LAMELLAR KERATOPLASTY

Outline of Seminar
 SURGICAL ANATOMY OF CORNEA(STROMA)
WHAT IS LAMELLAR KERATOPLASTY ?
NEED FOR LK ?
ANTERIOR LK PROCEDURES
POSTERIOR LK PROCEDURES

ANATOMY OF CORNEA_HISTOLOGIC STRUCTURE
Layer Thickness
EPTHELIUM 50-90 µ
BOWMAN’s MEMBRANE 8-14 µ
STROMA 478-500 µ
DUA’s LAYER(DL)/ pre-
descemet’s layer(PDL)
10-15 µ
DESCEMET’s
MEMBRANE(DM)
3-4 µ : childhood
10-12 µ : adult life
ENDOTHELIUM 4-6 µ
Ophthalmology 2014; 121: e24-25

SURGICAL ANATOMY
OF STROMA
Thickness : 478-500µ
Collagen fibrils (lamellae)
The deeper in the stroma the surgeon is, the easier it is to dissect between the lamellae
Easier to do LK, the deeper we go
Collagen
fibrils in
Anterior 1/3 Posterior 2/3
Orientation to
corneal
surface
Oblique Parallel
Arrangement Branching present
Lamella
interweave
Less
Loosely placed

WHAT IS LAMELLAR KERATOPLASTY ?
Replacement of diseased cornel tissue while retaining normal tissue
1830 : Von Walther first suggested Lamellar keratoplasty
1880 : Von Hippel and 1930 : Filatov : further improved on it
Paufique revived techniques of Lamellar keratoplasty in 1948
.

WHY LAMELLAR KERATOPLASTY ?
Penetrating keratoplasty is the most commonly performed corneal surgery and was the only method
of endothelial replacement for past 80 year
Disadvantages of PENETRATING KERATOPLASTY :
Unpredictable post operative astigmatism
Long post operative visual recovery
Loose suture can induce epithelial breakdown, ulceration, infection, vascularisation (all of these can
result in graft rejection or loss of graft)
Dramatic shift in corneal topography can occur following suture removal resulting in irregular
astigmatism
The corneal wound following PK is relatively fragile, with poor tectonic strength, making eye
susceptible to minor trauma even several years following surgery
Increased risk of all complications such as vitreous loss, retinal detachment, choroidals, expulsive
choroidal hemorrhage etc related to open sky procedures.

POSTERIOR (PLK)ANTERIOR (ALK)
Descemet’s stripping
endothelial keratoplasty (DSEK)/
Descemet’s stripping automated
endothelial keratoplasty
(DSAEK)
Descemet’s membrane
endothelial keratoplasty (DMEK)
Deep anterior lamellar
keratoplasty( DALK)
Automated lamellar therapeutic
keratoplasty( ALTK)
Superficial anterior lamellar
keratoplasty (SALK)
LAMELLAR
KERATOPLASTY
Surv Ophthalmol 2012; 57: 510-29
Pre-descemet’s endothelial
keratoplasty (PDEK)

LAMELLAR KERATOPLASTY_ADVANTAGES
 Avoids open sky procedure
Shorter, less complicated post op course
Insignificant endothelial cell loss
Less risk of Allograft rejection
Faster visual recovery
Stronger globe against trauma
Sub optical grade corneas can be used

ANTERIOR LAMELLAR KERATOPLASTY (ALK)
Removal of diseased corneal tissue, leaving behind healthy stroma, endothelium & DM
1. Superficial Anterior Lamellar Keratoplasty (SALK)
 anterior 30 to 50% of cornea
 stroma-to-stroma interfaces can degrade visual acuity over time
Ophthalmologe 2002; 99: 946-8.
2. Deep Anterior Lamellar Keratoplasty (DALK)
corneal stroma is completely excised up to DM
stroma-to-DM interface provides higher quality vision
J Refract Surg 2003; 19: 52-7.

DEEP ANTERIOR LAMELLAR KERATOPLASTY (DALK)
DESCEMETIC DALK : total stromal replacement down to DM
PRE- DESCEMETIC DALK : failed attempts to attain DM baring (some posterior stroma not
removed)

DALK : Type 1 v/s Type 2 BB
Type 1 BB Type 2 BB
b/w stroma and DL Plane of cleavage DL and DM
well circumscribed thin walled
8.5 mm Diameter 10.5 mm
white Edges clear
Center to periphery Periphery to center
Dua et. al. Clinical Ophthalmology 2015:9 1155–1157

DALK : Type 1 v/s Type 2 BB
Type 1 BB where the air separates Dua’s layer (DL) from the deep stroma creating a large
central bubble of around 8 to 9 mm in diameter.
This is the preferred type of bubble in DALK, as DL confers additional strength to the recipient
cornea. After excising the recipient stroma, the complex of host DL and DM and endothelial cells
is retained.
Type 2 BB wherein the DM is separated from the posterior surface of DL by the air bubble.
This BB is larger with a thinner wall and more susceptible to tears and bursting.
Dua et. al. Clinical Ophthalmology 2015:9 1155–1157

MILESTONES IN DALK
Anwar (1974) Deep Anterior Lamellar Dissection in the potential space between stroma and
DM
Archila (1980) : used intrastromal air injection for dissection
Sugita (1994/1997) : hydrodelamination and spatula delamination
Tsubota (1998) : divide and conquer technique in 2 layers
Melles (1999) : Limbal approach to deep lamellar dissection in closed fashion

DALK : Indications
Optical
1. Keratoconus
2. Stromal corneal
dystrophies
3. BSK, Sphenoidal
degeneration
4. Trachomatous
keratopathy
5. Superficial scars
secondary to healed
keratitis
Tectonic
1. Descemetocele
2. Terrien’s marginal
degeneration
3. Pellucid marginal
degeneration
4. Mooren’s ulcer
Therapeutical
1. Pterygium
2. Dermoid

DALK : Surgical techniques
A. Preparation of recipient's bed
1. Dissection with Melle’s Technique
2. Dissection with Anwar’s Big Bubble Technique
3. Dissection with Double Big Bubble Technique
B. Preparation of donor tissue

Melle’s technique :
Optical visualisation of dissection depth
Depth of lamellar dissection relative to corneal thickness may be visualised by creating an
optical interface at posterior corneal surface by completely filling AC with air
The interface between air & endothelium can be used as a reference plane in 3 ways.
1. Mirror effect
2. Indentation effect
3. Folding effect

Dissection
1. Manual Deep Stromal dissection through scleral tunnel incision
- Conjunctiva opened at 12’O clock limbus
- Superficial scleral incision (length 5mm, 1 mm outside limbus) made
- Lamellar dissection done in superior cornea only
- Tip of blade tilted down, advanced till it reaches posterior surface
- Deep stromal pocket 360° upto limbus created with help of blade
- Viscoelastic injected into stromal pocket

Dissection
2. Viscodissection
- At 12’O clock, in midperipheral cornea, 30-G needle attached to syringe filled with viscoelastic
inserted into stroma
- When tip reached posterior corneal surface, viscoelastic injected into cornea to separate DM
from overlying stroma.

Dissection
Final common step
• Trephine is turned down until stromal pocket entered - viscoelastic is seen to escape
• Remaining unincised stromal attachments cut with scissors
• Bed irrigated thoroughly - remove viscoelastic & debris

ANWAR’s Big bubble technique
1. Partial trephination, Groove deepened
2. 27/30 G needle attached to air filled syringe is bent by 30-40° (5 mm form tip, bevel facing
down)
3. Needle inserted deep into stroma at 80% depth through trephination groove & advanced to
paracentral region
4. Inject air when needle tip is well buried into stroma for 3-4 mm. End point - border of bubble
coincides with trephine incision.
J Cataract Refract Surg 2002; 28:398–403

Keratectomy anterior to bubble
View of bubble after
keratectomy
Formation of big bubble
Limbal paracentesis away from peripheral
edge of big bubble

Collapse of air bubblePuncture of bubble
Anwar keratoplasty/ barraquer wire spatula is
introduced into pre-DM & lifted to tent up
residual stroma
Residual stroma is excised along trephine cut

Double Big bubble technique
1. Partial trephination
2. Paracentesis just posterior to limbus at 11’O clock
3. First bubble - Air injected in AC (3-4 mm in diameter)
4. Second bubble - 27/30 G needle attached to air filled syringe bent by 90°, with bevel facing
down, used to inject air in corneal stroma
End point - sudden peripheral movement of air bubble in AC.
Confirmation - rotate eyeball in all directions. DM in centre bulges in AC, small bubbles in AC
will be confined in periphery

Double Big bubble technique
Debulk anterior 2/3 stroma
Create shelved opening
into space between DM
& posterior stroma
Entry identified by
dynamic movement of
small bubbles in AC from
periphery to centre
Discontinue
incision. Inject
HPMC to keep
DM away
Thin layer of posterior
stromal tissue
divided into 4
quadrants with
vannas scissors
DM completely
barred

Preparation of recepient’s bed
 Posterior surface gently touched with cellulose sponge to remove endothelium
 Trypan blue 0.06% applied to stain DM
 Dry wick sponge used to detach DM from peripheral inner edge by gently scrapping
 Held with non toothed tying forceps and peeled off in one piece

Complications of LKP : Intraoperative
Perforation of DM - presence of aqueous on lamellar bed (keep it dry)
1. During trephination - close wound. Post pone surgery for 3 months
2. During lamellar dissection - depends on size of perforation
a. Small - Reform anterior chamber with air. Apply mattress suture
b. Medium - Auto-intralamellar patch.
 Lamellar dissection commenced 180° away in different plane.
 Lamellar flap, created, is everted on site of perforation
 Suture applied from edge of everted flap to host bed.
c. Large - penetrating keratoplasty

Complications of LKP : Postoperative
1. Delayed epithelization
2. Stromal melting
3. Microbial keratitis
4. Epithelial proliferation & ingrowth
5. Astigmatism
6. Double Anterior Chamber
o due to inadvertent perforation of host
o drain aqueous from AC & supernumerary chamber
o reform AC with air

COMPLICATIONS : DALK v/s PK
• 5-year postoperative endothelial cell loss - 22.3% vs 50.1%
• Median predicted graft survival was 49.0 years vs 17.3
• Eyes with atleast 1 complications were 19% vs 59% in PK
• Rejection - 12% vs 22%
Ophthalmology 2012; 119: 249-55
•

MICROTOME ASSISTED ALK
Automated surgical techniques that have been developed for refractive corneal surgery can
now be used for keratoplasty surgery
This includes
1. Automated lamellar therapeutic keratoplasty surgical unit (ALTK) (Moria, Anthony, France)
2. Use of a laser in situ keratomileusis (LASIK) type microkeratome mounted on an artificial
chamber
Moria ALTK instrument combining a microkeratome with varying head thicknesses with an
artificial chamber maintainer for lamellar dissection of the donor

MICROTOME ASSISTED ALK
To perform automated lamellar dissection of both the donor and recipient cornea.
The resultant bed is smooth
Provides greater precision and reproducibility in lamellar corneal dissection.

FEMTOSECOND ASSISTED ALK
Femtosecond surgical lasers used for LASIK surgery today employ near-infrared pulses to cut
tissue with minimal collateral damage.
Currently there are four FDA-approved femtosecond lasers that are available and include the
 IntraLase (IntraLase FS; Irvine, CA,USA)
 Femtec (20/10 Perfect Vision, Heidelberg,Germany)
 Femto LDV (Ziemer Ophthalmic systems, AG, Jena, Germany)
 VisuMax (Carl Zeiss Meditec AG, Jena, Germany).

It has been programmed to create anterior lamellar interfaces and
peripheral trephinations of desired depth and diameters.
The energy settings used for lamellar interface and peripheral
trephination cuts are similar to those used in LASIK
Peripheral trephination requires higher energy level than lamellar
incisions and for DALK the energy levels are further increased and the
spot size set closer together to overcome the laser scatter caused by
the additional thickness of stroma.
The donor cornea is also trephined in a similar fashion.

Scanning electron microscopy comparing corneal dissection between the Femtec femtosecond
laser and a mechanical Hansatome microkeratome

Clinical and Experimental Ophthalmology 2010; 38: 118–127

POSTERIOR LAMELLAR KERATOPLASTY
GERRIT MELLES : PLK in 1998
Replacement of diseased posterior corneal layers and the endothelium with donor
corneal tissue, the host anterior corneal stroma is retained
Dysfunctional host endothelium Healthy donor endothelium
Regression of epithelial and stromal edema
in Endothelial decompensation
(Bullous keratopathy, Fuch’s endothelial dystrophy)

POSTERIOR LAMELLAR KERATOPLASTY/
ENDOTHELIAL KERATOPLASTY
PRICE and PRICE : DSEK
GOROVOY : DSAEK
MELLES : DMEK
DSEK/
DSAEK
DMEK

Goals of endothelial transplant surgery
 a smooth surface topography without significant change in astigmatism from preoperative to
postoperative status.
 a healthy donor endothelium that resolves all edema.
 a tectonically stable globe, safe from injury and infection.
 an optically pure cornea.
 a surgical technique that is quickly and easily acquired.

DSAEK/DSEK : Indications
Endothelial dusfunction, with no scarring of the anterior corneal layers
Fuchs endothelial dystrophy
Pseudophakic bullous keratopathy
Aphakic bullous keratopathy
Failed graft
Iridocorneal endothelial syndrome
Argon laser iridotomy induced bullous keratopathy
Descemet membrane breaks due to birth trauma after forceps delivery
Congenital hereditary endothelial dystrophy

DSAEK/DSEK : Surgical steps
A scleral or corneal tunnel incision is made to enter the anterior
chamber and paracentesis ports are created
A 7 to 8 mm mark is made using a trephine on the cornea. This helps
in guiding the descemetorrhexis
Descemetorhexis is performed using a reverse Sinskey hook. This
process can be assisted by improving the visibility by using air, trypan
blue or chandelier illumination system
In case phacoemulsification is to be done as a combined surgery, first
the phacoemulsification is completed and then descemetorhexis is
carried out.
Having scored the Descemet's membrane, the diseased Descemet's
membrane can be peeled off using a forceps or a Descemet's stripper
or using an automated irrigation and aspiration cannula.

Insertion of the donor lenticule:
The taco fold : folding the donor lenticule into a 60:40 taco fold
followed by insertion using a noncoapting forceps
Endothelial cell loss : 34.3%
Kelmann
McPherson

Insertion of the donor lenticule:
Busin glide : a specialized instrument that can load and carry the
lenticule with the endothelial side up and helps in inserting the
lenticule using the pull through technique using a specialized forceps.
Endothelial cell loss : 25%
Sheet glide :
Tan’s endoglide :

Anterior chamber tamponade : to secure the donor into position to
allow adequate apposition with the stroma of the host.
air fill only for a period of seven to ten minutes followed by partial air
removal, in order to prevent any undue increase in intraocular
pressure and related optic nerve damage.

DSEK : Post op week 1VA cf at ½ m
PR accurate

DSAEK/DSEK : Complications
Complications inherent to DSAEK surgery :
Increased handling of the posterior stromal donor tissue (dissection, folding and insertion into
the anterior chamber) enhances the likelihood of increased endothelial cell loss.
Postoperative dislocation of the posterior lamellar disc can occur in upto 30 percent with
necessitation of further intervention which might enhance endothelial damage.
Air bubble tamponade in the anterior chamber to facilitate donor lenticule adhesion can result
in postoperative pupillary block and secondary angle closure glaucoma.
Primary graft failure.

DSAEK/DSEK : Complications
Major reported complications of DSAEK surgery :
Posterior graft dislocations (mean, 14%; range, 0%–82%)
Endothelial graft rejection (mean, 10%; range, 0%–45%)
Primary graft failure (mean, 5%; range, 0%–29%)
Iatrogenic glaucoma (mean, 3%; range, 0%–15%).
Average endothelial cell loss
At 6 months: 37 percent
At 12 months: 42 percent.
Intraoperative complication :
Inversion of donor lenticule

DSEK versus DSAEK
DSEK
•Manual dissection has increased risk of donor tissue
perforation
•Manual dissection does not yield a smooth anterior
surface of the donor posterior lamella
•Adhesion of the posterior lamellar lenticule is better due
to the greater tissue thickness and irregular anterior
surface
•Anterior stromal stab incisions are not required to
provide for interface fluid regress
•Donor lenticule dislocation is lesser
•More time consuming
•Visual recovery is slower
DSAEK
•Microtome dissection reduces risk of donor tissue
perforation
•Microtome dissection yields a posterior donor lamella of
superior quality
•Adhesion of the posterior lamellar lenticule is not as easy
as in DSEK as the posterior stromal lenticule is thinner
and has a smooth anterior surface
•Anterior stromal stab incisions are required to provide
for interface fluid regress to enhance donor button
adhesion
•Donor lenticule dislocation is more
•Less time consuming

DSAEK versus PK: Advantages
DSAEK
•The 5 mm scleral entry incision in DSAEK
results in a structurally stronger globe
•The scleral wound may be left sutureless or
closed with minimal suturing
•Ocular surface topography is not altered and
retains the corneal innervation
•Rapid refractive rehabilitation
•Repeat surgery is less invasive and can be
easily performed
PK
•No new skill involved
•Endothelial damage risks are low

DSAEK versus PK: Disadvantages
DSAEK
•Requires learning new surgical skill
•Significant manipulation of the posterior
stromal lenticule (dissection, folding and
implantation into the anterior chamber)
results in greater endothelial damage than PK
•Postoperative donor dislocation may occur in
up to 30 percent of the cases
•Air bubble induced pupillary block may occur.
PK
Intraoperative risks associated with open
globe surgery.
•Full thickness wound in penetrating
keratoplasty results in a weaker wound
•16 interrupted sutures of PK and the
associated suture related problems remain
•Ocular surface topography is altered
•Considerable time also taken for re-
innervation of the full thickness graft in PK
•Visual rehabilitation is slow
•Repeat surgery is more invasive

DMEK
 Donor DM and endothelial cells are transplanted and no stroma tissue is transferred
Thus recipient cornea retains its optical quality with no interface and majority of these patients
attain 20/20 vision
The physiological properties of DM to roll on itself makes procedure more demanding.
DMEK

DMEK : Indications
Fuchs dystrophy
 Pseudophakic bullous keratopathy
 Posterior polymorphous dystrophy
 Congenital hereditary endothelial dystrophy
 Iridocorneal endothelial syndrome
 Endothelial failure from trauma, previous surgery, angle closure
 Failed PK (if acceptable refractive result was achieved)
(International Ophthalmology Clinics 2010 : Volume 50, Number 3, 137–147)

DMEK : Advantages
Minimal surgical trauma to recipient eye
Near normal restoration of anatomy of grafted cornea
Faster and near complete visual rehabilitation-elimination of interface haze –pts may achieve
20/20 vision
Better fit the current requirements of modern anterior segment surgery as transplantation can
be performed through clear corneal tunnel incision widely used in phacoemulsification surgery,
which induces minimal astigmatism
Less strong host graft apposition at interface allows easier removal of failed/ rejected donor
lenticule
(Cornea Volume 25, Number 8, September 2006)

DMEK : Advantages over DSEK
DMEK has better visual outcomes in terms of contrast visual acuity and aberrations than DSEK.
36%–79% of DMEK patients achieve logMAR 0.8 or better, as compared to 23%–47% of DSEK
patients.
The general consensus is that DM-to-stroma interface in DMEK is better than stroma-to-stroma
interface in DSEK for optical clarity.
Furthermore, the thin DM graft has almost no hyperopic shift postoperative.
Singh NP, Said DG, Dua HS. Lamellar keratoplasty techniques. Indian J Ophthalmol 2018;66:1239-50

Cornea. 2017 Nov;36(11):1437-1443

DMEK : Donor graft preparation
Direct peel method
 donor corneoscleral rim immersed in BSS or corneal storage solution
Using forceps the membrane gently peeled off, either completely or partially (between 30% and
70% of the way across)
After detachment, DM curls up with the endothelium on outside
 Staining with Vision Blue is essential for adequate membrane visualization during handling and
subsequent implantation

 Big bubble technique
Stroma dissected, either manually or with microkeratome
 Donor corneoscleral rim turned endothelial side up and air injected to create a big bubble that
separates DM from the posterior stroma
After creation of a big bubble 5 to 7mm in diameter, corneoscleral rim is mounted stromal side
up on an artificial anterior chamber and the stromal tissue over the big bubble is excised with
scissors

DMEK : Graft insertion and positioning
 Recipient eye is prepared by marking the epithelium with a trephine to indicate the planned
graft diameter, scoring DM just inside this mark, and removing DM from within the scored area
Inserting a scroll of donor Descemet membrane and endothelium
into recipient eye using intraocular lens insertor

DMEK : Complications
Endothelial cell loss : at 5 years : 39%
 : 53% - DSEK
: 70% - PK
J Cataract Refract Surg 2014;40:1116-21
Primary graft failure : 6% - 8%
Ophthalmology 2009;116:2361-8
Graft detachment : greater in DMEK than in DSEK

DMEK : Limitations
Steep learning curve
Terry MA. Endothelial keratoplasty: Why aren’t we all doing Descemet membrane endothelial keratoplasty?
Cornea 2012;31:469-71
Difficulties in handling the very thin and friable DM
Price MO, Price FW Jr. Descemet’s membrane endothelial keratoplasty surgery: Update on the evidence and hurdles to acceptance.
Curr Opin Ophthalmol 2013;24:329-35.
DMEK has higher rates of primary graft failure and donor tissue wastage than DSEK
Descemet’s membrane endothelial keratoplasty: Prospective study of 1-year visual outcomes, graft survival, and endothelial cell loss.
Donor age > 50 years : easy removal of DM scroll

Clinical and Experimental Ophthalmology 2010; 38: 128–140

PDEK
The paper reporting the presence of the PDL also describes its use, together
with the DM in EK
It was noted that the PDEK tissue scrolled less and was easier to handle and
unscroll in the eye compared to DMEK tissue.
The donor endothelial graft in DSEK has 100–150 µ of posterior stroma,
while the PDEK graft is much thinner as it consists of DM and PDL, the PDL
being 10–13.6µ thick
Visual outcomes are similar for both PDEK and DMEK grafts.
Endothelial cell loss during donor tissue preparation is slightly less in PDEK
than DMEK.
As it is a relatively new procedure, graft failure rates and long-term
outcomes are yet to be published.
PDEK is still in its early stages and more experience, with time, will help
establish its position in EK.
Singh NP, Said DG, Dua HS. Lamellar keratoplasty techniques. Indian J Ophthalmol 2018;66:1239-50

SUMMARY
Lamellar keratoplasty (LK) has revolutionized corneal graft surgery in several ways.
Deep anterior LK (DALK) has eliminated risk of failure due to endothelial rejection.
Endothelial keratoplasty (EK) has almost eliminated induced astigmatism and the "weak" graft-
host junction as seen with penetrating keratoplasty (PK) and also reduced the risk of endothelial
rejection.
Surgical procedures for LK are further getting refined based on the improved understanding
and are able to deliver better surgical outcomes in terms of structural integrity and long-term
patient satisfaction, reducing the need of further surgeries and minimizing patient discomfort
Although LK is here to stay, PK will always remain for a “rainy day!”

LAMELLAR KERATOPLASTY

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