCDVA = 0.30 (0.50 LogMAR)
SEQ = -0.125 D

Measured cylinder was -4.19 CD – (-0.74 CD) = -3.45 CD
TMR = sph -8.15 SD * cyl -3.45 CD * ax 9°

Difference Map

SD * cyl -3.25 CD * ax 170°

ΔK = 2.75 D
BCDVA = 0.50 (0.30 LogMAR)

1D PostOp
AR OD sph +0.50 SD * cyl 0.00 CD * ax 0°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = +0.50 D

Measured cylinder was -4.35 CD – (-1.45 CD) = -2.90 CD. The value of cylinder measured by AR and ΔK are significantly less, so we reduced amount of cylinder for entering in TMR.
TMR = sph -7.90 SD * cyl -2.90 CD * ax 172° (V.2)
With conventional method of calculation it will be:
TMR = sph -7.60 SD * cyl -4.35 CD * ax 172° (V.1)

Difference Map

PreOp
AR OS sph -2.75 SD * cyl -0.75

CD * ax 175° ΔK = 1.00 D
BCDVA = 1.00 (0.00 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl 0.00 CD * ax 0°
NCDVA = 1.25 (0.00 LogMAR)
SEQ = +0.25 D and we can see presence of WTR astigmatism ≈ 0.75 D on topogram

Measured cylinder was -1.58 CD – (-0.88 CD) = -0.70 CD. The value of cylinder measured by AR and ΔK are slightly less, so we reduced amount of cylinder for entering in TMR.
TMR = sph -2.95 SD * cyl 0.70 CD * ax 1°

Difference Map

mixed astigmatism situations

Previously we successfully used Arthur Cammings method for

calculation in mixed astigmatism situations:
Turn refraction into the plus-cylinder form
Minus sphere planned with standard nomogram
Reduction of the (+) cylinder


We tried to join it together with TMR method:
In our practice we subtract ≈ 30% from the (+) cylinder
We entering topo-measured axis of cylinder not from AR
or manifest refraction

+2.00 SD * cyl -4.50 CD * ax 0° =

sph -2.50 SD * cyl +4.50 CD * ax 90°
ΔK = 3.75 D
BCDVA = 0.60 (0.20 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl -0.50 CD * ax 165°
NCDVA = 0.80 (0.10 LogMAR)
SEQ = +0.50 D

Spere: -2.50 - 0.25 (from the nomogram) – 0.15 (to prevent myopic shift) = 2.85 SD Cylinder: +4.50 - 30% = 3.15 CD Measured axis of (-) cylinder was 5°
TMR = sph -2.85 SD * cyl +3.15 CD * ax 95°

Difference Map

+1.50 SD * cyl -5.00 CD * ax 170° =

sph -3.50 SD * cyl +5.00 CD * ax 80°
ΔK = 3.75 D
BCDVA = 0.60 (0.20 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl +0.50 CD * ax 60°
NCDVA = 0.70 (0.15 LogMAR)
SEQ = +0.50 D

Spere: -3.50 – 0.15 (to prevent myopic shift) = 3.65 SD
Cylinder: +4.50 - 30% = 3.15 CD Measured axis of (-) cylinder was 174°
TMR = sph -3.65 SD * cyl +3.50 CD * ax 84°

Difference Map

+1.50 SD * cyl -5.25 CD * ax 0° =

sph -3.75 SD * cyl +5.25 CD * ax 90°
ΔK = 3.50 D
VA = 0.40 NC (0.40 LogMAR)

1D PostOp
AR OD sph +0.25 SD * cyl -0.50 CD * ax 25°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = +0.50 D

Spere: -3.75 – 0.15 (to prevent myopic shift) = 3.90 SD
Cylinder: +5.25 - 28% = 3.75 CD Measured axis of (-) cylinder was 8°
TMR = sph -3.90 SD * cyl +3.75 CD * ax 98°

Difference Map

+1.75 SD * cyl -5.75 CD * ax 170° =

sph -4.00 SD * cyl +5.75 CD * ax 80°
ΔK = 4.50 D
VA = 0.40 NC (0.40 LogMAR)

1D PostOp
AR OD sph +1.50 SD * cyl -2.00 CD * ax 145° (you can see slight torque-effect)
NCDVA = 0.80 (0.10 LogMAR)
SEQ = +0.50 D

Spere: -4.00 – 0.15 (to prevent myopic shift) = 3.65 SD
Cylinder: +5.75 - 30% = 4.00 CD Measured axis of (-) cylinder was 177°
TMR = sph -4.15 SD * cyl +4.00 CD * ax 87°

Difference Map

1.00
AR OS sph +5.50 SD * cyl -6.00 CD *

ax 170° = sph -0.50 SD * cyl +6.00 CD * ax 80°
ΔK = 4.75 D
BCDVA = 0.80 (0.10 LogMAR)

1D PostOp
AR OD sph +0.50 SD * cyl -0.75 CD * ax 25°
NCDVA = 1.00 (0.00 LogMAR)
SEQ = +0.125 D

Spere: -4.00 – 0.25 (from the nomogram) – 0.15 (to prevent myopic shift) = 3.65 SD
Cylinder: +6.00 - 28% = 4.30 CD Measured axis of (-) cylinder was 177°
TMR = sph -1.00 SD * cyl +4.30 CD * ax 87°

Difference Map

astigmatic cases. For example, for mixed astigmatism: 9.3 mm X

8.5 mm flap with hinge position according to the astigmatism axis

can already see good functional results in early PostOp period
We

specially show you autorefractometry data despite the fact that the analysis of the refractive outcomes is based on the manifest refraction
You can more accurately evaluate the quality of surgery with Autorefractometry as well as Topography and not only manifest refraction
Amount of reduction in 0.80 CD of measured minus-cylinder is based on my individual surgical factor and also may vary due to the clinical situation: value of cylinder, ΔK from AR and IOL-Master (or equal device) and etc. and are only recommended!

÷ 0.75 D WTR astigmatism in the corneal plane
It can

be applied not only in presence of significant astigmatism
We suggest to use measured axis of astigmatism in situations with mixed and hyperopic astigmatism
It’s only my point of view
No other conclusions – You Can Try It Yourself!