Posterior Lamellar Surgery: Posterior Lamellar Surgery: Techniques, complications and Techniques, complications and

clinical resultsclinical results

Mark A. Terry, MDMark A. Terry, MDDirector, Corneal ServicesDirector, Corneal Services

Devers Eye InstituteDevers Eye Institute

DD

Scientific Director Scientific Director Lions Eye Bank of Oregon Lions Eye Bank of Oregon

Vision Research LabVision Research Lab

Portland, Oregon, U.S.A.Portland, Oregon, U.S.A.

Thank youThank you

Dr Esteve Adroher and Dr Juan Elizalde: Dr Esteve Adroher and Dr Juan Elizalde: for the kindness of your invitation to this for the kindness of your invitation to this wonderful meetingwonderful meeting

Jeff Young CEBT: for your help in Jeff Young CEBT: for your help in coordinating my visit to Barcelonacoordinating my visit to Barcelona

Chris Stoeger CEBT, Director of Chris Stoeger CEBT, Director of Operations, Lions Eye Bank of Oregon: for Operations, Lions Eye Bank of Oregon: for your critical support, enthusiasm, and your critical support, enthusiasm, and scientific contributions to our corneal scientific contributions to our corneal research program research program

The speaker has a financialThe speaker has a financialinterest in the EK instruments which he designed.interest in the EK instruments which he designed.

The author has been a sponsored speaker for MoriaThe author has been a sponsored speaker for Moria

The author has been a sponsored speaker for AlconThe author has been a sponsored speaker for Alcon

DISCLOSUREDISCLOSURE

Endothelial Keratoplasty: Multiple Endothelial Keratoplasty: Multiple names and acronymsnames and acronyms

PLKPLK: Posterior Lamellar Keratoplasty : Posterior Lamellar Keratoplasty (Melles)(Melles)DLEKDLEK: Deep Lamellar Endothelial : Deep Lamellar Endothelial Keratoplasty Keratoplasty (Terry)(Terry)DSEKDSEK: Descemets Stripping Endothelial : Descemets Stripping Endothelial Keratoplasty Keratoplasty (Price)(Price)DSAEKDSAEK: Descemets Stripping with Automated : Descemets Stripping with Automated Endothelial Keratoplasty Endothelial Keratoplasty (Gorovoy)(Gorovoy)DMEKDMEK: Descemets Membrane Endothelial : Descemets Membrane Endothelial KeratoplastyKeratoplasty (Melles)(Melles)DMAEK: DMAEK: Descemets Membrane Automated Descemets Membrane Automated Endothelial KeratoplastyEndothelial Keratoplasty (Price)(Price)

DLEK v DSEK/DSAEK AnatomyDLEK v DSEK/DSAEK Anatomy

DLEK: Pocket dissectedDLEK: Pocket dissectedStromal fibers exposedStromal fibers exposed

DSEK/DSAEK: DSEK/DSAEK: No pocket or dissectionNo pocket or dissection

Our Current experience with over Our Current experience with over 1,100 cases of EK surgery from 1,100 cases of EK surgery from March 2000 to September 2009 March 2000 to September 2009

(Prospective IRB Study)(Prospective IRB Study)We developed and performed the first EK We developed and performed the first EK

procedure in the U.S.:procedure in the U.S.:About 275 cases of DLEKAbout 275 cases of DLEKAbout 37 cases of DSEKAbout 37 cases of DSEKOver 750 cases of DSAEK (this includes Over 750 cases of DSAEK (this includes over 625 cases using over 625 cases using ““prepre--cutcut”” tissue)tissue)

We currently perform 6 to 10 DSAEK surgeries a weekWe currently perform 6 to 10 DSAEK surgeries a weekwith the Fellow doing >70 cases a yearwith the Fellow doing >70 cases a year

2008 Published Peer2008 Published Peer--Review EK Papers by Review EK Papers by Devers Eye InstituteDevers Eye Institute

Terry MA: PreTerry MA: Pre--cut Tissue in DSAEK: Complications are from technique, not tissucut Tissue in DSAEK: Complications are from technique, not tissue. Cornea 2008 (Editorial); e. Cornea 2008 (Editorial); 6:6276:627--99Terry MA, Shamie N, Chen ES, Hoar KL, Friend DF. Endothelial KerTerry MA, Shamie N, Chen ES, Hoar KL, Friend DF. Endothelial Keratoplasty: A simplified technique to atoplasty: A simplified technique to minimize graft dislocation, iatrogenic graft failure and pupillaminimize graft dislocation, iatrogenic graft failure and pupillary block. Ophthalmology 2008 (Epub ahead of ry block. Ophthalmology 2008 (Epub ahead of print)print)Chen ES, Terry MA, Shamie N, Hoar KL, Friend DJ. PreChen ES, Terry MA, Shamie N, Hoar KL, Friend DJ. Pre--cut tissue in Descemetcut tissue in Descemet’’s Stripping Automated s Stripping Automated Endothelial Keratoplasty: Donor characteristics and early postEndothelial Keratoplasty: Donor characteristics and early post--operative complications. Ophthalmology 2008; operative complications. Ophthalmology 2008; 115: 497115: 497--502502Terry MA, Shamie N, Chen ES, Phillips PM, Hoar KL, Friend DJ. PrTerry MA, Shamie N, Chen ES, Phillips PM, Hoar KL, Friend DJ. Pree--cut tissue for Descemetcut tissue for Descemet’’s stripping s stripping endothelial keratoplasty: Vision, Astigmatism and Endothelial Suendothelial keratoplasty: Vision, Astigmatism and Endothelial Survival. Ophthalmology 2008 (in review).rvival. Ophthalmology 2008 (in review).Chen ES, Terry MA, Shamie N, Hoar KL, Friend DJ. DescemetChen ES, Terry MA, Shamie N, Hoar KL, Friend DJ. Descemet’’s stripping endothelial keratoplasty: Six s stripping endothelial keratoplasty: Six months results in a prospective study of 100 eyes. Cornea 2008 (months results in a prospective study of 100 eyes. Cornea 2008 (in press)in press)Terry MA, Shamie N, Chen ES, Hoar KL, Phillips PM, Friend DJ. EnTerry MA, Shamie N, Chen ES, Hoar KL, Phillips PM, Friend DJ. Endothelial keratoplasty: The influence of dothelial keratoplasty: The influence of prepre--operative donor endothelial densities on dislocations, primary goperative donor endothelial densities on dislocations, primary graft failure, and one year cell counts. raft failure, and one year cell counts. Cornea 2008 (in press)Cornea 2008 (in press)Chen ES, Shamie N, Terry MA, Hoar KL. Chen ES, Shamie N, Terry MA, Hoar KL. Endothelial KeratoplastyEndothelial Keratoplasty : Improvement of vision after healthy donor : Improvement of vision after healthy donor tissue exchange. Cornea 2008; 27: 279tissue exchange. Cornea 2008; 27: 279--282.282.Chen ES, Shamie N, Terry MA. Chen ES, Shamie N, Terry MA. Improved vision following replacement of a healthy DSEK graft. JImproved vision following replacement of a healthy DSEK graft. J Cataract Cataract Refract Surg 2008 (in Press)Refract Surg 2008 (in Press)Terry MA, Chen ES, Shamie N, Hoar KL, Friend DF. Endothelial celTerry MA, Chen ES, Shamie N, Hoar KL, Friend DF. Endothelial cell loss after Descemetl loss after Descemet’’s stripping s stripping endothelial keratoplasty in a large prospective series. Ophthalmendothelial keratoplasty in a large prospective series. Ophthalmology 2008; 115: 488ology 2008; 115: 488--496496Terry MA. Donor tissue damage in endothelial keratoplasty. OphthTerry MA. Donor tissue damage in endothelial keratoplasty. Ophthalmology 2008; 115: 420almology 2008; 115: 420--421.421.Terry MA. Trauma and Wound Rupture in Endothelial Keratoplasty.Terry MA. Trauma and Wound Rupture in Endothelial Keratoplasty. Cornea 2008; 27: 127Cornea 2008; 27: 127--128.128.Terry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, StoTerry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, Stoeger C. Endothelial Keratoplasty: The eger C. Endothelial Keratoplasty: The influence of insertion techniques and incision size on donor endinfluence of insertion techniques and incision size on donor endothelial survival. Cornea 2008 (in press)othelial survival. Cornea 2008 (in press)Saad HA, Terry MA, Shamie N, Chen ES, Friend DF, Holiman JD, StoSaad HA, Terry MA, Shamie N, Chen ES, Friend DF, Holiman JD, Stoeger C. An easy and inexpensive eger C. An easy and inexpensive method for quantitative analysis of endothelial damage by using method for quantitative analysis of endothelial damage by using vital dye staining and Adobe Photoshop vital dye staining and Adobe Photoshop software. Cornea 2008 (in Press)software. Cornea 2008 (in Press)Terry MA. Endothelial keratoplasty: Clinical outcomes in the twoTerry MA. Endothelial keratoplasty: Clinical outcomes in the two years following deep lamellar endothelial years following deep lamellar endothelial keratoplasty. (an American Ophthalmological Society thesis) Trankeratoplasty. (an American Ophthalmological Society thesis) Trans Am Ophthalmol Soc 2007; 105: 530s Am Ophthalmol Soc 2007; 105: 530--563. 563.

2009 Published Peer2009 Published Peer--Review EK Papers by Devers Eye InstituteReview EK Papers by Devers Eye InstituteTerry MA, Shamie N, Chen ES, Phillips PM, Hoar KL, Friend DJ. PrTerry MA, Shamie N, Chen ES, Phillips PM, Hoar KL, Friend DJ. Pree--cut tissue for Descemetcut tissue for Descemet’’s stripping endothelial s stripping endothelial keratoplasty: Vision, astigmatism, and endothelial survival. Ophkeratoplasty: Vision, astigmatism, and endothelial survival. Ophthalmology 2009;116:248thalmology 2009;116:248--5656

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Hoar KL, Phillips PM, Friend DJ. Endothelial keratop, Shamie N, Hoar KL, Phillips PM, Friend DJ. Endothelial keratoplasty: vision, endothelial survival, and lasty: vision, endothelial survival, and complications in a comparative case series of fellows vs attendicomplications in a comparative case series of fellows vs attending surgeons. Am J Ophthalmol 2009;148:26ng surgeons. Am J Ophthalmol 2009;148:26--31.31.

Terry MA. Endothelial keratoplasty: A comparison of complicationTerry MA. Endothelial keratoplasty: A comparison of complication rates and endothelial survival between prerates and endothelial survival between pre--cut tissue and cut tissue and surgeon cut tissue by a single DSAEK surgeon. Trans Am Ophthalmosurgeon cut tissue by a single DSAEK surgeon. Trans Am Ophthalmol Soc 2009 (in press) l Soc 2009 (in press)

Terry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, StoTerry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, Stoeger C. Endothelial Keratoplasty: The influence of eger C. Endothelial Keratoplasty: The influence of insertion techniques and incision size on donor endothelial survinsertion techniques and incision size on donor endothelial survival. Cornea 2009; 28:24ival. Cornea 2009; 28:24--31.31.

Terry MA, Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, FrieTerry MA, Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, Friend DJ. Endothelial keratoplasty for Fuchsnd DJ. Endothelial keratoplasty for Fuchs’’ dystrophy dystrophy with cataract: Complications and clinical results with the new Twith cataract: Complications and clinical results with the new Triple Procedure. Ophthalmology 2009; 116:631riple Procedure. Ophthalmology 2009; 116:631--99

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Phillips PM. Busin Glide vs Forceps in DSAEK: Not Al, Shamie N, Phillips PM. Busin Glide vs Forceps in DSAEK: Not All Forceps Insertions are Created l Forceps Insertions are Created Equal (Letter): Amer J Ophthalmol 2009 (in press)Equal (Letter): Amer J Ophthalmol 2009 (in press)

Phillips PM, Phillips PM, Terry MATerry MA , Shamie N, Chen ES, Hoar KL, Dhoot D, Friend DJ. Descemet, Shamie N, Chen ES, Hoar KL, Dhoot D, Friend DJ. Descemet’’s stripping automated endothelial s stripping automated endothelial keratoplasty (DSAEK) in eyes with previous trabeculectomy and tukeratoplasty (DSAEK) in eyes with previous trabeculectomy and tube shunt procedures: Intrabe shunt procedures: Intra--operative and postoperative and post--operative operative complications. Cornea 2009 (in press)complications. Cornea 2009 (in press)

Phillips PM, Phillips PM, Terry MATerry MA , Shamie N, Chen ES, Hoar KL, Stoeger C, Friend DJ, Saad HA. Des, Shamie N, Chen ES, Hoar KL, Stoeger C, Friend DJ, Saad HA. Descemet's stripping automated cemet's stripping automated endothelial keratoplasty (DSAEK) using corneal donor tissue not endothelial keratoplasty (DSAEK) using corneal donor tissue not acceptable for use in penetrating keratoplasty due to acceptable for use in penetrating keratoplasty due to anterior stromal scars, pterygia, and previous corneal refractivanterior stromal scars, pterygia, and previous corneal refractive surgeries. Cornea 2009;28:871e surgeries. Cornea 2009;28:871--66

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Phillips PM, Friend DJ. Management of psuedophakic b, Shamie N, Phillips PM, Friend DJ. Management of psuedophakic bullous keratopathy by combined ullous keratopathy by combined DescemetDescemet--stripping endothelial keratoplasty and intrastripping endothelial keratoplasty and intra--ocular exchange. (Letter) J Cat Refract Surg 2009 (in press)ocular exchange. (Letter) J Cat Refract Surg 2009 (in press)

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Phillips PM, Friend DJ. The stability of hyperopic r, Shamie N, Phillips PM, Friend DJ. The stability of hyperopic refractive shift following Descemetefractive shift following Descemet’’s s stripping automated endothelial keratoplasty. (Letter) J Cat Refstripping automated endothelial keratoplasty. (Letter) J Cat Refract Surg 2009;35:1473ract Surg 2009;35:1473

Chen ES, Chen ES, Terry MA,Terry MA, Shamie N, Phillips PM, Friend DJ. Retention of an anterior chamShamie N, Phillips PM, Friend DJ. Retention of an anterior chamber IOL versus IOL exchange in ber IOL versus IOL exchange in endothelial keratoplasty.endothelial keratoplasty.

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Friend DJ. Endothelial keratoplasty: Endothelial cel, Shamie N, Friend DJ. Endothelial keratoplasty: Endothelial cell loss after deep lamellar endothelial l loss after deep lamellar endothelial keratoplasty with retention of an openkeratoplasty with retention of an open--loop anterior chamber intraocular lens. Cornea 2009 (in press)loop anterior chamber intraocular lens. Cornea 2009 (in press)

Phillips PM, Phillips PM, Terry MATerry MA , Kaufman SC, Chen ES. Epithelial downgrowth after Descemet, Kaufman SC, Chen ES. Epithelial downgrowth after Descemet’’s stripping automated endothelial s stripping automated endothelial keratoplasty. J Cat and Refract Surg 2009; 35:193keratoplasty. J Cat and Refract Surg 2009; 35:193--66

Lombardo M, Eng GL, Friend DJ, Serrao S, Lombardo M, Eng GL, Friend DJ, Serrao S, Terry MATerry MA . Long term anterior and posterior topographic analysis of the c. Long term anterior and posterior topographic analysis of the cornea ornea after deep lamellar endothelial keratoplasty. Cornea 2009 (in prafter deep lamellar endothelial keratoplasty. Cornea 2009 (in press)ess)

Chen ES, Shamie N, Chen ES, Shamie N, Terry MATerry MA , Phillips PM, Wilson, DJ. Retention of host embryonic Descemet , Phillips PM, Wilson, DJ. Retention of host embryonic Descemet membrane in endothelial membrane in endothelial keratoplasty. Cornea 2009,28:351keratoplasty. Cornea 2009,28:351--3 3

2 year Visual results: 2 year Visual results: FuchsFuchs ’’ Dystrophy EyesDystrophy Eyes

Visual Results (eyes with no retinal Visual Results (eyes with no retinal disease)disease)

mean BSCVA 20/28mean BSCVA 20/28

99% with vision 20/40 or better99% with vision 20/40 or better

30% with vision 20/20 or better30% with vision 20/20 or better

Major Problems with DSAEK Major Problems with DSAEK surgerysurgery

Dislocation of Donor from Recipient BedDislocation of Donor from Recipient Bed

Primary (iatrogenic) Graft FailurePrimary (iatrogenic) Graft Failure

Pupillary Block Glaucoma immediately postPupillary Block Glaucoma immediately post--op from residual air bubbleop from residual air bubble

Kitsmann AS, Goins KM, Reed C, PadnickKitsmann AS, Goins KM, Reed C, Padnick--Silver L, Macsai MS, Sutphin JE. Eye bank Silver L, Macsai MS, Sutphin JE. Eye bank survey of surgeons using presurvey of surgeons using pre--cut donor tissue for Descemetcut donor tissue for Descemet’’ s stripping endothelial s stripping endothelial keratoplasty. Cornea 2008; 27:634keratoplasty. Cornea 2008; 27:634--639639

Current Complication Rates Current Complication Rates Devers Eye Institute, Portland, Devers Eye Institute, Portland,

Oregon, USAOregon, USA

First 725 cases:First 725 cases: samesame surgical techniquesurgical technique

(1 experienced surgeon and 6 novice)(1 experienced surgeon and 6 novice)

Dislocation rate: 2.6% Dislocation rate: 2.6% (19 out of 725)(19 out of 725)

Primary graft failure rate: 0.1% Primary graft failure rate: 0.1% (1 out of 725)(1 out of 725)

Pupillary Block rate: 0.1% Pupillary Block rate: 0.1% (1 out of 725)(1 out of 725)

Why does our surgical technique have such a low rate of complicaWhy does our surgical technique have such a low rate of complications?tions?

DSAEKDSAEK

WHY DO OUR DSAEK GRAFTS WHY DO OUR DSAEK GRAFTS HAVE SUCH A LOW HAVE SUCH A LOW

DISLOCATION RATE??DISLOCATION RATE??

DLEKDLEK DSEKDSEK

Terry MA, Hoar KL, Wall J, Ousley, PJ. The Histology of DislocatTerry MA, Hoar KL, Wall J, Ousley, PJ. The Histology of Dislocations in Endothelial Keratoplasty (DSEK and DLEK): ions in Endothelial Keratoplasty (DSEK and DLEK): Prevention of dislocation with a laboratoryPrevention of dislocation with a laboratory--based surgical solution in 100 consecutive DSEK cases. Cornea 20based surgical solution in 100 consecutive DSEK cases. Cornea 2006; 25: 92606; 25: 926--932. 932.

Clinical Implications of Lab ResultsClinical Implications of Lab Results

The smoother surface of The smoother surface of DSEKDSEK recipient bed can recipient bed can provide better optics for provide better optics for vision but make dislocation vision but make dislocation rate much higher.rate much higher.The rougher surface of The rougher surface of DLEKDLEK recipient bed allows recipient bed allows attachment of the graft with attachment of the graft with NO air bubble support (ie: NO air bubble support (ie: better adhesion) but may better adhesion) but may limit visual acuity by one line limit visual acuity by one line worse than DSEKworse than DSEK

Do you want to Do you want to ““insureinsure”” your your DSAEK graft will stick?DSAEK graft will stick?

Take a Lesson from the Gecko anatomyTake a Lesson from the Gecko anatomy……

The gecko knows how to stick.The gecko knows how to stick.

Tokay gecko demonstrating how good Tokay gecko demonstrating how good peripheral adherence allows a DSAEK peripheral adherence allows a DSAEK

graft to stick.graft to stick.

“Peripheral scraped stromal fibrils of recipient bed”

“Central smooth recipient bed”

The gecko foot padThe gecko foot pad

Actual studies at Lewis and Clark College in Portland, OR:Actual studies at Lewis and Clark College in Portland, OR:

DSAEK Videos DSAEK Videos ---- (on AAO website; also on website of (on AAO website; also on website of dlekdlek--dsek.comdsek.com) )

Terry MA, et al. Terry MA, et al. Endothelial Keratoplasty: A simplified technique to minimize graft dislocation,iatrogenic graft failure and pupillary block. Ophthalmology 2008; 115: 1179Ophthalmology 2008; 115: 1179 --11861186.

How many of you are scraping How many of you are scraping the recipient bed in DSAEK the recipient bed in DSAEK

surgery?surgery?If not, WHY not?If not, WHY not?

Not difficultNot difficult

Takes very little timeTakes very little time……2 minutes tops2 minutes tops

Area of scraping is invisible at 6 weeksArea of scraping is invisible at 6 weeks

Does not affect visionDoes not affect vision

Will reduce your dislocation rateWill reduce your dislocation rate……if done properly if done properly with with obviousobvious band of white fibrilsband of white fibrils

Has no real downside!Has no real downside!

WhatWhat’’ s Not To Love About Scraping??s Not To Love About Scraping??

Interface Fluid CentrallyInterface Fluid Centrally : Only where the recipient bed edges : Only where the recipient bed edges were scraped are holding the graft onwere scraped are holding the graft on

Different meridians show the areas of attachmentDifferent meridians show the areas of attachmentand also the access region for interface fluidand also the access region for interface fluid

POD 7POD 7

Note that inferior edge of graft is stillstill allowing entrance of interface fluid

1 month s/p DSAEK1 month s/p DSAEK–– VA 20/60 VA 20/60 –– EK graft fully EK graft fully

attachedattached

1 month post1 month post--opop

1 year s/p DSAEK1 year s/p DSAEK-- VA (without glasses!) = 20/25VA (without glasses!) = 20/25-- Graft interface clearGraft interface clear--Endothelial Specular = 2580 cells/mmEndothelial Specular = 2580 cells/mm22

Interface fluid resolves without interventionInterface fluid resolves without intervention

1 day post1 day post--DSAEKDSAEK

UCVA=20/200UCVA=20/200

1 weeks post1 weeks post--DSAEKDSAEK

UCVA=20/200UCVA=20/200

3 weeks post3 weeks post--DSAEKDSAEK

UCVA=20/100UCVA=20/100

2 months post2 months post--DSAEKDSAEK

+1.25 + 1.00 x 25 = 20/40+1.25 + 1.00 x 25 = 20/40

UCVA=20/60UCVA=20/60

Take Home PointsTake Home Points

Scraping can provide a physical adhesion of tissue to Scraping can provide a physical adhesion of tissue to prevent dislocation until the endothelium prevent dislocation until the endothelium ““wakes upwakes up””to solidify adhesionto solidify adhesion

If tissue is attached but interface fluidIf tissue is attached but interface fluid……do NOT redo NOT re--bubblebubble……WAITWAIT……tissue will attach without tissue will attach without intervention.intervention.

Only reOnly re--bubble if detachment is imminent or patient is bubble if detachment is imminent or patient is impatient for visionimpatient for vision

One exception to the ruleOne exception to the rule……

Full Thickness Edge from Eccentric Trephination Full Thickness Edge from Eccentric Trephination Implanted Tissue Shows Implanted Tissue Shows ““Architectural SeparationArchitectural Separation””

(Which will NOT resolve with observation and (Which will NOT resolve with observation and risks epithelial ingrowth of donor epithelium)risks epithelial ingrowth of donor epithelium)

Take Home PointTake Home Point

Use the Use the MicroscopeMicroscope for Trephination of the for Trephination of the Donor Tissue to avoid Eccentric Donor Tissue to avoid Eccentric TrephinationTrephination……even if you are a even if you are a ““prepre--presbyopepresbyope”” you cannot reliably discern a you cannot reliably discern a tolerance of tolerance of ¼¼ mm with the naked eye! (ie: mm with the naked eye! (ie: an 8.5 mm trephination in a 9.0 mm bed)an 8.5 mm trephination in a 9.0 mm bed)

Terry MA, Shamie N. Avoiding eccentric trephination . Terry MA, Shamie N. Avoiding eccentric trephination . Ophthalmology 2009 (Letter); 116:2481Ophthalmology 2009 (Letter); 116:2481 --2.2.

Summary of practical points regarding Summary of practical points regarding prepre--cut tissue for DSAEK:cut tissue for DSAEK:

((Experience with COLD STORAGE OPTISOL only)Experience with COLD STORAGE OPTISOL only)

My personal experience with it is with over 625 cases My personal experience with it is with over 625 cases and it has worked as well as tissue cut on site. and it has worked as well as tissue cut on site. Request tissue that is at least 150 microns in Request tissue that is at least 150 microns in thicknessthickness……thicker is easier, no detriment to vision.thicker is easier, no detriment to vision.Do NOT trust any centering marks made by Eye Do NOT trust any centering marks made by Eye Bank TechnicianBank Technician……made with naked eye and can made with naked eye and can smudge in transit. smudge in transit. Care must be taken in not getting an eccentric Care must be taken in not getting an eccentric punchpunch……use the microscope to punch tissue!use the microscope to punch tissue!Ink Marks on stromal surface KILL endothelial cells! Ink Marks on stromal surface KILL endothelial cells! (and are not necessary)(and are not necessary)

Terry MA: PreTerry MA: Pre --cut tissue for Descemet stripping automated endothelial keratoplcut tissue for Descemet stripping automated endothelial keratopl asty: asty: Complications are from technique, not tissue. Cornea 2008 (EditoComplications are from technique, not tissue. Cornea 2008 (Editorial); 6:627rial); 6:627--99

Key points to avoiding Key points to avoiding complications in DSAEK surgerycomplications in DSAEK surgery

My surgery for DSAEK takes 40 minutes to complete every My surgery for DSAEK takes 40 minutes to complete every stepstep……faster surgery may cause more damage and complicationsfaster surgery may cause more damage and complicationsUse 5 mm scleral incision at limbusUse 5 mm scleral incision at limbusMinimize trauma to donor at EVERY step of the surgeryMinimize trauma to donor at EVERY step of the surgeryDo peripheral scraping of bed Do peripheral scraping of bed –– NOT SUBTLE!NOT SUBTLE!ModulateModulate the size of the pupil for what you need:the size of the pupil for what you need:----dilate pupil (without NSAIDS) for cataract surgerydilate pupil (without NSAIDS) for cataract surgery----constrict pupil (with Miochol and stroking iris) for insertion oconstrict pupil (with Miochol and stroking iris) for insertion of tissuef tissue----dilate pupil (with standard drops) at end of case to prevent blodilate pupil (with standard drops) at end of case to prevent blockckTo remove interface fluid: sweep cornea with elevated IOP of airTo remove interface fluid: sweep cornea with elevated IOP of air--leave IOP at above 40 for 2 to 3 minutes then lower to normal foleave IOP at above 40 for 2 to 3 minutes then lower to normal for 7 r 7 to 8 minutesto 8 minutesClose wound with vicryl sutures: prevent hypotonyClose wound with vicryl sutures: prevent hypotonyRemove ALL air from eye, then replace with only a 5 or 6 mm air Remove ALL air from eye, then replace with only a 5 or 6 mm air bubblebubblePatient SUPINE for 1 hour then as much as possible day of surgerPatient SUPINE for 1 hour then as much as possible day of surgery y –– NO Pressure on Eye!NO Pressure on Eye!

Update on longer termUpdate on longer termEndothelial Survival in DSAEKEndothelial Survival in DSAEK

Devers Eye InstituteDevers Eye Institute

ECD After DSAEK

2974

1954 1974 1916 1823

0

500

1000

1500

2000

2500

3000

3500

Pre-op 6 Months 1 Year 2 Years 3 Years

Time Post-op

EC

D

Endothelial Cell Survival After DSAEK

0.66 0.67 0.65 0.61

00.10.20.30.40.50.60.70.80.9

1

Pre-Op 6 Months 1 Year 2 Years 3 Years

Time Post-op

Per

cent

Ce

ll S

urvi

val

N = 40 eyes N = 40 eyes –– Fuchs + PBKFuchs + PBK(all eyes at all time points)(all eyes at all time points)

p Valuesp ValuesYears 1Years 1 --2: p=0.42: p=0.4Years 2Years 2 --3: p=0.23: p=0.2

Years 1Years 1 --3: p=0.073: p=0.07

Percent Cell LossPercent Cell Loss1 year: 33%1 year: 33%2 year: 35%2 year: 35%3 year: 39%3 year: 39%

What else do we know about DSAEK?What else do we know about DSAEK?Most any case of endo failure can be treated successfully with DMost any case of endo failure can be treated successfully with DSAEKSAEK

EK under PK for old RKEK under an old RK

EK for CHED in a 7 year oldEK over a Phakic Artisan AC IOL for PBK

Anecdotal EvidenceAnecdotal Evidence

What else do we know about DSAEK?What else do we know about DSAEK?(Peer review data(Peer review data……more than just anecdotal)more than just anecdotal)

Use of cohesive viscoelastic (Healon) for DSAEK does NOT cause Use of cohesive viscoelastic (Healon) for DSAEK does NOT cause dislocations or cause the dislocation rate to increase.dislocations or cause the dislocation rate to increase.

DSAEK with Phaco/IOL should be done as a triple, NOT DSAEK with Phaco/IOL should be done as a triple, NOT sequentiallysequentially……no difference in complications rate or endo survivalno difference in complications rate or endo survival

Dislocation rates are still low (<3%) in complex cases such as PDislocation rates are still low (<3%) in complex cases such as PBK BK with filters, tubes, and under failed PK graftswith filters, tubes, and under failed PK grafts……as long as hypotony as long as hypotony is avoidedis avoided

Donor PREDonor PRE--OP Endo counts donOP Endo counts don’’t mattert matter……tissue with a cell count of tissue with a cell count of 2,100 is just as good as a cell count of 3,100.2,100 is just as good as a cell count of 3,100.

Storage time doesnStorage time doesn’’t mattert matter……tissue stored for 1 day is no better tissue stored for 1 day is no better than tissue stored for 7 daysthan tissue stored for 7 days……no difference in complications or ECDno difference in complications or ECD

Donor tissue with RK scars, LASIK, surface scars can all be usedDonor tissue with RK scars, LASIK, surface scars can all be usedsafely for DSAEKsafely for DSAEK……no difference in refractive results, complications no difference in refractive results, complications or ECD. or ECD.

Fellows can do DSAEK during their fellowship just as well as theFellows can do DSAEK during their fellowship just as well as their ir Attendings Attendings ……as long as the same surgical technique is followed.as long as the same surgical technique is followed.

References for Previous SlideReferences for Previous SlideTerry MATerry MA , Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, Friend DJ. , Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, Friend DJ. Endothelial keratoplasty for FuchsEndothelial keratoplasty for Fuchs’’ dystrophy with cataract: Complications and clinical dystrophy with cataract: Complications and clinical results with the new Triple Procedure. Ophthalmology 2009; 116:6results with the new Triple Procedure. Ophthalmology 2009; 116:63131--99

Phillips PM, Phillips PM, Terry MATerry MA , Shamie N, Chen ES, Hoar KL, Dhoot D, Friend DJ. , Shamie N, Chen ES, Hoar KL, Dhoot D, Friend DJ. DescemetDescemet’’s stripping automated endothelial keratoplasty (DSAEK) in eyes ws stripping automated endothelial keratoplasty (DSAEK) in eyes with ith previous trabeculectomy and tube shunt procedures: Intraprevious trabeculectomy and tube shunt procedures: Intra--operative and postoperative and post--operative complications. Cornea 2010 (in press)operative complications. Cornea 2010 (in press)

Staiko MD, Staiko MD, Terry MATerry MA , Shamie N, Friend DJ, Davis, Shamie N, Friend DJ, Davis--Boozer D. Boozer D. Endothelial Endothelial keratoplasty for failed penetrating keratoplasty grafts: Surgicakeratoplasty for failed penetrating keratoplasty grafts: Surgical strategies to minimize l strategies to minimize complications. Ophthalmology 2010 (in review)complications. Ophthalmology 2010 (in review)

Terry MATerry MA , Shamie N, Chen ES, Hoar KL, Phillips PM, Friend DJ. Endothelia, Shamie N, Chen ES, Hoar KL, Phillips PM, Friend DJ. Endothelial l keratoplasty: The influence of prekeratoplasty: The influence of pre--operative donor endothelial densities on operative donor endothelial densities on dislocations, primary graft failure, and one year cell counts. Cdislocations, primary graft failure, and one year cell counts. Cornea 2008; 27:1131ornea 2008; 27:1131--7.7.

Terry MATerry MA , Shamie N, Straiko MD, Friend DJ, Davis, Shamie N, Straiko MD, Friend DJ, Davis--Boozer, D. Endothelial Boozer, D. Endothelial Keratoplasty: The influence of donor storage time on endothelialKeratoplasty: The influence of donor storage time on endothelial survival. survival. Ophthalmology 2010 (in press).Ophthalmology 2010 (in press).

Phillips PM, Phillips PM, Terry MATerry MA , Shamie N, Chen ES, Hoar KL, Stoeger C, Friend DJ, Saad , Shamie N, Chen ES, Hoar KL, Stoeger C, Friend DJ, Saad HA. Descemet's stripping automated endothelial keratoplasty (DSAHA. Descemet's stripping automated endothelial keratoplasty (DSAEK) using corneal EK) using corneal donor tissue not acceptable for use in penetrating keratoplasty donor tissue not acceptable for use in penetrating keratoplasty due to anterior stromal due to anterior stromal scars, pterygia, and previous corneal refractive surgeries. Cornscars, pterygia, and previous corneal refractive surgeries. Cornea 2009;28:871ea 2009;28:871--66

Chen ES, Chen ES, Terry MATerry MA , Shamie N, Hoar KL, Phillips PM, Friend DJ. Endothelial , Shamie N, Hoar KL, Phillips PM, Friend DJ. Endothelial keratoplasty: vision, endothelial survival, and complications inkeratoplasty: vision, endothelial survival, and complications in a comparative case a comparative case series of fellows vs attending surgeons. Am J Ophthalmol 2009;14series of fellows vs attending surgeons. Am J Ophthalmol 2009;148:268:26--31.31.

OTHER DSAEK TECHNIQUESOTHER DSAEK TECHNIQUES

WHAT ABOUT WHAT ABOUT ““ VENTING VENTING INCISIONSINCISIONS”” TO REMOVE TO REMOVE INTERFACE FLUID AND INTERFACE FLUID AND REDUCE DISLOCATION REDUCE DISLOCATION RATES?RATES?

Venting Incisions in DSAEKVenting Incisions in DSAEK

Introduced by Dr Frank Price: reduced his Introduced by Dr Frank Price: reduced his dislocation rate from about 25% to about 6% in dislocation rate from about 25% to about 6% in his initial 165 caseshis initial 165 cases

We have not used them at all and with simple We have not used them at all and with simple sweeping have a dislocation rate of 2.6% in our sweeping have a dislocation rate of 2.6% in our first 725 cases by 6 different surgeonsfirst 725 cases by 6 different surgeons

Venting incisions have been documented to Venting incisions have been documented to cause epithelial downgrowth into the interface cause epithelial downgrowth into the interface and interface infectionsand interface infections

We do NOT recommend using venting incisions We do NOT recommend using venting incisions in routine casesin routine cases

What about Ant Ch What about Ant Ch Maintainers?Maintainers?

Irrigation with a separate metal device in Irrigation with a separate metal device in the eye causes:the eye causes:

----risk of damage to the endothelium risk of damage to the endothelium from the device itself hitting the endofrom the device itself hitting the endo

----risk of expulsing tissue from the eyerisk of expulsing tissue from the eye

----risk of flipping the tissue upside down risk of flipping the tissue upside down without the surgeon knowing itwithout the surgeon knowing it

We do not currently recommend using an We do not currently recommend using an AC maintainer for DSAEK surgeryAC maintainer for DSAEK surgery

What about incision size for What about incision size for insertion of tissue?insertion of tissue?

Also: Does technique of Also: Does technique of insertion of tissue matter?insertion of tissue matter?

Terry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, StoTerry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, Stoeger C. eger C. Endothelial Keratoplasty:The influence of insertion techniques aEndothelial Keratoplasty:The influence of insertion techniques and incision sizend incision sizeon donor endothelial survival. Cornea 2009; 28:24on donor endothelial survival. Cornea 2009; 28:24--31. 31.

Laboratory Study of DSAEK: Analysis of Laboratory Study of DSAEK: Analysis of Insertion and Incision SizeInsertion and Incision Size

5 mm incision v 3 5 mm incision v 3 mm incisionmm incision

Techniques used Techniques used in both inc sizes:in both inc sizes:

ForcepsForceps

Pull throughPull through

Busin GlideBusin Glide

Video:Video:BusinBusin’’s Glide insertion s Glide insertion through 3mm incisionthrough 3mm incision

3mm Forceps

3mm Pull-

Through

5mm Forceps

5mm Pull-

Through

3mm FoldedPull-

Through 6

1 2

5

3mm Busin’sGlide 43

Acute Endothelial Damage from Insertion: Acute Endothelial Damage from Insertion: Incision size matters, method is less importantIncision size matters, method is less important

8.64

18.3917.7420.26

27.9430.4429.92

55.88

0

10

20

30

40

50

60

Average Endo. Damage

Control5mm Forceps5mm Pull-Through5mm Busin's Glide3mm Busin's Glide3mm Forceps3mm Folded Pull-Through3mm Pull-Through

5 mm5 mm

3 mm3 mm

ManeuverManeuver--Induced Endo. DamageInduced Endo. Damage

5mm incision size: 8% +/5mm incision size: 8% +/-- 3% Damage3% Damage

VersusVersus3mm incision size: 26% +/3mm incision size: 26% +/-- 13% Damage13% Damage

7.71

26.41

0

10

20

30

40

50

60

Average Endo. Damage

5mm incision3mm incision

p< .001p< .001

5 mm5 mm

3 mm3 mm

Take Home MessageTake Home Message

REGARDLESS OF TECHNIQUEREGARDLESS OF TECHNIQUE

Because the wound Because the wound compressescompresses the tissue the tissue during insertion:during insertion:

Small incision Small incision –– Big DamageBig Damage

Larger incision Larger incision –– Small DamageSmall Damage

Terry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, StoTerry MA, Saad HA, Shamie N, Chen ES, Friend DJ, Holiman JD, Stoeger C. eger C. Endothelial Keratoplasty:The influence of insertion techniques aEndothelial Keratoplasty:The influence of insertion techniques and incision sizend incision sizeon donor endothelial survival. Cornea 2009; 28:24on donor endothelial survival. Cornea 2009; 28:24--31. 31.

Ideal insertion technique: Tissue injectorIdeal insertion technique: Tissue injector

Entirely avoid wound compressionEntirely avoid wound compression–– Tube injector that Tube injector that ““deliversdelivers”” tissue into AC tissue into AC

Entirely avoid folding tissueEntirely avoid folding tissue–– Tube injector that Tube injector that ““rollsrolls”” tissue without overlaptissue without overlap–– Minimal incision size = 4 mm for an 8.0 mm graft, Minimal incision size = 4 mm for an 8.0 mm graft,

otherwise get graft overlapotherwise get graft overlap

See: Letter to Editor and Response: by Donald Tan and Mark TerrySee: Letter to Editor and Response: by Donald Tan and Mark TerryOphthalmology 2008 February IssueOphthalmology 2008 February Issue

Bill NeusidlBill NeusidlPrototype Tissue Injector for Prototype Tissue Injector for

DSAEKDSAEK

Now available commercially by Fischer Instruments

Dr Terry has NO Financial interest in the NCI device

Neusidl Corneal Injector for DSAEKNeusidl Corneal Injector for DSAEK

Other injectors for DSAEKOther injectors for DSAEK

EndosaverEndosaver: similar platform device as NCI : similar platform device as NCI but overlaps tissue to go through a smaller but overlaps tissue to go through a smaller incision (3.5 mm)incision (3.5 mm)

Tan EndoglideTan Endoglide: similar to a : similar to a ““closed closed systemsystem”” Busin glide, but with a plastic Busin glide, but with a plastic base to prevent iris prolapse. Requires a base to prevent iris prolapse. Requires a ““pull throughpull through”” forceps from opposite forceps from opposite limbus. May be well suited for Asian eyes limbus. May be well suited for Asian eyes and eyes with shallow ACand eyes with shallow AC

What we need to know about injectorsWhat we need to know about injectors

Is the endothelial trauma truly less than Is the endothelial trauma truly less than other techniques going through a other techniques going through a compressive incision? If so, compressive incision? If so, wherewhere is the is the data?!data?!Is the technique using an inserter easier Is the technique using an inserter easier than other techniques?...and therefore than other techniques?...and therefore easier for the novice surgeon?easier for the novice surgeon?Is the cost of the injectors worth the Is the cost of the injectors worth the possible advantages?possible advantages?

We are doing a prospective study to answer these questions and we encourage other EKG members to do prospective studies as well

What About DMEK?What About DMEK?

1.1. Stripping of recipient DescemetsStripping of recipient Descemets’’

2. Implantation of just donor 2. Implantation of just donor DescemetsDescemets’’ with NO donor with NO donor stromastroma

DMEK AdvantagesDMEK Advantages

Represents the pure anatomic Represents the pure anatomic replacement of just the diseased part of replacement of just the diseased part of the corneathe corneaVisual rehabilitation (on average) Visual rehabilitation (on average) appears to be a month or two faster appears to be a month or two faster than DSAEKthan DSAEKA higher proportion of eyes reach the A higher proportion of eyes reach the level of 20/25 or 20/20 than with DSAEKlevel of 20/25 or 20/20 than with DSAEK

Ham and Melles: 2009 EYEHam and Melles: 2009 EYE

DMEKDMEK

Key questions:Key questions:----what is the what is the ““learning curvelearning curve””??----what is the dislocation rate in the hands of novice v what is the dislocation rate in the hands of novice v experienced surgeons?experienced surgeons?----what is the PGF rate in novice v experienced what is the PGF rate in novice v experienced surgeons?surgeons?----what is the tissue wastage rate and endothelial cell what is the tissue wastage rate and endothelial cell damage in DMEK?damage in DMEK?----can we ever have can we ever have ““prepre--cutcut”” DMEK tissue and is DMEK tissue and is there a way to determine the health of the tissue there a way to determine the health of the tissue before it is sent to the surgeon?before it is sent to the surgeon?----Are the results of DMEK (v DSAEK) worth it?Are the results of DMEK (v DSAEK) worth it?

Current Challenges with DMEK:Current Challenges with DMEK:Melles Initial SeriesMelles Initial Series

N = 50N = 50Dislocation rate = 25%Dislocation rate = 25%Primary graft failure rate = 20%Primary graft failure rate = 20%Tissue positioned Tissue positioned ““Upside downUpside down”” in several in several casescasesEndothelial cell damage reported on only Endothelial cell damage reported on only handful of caseshandful of cases

Ham and Melles: 2009 EYEHam and Melles: 2009 EYE

DMEK Results: M Price et al 2009DMEK Results: M Price et al 2009

N = 60 (51 Fuchs)N = 60 (51 Fuchs)

Vision at 3 months: 26% were Vision at 3 months: 26% were >>20/2020/20

63% were 63% were >>20/2520/25

Refractive: mean hyperopic shift of +.49 DRefractive: mean hyperopic shift of +.49 D

Endothelial cell loss: 30%=/Endothelial cell loss: 30%=/--20 at 3 months20 at 3 months

Iatrogenic Primary Graft Failure: 8%Iatrogenic Primary Graft Failure: 8%

Interface fluid reInterface fluid re--bubbling rate: 48% oncebubbling rate: 48% once

8% twice8% twice

Upside down grafts: 2 (4%)Upside down grafts: 2 (4%)

Tissue wastage (8%): 72 donors for 60 casesTissue wastage (8%): 72 donors for 60 cases

6 grafts converted to DSAEK6 grafts converted to DSAEK

6 grafts totally destroyed (8%)6 grafts totally destroyed (8%)

Price MO, Giebel AW, Fairchild KM, Price FW. Ophthalmology 2009; 116:2361-8

Practical considerations with Practical considerations with DMEKDMEK

““You break it, You buy it!You break it, You buy it!”” ……monetary cost to surgeon/ASC of monetary cost to surgeon/ASC of destroying tissue at time of DMEK surgery is huge (>U.S.$2800 pedestroying tissue at time of DMEK surgery is huge (>U.S.$2800 per r tissue) and so tissue) and so ““PrePre--cut DMEK Tissue by Eye Bankcut DMEK Tissue by Eye Bank”” is essential to is essential to general adaptation of DMEK.general adaptation of DMEK.

Donor Supply is Limited: DSAEK has already hampered the donor Donor Supply is Limited: DSAEK has already hampered the donor supply. The published supply. The published ““learning curvelearning curve”” of DMEK (8% to 20% donor of DMEK (8% to 20% donor failure) may overwhelm our donor supply creating severe shortagefailure) may overwhelm our donor supply creating severe shortages of s of tissue for other transplant procedures.tissue for other transplant procedures.

How about How about ““DMAEKDMAEK””: Price has shown the complex donor prep : Price has shown the complex donor prep technique of DMAEK using combination technique of DMAEK using combination ““big bubblebig bubble”” and and ““scubascuba””techniques with high tissue wastage ratestechniques with high tissue wastage rates…….can eye banks do this for .can eye banks do this for us and at what cost of tissue wastage?us and at what cost of tissue wastage?

DMAEK: A hybrid technique of DMAEK: A hybrid technique of DMEK and DSAEKDMEK and DSAEK

DescemetsDescemets’’ membrane with a peripheral membrane with a peripheral ring (or crescent) of posterior stromaring (or crescent) of posterior stroma

Hope is for better peripheral attachment of Hope is for better peripheral attachment of the stroma edges (like DSAEK) but better the stroma edges (like DSAEK) but better vision with the central area (like DMEK)vision with the central area (like DMEK)

Tissue preparation is complex, involving Tissue preparation is complex, involving techniques of Big Bubble and DSAEKtechniques of Big Bubble and DSAEK

No data on outcomes currently published, No data on outcomes currently published, but early work by Busin is encouragingbut early work by Busin is encouraging

PrePre--Cut DMAEK Preparation and Cut DMAEK Preparation and Evaluation by Eye Banks:Evaluation by Eye Banks:

Is this our future?Is this our future?

DMAEK tissue can be stored in Optisol in standard c ontainersDMAEK tissue can be stored in Optisol in standard c ontainersand slit lamp exam and central specular ECD can be obtainedand slit lamp exam and central specular ECD can be obtained ……But what will be the tissue wastage rate and damage to theBut what will be the tissue wastage rate and damage to theendothelium from technician processing?endothelium from technician processing?

The evolution of EK The evolution of EK

WeWe’’ve come a long way from 9.0 mm ve come a long way from 9.0 mm incision PLK/DLEK with manual incision PLK/DLEK with manual dissections and average vision of 20/50dissections and average vision of 20/50

DSAEK is well established with minimal DSAEK is well established with minimal tissue wastage, low complications and tissue wastage, low complications and happy patients.happy patients.

Can DMEK/DMAEK give us the same high Can DMEK/DMAEK give us the same high benefit to low complications ratio as benefit to low complications ratio as DSAEK? Only then will general DSAEK? Only then will general acceptance of DMEK become realityacceptance of DMEK become reality……

SummarySummaryThe current technique that we use with DSAEK The current technique that we use with DSAEK surgery yields a very low dislocation rate in the hands surgery yields a very low dislocation rate in the hands of novice and experienced surgeons alike.of novice and experienced surgeons alike.Central Endothelial cell density (with our technique) Central Endothelial cell density (with our technique) appears to be relatively stable over the first 3 years appears to be relatively stable over the first 3 years after DSAEK, but longer term data is neededafter DSAEK, but longer term data is neededDSAEK surgery should be done with 5mm or larger DSAEK surgery should be done with 5mm or larger wounds to prevent endothelial damage wounds to prevent endothelial damage –– Regardless Regardless of what technique of insertion is used.of what technique of insertion is used.Newer insertion devices (such as injectors) which Newer insertion devices (such as injectors) which avoid wound compression should help reduce avoid wound compression should help reduce endothelial damage and improve long term cell endothelial damage and improve long term cell counts, but data is needed.counts, but data is needed.DMEK and DMAEK surgery can offer marginally DMEK and DMAEK surgery can offer marginally faster and better visual results, but the failure rate (8faster and better visual results, but the failure rate (8--20%), complication rate (2520%), complication rate (25--63%) and tissue wastage 63%) and tissue wastage rate (>8%) are unacceptable at this time. rate (>8%) are unacceptable at this time. StrictStrict adherence to an established DSAEK technique adherence to an established DSAEK technique will yield a near 0% rate of PGF and a dislocation will yield a near 0% rate of PGF and a dislocation rate of less than 2%.rate of less than 2%.

CharlieCharlieNicholasNicholas

Thank YouThank You

CindyCindy