Evaluation of Corneal Parameters Evaluation of Corneal Parameters and Spherical Aberration After and Spherical Aberration After

DSAEK Measured with Pentacam DSAEK Measured with Pentacam

SystemSystem

Orkun MuftuogluOrkun Muftuoglu,, Pawan Pawan PrasherPrasher,,R. Wayne Bowman, Steven M. Verity, H. R. Wayne Bowman, Steven M. Verity, H.

Dwight Cavanagh, James P. McCulleyDwight Cavanagh, James P. McCulleyV V ..Vinod Mootha MDVinod Mootha MD

University of Texas Southwestern Medical Center at Dallas, Texas

Financial DisclosureFinancial Disclosure► UT Southwestern Medical Center & Aston

Ophthalmology Clinic, Dallas, TX.► Drs. Bowman, Verity, and McCulley receive

consultant reimbursement from Alcon Inc.► Dr. Cavanagh receives research

reimbursements from Ciba Inc and Menion Inc.► None of the authors have financial interest in

the subject matter of this poster.► Acknowledgements: Supported in part by an

unrestricted research grant from Research to Prevent Blindness, Inc., New York, New York.

IntroductionIntroduction

► DSAEK is a technique for selective replacement of dysfunctional DSAEK is a technique for selective replacement of dysfunctional endotheliumendothelium Rapid recovery of visionRapid recovery of vision Minimal induced astigmatism and anisometropia Minimal induced astigmatism and anisometropia Enhanced resistance to traumaEnhanced resistance to trauma Less risk of expulsive choroidal hemorrhageLess risk of expulsive choroidal hemorrhage Fewer ocular surface problemsFewer ocular surface problems

► Despite favorable visual outcomes, fewer patients than expected Despite favorable visual outcomes, fewer patients than expected achieve BCVA of 20/20. achieve BCVA of 20/20.

► Probable limiting factors: subepithelial scarring, interface changes, Probable limiting factors: subepithelial scarring, interface changes, increased corneal thickness and increased higher order aberrationsincreased corneal thickness and increased higher order aberrations

► Hyperopic shift- Anatomical changes induced to posterior corneal Hyperopic shift- Anatomical changes induced to posterior corneal surface???surface???

PurposePurpose

►Compare corneal parameters of the eyes Compare corneal parameters of the eyes that underwent DSAEK with age-that underwent DSAEK with age-matched controls using rotating matched controls using rotating Scheimpflug imaging systemScheimpflug imaging system

► 32 eyes (28 patients) who underwent DSAEK32 eyes (28 patients) who underwent DSAEK► 32 eyes (32 patients) age-matched controls (no previous ocular surgery)32 eyes (32 patients) age-matched controls (no previous ocular surgery)PentacamPentacam

Study group had Scheimpflug images (Pentacam, Oculus, Germany) taken after 3 months post-Study group had Scheimpflug images (Pentacam, Oculus, Germany) taken after 3 months post-operativelyoperatively

Scheimpflug camera and a monochromatic light source Scheimpflug camera and a monochromatic light source The system rotates 180 degrees and takes 25-50 images of the anterior segment in about 2 The system rotates 180 degrees and takes 25-50 images of the anterior segment in about 2

secondsseconds Calculates a 3-dimensional model of the anterior eye segment from as many as 25,000 true Calculates a 3-dimensional model of the anterior eye segment from as many as 25,000 true

elevation pointselevation points► Paremeters evaluatedParemeters evaluated

Mean anterior keratometry (Ka)Mean anterior keratometry (Ka) Mean posterior keratometry (Kp)Mean posterior keratometry (Kp) Mean anterior radius of curvature (Ra)Mean anterior radius of curvature (Ra) Mean posterior radius of curvature (Rp)Mean posterior radius of curvature (Rp) True net power (TNP)True net power (TNP) Central corneal thickness (CCT)Central corneal thickness (CCT) Corneal volume (CV)Corneal volume (CV) Keratometric Power Deviation (KPD)Keratometric Power Deviation (KPD) Mean anterior and posterior astigmatism Mean anterior and posterior astigmatism Equivalent K Readings (EKR) in 2, 4 and 6mm zoneEquivalent K Readings (EKR) in 2, 4 and 6mm zone HOAs data up to 6HOAs data up to 6thth order from anterior and posterior surface in the central 6.0 mm zone order from anterior and posterior surface in the central 6.0 mm zone Corneal densitometry Corneal densitometry

► DSAEK- 16 eyesDSAEK- 16 eyes► Phacoemulsification with DSAEK- 14 eyesPhacoemulsification with DSAEK- 14 eyes► DSAEK with IOL exchange- 2 eyesDSAEK with IOL exchange- 2 eyes► 17 clear corneal and 15 scleral tunnel17 clear corneal and 15 scleral tunnel► Graft size was 8.0mm or larger in all casesGraft size was 8.0mm or larger in all cases

Materials and MethodsMaterials and Methods

ResultsResults

Mean AgeMean Age MaleMale FemaleFemale

DSAEKDSAEK70.1 ± 10.2 70.1 ± 10.2 yearsyears

(49 to 87)(49 to 87)1717 1515

ControlsControls69 69 ± 7 ± 7 yearsyears

(58 to 83)(58 to 83)1616 1616

Visual Acuity Visual Acuity logmar (Snellen)logmar (Snellen)

NN MinimumMinimum MaximumMaximum MeanMean Std. Std. DeviationDeviation

3322 00 (20/20)(20/20)

0.0.60 60 (20/80)(20/80)

0.230.23 (20/30)(20/30) 0.10.144

DSAEKDSAEK ControlControl pp

RaRa 7.93±0.37.93±0.3 7.73±0.277.73±0.27 0.110.11

RpRp 5.91±0.475.91±0.47 6.45±0.316.45±0.31 00

KaKa 42.53±1.5242.53±1.52 43.6±1.6243.6±1.62 0.0090.009

KpKp 6.8±0.556.8±0.55 6.2±0.316.2±0.31 00

True net powerTrue net power 40.55±1.7940.55±1.79 42.49±1.5742.49±1.57 00

PachymetryPachymetry 627.75±46.41627.75±46.41 552.53±34.54552.53±34.54 00

VolumeVolume 72.9±7.7772.9±7.77 58.2±4.4258.2±4.42 00

KPDKPD 1.89±0.781.89±0.78 1.23±0.271.23±0.27 00

EKR-2mmEKR-2mm 41.64±1.8941.64±1.89 43.39±1.5243.39±1.52 00

EKR-4mmEKR-4mm 42.1±1.7342.1±1.73 43.77±1.5243.77±1.52 00

EKR-6mmEKR-6mm 43.03±1.7243.03±1.72 44.29±1.4444.29±1.44 0.0030.003

Ant astigmatismAnt astigmatism 0.13±1.770.13±1.77 0.1±0.870.1±0.87 0.7170.717

Post astigmatismPost astigmatism (-1.25±1.4)(-1.25±1.4) 0.26±0.280.26±0.28 0.0160.016

Comparison between DSAEK and Comparison between DSAEK and controlscontrols

P* = Mann-Whitney U test

Cornea HOAs 6mmCornea HOAs 6mm

  Anterior corneaAnterior cornea DSAEKDSAEK CONTROLCONTROL DifferenceDifference % Difference% Difference P*P*

Total HOATotal HOA 3.165 ± 1.3543.165 ± 1.354 2.15 ± 0.652.15 ± 0.65 1.011.01 4747 0.0010.001

Z31Z31 0.590 ± 0.4260.590 ± 0.426 0.409 ± 0.2230.409 ± 0.223 0.1810.181 4444 0.0450.045

Z33Z33 0.313 ± 0.3230.313 ± 0.323 0.154 ± 0.1030.154 ± 0.103 0.1580.158 102102 0.010.01

Z40Z40 0.730 ± 0.2640.730 ± 0.264 0.667 ± 0.3260.667 ± 0.326 0.0630.063 99 0.3980.398

*Mann-whitney U test*Mann-whitney U test

All data are mean ± SD (range)All data are mean ± SD (range)

  Posterior corneaPosterior cornea DSAEKDSAEK CONTROLCONTROL DifferenceDifference % Difference% Difference P*P*

Total HOATotal HOA 19.284 ± 8.41319.284 ± 8.413 4.414 ± 0.7884.414 ± 0.788 14.87414.874 338338 <0.001<0.001

Z31Z31 3.419 ± 1.8753.419 ± 1.875 0.739 ± 0.4240.739 ± 0.424 2.6792.679 362362 <0.001<0.001

Z33Z33 2.719 ± 1.7652.719 ± 1.765 0.375 ± 0.2320.375 ± 0.232 2.3442.344 625625 <0.001<0.001

Z40Z40 1.763 ± 1.4301.763 ± 1.430 0.823 ± 0.2960.823 ± 0.296 0.940.94 114114 <0.001<0.001

AnteriorAnterior PosteriorPosterior

VA : 20 / 25

ControlControl

DSAEKDSAEK

Corneal DensitometryCorneal Densitometry

DSAEKDSAEK ControlControl pp

AnteriorAnterior 48.07±15.948.07±15.9 27.58±2.7327.58±2.73 <0.001<0.001

PosteriorPosterior 30.08±730.08±7 19.86±2.919.86±2.9 <0.001<0.001

P* = Mann-Whitney U test

DiscussionDiscussionDSAEK surgery- DSAEK surgery- ► Creation of a new steeper endothelial surfaceCreation of a new steeper endothelial surface► Meniscus shaped endothelial graftMeniscus shaped endothelial graft► Alteration of physiological relationship between anterior and posterior surfaceAlteration of physiological relationship between anterior and posterior surface► Placido based imaging systems could produce erroneous measurements of corneal powerPlacido based imaging systems could produce erroneous measurements of corneal power► Measures both anterior and posterior surfaceMeasures both anterior and posterior surface► Calculates true net power based on thick lens formulaCalculates true net power based on thick lens formula► Incorporates refractive indices at each interface along with anterior and posterior curvature and Incorporates refractive indices at each interface along with anterior and posterior curvature and

corneal thicknesscorneal thickness► Has been shown to be useful in studying changes in posterior curvature and give repeatable Has been shown to be useful in studying changes in posterior curvature and give repeatable

measurements of corneal thickness- the parameters most affected in DSAEKmeasurements of corneal thickness- the parameters most affected in DSAEK

Changes induced by DSAEKChanges induced by DSAEK► Increased corneal thickness and volumeIncreased corneal thickness and volume

additional stromal tissueadditional stromal tissue► Lower radius of curvature of posterior surface (relative steepening)Lower radius of curvature of posterior surface (relative steepening)

Meniscus shaped graft thicker in the peripheryMeniscus shaped graft thicker in the periphery► Higher radius of curvature of anterior surface (relative flattening)Higher radius of curvature of anterior surface (relative flattening)

Wound related?Wound related? Alteration of curvature on resolution of bullous changes??Alteration of curvature on resolution of bullous changes??

► Lower true net power in DSAEK corneasLower true net power in DSAEK corneas

ConclusionsConclusions

►Pentacam measurements show lower Pentacam measurements show lower true net power in DSAEK as compared true net power in DSAEK as compared to controls likely due to to controls likely due to increased posterior curvature (increased increased posterior curvature (increased

minus lens effect)minus lens effect) Decreased anterior curvature (decreased Decreased anterior curvature (decreased

plus lens effect)??plus lens effect)??►Spherical aberration is variable after Spherical aberration is variable after

DSAEK surgery. DSAEK surgery.