About corneal grafts

1. Corneal Transplantation
Dr R S Walpitagamage

2. Evolution of Corneal Grafting Surgery
• Corneal transplantation refers to surgical
replacement of a full-thickness host
cornea(penetrating keratoplasty [PK]) or lamellar
portion of the host cornea with that of a donor
cornea.
• Today, the keratoplasty is considered as the most
frequently performed and the most successful
organ transplantation technique worldwide.
• The success of this procedure has not been
an overnight event.

3. • 1813 K Himly- Suggested replacing opaque cornea in
one animal with clear cornea from another animal.
• 1824 F Reisinger -Suggested replacing opaque human
cornea with clear animal cornea- Coined the term
• 1906 Edward Konrad Zirm-Reported first successful
penetrating keratoplasty in a human
• 1910-1950 VP Filatov -Father of keratoplasty
Performed systematic study of keratoplasty
Suggested using cadaver corneas as donor tissues
Devised numerous instruments

4. • 1974 B McCarey and H Kaufman -Developed
Corneal Storage Media
• 1985 Archila EA -DALK with air assisted dissection
• 1998 Melles GR -Deep anterior lamellar
keratoplasty
• 2006 Price and Gorovoy- Descemet’s stripping
endothelial keratoplasty (DSEK) and Descemet’s
stripping automated endothelial keratoplasty
(DSAEK)
• 2006 Melles GR Descemet’s membrane
endothelial keratoplasty (DMEK)

5. • Ongoing innovations in lamellar transplantation have
produced a virtual alphabet soup of nomenclature to
describe the various approaches.

6. Penetrating Keratoplasty(PKP)

7. Indications for PKP
1. Optical-
The keratoplasty is performed with the main purpose of
improving the visual acuity. This is the most common indication
of penetrating keratoplasty and comprises more than 90 percent
of the total penetrating keratoplasties performed in majority of
the countries.
• Bullous keratopathy
• Keratoconus
• Corneal dystrophy
• Corneal inflammatory diseases —
interstitial keratitis, HSV
• Corneal traumatic scars
• Failed grafts

8. 2. Tectonic- The prime purpose of tectonic/reconstructive
keratoplasty is to restore the altered corneal structure. Although
improved visual acuity remains a relevant consideration,
restoration or at least preservation of ocular anatomy and
physiology are the principal indications for tectonic corneal
grafts
• Corneal perforation
• Peripheral corneal thinning

9. 3. Therapeutic- Therapeutic keratoplasty is mainly
indicated in cases of infectious keratitis to eliminate the
infectious load in eyes with keratitis unresponsive to specific
antimicrobial therapy
• Infective keratitis

10. How do You Grade Corneal Graft Prognosis According to Disease
Categories?
Brightbill’s Classification

13. • Evaluate patient’s ocular condition and
manage poor prognostic factors prior to PKP
• Big 4 poor prognostic factors
– • Ocular inflammation
– • Glaucoma
– • Corneal vascularization
– • Ocular surface abnormalities

14. Keratoplasty and Eye Banking
Contraindications for Cornea Donation
1. Systemic diseases
• Death from unknown cause
• CNS diseases of unknown cause
• Creutzfeldt–Jakob disease, CMV encephalitis, slow virus
diseases
• Infections:
• Congenital rubella, rabies, hepatitis, AIDS, Syphilis
• Septicemia
• Malignancies
• Leukemias, lymphomas, disseminated cancer

15. 2. Ocular diseases
• Intraocular surgery
• History of glaucoma and iritis
• Intraocular tumors
3. Age
• < 1 year old
• Corneas are difficult to handle
• Small diameter; friable
• Very steep cornea (average K = 50D)
• > 75 years
• Low endothelial cell count
4. Duration of death > 6 hours(Can go up to 24hrs AAO)
5. Severe hemodilution: Affects accuracy of serological testing

16. How is the Donor Corneal Button
Stored?
Storage Media
1. Short term (days)
•Moist chamber:
• Humidity 100%
• Temp 4°C
• Storage duration: 48 hours
• McCarey-Kaufman medium:
• Standard tissue culture medium (TC199, 5% dextran,
antibiotics)
• Temp 4°C
• Storage duration: 2–4 days

17. 2. Intermediate term (weeks)
• Dexsol/Optisol/Ksol/Procell:
• Standard tissue culture medium (TC 199)
plus chondroitin sulfate,
HCO3 buffer, amino acid, gentamicin
• Temp 4°C
• Storage duration: 1–2 weeks
• Organ culture:
• Advantages: Decreased rejection rate? (Culture kills antigen
presenting cells)
• Disadvantages: Increased infection rate?
• Temp 37°C
• Storage duration: 4 weeks

18. 3. Long term (months)
• Cryopreservation:
• Liquid nitrogen
• Temp -196°C
• Storage duration: 1 year
• Disadvantages: Expensive and unpredictable results; usually
not suitable for optical grafts

19. National Eye Bank Sri Lanka

22. Steps in PKP
1. Preoperative preparation
• GA Preferble
• Maumenee/Wire/Screw speculum
• Flieringa ring if necessary
(indications: Post vitrectomy, aphakia,trauma, children)
Measure the recipient graft size with a caliper
“How do you check the corneoscleral disc?”
• Container (name, date of harvest, etc.)
• Media (clarity and color)
• Corneal button (clarity, thickness, irregularity,surface damage)
Grade A+ or A depending on the indication
Endothelial cell count >2000/mm3

23. 2. Donor button
• Check corneoscleral disc
• Harvest donor cornea
button with Weck trephine on
Troutman punch:
• Approach from posterior
endothelial side
• Use trephine size 0.25–0.5
mm larger than recipient bed
• Keep button moist with
viscoelastic
• Because donor button is punched from
posterior endothelial surface
• Tighter wound seal for graft
• Increases convexity of button (less
peripheral anterior synechiae postop)
• More endothelial cells with larger button
“Why is the donor button made larger than
the recipient bed?”

24. 3. Recipient bed
• 3-point fixation (two from bridle suture, one
with forceps)
• Weck trephine imprint to check size and
centration
• Other types of trephine:
Baron Hessburg trephine and Hanna trephine
(suction mechanism)
• Set trephine to 0.4 mm depth

25. • Enter into AC with blade
• Complete incision with corneal
scissors
• Fill AC with viscoelastic

26. 4. Fixation of graft
• Place donor button on recipient bed
• Four cardinal sutures with 10/0 nylon (at 12 o’clock first,
followed by 6,3 and then 9)
• 16 interrupted sutures
Advantages of interrupted sutures:
• Easier for beginners
• Better for inflamed eyes and
eyes with vascularization
• Better for pediatric
patients/active infections
• Suture manipulation can be
done

27. SUTURING TECHNIQUES IN PKP
 Single Interrupted Suturing Technique
 Single Continuous Suturing Technique
 Double Continuous Suturing Technique
 Combined Continuous and Interrupted Suturing (CCIS)
Technique
Continuous suture:
• Faster
• Better astigmatism control
• Not for cases where selective suture removal may be needed
(e.g.infections)
• A single continuous suture is technically more difficult than interrupted sutures,
because one irregular bite can impair the integrity of the closure and cannot be
removed without removing the entire suture. The four cardinal sutures are placed
in the regular manner followed by a 24 bite continuous suture with 10-0 nylon
with a 95 percent depth.

28. Single Continuous Suturing Technique
– There are 3 types of single continuous suturing
techniques namely, torque, anti torque and no torque
.
– The torque pattern rotates the corneal graft
counterclockwise by 0.7 +/- 0.1 mm at the wound or
11 degrees;
– the anti torque pattern rotates the corneal graft
clockwise by 0.7 +/- 0.1 mm at the wound or 11
degrees;
– the no torque pattern, the bites of which form an
isosceles triangle, produces no rotational effect.

29. 5. End of operation
• Check water tightness
• Check astigmatism with keratometer
• Intra cameral Moxifloxacine
• Subconjunctival steroids/antibiotics
• BCL

30. Complication of PKP
1. Intra Operative
2. Early Post Operative
3. Late postoperative

31. 1. Intra Operative Complications

32. 2. Early postoperative:
• Hypotony (wound leak)
• Raised IOP
— retained viscoelastic
— pupil block
• Persistent epithelial defect
• Endophthalmitis
• Recurrence of primary disease
3. Late postoperative:
• Rejection
• Infective keratitis
• Recurrence of disease
• Astigmatism
• Persistent iritis/iris atrophy/dilated pupil (Urrets–Zavalia syndrome)
• Late endothelial failure
• Glaucoma
Cataract,RD

33. What are the Causes of Graft Failure?
1. Early failure (< 72 hours):
• Primary donor cornea failure
• Unrecognised ocular disease
• Low endothelial cell count
• Storage problems
• Surgical and postoperative trauma:
• Handing
• Trephination
• Intraoperative damage
• Recurrence of disease process (e.g. infective keratitis)
• Others:
• Glaucoma
• Infective keratitis
2. Late failure (> 72 hours):
• Rejection (30% of late graft failures)
• Glaucoma
• Persistent epithelial defect
• Infective keratitis
• Recurrence of disease process
• Late endothelial failure

34. Post Op Management PKP
• Topical antibiotics
• Topical steroids
• IOP control
• Regular follow-up and detect and treat
complications
• Suture management

36. Deep Anterior Lamellar Keratoplasty
(DALK)

37. Introduction to DALK
• Deep anterior lamellar keratoplasty: In this
type of keratoplasty the host dissection is
done up to the level of the Descemet’s
membrane and a full thickness graft which is
devoid of endothelium is sutured with 10-0
monofilamemt to the host.

38. Indications for DALK
1.Optical
• Reis-Bücklers dystrophy
• Salzmann’s nodular dystrophy
• Keratoconus
• Granular dystrophy
• Band shaped keratopathy
• Spheroidal degeneration
• Trachomatous keratopathy
• Superficial scars secondary to
infections and trauma
• Superficial corneal opacification
caused by keratorefractive
surgeries
• Hurler’s syndrome

39. 2.Tectonic
• Dermoid
• Terrien’s marginal degeneration
• Mooren’s ulcer
• Corneal melting
• Pellucid marginal degeneration
• Keratoglobus
• Acne keratitis with thinning
3.Therapeutic
• Recurrent pterygium
• Conjunctival intraepithelial neoplasia
• Epithelioma

40. Contraindications for DLK

41. DALK vs PKP
Advantages
• Extraocular procedure
• Less potential for intraocular complications
• Less astigmatism
• Less chances of graft rejection
• Donor quality criteria less stringent
• Does not preclude a future penetrating keratoplasty.
Disadvantages
• Technically difficult
• Interface scarring
• Epithelial defects
• Less than optimal visual results.

42. Steps in DALK
• Main requirements other than in PKP
– Corneal topography
– Corneal pachymetry- detect the thickness of cornea and to get a idea
of the depth of initial trephination
– Anterior segment OCT- detect the depth of corneal scar, important in
deciding the technique of stromal dissection
– Donor corneal stroma and epithelium should be healthy and not
depend on endothelial cell count because it is removed.
– Need a backup cornea ready if convection to PKP is required

43. Steps in DALK
• Prepare donor cornea, keep in optisol
• Surgery usually under GA
• Patient corneal markings
• Trephination of desired thickness with Barren suction trephine, 2/3
thickness
• Dissection of superficial lamella
• Anwar’s big bubble
• Parasentesis, insert air bubble in to AC, confirm big bubble
• Brave slash
• Replace the air with viscoelastic
• Cut the deep stromal tissue
• Washout the viscoelastic thoroughly
• Remove the donor corneal endothelium
• Keep it on the recipient bed
• Suture the graft with 16 interrupted 10 0 nylon
• BCL

44. • If there is deep cornel scar, big bubble
technique cannot be performed
• After superficial lamella is removed , manual
dissection of stroma up to the Descemets
membrane should be done
• Donor cornea and recipient size is similar

45. Complications of DALK

47. SUTURE REMOVAL
• Interrupted sutures should be removed as soon
as the vessels bridge the host-graft junction or at
6 months postoperatively in a non-vascularized
cornea.
• Suture removal may be undertaken earlier for any
suture related problems such as loose sutures,
broken sutures and suture abscesses.
• Selective suture removal may be done for the
control of postkeratoplasty astigmatism
beginning from 1st month onwards.

48. Endothelial Keratoplasty

49. Types of EK
• Descemet’s Stripping Endothelial Keratoplasty
(DSEK/DSAEK)
• Descemet’s membrane endothelial keratoplasty (DMEK)

50. Descemet’s stripping endothelial
keratoplasty (DSEK),
• In Descemet’s stripping endothelial keratoplasty (DSEK), the
patient’s Descemet membrane is peeled off, using specially
designed strippers and replaced with a partial thickness graft:
a transplanted disc of Posterior Stroma, Descemet and
Endothelium (20-30 % of the inner donor cornea).
• Both donor and host cornea are manually dissected.
• Differently, in Descemet’s stripping automated endothelial
keratoplasty (DSAEK) the donor dissection is carried out using
a mechanical microkeratome. DSAEK is described as the
procedure of choice for corneal endothelial failure in many
centers

51. Indications for DSEK
• Fuchs’ endothelial dystrophy
• Posterior polymorphous membrane dystrophy
• Congenital hereditary endothelial dystrophy
• Bullous keratopathy
• Iridocorneal endothelial (ICE) syndrome

52. Contraindications for DSEK

53. Advantages of EK over PKP
• Rapid visual rehabilitation
• No suture-related problems
• No induced Astigmatism
• Tectonic stability
• Normal corneal sensitivity post op
• No ocular surface problems
• Fewer rejections
• Small incision with less risk of SCH

54. Surgical Technique EK

55. Surgical Technique DSEK
Donor Graft Preparation
Manual Dissection Microkeratome assisted(DSAEK)
• Convenient
• Thinner graft
• Costly
• Not available in Sri Lanka
• Cost effective
• Learning curve

56. Manual Dissection

57. PKP VS DSAEK VS DMEK(Woo at al.)
PKP DSAEK DMEK
Graft survival rate 73.5% 96.2% 98.7%
Graft rejection rate 14.1% 5% 1.7%
Suture related
complications
High Minimal Minimal
Tectonic stability Poor High Hgh

58. Complications of EK

60. Follow-up

61. What is DWEK?

63. References

64. Thank You!