Docstoc

IC-08_Koch_Handout

Document Sample
IC-08_Koch_Handout Powered By Docstoc
					Financial Disclosure
I have a financial interest with the following
companies:

Abbott Medical Optics
Alcon
Calhoun Vision
NuLens
Optimedica
Optivue
IOL power calculations in
post-LASIK/PRK eyes

    Douglas D. Koch, M.D.
    Cullen Eye Institute,
    Baylor College of Medicine,
    Houston, TX
Challenges
   Difficulties in determining true corneal
    refractive power
       Keratometric inaccuracy
       Invalid use of effective refractive index of
        cornea (1.3375)
   Problems in 3rd and 4th generation IOL
    formulas
       Inaccurate estimation of ELP
       Exception: Haigis formula
So many formulas. . So we developed:
http://www.ascrs.org/
IOL power calculation
Prior myopic-LASIK/PRK
   Double-K
  Holladay 1
and Haigis-L
   formulas


3 categories of
      formulas
3 categories

   Traditionally
  “Gold” standard     Use a fraction
   KEY – accurate        of ∆MR
    historical data    Data error ↓    Rely only on
    Data error 1:1     to 20 – 30%      current data
         ratio
Pop-up
windows
explain
methods
used
Prior
hyperopic-
LASIK/PRK
Prior RK
Monthly visits to the calculator in 2010

  9,000                                                                                 8,249
                          7,853                                                 7,666
  8,000                                                                                         7,257
                                  7,218                                 7,105
                  6,570                   6,758 6,825           6,791
  7,000                                                 6,369
          6,173
  6,000
  5,000
  4,000
  3,000
  2,000
  1,000
     0
           Jan    Feb     Mar     Apr     May   Jun      Jul    Aug     Sep     Oct     Nov     Dec
Patients

   2 study centers
   Consecutive cases of IOL implantation in
    eyes with prior myopic-LASIK
       SN60WF
   72 eyes of 57 patients included
       Mean age: 58 ± 8 years (range 42 to 77
        years)
       Myopic LASIK correction: 5.10 ± 2.55 D
        (range 0.98 to 11.21 D)
Methods

   IOL prediction error
       = IOL implanted – IOL calculated
       Negative value  myopic results
   Consistency of prediction performance
       F-test for variances
                                          0.0
                                                2.0
                                                              4.0




                        -4.0
                                   -2.0

                               A
                               A
                                                          A
                                                          A
                                                                    S




     Clinical History




                        A
                        A
                                                                    A




       Feiz-Mannis
                                                          A
                                                                A




    Corneal Bypass


    Adjusted EffRP
                                                      A




  Adjusted Atlas0-3
                                                          A




             Masket
                                                 A




   Modified-Masket


Wang-Koch-Maloney


          Shammas
                                                          A




            Haigis-L
                                      A
                                      A
                                                A
                                                A




 Average IOL power
Variances of IOL prediction errors (SD2)
- consistency of performance
           Pre-LASIK Ks + ∆ MR
              Clinical History             2.06
              Feiz-Mannis                  2.53
              Corneal Bypass               1.99
           ∆ MR
              Adjusted EffRP               0.70
      *       Adjusted Atlas0-3            0.68
              Masket                       0.63
              Modified-Masket              0.62
            No prior data
               Wang-Koch-Maloney            0.68
               Shammas                      0.66
               Haigis-L                     0.66
          * Significant differences (all P<0.05 with
          Bonferroni correction)
Refractive prediction error
                                   ± 0.5                      Proposed UK NHS
 Methods                            D         ± 1.0 D        benchmark in normal
 Pre-LASIK Ks + ∆MR*                                               eyes*:
    Clinical History                 44          69               85% ±1.0 D
    Feiz-Mannis                      37          60
                                                                  55% ±0.5 D
    Corneal Bypass                   37          68
 ∆MR
   Adjusted EffRP                    62          86                  Met
   Adjusted Atlas0-3                 64          90                  benchmark
                                                                     in normal
   Masket                            57          91
                                                                     eyes but
   Modified-Masket                   67          90                  well below
 No prior data                                                       latest
   Wang-Koch-Maloney                 58          96                  standards
   Shammas                           60          90
   Haigis-L                          60          94
       *Significant lower % with historical methods (P<0.05). Gale RP, et al.
        Benchmark standards for refractive outcomes after NHS cataract
        surgery. Eye. 2009;23:149-52
Summary

   Using double-K Holladay 1 formula
       Greater prediction errors and variances with
        methods requiring Pre-LASIK Ks and ∆MR
           Use 100% of historical data
       Superior and essentially equivalent results
        with:
           Methods using a fraction of ∆MR and
           Methods using no prior data
Optical coherence tomography (OCT)

   RTVue-CAM: an Fourier domain OCT
    system for both retinal and corneal
    imaging
       RTVue with CAM
           module
Net Corneal Power (NCP):

Combines anterior & posterior
curvature measurements from OCT
meridional scans

                       1.5mm                  1.5mm

                                                        n0 = 1
                                  D

                                                         n1 = 1.376

                         Rp                     Ra

                                                        n2 = 1.336

                      Kp 
                             n2  n1          n1  n0
                                       Ka 
                               Rp               Ra
Evaluation of OCT-based formula
   IOL power calculation in post-LASIK
    eyes
     12 eyes at Cullen Eye Institute
     8 eyes at Doheny Eye Institute
     Refractive correction: -4.04 ± 3.60 D
      (range -0.88 to -9.81 D)
 OCT-based IOL power formula
ELP = 0.711 * (AL – ACD) – 0.25 * Pp + 0.623 * ALadj + pACD – 8.11
Where
   AL = axial eye length (mm)
   ACD = Anterior chamber depth (mm)
   Pp = posterior corneal power (D)
   ALadj = sqrt(AL)                 if AL < 24.4mm
           sqrt(AL+0.8*(AL-24.4)),  if AL > 24.4mm
   pACD = personalized ACD (ACD-constant)




            *Tang M, Li Y, Huang D. An Intraocular Lens Power Calculation Formula Based on Optical Coherence
            Tomography: a Pilot Study. J Refract Surg. 2010;26(6):430-437
Refractive prediction error

Keratometry   Best IOL   Prediction     Range         MAE    Adjusted
  Method      Formula    Error (D)       (D)          (D)    MAE (D)


IOL-Master    Haigis-L    -0.23 ±     (-1.93, 1.30)   0.66    0.65*
                            0.83

   OCT         OCT-       -0.01 ±     (-0.85, 1.79)   0.56    0.56*
               based        0.70



  *P=0.65, n = 20 eyes of 15 subjects.
Refractive prediction error

                            Haigis-L     OCT formula
               8

               6                                                     Within 0.5D:
   # of eyes




                                                                     •Haigis-L: 11/20
               4                                                     •OCT: 10/20

               2                                                     Within 1D:
                                                                     •Haigis-L: 15/20
               0                                                     •OCT: 19/20


                   Predicted – Actual Postoperative Refraction (D)
Summary

   Limitation:
       Small numbers
       Performance of OCT-based IOL formula was
        not compared to many methods on the
        ASCRS calculator


   Further studies desirable
Recent study

   Accuracy of Galilei in IOL power
    calculation in eyes with prior myopic
    LASIK/PRK
   Consecutive cases of IOL implantation
    between April 08 to Feb. 11
Patients

   19 eyes of 16 patients had all
    historical data
     MyopicLASIK correction: 4.28 ± 2.61
     D (range 0.88 to 8.50 D)
Refractive MAE with all methods (n=19)
  1.2



                                    0.99
           1.0   0.94                             0.93

                                                                                                                                                                             0.78
           0.8                                                                                                                                                                           0.75
                                                                                                                                                                                                    0.72 0.70
                                                                   0.65
                                                                                                                                                                  
 MAE (D)




           0.6                                                                        
                                                                                    0.52                                          0.57 0.57
                                                                                                                                                                 0.47
                                                                                                        0.42 0.44
           0.4


           0.2


           0.0




                                                                                                                                                                  Haigis-L
                                                                                                                                                       Shammas




                                                                                                                                                                                                               TCP-5mm
                                                                                                                                                                                                     TCP-4mm
                                                                                                                                                                              TCP-2mm

                                                                                                                                                                                          TCP-3mm
                                    Feiz-Mannis




                                                                                                                                   Wang-Koch-Maloney
                 Clinical History




                                                                   Adjusted EffRP
                                                  Corneal Bypass




                                                                                                                 Modified-Masket
                                                                                    Adjusted Atlas0-3

                                                                                                        Masket




                                                                                                                                                                                        Galilei

                 Significant greater MAE with methods using pre-LASIK
                 Ks and ∆MR than those with  (all P<0.05)
            Refractive prediction error with all methods
            (n=19)                                     UK NHS
            100                                                                                                                                                          95                                                     benchmark
                                                                                                             89          89
             90                                                                                                                                                                                                       84
                                                                           79                79                                                                                                            79
                                                                                                                                                                                                                                   85%
             80                      +/- 0.5 D                                                                                              74                74                     74         74                                ±1.0 D
                                     +/- 1.0D                                                               68       68
             70
                                                                                                                                                                        63
             60          58                               58                            58
% of eyes




                                            53                                                                                          53                                                                                         55%
                                                                                                                                                             47
             50
                                                                       42                                                                                                                                                         ±0.5 D
             40
                  32                   32             32                                                                                                                                                  32         32
             30                                                                                                                                                                     26
                                                                                                                                                                                               21
             20

             10




                                                                                                                                                                         Haigis-L




                                                                                                                                                                                                                      TCP-5mm
                                                                                                                                                                                                           TCP-4mm
                                                                                                                                                                                     TCP-2mm

                                                                                                                                                                                                TCP-3mm
              0
                                                                                                                                                              Shammas
                                        Feiz-Mannis




                                                                                                                                         Wang-Koch-Maloney
                  Clinical History



                                                      Corneal Bypass

                                                                       Adjusted EffRP




                                                                                                                      Modified-Masket
                                                                                        Adjusted Atlas0-3

                                                                                                            Masket




                                                                                                                                                                                               Galilei
Accuracy of IOL power
calculation in eyes with prior
RK
Purpose

   Because RK eyes have variable front and
    back curvatures, IOL calcs are especially
    challenging
   To evaluate the accuracy of 4 devices for
    calculating corneal power for IOL
    calculations in RK eyes undergoing
    cataract surgery
       IOLMaster, EyeSys, Atlas, Galilei
Patients

   Consecutive cases of IOL implantation
    between April 08 to February 11

   27 eyes of 18 patients, age 47 to 79 years
Refractive mean absolute error (MAE)
with different devices
            0.8

            0.7                     0.67           0.66
                      0.65

            0.6                                                     0.58


            0.5
  MAE (D)




            0.4

            0.3

            0.2

            0.1

            0.0
                  EyeSys EffRP   IOLMasterK     Atlaszone0-3   TCPannuli1-4

                  Galilei TCPannuli1-4 tended to produce smallest
                  MAE (all P>0.05).
   Refractive prediction error                                                      UK NHS
                                                                                   benchmark
                            +/- 0.50 D
            90                         85                85                85
                            +/- 1.0 D                                                  85%
            80         78                                                             ±1.0 D

            70
                                                                     59
            60
                  52                                                                   55%
% of eyes




            50                                                                        ±0.5 D

            40
                                  33
                                                    30
            30

            20

            10

            0
                 EyeSys EffRP    IOLMaster K       Atlaszone0-3     TCPannuli1-4
                 Proposed benchmark for normal eyes: Gale RP, et al. Benchmark
                     standards for refractive outcomes after NHS cataract surgery. Eye.
                     2009;23:149-52.
Galilei

 Needs further work to improve IOL
  calculations after LASIK
 Helpful in eyes that have undergone
  radial keratotomy
Thank you for your attention

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:9
posted:9/17/2011
language:English
pages:36