penetrating keratoplasty

2. INTRODUCTION
 Corneal transplantation or grafting
comprises of replacing full thickness
abnormal host corneal tissue with a
full thickness healthy donor corneal
tissue.

3. TYPES OF KERATOPLASTY
 FULL THICKNESS
OR
PENETRATING
KERATOPLASTY
 PARTIAL THICKNESS
OR
LAMELLAR KERATOPLASTY
• ROTATIONAL KERATOPLASTY
( AUTOGRAFT)

5. INDICATIONS OF KERATOPLASTY
Optical
• Most common indication
• To improve the vision
Tectonic
• To preserve the corneal integrity
Therapeutic
• Remove the infected cornea unresponsive to Rx
Cosmetic
• To improve the appearance of eye
• Very rare indication

6. INDICATIONS
OPTICAL-
• Keratoconus
• Corneal degenerations
• Corneal dystrophies
• Primary corneal
endotheliopathies.
• Corneal ectasias & thinning.
• Congenital corneal opacity
• Acquired corneal scars
• Non infectious ulcerative
keratitis.

7. THERAPEUTIC
• NON HEALING INFECTIOUS KERATITIS
• INFECTIOUS KERATITIS WITH PERFORATION
• POST CHEMICAL INJURY

8. TECTONIC
 RECONSTRUCTION OF OCULAR SURFACE
• To strengthen the cornea in case of :
 CORNEAL MELTS
 CORNEAL THINNING
Eg. Anterior Staphyloma
Descematocele

9. PREOPERATIVE EVALUATION
OCULAR EVALUATION-
• Ocular history
• Visual acuity
• Detailed examination:
 Underlying pathology
 IOP
 Vascularization
 Tear film status
 Presence of cataract
 Need for IOL exchange
 B-scan

10. PREOPERATIVE PREPARATION
• ANTI INFECTIVE AGENTS: Pre-op antibiotics( broad-spectrum)
- 5% povidine iodine solution .
 IOP control: Pre-op 15-20% i.v. mannitol over 30-60min. before
surgery.(Dose- 0.25-2g/kg)
- Honan’s balloon compression given at 30 mm Hg
or digital compression for extra-ocular akinesia.
 Anesthesia : Peribulbar anesthesia with or without lid block
- General anaesthesia for paediatric cases, apprehensive
patients,
and in case of corneal perforation.

11. SURGICAL PROCEDURE
• TREPHINATION-
- DONOR TREPHINATION
- HOST TREPHINATION
• GRAFT SIZING
• HIGHLIGHTS OF TRIPLE PROCEDURE.

12. DONOR TREPHINATION
 Trephination of the donor button should preferably be
performed from endothelial side (around 7-7.5mm),
according to underlying pathology.
( usually 1.5mm from limbus from each side is left ).
 Then the donor button is kept on Teflon Block, with
endothelium side up.

14. GRAFT
 A good optical performance requires a larger graft, whereas
a low rate of immunologic graft reactions tend to be seen with
smaller grafts.
 IDEAL CORNEAL BUTTON- Round
- Perpendicular edges
- Endothelium damage should be less (3%)
Normal oversize (diam).- Adult- 0.25-0.50 mm
- Paediatrics/Aphakic/PAS+ : 0.75-1.0 mm

15. HOST TREPHINATION
 A hand-held disposable trephine is held perpendicular to the cornea &
progressively rotated, allowing its sharp edges to penetrate gently to
pre-Descemet’s membrane or until the anterior chamber is entered.
 Fleiringa ring(Scleral fixation ring) is only necessary in pediatric
patients, aphakic and myopic patients (to give scleral support).
 The higher the intraocular pressure (iatrogenic!), the more
divergent are the cut angles to be expected .

16.  Combination of donor trephined from
endothelial side (convergent cut angle) and
mechanically trephined recipient (divergent
cut angle) results in a triangular-shaped
tissue deficit at the level of Descemet’s
membrane which has to be compensated
by suture tension resulting in central corneal
flattening.

17. Hessburg-
Barron
suction
trephine
A - Recipient
trephine with
cross-hairs for
centration;
B- Donor
trephination is
performed
from
endothelial
side.

18. Anterior chamber may be entered using the trephine
o Leads to a very perpendicular cut and easy removal of host cornea
o Chances of iris and lens injury are high
Most of the surgeons prefer to make a controlled entry into enterior
chamber with a knife
• The chamber is entered with a sharp blade (B.P.No.11/15° lancetip knife)
inserted vertically avoiding the iris
• The cut is extended to 3 to 4 mm to allow the insertion of the corneal scissors
• The corneal button is removed with curved corneal scissors.

20.  Comprises of Penetrating Keratoplasty + extraction of cataract
(ECCE) + IOL implantation.
• Cataract should be removed regardless of the stage as later it will
progress & can cause damage to corneal endothelium.
• Vitreous can be removed with vannas or wide bore cannula.
(host –graft junction should be free of vitreous)
• IOL insertion.

21. • An intact vitreous face should always be preserved.
• If vitreous is present in front of iris then it can be removed with
cellulose sponges and Vannas scissors.
• When available, application of mechanized vitrectomy technique
is preferred.

22. • IOL can be inserted if there is good potential for useful vision
• If PC is not intact; iris fixated or scleral fixated IOL can be
implanted.

23. • Viscoelastic material is placed over the iris and anterior
lens capsule to keep the iris and lens back and avoid their
coming in contact with endothelium.
• Then the donor button is placed over the host site , by
grasping from anterior one-third of donor edge.

24.  Suturing is the most crucial step in keratoplasty
 First four sutures known as the cardial sutures are
most crucial in orienting the graft evenly in the bed.
 The first suture is placed at 12 o’clock position ,
followed by a suture at 6 o’clock.
 Two sutures are then placed at 3 and 9 o’clock positions,
respectively.

26. • Subsequent suturing consists of placement of 12 or
more interrupted sutures, 4 or 8 interrupted and a
running suture, or a double running suture with
removal of initial 4 sutures.
• 10-0 NYLON suture should be used.
• Each bite is approximately 0.75 mm from donor
edge and 0.75mm from edge into host tissue.

27. Interrupted sutures
Advantageous-
 In children(elasticity of cornea)
 Vascularised corneas
 Cornea with uneven thickness
 Cornea with localised areas of inflammation
 Less difficulty in placement or removal
Disadvantages
 More inflammation
 More vascularization

29. MEDIUM FOR CORNEAL
PRESERVATION
• Short term storage
• Intermediate storage
• Long term storage

30. SHORT TERM STORAGE
 Method:
• Moist chamber method:
when globe is preserved at 4
degree Celsius with saline
humidification for upto 48 hrs.
 Endothelial viability depends on:
- -Enucleation within 6 hours of
death.
- Cool environment maintainence
until enucleation .
- Maintaining 4 degree Celsius

31. INTERMEDIATE TERM STORAGE
 McCAREY- KAUFMAN medium
 Optisol medium
 Chondroitin sulfate enriched medium
 Dexol medium.

32. McCAREY –KAUFMAN MEDIUM
 ORIGINAL -
• TC199
• 5% Dextran
• Bicarbonate buffer
• Penicillin & streptomycin
(100unit/ml) later substituted
by gentamycin in concn. of
50-200μg/mi
 MODIFIED-
• Added phenol red as a pH
indicator
• Osmolarity -290mOsm/kg
• pH is 7.4
• known as modified MK medium
• Cornea can be stored at 4
degree celsius upto 4 days

33. LONG TERM STORAGE
 ORGAN CULTURE -
- Donor cornea can be stored
upto 35 days.
- No remarkable loss of
endothelial cells .
 CRYOPRESERVATION
• CAPELLA & KAUFMAN
• Corneoscleral rim—in a series
of soln of dimethyl sulfoxide
(DMSO) upto 7.5%.---placed for
10mins— upto - 80 degree celsius
& subsequently stored at - 160
degree celsius indefinitely.

34. COMPLICATIONS
 INTRAOPERATIVE-
- Increased vitreous pressure
- Scleral perforation ( d/t scleral rings)
- Trephination related - small donor tissue/ eccentric donor tissue
cut.
- Damaged donor button
- Inversion of graft ( Flat donor)
- Endothelial damage
- Intraoperative bleeding- from iris vessels/limbal vessels.
- Expulsive choroidal haemorrhage ( d/t Open Sky technique)
- Posterior capsular tear ( in Triple procedure).

35.  EARLY POSTOPERATIVE -
- Shallow AC due to wound leak
- Persistent Epithelium Defect (cause ulceration/melting of
cornea)
- Immune- related infiltrates/infection
- Suture related -loose/broken sutures/exposed knot
- Descemet membrane detachment
- Infection (M/C- H.simplex infection)
- Endophthalmitis
- Graft failure ( primary/ secondary).

36.  LATE POSTOPERATIVE-
- Glaucoma ( pre-existing glaucoma/ disruption of TM/ PAS/
Aphakic/ Pseudophakic/ steroid-induced/
epithelial ingrowth/ fibrous downgrowth).
- Secondary graft failure d/t- recurrence, infection or iritis.
- Urrets Zavali Syndrome (iris atrophy, fixed mydriatic pupil,
secondary glaucoma).
- Astigmatism.

37. SURGICAL OUTCOMES
 GROUP 1
• Excellent prognosis >90%
- Keratoconus
-Central/paracentral corneal
scars
-Stromal dystrophy
 GROUP 2
• Very good prognosis
 Expected success rate of 80-
90 %
- Aphakic/pseudophakic
- Corneal odema & bullous
keratopathy
- Inactive herpetic keratitis
- Macular stromal dystrophy

38.  GROUP 3 -
• Fair prognosis-
Success Rate 50 to 80%
-Active microbial /herpetic
keratitis .
-Mild chemical injury
-Moderate keratoconjunctivitis
sicca.
 GROUP 4 -
• Poor prognosis- 50%
- Severe chemical injury
- Radiation injury
- Steven Johnson syndrome
- Multiple failed grafts.

39. PRIMARY ( EARLY ) SECONDARY ( LATE )
 Poor donor storage
 Mishandling donor tissue
during surgery
 Increased enucleation time
after death
 Age of donor > 70 yrs
 Less endothelium in donor tissue
 H.simplex infection
 Graft rejection
 Glaucoma
 Persistent Epithelial Defect
 Infective keratitis
 Recurrence of disease
 Late endothelial failure

40. CORNEAL GRAFT REJECTION
 Four clinical forms-
• EPITHELIAL REJECTION:
Immune response— donor epithelium - lymphocytes
cause elevated linear epithelial ridge—
centripetally ( Stained by dye)
- Occurs in around 10% of patients.
- Usually seen in the post-op period
(1-13 months).
 Treatment- Topical steroids.

41. STROMAL / SUBEPITHELIAL
REJECTION
 They may present as small discrete sub-
epithelial infiltrates ( Krachmer dots).
• Look like adenoviral infiltrates.
 Also characterised by- Hyperemia
- Diffuse corneal haze.

42. ENDOTHELIAL REJECTION
 The most common type (8%-37%)
• Loss of significant number of endothelial
cells leads to graft rejection
• Inflammatory cells seen in AC .
• Endothelium lost—stroma thickens—
epithelium odematous
• Patients have--- photophobia ,
redness ,irritation , halos around light.
Treatment- Agressive topical steroids with
i.v. pulsed steroids.

43. TREATMENT
 Frequent steroid instillation
• Dexamethasone 0.1%
• Prednisolone0.1%
• Periocular injection of
triamcinolone acetonide for
severe rejection or non
compliant patient.
 PREVENTION -
• Early attention to loosening
sutures.
• Use of cyclosporine ,
Tacrolimus , mycophenolate.