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Forum Keraring, Santa Maria da Feira, 6 May 2011
                               Feira,


The SA.ANA Classification

Making Sense of Intracorneal
Ring Segments

            Rafael I. Barraquer MD, PhD
           Titular de la Càtedra “Joaquín Barraquer”
              Institut Universitari Barraquer – UAB
                        Barcelona - SPAIN
Background
   IntraCorneal Segments
    (ICS) “Rings” evolved:
      Initial purpose:
        Myopia (mild)
       2 Equal & Wide ICS
                (encircling)
      Current use:
        Keratoconus & other
       ectasia
        Single/ Unequal ICS
1st Author
(year)
                    Eyes (n)                     INTACS
                                                 Segments
                                                                                    Incision
                                                                                    (technique)
                                                                                                            Follow-up
                                                                                                            mean
                                                                                                            (range)
                                                                                                                             Refractive change (D =
                                                                                                                             mean reduction)                (± =
                                                                                                                                                                     Visual change (m=
                                                                                                                                                                     mean improvement)               Published series
                                                 (thickness in mm)                                                           st. deviation)
Colin               10                           As (0.45 inf +0.25 sup)            Temporal                12 m (all)       DK1=4.6D; DK2=3.6D Dcyl=2.70D (-        UCVA m=3L BSCVA                                                                Follow-
(2001)                                                                                                                       4.00-1.30D)                            m=2L                           1st             Eyes   Ferrara /    Incision              Refractive        Visual
                                                                                                                                                                                                                                                    up
Siganos             19 (A) inferior cone         S (2x 0.45)                        (A)Temporal (sup-inf      11.3 m
                                                                                    impl.) (B) Superior (nas- 24 m)
                                                                                                                         (1- DK= 1.94 ±3.51D                         UCVA m=2.5L AVCC               Author          (n)    Keraring     (techniqu             change (D =       change (m=
(2003)              14 (B) central cone                                                                                      (50.8647.63D)                          m=1.7L (impr. 76% m=1 to                                                       mean
                                                                                    temp imp.)
                                                                                                                             DSE= 1.82 ±3.03D                        6L; 12% worse, high Ks)        (year)                 Segments     e)                    mean reduction)   mean
                                                                                                                                                                                                                                                    (range
Boxer Wachler       74                           As (0.30-0.35 inf +0.25            Eje + Cyl (exc. if topo 9 m          (1- DI-S: 25.626.60D                       UCVA m=4L      BSCVA m=2L                             (thickness                                           improvement)
(2003)                                           sup)                               axis @90º of Cyl)       20 m)            DSE=2.43D (-3.89-1.46D)                (12% worse)                                                                    )
                                                                                                                                                                                                                           in mm)
Hellstedt (2005) 50                              As (0.45 inf +0.25 sup)            Temporal                6.3±3.2m         DK1=4.2D; DK2=3.3D                      UCVA m=1.0±2.0L BSCVA
                                                                                                            (1-12 m)         SIA = 2.9 ±2.9D                         m=2.2±2.3L (10% worse)         Siganos[2       26     S (2x160º;   + Axis      6m        DK = no data      UCVA
                                                                                                                             DSE=2.72D(-2.12+0.66D)                                                2] (2002)                                                 Dcyl=2.22D (-     m=1.3L(88.4%)
Levinger            58                           S (2x 0.30-0.45); As (1x 0.45      Temporal (Sup if central 12 m            DK1=3.44D; DK2=2.74D                    UCVA m=3L(81%≥2L)
                                                                                                                                                                                                                           0.15-0.35)   (manual)    (min.)
                                                                                                                                                                                                                                                              4.42-2.20)       BSCVA m=2.3L
(2005)                                           inf, only if inf cone & SE<-3.0)   cone & SE > -3.75)       (all)           Dcyl=1.57D (-3.34-1.97D)               BSCVA m=0L (20/32
                                                                                                                             DSE=2.84D (-3.88-1.04D)                ±2.0L; 10% worse ≥2L)
                                                                                                                                                                                                                                                              DSE=5.80D (-      (0.370.60)
                                                                                                                                                                                                                                                              6.91-1.11D)      (2 explants)
Alió                9 (p-central cone)        4 As (0.45 inf +0.25 sup)             Temporal (+ axis)       36 m     (36- DK=3.13D @6m (1.69D                        BSCVA m=2L
(2006)              (inferior cone)              or (1x 0.45 inf)                                           48 m)         regression @36m)                           (0.460.66; maintained
                                                                                                                          DSE=1.45D (-5.40-3.95D) DI-               636m)
                                                                                                                          S: 7.094.27D                                                             Miranda[2       36     S (2x160º;   + Axis      6m        DK1=9.6D          UCVA m≥2L
Alió                20 (A) K≤53D                 As (0.45 inf +0.25 sup)            Temporal (+ axis)       6m            DK: (A)=4.30D; (B)=6.19D                   BSCVA: (A) m=3.8L (B)          3] (2003)                                                 (62.352.7D)      (77.78%) BSCVA
(2006)              5 (B) K≥54D                  or (1x 0.45 inf)                                           (all)         DSE: (A)=2.81D; (B)=2.25D                  m= -1.2L (in 3 eyes, 1x
                                                                                                                                                                                                                           0.25-0.35)   topograp    (3- 12
                                                                                                                                                                                                                                                              DK2=7.5D          m≥2L (80.56%)
                                                                                                                          (significant only in A)                    implant)                                                           hic         m)        (58.150.6D)      (VA worse =
Colin               57                           S (2x 0.40-0.45) As                Temporal (0º -          6m            DK = 4.3 ±2.8D           Dcyl=             UCVA m≥2L (78% ) BSCVA
(2006)                                           (0.30-0.45 inf +0.25-0.40 sup) 180º)                       (1-12 m)      1.52 ±1.60D                                m=2 to 8L (62% ) (6% worse                                         (manual)              Dcyl: no data     none, 5
                                                                                                                                                                     ≥2L)
                                                                                                                          DSE= 3.07 ±2.54D                                                                                                                    DSE=2.49D (-      extrusions)
Ertan               118                          S (2x 0.25-0.45?) As (0.45 inf     Temporal (?) (FsL)      12 m             DK=3.90D (51.5647.66D)                 UCVA m=2L (81.3% )
                                                                                                                                                                                                                                                              7.29-4.80D)
(2006)                                           +0.25 sup, inferior cone)                                                   DSE=3.85D (-7.57-3.72D)                BSCVA m=1.8L (impr. 73.7% ,
                                                                                                                                                                     worse 9.3%)
Ibrahim             186                          S or As         (0.25 á            + Cyl axis              5 years          DK = 4.48D (52.5348.05D)               UCVA m=85.2% BSCVA             Kwitko          51     S (2x160º;   + Axis      13±8.     DK =5.69D         UCVA m=86.4%
(2006)                                           0.45)                                                                                                               m=87.9%                                                                                  (48.7643.17D)    BSCVA m=86.4%
                                                                                                                                                                                                    (2004)                 0.20-0.30)   (manual)    7m
Kanellopoulos       20                           As (0.35-0.45 inf +0.25-           Temporal (above         6m               DK= 3.10D (49.4546.35D)                UCVA m=6L                                                                                Dcyl=1.66D (-     (11.7% worse,
(2006)                                           0.40 sup)                          horizontal)             (6 -12 m)        Dcyl=2.54D (-3.75-1.21D)               (20/15420/28) BSCVA
                                                                                                                                                                                                                                                              3.82-2.16D)      10 extrusions)
                                                                                                                             Dsph=2.23D(-3.38-1.15D)                m=3.5L (20/3720/22)
                                                                                                                             DSE=3.69D(-5.33-1.64D)                                                                                                          DSE=1.53D (-
Rabinowitz          10 (A) manual        20      S (2x 0.35, 15 eyes)       As      Temporal (?) (A)        A: 12 m          DK: (A)=2.52D; (B)=2.91D DSE:           UCVA: (A) m=3.6L; (B) m=4.1L                                                             6.08-4.55D)
(2006)              (B) Lfs                      (1x 0.35, 4 eyes; 0.35 inf         manual (B) FsL          B: 6 m           (A)=2.96D; (B)=3.98D (N.S.)             BSCVA (A) m=1.6L;      (B)
                                                 +0.25 sup, 1 eye, all FsL)                                                                                          m=3.9L (all n.s.)


Sharma              17 (1x) 20 (2x) (inf.        As (1x: 0.25-0.35) ó (2x:          + Cyl axis              3m               DK1: (1x)=2.76D; (2x)=0.93D     DK2:    UCVA: (1x) m=9L; (2x)
(2006)              cones, incl. post-LASIK      0.30-35 inf, 0.25-0.30 sup)                                (1 – 13 m)       (1x)=0.92D; (2x)=0.13D           SIA:   m=2.5L BSCVA: (1x)             Shabayek        21     S, As        + Axis      3m        DK1=3.37D;        UCVA m=2.5L
                    ectasia)                     S (2x 0.35, 1 eye)                                                          (1x)=5.69D; (2x)=1.58D
                                                                                                                                                                     m=2.5L (2x) m<1L                                                                         DK2=1.21D         BSCVA m=1.7L
                                                                                                                             DI-S: (1x)=9.51D; (2x)=4.22D    DSE:                                   (2007)                 (120º-       (FsL)       (1-6
                                                                                                                             (1x)=1.45D; (2x)=2.26D                                                                                                           DK =2.24D         (70%) (5%
Colin               100                          S (2 x 0.40-0.45)                  Temporal                24 m             DK= 3.3D (50.146.8D)                   UCVA: m=1 to ≥5L (80.5%                               160º;                    m)        (48.7946.54D)    worse, 1 grade IV
(2007)                                                                                                                       Dcyl=1.31D (-4.62-3.31D)               BSCVA: m=1 to ≥5L
                                                                                                                             DSE=3.13D (-6.93-3.80D)                68.3% 14.6% worse 1-4L)
                                                                                                                                                                                                                           0.15-0.35)                         Dcyl=2.68D (-     cone, 1 explant)
Kymionis            11 (A) inferior cone         S (2x 0.45)                        (A)Temporal (sup-       5 years  (58- DK= 1.57D (49.59 45.20 @6m                UCVA m=2.8L (0-9L)
                                                                                                                                                                                                                                                              4.83-2.15D)
(2007)              6 (B) central cone                                              inf impl.) (B)          78 m)           48.02D@60m)                             BSCVA m=1.4L (0-8L) (6%                                                                  DSE=2.37D (-
                                                                                    Superior (nas-temp                      (6m60m change not signific.)            worse 3L, 1 eye)                                                                         6.33-3.96D)
                                                                                    impl)                                   DK1-K2=0.98D (4.463.48D)
                                                                                                                            DSE=2.52D (-5.54-3.02D)                                                                                                          DK1 =3.93D; DK2
                                                                                                                                                                                                    Barraquer       165    S, As        + Cyl/K1    6m                          UCVA m=2.0L
Zare       (2007)   30                           As (0.35-0.45 inf +0.25-           Temporal                6m        (all) DK =1.94D (49.8447.90D)                 UCVA m=3L         BSCVA
                                                                                                                                                                                                    (unpublished)                                             =2.27D            BSCVA m=1.0L
                                                 0.40 sup)                                                                  Dcyl=0.75D (-4.65-3.90D)                m=2L                                                  (90º-210º;   axis        (3-27
                                                                                                                            DSE=3.0D (-6.93-3.23D)                                                                                                           Dcyl=2.48D (-     (6% worse ≥2L,
Ertan      (2008)   306                          S (2x 0.25-0.45?) As               Temporal (?) (FsL)      10.4 ±5m (4- DK =2.79D (50.7047.91D)                    UCVA m=2.5L(75.7%)                                    0.15-0.35)   (manual,    m)        5.91-3.43D)
                                                 (0.45 inf +0.25 sup, inf.                                  30 m)           Dcyl=0.29D (-4.11-3.82D)                BSCVA m=2L (71.6% ) (3.7%                                                                                  5 extrusions)
                                                 cone)                                                                      DSE=3.09D (-7.81-4.72D)
                                                                                                                                                                     worse ≥2L)                                                         FsL)                  DSE=3.57D (-
Shetty (2008)       14 (stage III cone)          S (11 eyes); As (3 eyes 0.45       K1 axis (Orbscan)       6m              DK =3.59D (53.0149.42D)                 UCVA m=1.1L BSCVA                                                                        5.21-1.64D)
                                                 inf +sup “thinner” ¿?)                                     (1-12 m)        Dcyl=1.25D (-4.89-3.64D)                m=1.7L (7.14% worse 1L)
                                                                                                                            DSE=4.20D (-9.13-4.93D)
ICS for KC: Results (summary)
                         summary)

   All agree they are “Effective”, BUT…
                       “Effective”
    ►Increased UCVA          ~ 2 - 3 lines (average)
    ►Increased BSCVA         ~ 1 - 4 lines (~ 2 ave.)
                                                ave.)
    ►Decreased Spher.Eq.
                Spher.Eq.    ~ 1.5 – 4.2 D (5.8 w KR)
    ►Decreased Topo. K
                Topo.        ~ 1.5 – 4.5 D (8.0 w KR);
    ►Decreased Refract. Cyl. ~ 0.3 – 2.7 D
                        Cyl.
     [50-
     [50-65% ave.: NOT a “REFRACTIVE” procedure]
             ave.:
ICS for KC: Results (summary)
                     summary)
   But:
    ►Why incomplete results? How can we improve them?
    ►Why variable results? Is it a nomogram issue?,
     should we follow Topography?, or aberrations-Coma?
                                       aberrations-
    ►Long term effect? Do they stop KC progression?

   Safety: all agree it is “safe”, but:
    ►BSCVA  line LOSS: 3 to 14% of eyes
    ► 8-20% extrusion (w Keraring manual technique)
To Progress:
   Progress:
What We Need to Know…
                Know…


   Mechanism of Action: A better
    understanding of the basics of how ICS work
   Available Modalities: Organize = Classify
    the basic types of implant combinations (to
    enable comparisons, studies…)
   New/Refined Nomograms ? (later on…)
ICS: Mechanism of action?
   Commonly assumed to follow
    Thickness Law of José I. Barraquer
     ► The effect does increase with:
         Thicker segments
         Smaller 



   HOWEVER:
    ► They   work at deep position
       NO anterior lamellar effect
    ► The impl. meridian is steepened
           impl.
    ► The “open” meridian is flattened
      (just the opposite of JIB’s Law !!)
ICS: Biomechanical effects !!
   Space Occupation ?
    ► Force lamellae  to
      “detour” around impl.
                        impl.
    ► No forward thickness
      effect (deep location),
      or only a local “bump”
    ► Torsional effect?
New Options: Increased Complexity
    Options:
 Multiple types of ICS
  (varying diameters,
  thickness, arc widths) 
  greater number of possible
  combinations.
 Greater control possible
   independent effects on
     Sphere
     Astigmatism
     Coma
     Other irregularities?
ICS:astigmatic vs. sphere effects
Compressive suture-like effect:
            suture-
   A Sector only (~ 90º)
                  (~
    ►   steeps that meridian
    ►  flattens @ 90º
    ► Just the opposite of
      “Thickness Law”
    ► Corrects astigmatism

   A Circle ≈360º (180º x2)
    ►   gen. flattening
    ► Just like a tightly sutured PK

    ► Corrects myopia only
ICS in KC & Corneal Ectasia
¿What are we trying to correct?
 Astigmatism?  sector ICS
 Myopia ?  circle ICS

 Decentration ?
    ► Unique of KC & Ectasia
    ► Cannot correct w glasses

    ► Measurable   as Coma
What about Coma ?
How can we correct it ?




•   Astigmatism: a quadrant aberration  correction:
    Astigmatism:                         correction:
      •   90º arc  Max Effect
      •   2 equal, symmetric, ICS (coupling), centered over flat axis,
            equal, symmetric,     (coupling),
•   Coma: a half circle (hemispheric) aberration  correction:
                         hemispheric)              correction:
      •   180º arc  Max Effect
      •   1 ICS only (asymmetric), centered over coma (decentration) axis
                      asymmetric),                    (decentration)
Implant Options ?
Basic Patterns of ICS implantation
   Symmetry:
    ►   2 equal, paired ICS                  Symmetric
    ►   1 single / 2 different ICS (or more)  Asymmetric
   Axiality:
    Axiality:
    ►   ICS (1 or 2) over flat (-) astig. axis  Axial
                               (- astig.

    ►    ICS (1 or more) over an axis different
        from flat (-) astigmatism (≥ 30º)
                  (-                           Non-Axial
                                                 on-


                                  The SA.ANA classification
Combining the two criteria: 4+2 types (The SA.ANA classification)
SA.ANA      Segments                    Implantation Axis                            Frequency
           (Symmetric vs.                                                          found (n=1097)
 type                       (Axial= same, flat A axis vs. Non-Axial= other axis)
            Asymmetric)

         Symmetric          Axial
 SA      2 ICS                                                                      9.96%

                               ≈ 80%
                            (red= plus axis
         (equal)
                            blue= minus axis)

         Asymmetric Axial                                                          39.58%
AA1      1 ICS
         2 ICS (unequal)    (red= plus axis                                        28.31%
AA2                         blue= minus axis)                                      (Total 67.89%)

         Symmetric Non-Axial
                            (green= mid-ICS
SNA      2 ICS              axis, displaced ≥ 30º                                   5.77%
         (equal)            from minus axis)


         Asymmetric Non-Axial                                                       6.16%
ANA1     1 ICS (wide)
                            (green= mid-ICS axis,
                            displaced ≥ 30º from                                    4.98%
ANA2     2 ICS (unequal)    Minus axis  coma
                            axis or intermediate)                                  (Total 11.14%)
Central, symmetric ectasia/conus
 [ also: Regular astigmatism (congenital or post-PK);
 Mild myopia (congenital or residual after Rx.)]




red= steep ast. axis
            ast.
blue=
blue= flat ast. axis
           ast.
coma = minimal
 SA - Symmetric Axial ICS




red= steep ast. axis
            ast.
blue=
blue= flat ast. axis
           ast.
coma = minimal
SA - Symmetric Axial ICS




                               red= steep ast. axis
                                           ast.
                               blue= ast.
                               blue= flat ast. axis
                               coma = minimal

Preop: UCVA=0.04;
Preop: UCVA=0.04; -5.0 -4.0@0º= 0.8
K1= 55.5@90º; K2= 51.3@0º (D= 4.2D)
                          (D
Pach min= 360mm (Keratoconus/globus?)
           360m (Keratoconus/globus?)
Rx:
Rx: 2x Keraring 5 Ø 160º x 250 mm @0º

Result (1y.): UCVA = 0.85; -1@75º= 0.95
                     0.85;
K1= 50.7@155º; K2=47.8@68º (D= 2.9D)
                           (D
Asymmetric Ectasia
(markedly displaced, infero-temporal)




red= steep ast. axis
             ast.
blue=
blue= flat ast. axis
           ast.
coma = signficant,
         signficant,
close to flat axis
 AA1 - Asymmetric Axial (single ICS)




red= steep ast. axis
             ast.
blue=
blue= flat ast. axis
           ast.
coma = signficant,
         signficant,
close to flat axis
AA1 - Asymmetric Axial (single ICS)




                                 red= steep ast. axis
                                             ast.
                                 blue= ast.
                                 blue= flat ast. axis
                                 coma = significant,
                                          significant,
                                 towards flat axis


Preop: UCVA=0.08;
Preop: UCVA=0.08; -4.5@120º= 0.6
K1= 51.1@30º; K2= 45.2@120º (D= 5.9D)
                            (D
Pach min= 512mm (Early keratoconus, 11 y/o)
          512m (Early
Rx:
Rx: 1x Keraring 160º x 200 mm @120º (300º)
Result (3m.): UCVA = 0.8 plano
K1= 49.1@57º; K2=46.9@147º (D= 2.2D hyperc)
                           (D       hyperc)
AA2 - Asymmetric Axial (2 different ICS)




                              red= steep ast. axis
                                          ast.
                              blue= ast.
                              blue= flat ast. axis
                              coma = significant,
                                       significant,
                              towards flat axis




 •   Same as AA1, BUT:
             AA1,
 • Higher cylinder or sphere combinations
 •  Additive effect of ICS thickness/width
                            thickness/
 • Coma corrected by asymmetry
 •  Upper ICS must be smaller/thinner
                          smaller/
The Albertazzi/Keraring Classification
    Albertazzi/Keraring

   Nomograms based on cone
    eccentricity: 1, 2, 3
     Type 1: Very eccentric
      “moustache”, coma high but close
      to flatter (minus) astigmatism axis
     Type 3: Central bowtie, low coma

     Type 2: Intermediate  the most
      difficult because of significant
      coma is away from minus axis
      (even close to plus axis)
       dilemma: Ast. vs.Coma corr.?
                     Ast.
Intermediate ectasia
                       Paracentral
                       Relatively orthogonal


                                Coma towards
                                steep axis
                                Difficult choice:
                                if ICS implant
red= steep ast. axis
            ast.                @coma axis
blue=
blue= flat ast. axis
           ast.                  will increase
coma = signficant,
         signficant,            astigmatism &
close to steep axis             vice versa
 SNA Symmetric Non-Axial
                       Paired axis-displaced ICS
                       “encroaching” coma axis while
                       still acting on flat axis




red= steep ast. axis
            ast.
blue=
blue= flat ast. axis
           ast.
coma = signficant,
         signficant,
close to steep axis
SNA-
SNA- Symmetric Non-Axial (paired ICS)
               Non-




                             red= steep ast. axis
                                         ast.
                             blue= ast.
                             blue= flat ast. axis
                             coma = significant,
                                      significant,
                             towards steep axis

 • Intermediate ectasia
 • Paracentral, relat. orthogonal ectasia
                  relat.
 • Sphere mild/moderate
            mild/
 • Cylinder moderate/high
             moderate/
 • Coma towards plus cyl axis
 • Paired ICS, usually of 120º
 • Inferior displacement 15-30º each
                          15-
Intermediate ectasia
Paracentral – mid-peripheral
              mid-
Non-
Non-orthogonal




                       red= steep ast. axis
                                   ast.
                       blue=
                       blue= flat ast. axis
                                  ast.
                       coma = signficant,
                                signficant,
                       towards steep axis
                       or intermediate
 ANA1 – Asymmetric Non-Non-
Axial (single wide ICS)




                        red= steep ast. axis
                                    ast.
                        blue=
                        blue= flat ast. axis
                                   ast.
                        coma = signficant,
                                 signficant,
                        towards steep axis
                        or intermediate
ANA1-
ANA1- Asymmetric Non-Axial (single ICS)
                 Non-




                            red= steep ast. axis
                                        ast.
                            blue= ast.
                            blue= flat ast. axis
                            coma = significant,
                                     significant,
                            towards steep axis

 • Intermediate ectasia
 • Paracentral, non-orthogonal ectasia
                non-
 • Sphere mild
 • Cylinder moderate/high
            moderate/
 • Coma towards plus cyl axis (±)
                               (±
 • Single ICS, usually wide 160º- 210º
                            160º-
 • At coma axis or intermediate
ANA2 - Asymmetric Non-Axial (two ICS)
                  Non-




                            red= steep ast. axis
                                        ast.
                            blue= ast.
                            blue= flat ast. axis
                            coma = significant,
                                     significant,
                            towards steep axis

 • Intermediate ectasia
 • Paracentral, non-orthogonal ectasia
                non-
 • Sphere moderate/high
           moderate/
 • Cylinder moderate/high
            moderate/
 • Coma towards plus cyl axis (±)
                               (±
 • Two ICS: inferior wider (160º) @ coma
 • Superior small (90º-120º) @ flat axis
                  (90º-
ANA3 (ANA1  SA) - Triple ICS implant




                                  red= steep ast. axis
                                              ast.
                                  blue= ast.
                                  blue= flat ast. axis
                                  coma = significant,
                                           significant,
                                  towards steep axis

• Peripheral,
  Peripheral, orthogonal ectasia (early KC vs. PMD)
                                  (early
• Sphere mild, Cylinder mild/moderate
          mild,          mild/
• UCVA= 0.1; -2.0 -2.5@160º= 0.85
• SimK 41.5 / 45.8 (D= 4.3D, Orbscan)
                    (D         Orbscan)
• Coma towards plus cyl axis (± vertical @260º)
                               (±
• Rx: 1x inferior INTAC, 450 mm/150º wide @80º (260º)
  Rx:
ANA3 (ANA1  SA) - Triple ICS (2-step)
                              (2-




red= steep ast. axis
            ast.
blue= ast.
blue= flat ast. axis
coma = significant,
         significant,
towards steep axis



        After 1st ICS: Refr. Astigm. increased to -5 D (7 D by Orbscan Sim K)
                        Refr. Astigm.
       UCVA improved to 0.4 !! (BSCVA: -5@160º = 0.85)
       Coma (mostly vertical) reduced from 0.90 mm 0.20 mm (iTrace)
                                                              iTrace)
       Ectasia pattern changed  more central & symmetric
ANA3  After adding 2x90ºx150 mm Kerarings…
                                 Kerarings…




   UCVA:
      @day 1 = 0.65 PLANO

      @12 months = 0.95 PLANO

   Topography cylinder = 2.6 D (Orbscan Sim K)
   Ectasia pattern changed to more central & symmetric
   Apparent combination of centering & astigmatic effects in
    two stages
Intracorneal Segments (ICS) implantation types (The SA.ANA classification)
 Type                                                                                                     Frecuency
          Segments             Implantation Axis                     Indications               Examples
SA.ANA     (Symmetric or      (Axial = same, minus cyl axis
            Asymmetric)        Non-Axial = different axis)
                                                              Central (symmetric) ectasia
         Symmetric         Axial                              Regular astigmatism

  SA     2 ICS
         (equal)
                           (red= plus cyl
                           blue= minus cyl)
                                                              (congenital or post-PK)
                                                              Mild myopia (congenital or                  ≈   10%
                                                              residual after Rx.)


                                                              Asymmetric ectasia (markedly
         Asymmetric        Axial                              displaced inferiorly)

 AA1     1 ICS                                                Coma ± towards minus cyl axis
                                                              (roughly coincident <30º dif.)

                                                                                                          ≈ 68%
                                                              (1 or 2 ICS depending on
 AA2     2 ICS             (red= plus cyl                     amount of cylinder/sphere)
         (unequal)         blue= minus cyl)


                                                              Intermediate ectasia
         Symmetric         Non-Axial                          (paracentral, relatively

                                                                                                          ≈ 6%
                                                              orthogonal)
 SNA     2 ICS             (green= mid-ICS
                           axis, displaced)
                                                              Sphere mild/moderate
         (equal)                                              Cylinder moderate/high
                                                              Coma ± towards plus cyl axis

                                                              Intermediate ectasia
         Asymmetric        Non-Axial                          (paracentral, non-orthogonal)
                                                              Sphere variable
ANA1     1 ICS (wide)                                         Cylinder moderate/high
         2 ICS                                                Coma ± towards plus cyl axis
ANA2     (unequal)                                            (inferiorly)

                                                              Intermediate ectasia
                                                              (peripheral, ± incipient)
                                                                                                          ≈   11%
                                                              Sphere mild
ANA3     3 ICS                                                Cylinder mild/moderate
         (2-step)                                             Coma ± towards plus cyl axis
                                                              (almost at 90º of minus axis)
Summary
   The availability of multiple ICS types demands a
    classification  to enable a meaningful comparison
    between implant series.
   Observed ICS implantation modalities (n=1097) allow a simple
    while comprehensive classification based on 2 criteria: symmetry
                                                      criteria:
    & axiality. Combining the 2 criteria results in 4 types:
      axiality.
    The SA.ANA classification
       SA = Symmetrical & Axial        (always 2 equal ICS, @same, flat axis) = 9.96%
       AA = Asymmetrical & Axial      [either 1 (AA1) or 2 (AA2) ICS] = 67.89% (total)
       SNA = Symmetrical & Non-Axial (always 2 equal ICS, @different axis) = 5.77%
                             on-
       ANA = Asymmetrical & Non-Axial [either 1 (ANA1) or 2 (ANA2) ICS] = 11.14%
                              on-
Perspectives
   Classifiaction (SA-ANA)  a tool for outcome comparison 
                   (SA-
    opens new possibilities:
    ►   Better classification of keratoconus & other ectasia
    ► To  refine (redefine) indications for ICS
     ► To develop better ICS nomograms

   Testing/confirmation of basic theory (mechanism of action)
   Independent address of astigmatism and coma
    (decentration), esp. non-axial (ANA) minority? types
     decentration),      non-
Grupo Ibérico de Segmentología
                José Alfonso            (Oviedo)
                Federico Alonso         (Sevilla)
                                         Sevilla)
                Rafael I. Barraquer    (Barcelona)
                Margarita Cabanas       (Sevilla)
                                         Sevilla)
                Antonio Limao           (Lisboa)
                                         Lisboa)
                Joaquim Murta           (Coimbra)
                Cristina Peris          (Valencia)
                Vicente Rodríguez     (Las Palmas)
                Pedro Tañá              (Alicante)


                y con el apoyo de
Gracias
Obrigado

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SAANA Classification Explains Intracorneal Ring Segments

  • 1. Forum Keraring, Santa Maria da Feira, 6 May 2011 Feira, The SA.ANA Classification Making Sense of Intracorneal Ring Segments Rafael I. Barraquer MD, PhD Titular de la Càtedra “Joaquín Barraquer” Institut Universitari Barraquer – UAB Barcelona - SPAIN
  • 2. Background  IntraCorneal Segments (ICS) “Rings” evolved:  Initial purpose:  Myopia (mild) 2 Equal & Wide ICS (encircling)  Current use:  Keratoconus & other ectasia  Single/ Unequal ICS
  • 3. 1st Author (year) Eyes (n) INTACS Segments Incision (technique) Follow-up mean (range) Refractive change (D = mean reduction) (± = Visual change (m= mean improvement) Published series (thickness in mm) st. deviation) Colin 10 As (0.45 inf +0.25 sup) Temporal 12 m (all) DK1=4.6D; DK2=3.6D Dcyl=2.70D (- UCVA m=3L BSCVA Follow- (2001) 4.00-1.30D) m=2L 1st Eyes Ferrara / Incision Refractive Visual up Siganos 19 (A) inferior cone S (2x 0.45) (A)Temporal (sup-inf 11.3 m impl.) (B) Superior (nas- 24 m) (1- DK= 1.94 ±3.51D UCVA m=2.5L AVCC Author (n) Keraring (techniqu change (D = change (m= (2003) 14 (B) central cone (50.8647.63D) m=1.7L (impr. 76% m=1 to mean temp imp.) DSE= 1.82 ±3.03D 6L; 12% worse, high Ks) (year) Segments e) mean reduction) mean (range Boxer Wachler 74 As (0.30-0.35 inf +0.25 Eje + Cyl (exc. if topo 9 m (1- DI-S: 25.626.60D UCVA m=4L BSCVA m=2L (thickness improvement) (2003) sup) axis @90º of Cyl) 20 m) DSE=2.43D (-3.89-1.46D) (12% worse) ) in mm) Hellstedt (2005) 50 As (0.45 inf +0.25 sup) Temporal 6.3±3.2m DK1=4.2D; DK2=3.3D UCVA m=1.0±2.0L BSCVA (1-12 m) SIA = 2.9 ±2.9D m=2.2±2.3L (10% worse) Siganos[2 26 S (2x160º; + Axis 6m DK = no data UCVA DSE=2.72D(-2.12+0.66D) 2] (2002) Dcyl=2.22D (- m=1.3L(88.4%) Levinger 58 S (2x 0.30-0.45); As (1x 0.45 Temporal (Sup if central 12 m DK1=3.44D; DK2=2.74D UCVA m=3L(81%≥2L) 0.15-0.35) (manual) (min.) 4.42-2.20) BSCVA m=2.3L (2005) inf, only if inf cone & SE<-3.0) cone & SE > -3.75) (all) Dcyl=1.57D (-3.34-1.97D) BSCVA m=0L (20/32 DSE=2.84D (-3.88-1.04D) ±2.0L; 10% worse ≥2L) DSE=5.80D (- (0.370.60) 6.91-1.11D) (2 explants) Alió 9 (p-central cone) 4 As (0.45 inf +0.25 sup) Temporal (+ axis) 36 m (36- DK=3.13D @6m (1.69D BSCVA m=2L (2006) (inferior cone) or (1x 0.45 inf) 48 m) regression @36m) (0.460.66; maintained DSE=1.45D (-5.40-3.95D) DI- 636m) S: 7.094.27D Miranda[2 36 S (2x160º; + Axis 6m DK1=9.6D UCVA m≥2L Alió 20 (A) K≤53D As (0.45 inf +0.25 sup) Temporal (+ axis) 6m DK: (A)=4.30D; (B)=6.19D BSCVA: (A) m=3.8L (B) 3] (2003) (62.352.7D) (77.78%) BSCVA (2006) 5 (B) K≥54D or (1x 0.45 inf) (all) DSE: (A)=2.81D; (B)=2.25D m= -1.2L (in 3 eyes, 1x 0.25-0.35) topograp (3- 12 DK2=7.5D m≥2L (80.56%) (significant only in A) implant) hic m) (58.150.6D) (VA worse = Colin 57 S (2x 0.40-0.45) As Temporal (0º - 6m DK = 4.3 ±2.8D Dcyl= UCVA m≥2L (78% ) BSCVA (2006) (0.30-0.45 inf +0.25-0.40 sup) 180º) (1-12 m) 1.52 ±1.60D m=2 to 8L (62% ) (6% worse (manual) Dcyl: no data none, 5 ≥2L) DSE= 3.07 ±2.54D DSE=2.49D (- extrusions) Ertan 118 S (2x 0.25-0.45?) As (0.45 inf Temporal (?) (FsL) 12 m DK=3.90D (51.5647.66D) UCVA m=2L (81.3% ) 7.29-4.80D) (2006) +0.25 sup, inferior cone) DSE=3.85D (-7.57-3.72D) BSCVA m=1.8L (impr. 73.7% , worse 9.3%) Ibrahim 186 S or As (0.25 á + Cyl axis 5 years DK = 4.48D (52.5348.05D) UCVA m=85.2% BSCVA Kwitko 51 S (2x160º; + Axis 13±8. DK =5.69D UCVA m=86.4% (2006) 0.45) m=87.9% (48.7643.17D) BSCVA m=86.4% (2004) 0.20-0.30) (manual) 7m Kanellopoulos 20 As (0.35-0.45 inf +0.25- Temporal (above 6m DK= 3.10D (49.4546.35D) UCVA m=6L Dcyl=1.66D (- (11.7% worse, (2006) 0.40 sup) horizontal) (6 -12 m) Dcyl=2.54D (-3.75-1.21D) (20/15420/28) BSCVA 3.82-2.16D) 10 extrusions) Dsph=2.23D(-3.38-1.15D) m=3.5L (20/3720/22) DSE=3.69D(-5.33-1.64D) DSE=1.53D (- Rabinowitz 10 (A) manual 20 S (2x 0.35, 15 eyes) As Temporal (?) (A) A: 12 m DK: (A)=2.52D; (B)=2.91D DSE: UCVA: (A) m=3.6L; (B) m=4.1L 6.08-4.55D) (2006) (B) Lfs (1x 0.35, 4 eyes; 0.35 inf manual (B) FsL B: 6 m (A)=2.96D; (B)=3.98D (N.S.) BSCVA (A) m=1.6L; (B) +0.25 sup, 1 eye, all FsL) m=3.9L (all n.s.) Sharma 17 (1x) 20 (2x) (inf. As (1x: 0.25-0.35) ó (2x: + Cyl axis 3m DK1: (1x)=2.76D; (2x)=0.93D DK2: UCVA: (1x) m=9L; (2x) (2006) cones, incl. post-LASIK 0.30-35 inf, 0.25-0.30 sup) (1 – 13 m) (1x)=0.92D; (2x)=0.13D SIA: m=2.5L BSCVA: (1x) Shabayek 21 S, As + Axis 3m DK1=3.37D; UCVA m=2.5L ectasia) S (2x 0.35, 1 eye) (1x)=5.69D; (2x)=1.58D m=2.5L (2x) m<1L DK2=1.21D BSCVA m=1.7L DI-S: (1x)=9.51D; (2x)=4.22D DSE: (2007) (120º- (FsL) (1-6 (1x)=1.45D; (2x)=2.26D DK =2.24D (70%) (5% Colin 100 S (2 x 0.40-0.45) Temporal 24 m DK= 3.3D (50.146.8D) UCVA: m=1 to ≥5L (80.5% 160º; m) (48.7946.54D) worse, 1 grade IV (2007) Dcyl=1.31D (-4.62-3.31D) BSCVA: m=1 to ≥5L DSE=3.13D (-6.93-3.80D) 68.3% 14.6% worse 1-4L) 0.15-0.35) Dcyl=2.68D (- cone, 1 explant) Kymionis 11 (A) inferior cone S (2x 0.45) (A)Temporal (sup- 5 years (58- DK= 1.57D (49.59 45.20 @6m UCVA m=2.8L (0-9L) 4.83-2.15D) (2007) 6 (B) central cone inf impl.) (B) 78 m) 48.02D@60m) BSCVA m=1.4L (0-8L) (6% DSE=2.37D (- Superior (nas-temp (6m60m change not signific.) worse 3L, 1 eye) 6.33-3.96D) impl) DK1-K2=0.98D (4.463.48D) DSE=2.52D (-5.54-3.02D) DK1 =3.93D; DK2 Barraquer 165 S, As + Cyl/K1 6m UCVA m=2.0L Zare (2007) 30 As (0.35-0.45 inf +0.25- Temporal 6m (all) DK =1.94D (49.8447.90D) UCVA m=3L BSCVA (unpublished) =2.27D BSCVA m=1.0L 0.40 sup) Dcyl=0.75D (-4.65-3.90D) m=2L (90º-210º; axis (3-27 DSE=3.0D (-6.93-3.23D) Dcyl=2.48D (- (6% worse ≥2L, Ertan (2008) 306 S (2x 0.25-0.45?) As Temporal (?) (FsL) 10.4 ±5m (4- DK =2.79D (50.7047.91D) UCVA m=2.5L(75.7%) 0.15-0.35) (manual, m) 5.91-3.43D) (0.45 inf +0.25 sup, inf. 30 m) Dcyl=0.29D (-4.11-3.82D) BSCVA m=2L (71.6% ) (3.7% 5 extrusions) cone) DSE=3.09D (-7.81-4.72D) worse ≥2L) FsL) DSE=3.57D (- Shetty (2008) 14 (stage III cone) S (11 eyes); As (3 eyes 0.45 K1 axis (Orbscan) 6m DK =3.59D (53.0149.42D) UCVA m=1.1L BSCVA 5.21-1.64D) inf +sup “thinner” ¿?) (1-12 m) Dcyl=1.25D (-4.89-3.64D) m=1.7L (7.14% worse 1L) DSE=4.20D (-9.13-4.93D)
  • 4. ICS for KC: Results (summary) summary)  All agree they are “Effective”, BUT… “Effective” ►Increased UCVA ~ 2 - 3 lines (average) ►Increased BSCVA ~ 1 - 4 lines (~ 2 ave.) ave.) ►Decreased Spher.Eq. Spher.Eq. ~ 1.5 – 4.2 D (5.8 w KR) ►Decreased Topo. K Topo. ~ 1.5 – 4.5 D (8.0 w KR); ►Decreased Refract. Cyl. ~ 0.3 – 2.7 D Cyl. [50- [50-65% ave.: NOT a “REFRACTIVE” procedure] ave.:
  • 5. ICS for KC: Results (summary) summary)  But: ►Why incomplete results? How can we improve them? ►Why variable results? Is it a nomogram issue?, should we follow Topography?, or aberrations-Coma? aberrations- ►Long term effect? Do they stop KC progression?  Safety: all agree it is “safe”, but: ►BSCVA line LOSS: 3 to 14% of eyes ► 8-20% extrusion (w Keraring manual technique)
  • 6. To Progress: Progress: What We Need to Know… Know…  Mechanism of Action: A better understanding of the basics of how ICS work  Available Modalities: Organize = Classify the basic types of implant combinations (to enable comparisons, studies…)  New/Refined Nomograms ? (later on…)
  • 7. ICS: Mechanism of action?  Commonly assumed to follow Thickness Law of José I. Barraquer ► The effect does increase with:  Thicker segments  Smaller   HOWEVER: ► They work at deep position  NO anterior lamellar effect ► The impl. meridian is steepened impl. ► The “open” meridian is flattened (just the opposite of JIB’s Law !!)
  • 8. ICS: Biomechanical effects !!  Space Occupation ? ► Force lamellae to “detour” around impl. impl. ► No forward thickness effect (deep location), or only a local “bump” ► Torsional effect?
  • 9. New Options: Increased Complexity Options:  Multiple types of ICS (varying diameters, thickness, arc widths)  greater number of possible combinations.  Greater control possible  independent effects on  Sphere  Astigmatism  Coma  Other irregularities?
  • 10. ICS:astigmatic vs. sphere effects Compressive suture-like effect: suture-  A Sector only (~ 90º) (~ ► steeps that meridian ►  flattens @ 90º ► Just the opposite of “Thickness Law” ► Corrects astigmatism  A Circle ≈360º (180º x2) ► gen. flattening ► Just like a tightly sutured PK ► Corrects myopia only
  • 11. ICS in KC & Corneal Ectasia ¿What are we trying to correct?  Astigmatism?  sector ICS  Myopia ?  circle ICS  Decentration ? ► Unique of KC & Ectasia ► Cannot correct w glasses ► Measurable as Coma
  • 12. What about Coma ? How can we correct it ? • Astigmatism: a quadrant aberration  correction: Astigmatism: correction: • 90º arc  Max Effect • 2 equal, symmetric, ICS (coupling), centered over flat axis, equal, symmetric, (coupling), • Coma: a half circle (hemispheric) aberration  correction: hemispheric) correction: • 180º arc  Max Effect • 1 ICS only (asymmetric), centered over coma (decentration) axis asymmetric), (decentration)
  • 13. Implant Options ? Basic Patterns of ICS implantation  Symmetry: ► 2 equal, paired ICS  Symmetric ► 1 single / 2 different ICS (or more)  Asymmetric  Axiality: Axiality: ► ICS (1 or 2) over flat (-) astig. axis  Axial (- astig. ► ICS (1 or more) over an axis different from flat (-) astigmatism (≥ 30º) (-  Non-Axial on- The SA.ANA classification
  • 14. Combining the two criteria: 4+2 types (The SA.ANA classification) SA.ANA Segments Implantation Axis Frequency (Symmetric vs. found (n=1097) type (Axial= same, flat A axis vs. Non-Axial= other axis) Asymmetric) Symmetric Axial SA 2 ICS 9.96% ≈ 80% (red= plus axis (equal) blue= minus axis) Asymmetric Axial 39.58% AA1 1 ICS 2 ICS (unequal) (red= plus axis 28.31% AA2 blue= minus axis) (Total 67.89%) Symmetric Non-Axial (green= mid-ICS SNA 2 ICS axis, displaced ≥ 30º 5.77% (equal) from minus axis) Asymmetric Non-Axial 6.16% ANA1 1 ICS (wide) (green= mid-ICS axis, displaced ≥ 30º from 4.98% ANA2 2 ICS (unequal) Minus axis  coma axis or intermediate) (Total 11.14%)
  • 15. Central, symmetric ectasia/conus [ also: Regular astigmatism (congenital or post-PK); Mild myopia (congenital or residual after Rx.)] red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = minimal
  • 16.  SA - Symmetric Axial ICS red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = minimal
  • 17. SA - Symmetric Axial ICS red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = minimal Preop: UCVA=0.04; Preop: UCVA=0.04; -5.0 -4.0@0º= 0.8 K1= 55.5@90º; K2= 51.3@0º (D= 4.2D) (D Pach min= 360mm (Keratoconus/globus?) 360m (Keratoconus/globus?) Rx: Rx: 2x Keraring 5 Ø 160º x 250 mm @0º Result (1y.): UCVA = 0.85; -1@75º= 0.95 0.85; K1= 50.7@155º; K2=47.8@68º (D= 2.9D) (D
  • 18. Asymmetric Ectasia (markedly displaced, infero-temporal) red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = signficant, signficant, close to flat axis
  • 19.  AA1 - Asymmetric Axial (single ICS) red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = signficant, signficant, close to flat axis
  • 20. AA1 - Asymmetric Axial (single ICS) red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards flat axis Preop: UCVA=0.08; Preop: UCVA=0.08; -4.5@120º= 0.6 K1= 51.1@30º; K2= 45.2@120º (D= 5.9D) (D Pach min= 512mm (Early keratoconus, 11 y/o) 512m (Early Rx: Rx: 1x Keraring 160º x 200 mm @120º (300º) Result (3m.): UCVA = 0.8 plano K1= 49.1@57º; K2=46.9@147º (D= 2.2D hyperc) (D hyperc)
  • 21. AA2 - Asymmetric Axial (2 different ICS) red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards flat axis • Same as AA1, BUT: AA1, • Higher cylinder or sphere combinations •  Additive effect of ICS thickness/width thickness/ • Coma corrected by asymmetry •  Upper ICS must be smaller/thinner smaller/
  • 22. The Albertazzi/Keraring Classification Albertazzi/Keraring  Nomograms based on cone eccentricity: 1, 2, 3  Type 1: Very eccentric “moustache”, coma high but close to flatter (minus) astigmatism axis  Type 3: Central bowtie, low coma  Type 2: Intermediate  the most difficult because of significant coma is away from minus axis (even close to plus axis)  dilemma: Ast. vs.Coma corr.? Ast.
  • 23. Intermediate ectasia Paracentral Relatively orthogonal Coma towards steep axis Difficult choice: if ICS implant red= steep ast. axis ast. @coma axis blue= blue= flat ast. axis ast.  will increase coma = signficant, signficant, astigmatism & close to steep axis vice versa
  • 24.  SNA Symmetric Non-Axial Paired axis-displaced ICS “encroaching” coma axis while still acting on flat axis red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = signficant, signficant, close to steep axis
  • 25. SNA- SNA- Symmetric Non-Axial (paired ICS) Non- red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards steep axis • Intermediate ectasia • Paracentral, relat. orthogonal ectasia relat. • Sphere mild/moderate mild/ • Cylinder moderate/high moderate/ • Coma towards plus cyl axis • Paired ICS, usually of 120º • Inferior displacement 15-30º each 15-
  • 26. Intermediate ectasia Paracentral – mid-peripheral mid- Non- Non-orthogonal red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = signficant, signficant, towards steep axis or intermediate
  • 27.  ANA1 – Asymmetric Non-Non- Axial (single wide ICS) red= steep ast. axis ast. blue= blue= flat ast. axis ast. coma = signficant, signficant, towards steep axis or intermediate
  • 28. ANA1- ANA1- Asymmetric Non-Axial (single ICS) Non- red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards steep axis • Intermediate ectasia • Paracentral, non-orthogonal ectasia non- • Sphere mild • Cylinder moderate/high moderate/ • Coma towards plus cyl axis (±) (± • Single ICS, usually wide 160º- 210º 160º- • At coma axis or intermediate
  • 29. ANA2 - Asymmetric Non-Axial (two ICS) Non- red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards steep axis • Intermediate ectasia • Paracentral, non-orthogonal ectasia non- • Sphere moderate/high moderate/ • Cylinder moderate/high moderate/ • Coma towards plus cyl axis (±) (± • Two ICS: inferior wider (160º) @ coma • Superior small (90º-120º) @ flat axis (90º-
  • 30. ANA3 (ANA1  SA) - Triple ICS implant red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards steep axis • Peripheral, Peripheral, orthogonal ectasia (early KC vs. PMD) (early • Sphere mild, Cylinder mild/moderate mild, mild/ • UCVA= 0.1; -2.0 -2.5@160º= 0.85 • SimK 41.5 / 45.8 (D= 4.3D, Orbscan) (D Orbscan) • Coma towards plus cyl axis (± vertical @260º) (± • Rx: 1x inferior INTAC, 450 mm/150º wide @80º (260º) Rx:
  • 31. ANA3 (ANA1  SA) - Triple ICS (2-step) (2- red= steep ast. axis ast. blue= ast. blue= flat ast. axis coma = significant, significant, towards steep axis  After 1st ICS: Refr. Astigm. increased to -5 D (7 D by Orbscan Sim K) Refr. Astigm.  UCVA improved to 0.4 !! (BSCVA: -5@160º = 0.85)  Coma (mostly vertical) reduced from 0.90 mm 0.20 mm (iTrace) iTrace)  Ectasia pattern changed  more central & symmetric
  • 32. ANA3  After adding 2x90ºx150 mm Kerarings… Kerarings…  UCVA:  @day 1 = 0.65 PLANO  @12 months = 0.95 PLANO  Topography cylinder = 2.6 D (Orbscan Sim K)  Ectasia pattern changed to more central & symmetric  Apparent combination of centering & astigmatic effects in two stages
  • 33. Intracorneal Segments (ICS) implantation types (The SA.ANA classification) Type Frecuency Segments Implantation Axis Indications Examples SA.ANA (Symmetric or (Axial = same, minus cyl axis Asymmetric) Non-Axial = different axis) Central (symmetric) ectasia Symmetric Axial Regular astigmatism SA 2 ICS (equal) (red= plus cyl blue= minus cyl) (congenital or post-PK) Mild myopia (congenital or ≈ 10% residual after Rx.) Asymmetric ectasia (markedly Asymmetric Axial displaced inferiorly) AA1 1 ICS Coma ± towards minus cyl axis (roughly coincident <30º dif.) ≈ 68% (1 or 2 ICS depending on AA2 2 ICS (red= plus cyl amount of cylinder/sphere) (unequal) blue= minus cyl) Intermediate ectasia Symmetric Non-Axial (paracentral, relatively ≈ 6% orthogonal) SNA 2 ICS (green= mid-ICS axis, displaced) Sphere mild/moderate (equal) Cylinder moderate/high Coma ± towards plus cyl axis Intermediate ectasia Asymmetric Non-Axial (paracentral, non-orthogonal) Sphere variable ANA1 1 ICS (wide) Cylinder moderate/high 2 ICS Coma ± towards plus cyl axis ANA2 (unequal) (inferiorly) Intermediate ectasia (peripheral, ± incipient) ≈ 11% Sphere mild ANA3 3 ICS Cylinder mild/moderate (2-step) Coma ± towards plus cyl axis (almost at 90º of minus axis)
  • 34. Summary  The availability of multiple ICS types demands a classification  to enable a meaningful comparison between implant series.  Observed ICS implantation modalities (n=1097) allow a simple while comprehensive classification based on 2 criteria: symmetry criteria: & axiality. Combining the 2 criteria results in 4 types: axiality. The SA.ANA classification  SA = Symmetrical & Axial (always 2 equal ICS, @same, flat axis) = 9.96%  AA = Asymmetrical & Axial [either 1 (AA1) or 2 (AA2) ICS] = 67.89% (total)  SNA = Symmetrical & Non-Axial (always 2 equal ICS, @different axis) = 5.77% on-  ANA = Asymmetrical & Non-Axial [either 1 (ANA1) or 2 (ANA2) ICS] = 11.14% on-
  • 35. Perspectives  Classifiaction (SA-ANA)  a tool for outcome comparison  (SA- opens new possibilities: ► Better classification of keratoconus & other ectasia ► To refine (redefine) indications for ICS ► To develop better ICS nomograms  Testing/confirmation of basic theory (mechanism of action)  Independent address of astigmatism and coma (decentration), esp. non-axial (ANA) minority? types decentration), non-
  • 36. Grupo Ibérico de Segmentología José Alfonso (Oviedo) Federico Alonso (Sevilla) Sevilla) Rafael I. Barraquer (Barcelona) Margarita Cabanas (Sevilla) Sevilla) Antonio Limao (Lisboa) Lisboa) Joaquim Murta (Coimbra) Cristina Peris (Valencia) Vicente Rodríguez (Las Palmas) Pedro Tañá (Alicante) y con el apoyo de