Download MBBS (Bachelor of Medicine and Bachelor of Surgery) 3rd Year (Third Year) Ophthal Keratoplasty Topic Handwritten Notes
KERATOPLASTY
Keratoplasty, also known as corneal grafting or corneal transplantation, is an
operation in which the patient's diseased cornea is replaced by the healthy clear
cornea.
TYPES OF KERATOPLASTY
A. Autokeratoplasty
1. Rotational keratoplasty :
Here patient's own cornea is trephined and rotated to the periphery to transfer the
pupillary area having a small corneal opacity .
2. Contralateral keratoplasty:
Cornea of the two eyes are exchanged with each other. It is indicated when cornea of
one eye of the patient is opaque and the other eye is blind due to posterior segment
disease with clear cornea.
B. Allografting or Allo-keratoplasty
Patient's diseased cornea is replaced by the donor's healthy cornea.
It can be of following types:
1. Penetrating Keratoplasty (PK) (full-thickness grafting)
2. Lamellar keratoplasty (partial-thickness grafting) which may be:
? Deep anterior lamellar keratoplasty (DALK) : It is performed when endothelium and
Descemet's membrane are normal
e.g. keratoconus.
? Descemet's stripping endothelial keratoplasty(DSEK ) : It is performed when
only endothelium is defective e.g. after the surgical trauma during
phacoemulsification.
3. Small patch graft (for small defects), which may be full thickness or partial
thickness.
INDICATIONS
1. Optical, to improve vision
eg: corneal opacity, bullous keratopathy, corneal dystrophies, advanced keratoconus.
2. Therapeutic, to replace inflamed cornea not responding to conventional therapy,
corneal ulcer not responding to treatment, perforated corneal ulcer, irregular
irrepairable corneal lacerations with tissue loss, anterior staphyloma.
3. Tectonic graft, to restore integrity of eyeball.
e.g. after corneal perforation and in marked corneal thinning.
4. Cosmetic, to improve the appearance.
DONOR TISSUE
The donor eye are harvested from cadavers within 6 hours of death , somtimes upto
12 hours in countries with colder climates .
Eyes are taken by trained doctors.
It should be stored under sterile conditions.
Biomicroscopic examination of the whole globe.
Processing the tissue for media storage.
The donor corneal tissue is graded into excellent, very good, good, fair, and poor
depending upon the condition of corneal epithelium, stroma, Descemet's membrane
and endothelium.
GRADING OF DONOR CORNEA ON SLIT-LAMP BIOMICROSCOPIC EXAMINATION
Parameter
Grade I
Grade II
Grade III
Grade IV
Grade V
(Excellent)
(Very good)
(Good)
(Fair)
(Poor)
Epithelial defects None
Slight epithelial Obvious
and haze
haze or defects
moderate
epithelial defects
Corneal stromal
Crystal clear
Clear
Slight cloudiness
Moderate
Marked
clarity
cloudiness
cloudiness
Arcus senilis
None
Slight
Moderate (<2.5 Heavy (>2.5 mm Very heavy (>4
mm)
? 4 mm)
mm)
Descemet's
No folds
Few shal ow
Numerous shal ow Numerous deep
Marked deep
membrane
folds
folds
folds
folds
Endothelium
No defect
No defect
Few vacuolated
Moderate
Marked guttate
cells
guttate
METHODS OF CORNEAL PRESERVATION
1. Short-term storage (up to 48 hours) :
The whole globe is preserved at 4?C in a moist chamber.
2. Intermediate storage:
Donor cornea can be stored in McCarey-Kaufman (MK) medium and various
chondroitin sulfate enriched media such as optisol medium (up to 2 weeks)
By organ culture method using eagle's medium (up to 35 days )
3. Long-term storage (up to 1 year) :
By cryopreservation at ?70?C in liquid nitrogen or glycerol. But due to loss of
transparency of cornea, it is used only for tectonic purpose.
SURGICAL TECHNIQUE OF PENETRATING
KERATOPLASTY
1. Excision of donor corneal button
The donor corneal button should be cut 0.25 mm larger than the recipient, taking care
not to damage the endothelium. Donor cornea is placed in a tephlon block and the
button is cut with the help of a trephine from the endothelial side.
trephine
cornea
Tephlon block
2. Excision of recipient corneal button
With the help of a corneal trephine (7.5 mm to 8 mm in size) a partial thickness incision
is made in the host cornea. Then, anterior chamber is entered with the help of a razor
blade knife and excision is completed using corneoscleral scissors.
Standard corneal trephine
Removal of diseased corneal button from recipient
Entering through razor blade
Cutting using corneoscleral
Diseased part of cornea
knife
scissors
removed
3. Placing donor graft and suturing
After injecting the viscoelastic material to fill the anterior chamber, the donor
cornea is placed in the host bed and sutured.
There are 3 types of suture;16 interrupted sutures or continuous suture or
combination of interrupted and continuous suture of 10 ? 0 nylon.
Placing donor graft on recipient
Continuous
suture
Interrupted
suture
Combined
FOLLOW UP
VISUAL RECOVER : could be immediate or in few months due to initial graft oedema
and astigmatism.
Follow up :
Weekly or fortnight for the 1st 3 months
Monthly for 6 months.
Every 2 months for 1year
Yearly after that.
COMPLICATIONS
1. Early complications :
2. Late complications (after 3 weeks)
Wound leak
Graft rejection
Flat /shallow anterior chamber
Secondary glaucoma
Iris prolapse
Loose sutures
Uvitits
Astigmatism
Graft Infection
3. Very late complications(after 1 year)
Secondary glaucoma
Graft rejection
Inflammatory sterile suture infilterate
Wound dehiscence from primary trauma
Primary graft failure.
Recurrence of primary disease
GRAFT REJECTION
It refers to the immunological response of the host to the donor corneal tissue.
It can occur as early as 2 weeks and upto several years after grafting.
Rejection could be epithelial, stromal ,or endothelial. Or a combination of all 3.
Graft rejection is classically believed to be a delayed type of hypersensitivity
response.
Risk factors include younger age of recipient, previous graft failure, corneal
vascularization, larger graft size, donor epithelium and massive blood transfusion.
Clinical presentations:
Symptoms :
Diminution of vision
Photophobia
Mild pain
Redness
Epithelial rejection characterized by an elevated epithelial rejection line which
stains with fluorescein.
Subepithelial infiltrates known as Kayes dots
They are white punctate epithelial opacities representing epithelial cells at
various stages of degeneration.
Due to epithelial immune response to area of angulation.
Stromal rejection is characterized by sudden onset of full thickness stromal
haze in a previously clear graft.
Kayes dots
Corneal haze
Endothelial rejection may present as:
? Khodadaust line demarcating healthy and damaged endothelium. The rejection line consist of
monomnuclear white cellsthat damage endothilial cells.
Khodadaust line
? Diffuse endothelial rejection with lot of Keratic precipitates.
Rejected corneal graft
NATIONAL EYE DONATION FORTNIGHT FROM 25TH AUGUST TO 8TH SEPTEMBER
2018
This post was last modified on 11 August 2021