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UPDATE ON CORNEAL TRANSPLANTATION
Frank S. Hwang M.D.
Assistant Professor
Cornea, External Disease and Refractive Surgery
OBJECTIVES
• Types of corneal transplantation
• Donor Selection of corneal tissue
• Penetrating keratoplasty
• Anterior Lamellar Keratoplasty
• Endothelial Keratoplasty
CORNEAL TRANSPLANTATION
• Cornea: immunologic privilege , first
successfully transplanted solid tissue (1905)
• In the USA, ~ 40,000 corneal transplantations vs.
~ 12,000 other solid-organ transplantations.
• Penetrating keratoplasty (PK or PKP):
full-thickness, gold standard
• Lamellar keratoplasty: partial-thickness
• Anterior lamellar keratoplasty (ALK):
• Superficial ALK (SALK)
• Hemi-automated lamellar keratoplasty (HALK)
• Deep ALK (DALK)
• Posterior lamellar keratoplasty or endothelial
keratoplasty (EK)
• Descemet stripping and endothelial keratoplasty
(DSEK)
• Descemet’s membrane endothelial keratoplasty
(DMEK)
53% 5% 35%
DONOR CORNEA CONSIDERATION
• Donor corneas: stored in Optisol-GS
• Exclusion criteria: unknown cause of death,
systemic infections, CNS infection, leukemia,
ocular hx (infection/inflammation, malignancy,
prior refractive sx), Hep B/C, HIV, etc
• Certain considerations: endothelial cell density
(ECD) >2000/mm2, death-to-preservation time,
donor age, tissue storage time
PENETRATING KERATOPLASTY
• Indications: any stromal or endothelial corneal
pathology i.e. keratoconus, failed graft, post-cataract
edema, corneal dystrophies/degenerations
• trephination of donor tissue,
0.25-0.50 mm larger
• trephination & excision of host
cornea
• suture (interrupted, continuous,
or combined)
PK COMPLICATIONS
• Intraoperative: lens/iris damage, poor graft/donor
centration, iris/vitreous incarceration, damage to
donor endothelium, hemorrhage
• Postoperative: wound leak, flat chamber, glaucoma,
endophthalmitis, persistent epi defect, recurrent
primary disease, epithelial ingrowth, primary graft
failure, infected sutures, graft rejection,
regular/irregular astigmatism (most common)
THE CORNEA DONOR STUDY (CDS)
• Designed as a prospective, double-masked, controlled trial to
determine:
• The role of donor age in long-term corneal graft survival
• The effect of ABO blood type matching on corneal graft
survival
• The effect of donor age on long-term donor endothelial cell
density
• Patient enrollment 2000-2002: 40 to 80 years old, and in ‘‘moderate-
risk’’ corneal transplant categories, mostly endothelial diseases,
Fuchs’ dystrophy 675 (61%), Pseudophakic/aphakic corneal
edema 369 (34%)
• Donor Baseline characteristics: 1101 donor corneas, age 10-75,
ECD 2300 to 3300/mm2
• Preoperative management, surgical technique (PKP), and
postoperative care, including prescription of medications, were
provided according to each investigator’s customary routine
THE CDS RESULTS – FIVE YEAR
Graft failure, defined as a re-graft or a cloudy cornea
that was sufficiently opaque as to compromise vision
for a minimum of 3 consecutive months.
ABO incompatibility does NOT increase the risk of
transplant failure
CDS 5-year result
Donor age
(yr)
12-65 66-75
Graft survival 86% 86%
Median cell
loss
69% 75% *
Median ECD 824
cells/mm2
654 cells/mm2
*
THE CDS RESULTS – TEN YEAR
• When analyzed as a continuous variable, higher donor age was
associated with lower graft success beyond first 5 years (P<0.001)
• The 10-year success rate was relatively constant for donors aged 34 to
71 years (75%). The success rate was higher for 80 donors aged 12 to
33 years (96%) and lower for 130 donors aged 72 to 75 years (62%)
CDS 10- year result
Donor age
(yr)
12-65 66-75
Graft survival 77% 71%
Median cell
loss
76% 79% *
Median ECD 628
cells/mm2
550 cells/mm2
*
Anterior Lamellar Keratoplasty (ALK)
• Indicated in corneal conditions where the endothelium is still functional, such as
ectatic disorders, superficial scars, and various dystrophies.
• Superficial ALK (SALK): pathology limited to anterior third
• Hemi-automated lamellar keratoplasty (HALK): 50% thickness
• Deep ALK (DALK): deeper stroma
• Dissections were achieved freehand or automated by a microkeratome or
femtosecond laser
• Stroma-to-stroma interfaces, as in
SALK, can degrade visual acuity over time
• Stroma-to-DM interfaces, as in DALK, provide higher quality vision
• HALK: donor cornea prepared with microkeratome, recipient cornea prepared freehand
ANTERIOR LAMELLAR KERATOPLASTY (ALK)
• Advantanges: Extraocular procedure resulting in a low risk of
many complications, including transplant rejection and failure.
Less topical steroid use than PK or EK. Early suture removal
safe.
• Disadvantages: Usually more technically demanding than PK.
Fails unless host endothelium is healthy. Regular and irregular
astigmatism the same as for PK.
• Most common intraocular complication is Descemet’s
performation and conversion to PK.
12-mo DALK (28) PK (28)
BCVA logMAR 0.39 (20/50) 0.31 (20/40)
Endothelial loss 12.9% 27.7% *
Spherical equivalent -2.02 -2.30
Endothelial rejection 0 3
(Micro)perforation of the Descemet’s membrane occurred in 32% of the
DALK eyes, and 18% of the patients required conversion to PK
• Indicated in endothelial dysfunctions such as pseudophakic/phakic
bullous keratopathy, Fuch’s dystrophy, Posterior Polymorphous
dystrophy, and Iridocorneal Endothelial syndrome
• DSEK/DSAEK: DM & endo with a thin layer of posterior stroma
• DMEK/DMAEK: only DM & endo, no stroma; 748 DMEK performed in
2012
• “A” stands for “automated”: using keratome to dissect
• Eye banks now provide pre-cut tissue for DSAEK and DMEK
Endothelial Keratoplasty (EK)
• Descemet stripping and endothelial keratoplasty
(DSEK)
• Descemet stripping automated endothelial
keratoplasty (DSAEK)
• Descemet’s membrane endothelial keratoplasty
(DMEK)
• Descemet’s membrane automated endothelial
keratoplasty (DMAEK)
ENDOTHELIAL KERATOPLASTY (EK)
DSAE
K
DME
K
ENDOTHELIAL KERATOPLASTY (EK)
• Advantages: No induced astigmatism resulting in
early visual recovery and better visual outcomes.
Fewer suture and wound related complications. Lower
risk of other complications.
• Disadvantages: Suboptimum visual result unless
corneal stroma is relatively free of opacity; reduced
vision due to interface opacity or transplant folds in
some cases
• Complications: Detachment in 5–30% of cases. Can
be re-attached by re-injecting air. Possible pupil
block following air tamponade
DSAEK VS DMEK • Potential advantages of DMEK: faster visual rehabilitation, better visual
outcomes, and lower rejection rates.
COMPARISON OF PK, ALK & EK PK
Can be used for any
indication
Potentially best optical
result
Relatively undemanding
technique
ALK
Minimal requirement for
donor material
Extraocular procedure
Low risk of rejection
Less topical steroid use
Early suture removal safe
EK
Better globe integrity
Fewer wound cx
Faster recovery
No suture-related issues
Less post-op astigmatism
Higher rejection rate
Many complications
Astigmatism common
Graft-host interface limit VA
Astigmatism similar to PK
Dependent on endo quality
Technically more difficulty
Graft-host interface limit VA
Rejection rate similar to PK
Dependent on epi/stroma
quality
Long term survival unknown
FUTURE DIRECTIONS
• Descemetorhexis Without Endothelial Keratoplasty (DWEK)
• Rho Kinase Inhibitors
REFERENCES:
• Arenas E, Esquenazi S, Anwar M, Terry M. Lamellar corneal transplantation. Surv Ophthalmol. 2012 Nov;57(6):510-29. doi: 10.1016/j.survophthal.2012.01.009. Review.
• Tan DT, Dart JK, Holland EJ, Kinoshita S. Corneal transplantation. Lancet. 2012 May 5;379(9827):1749-61. doi: 10.1016/S0140-6736(12)60437-1. Review.
• Price, Marianne and Price, Francis. Endothelial keratoplasty – A Review. Clinical and Experimental Ophthalmology 2010, 38:128-140
• Waring G, Lynn M, McDonnell P, Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study 10 Years After Surgery Arch Ophthalmol. 1994;112(10):1298-1308.
• Anshu A, Price MO, Tan DT, Price FW Jr. Endothelial keratoplasty: a revolution in evolution. Surv Ophthalmol. 2012 May-Jun;57(3):236-52. doi:
10.1016/j.survophthal.2011.10.005. Review.
• Jean Y Chuo, Sonia N Yeung and Guillermo Rocha, Modern corneal and refractive procedures, Expert Rev. Ophthalmol. 6(2), 247–266 (2011)
• Writing Committee for the Cornea Donor Study Research Group, Lass JH, Benetz BA, Gal RL, Kollman C, Raghinaru D, Dontchev M, Mannis MJ, Holland EJ, Chow C, McCoy K,
Price FW Jr, Sugar A, Verdier DD, Beck RW. Donor age and factors related to endothelial cell loss 10 years after penetrating keratoplasty: Specular Microscopy Ancillary
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