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Lamellar Keratoplasty

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Ahmed Samir

on 12 August 2014

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Transcript of Lamellar Keratoplasty

Lamellar Keratoplasty
Lamellar Keratoplasty
Anterior lamellar keratoplasty
Posterior lamellar keratoplasty
Superficial anterior lamellar keratoplasty (SALK)
Deep anterior lamellar keratoplasty (DALK)
DLEK
Removal of stroma/endothelium + posterior implant

Small incision DLEK = same – 5 mm incision

DSEK
stripping DM + posterior implant

DSAEK
= same + microkeratome for donor

FS-DSEK
= same + femtosecond for donor

DMEK
stripping DM + implantation of DM without stroma
Superficial anterior lamellar keratoplasty (SALK)
Indications
Stromal dystrophies

Post traumatic scars

Post infectious scars

Postrefractive surgery

Technique
• Preparation of the recipient bed: same a lasik flap; Various heads such as 120, 180, 200, 250 and 350

• Preparation of donor lenticule:
* corneoscelral button
* Positioned on artificial AC

• Donor recipient apposition and suturing

Complications
Incorrect sizing
Irregular cut
Infections
Delayed epithelial healing
Interface opacities
Stromal rejection

Deep anterior lamellar keratoplasty (DALK)
• Surgical procedure in which the anterior layers of the cornea (epithelium, its basement membrane, bowman’s layer, and storma) to a variable depth are replaced by donor tissue.

• Several corneal layers may be dissected until the desired depth of the recipient stromal bed is obtained.

DALK
Advantages of DALK
• Preservation of host endothelium.

• No requirements for donor endothelium
-eliminates endothelial graft rejection
-allows using buttons with poor endothelial count (lamellar grade tissue)

• Allows for incorporation of more
diseased stromal tissue (larger grafts)

• Safer option than PKP

Disadvantages of PKP
• Expulsive choroidal hemorrhage
(0.5-1%)
Endothelial graft rejection and failure:


• up to 30% of eyes with PKP experience at least on episode of rejection

• graft failure = 12-68% of rejection cases

Graft Survival:

• Estimated: 74% at 5 years, 64% at 10 years

• Predicted: 48% at 15 years, 27% at 20 years, 2% at 30 years

Endothelial cell loss:


Estimated ECD: 1058 c/mm² at 5 years, 865 c/mm² at 10 years

• Predicted average time to reach ECD of 500 c/mm² 21-28 years

DALK versus PKP

Closed eye surgery


Slower endothelial decay


Reduced risk of rejection


Long term graft survival


Stronger wound construction


Better posterior corneal surface alignment


Visual results similar to PKP in eyes with <20 microns residual bed

Deep anterior lamellar keratoplasty (DALK)
DALK Indications
Visual
Keratoconus

Corneal scarring

Stromal dystophies and degenerations

Tectonic
Descematocele

Severe or peripheral corneal thinning

Ocular surface disease
High risk patients with poor surface and LSCD

Ilari & Daya demonstrated poor PKP survival but good lamellar graft survival

DALK Disadvantages
Steep learning curve
Visual results compared to PKP is slightly worse depending upon the thickness of residual bed
Visual rehabilitation longer
Interface haze
Persistent Descemet separation (double chamber)
DALK Contraindications
Endothelial dysfunction (absolute contraindication)

Posterior dystrophies (Fuchs, PPMD, CHED)

Corneal oedema (PBK)


procedure of choice: endothelial keratoplasty

Epithelial dysfunction (relative contraindication)

Limbal stem cell deficiency states (aniridia, etc.)
Chronic surface diseases (KCS, etc.)

procedure of choice:May combine DALK with other procedures that optimize surface (punctal occlusion, LSC transplantation)

DALK Techniques
Pre-Descemet’s

• Optical reference plane –Melles 1998


• Fluid DALK – Amayem 1999

Descemet’s

• Viscodissection –Melles 2000

• Big bubble – Anwar 2002

Femtosecond-Assisted
DALK
Optical reference plane

• Lamellar dissections bear the risk of perforation, because the posterior corneal surface cannot be seen through an operating microscope with full field illumination

• Melles (1998) invented a technique to visualize the depth of lamellar dissection relative to the corneal thickness by filling the AC with air creating an optical interface at the posterior corneal surface

DALK−Optical reference plane
DALK Optical reference plane
Advantages & Disadvantages
Advantages
• Suitable for cases with scars, post PKP

• Less than 10% risk of perforation

• No intraoperative rise of IOP

Disadvantages
• Interface haze

• Needs special instrumentation

• Difficult procedure, time consuming


• Fluid DALK:

DALK−hydrodelamination
Injection of BSS is carried out intrastromally in the four quadrants of the partially trephined central disc. This disc is converted to a completely opaque and swollen area relative to the clear outer rim
A lamellar dissection is performed in layers guided by the opacified swollen stromal fibers to the trephined edge; it is then cut by corneal scissors. This is carried to Descemet’s membrane with its glistening clear surface or to the clear fine deep stromal layer adjacent to it.
DALK-Viscodissection
Identify supradescemetic plane using mirror reflex created by air bubble in the AC (optical reference plane)

Detach DM from posterior stroma by injecting viscoelastic directly into the supradescemetic plane

Remove stromal tissue using blunt instruments

DALK
Big Bubble

Indications
Keratoconus
RGB intolerant.

Poor BSCVA

Apical scarring.

Superficial corneal scarring
Stromal dystophies and degenerations


Advantages and Disadvantages
Advantages
• Perfect interface
Disadvantages
• 10-40% failure of big bubble formation
• 10% perforation in best hands
• Not suitable for deep corneal scars, breaks in DM
• Time consuming

• relatively difficult procedure
The hypodermic needle:

Preferably 27 gauge
Angled 90 degrees
Bent 4-5 mm from its tip with bevel down
Attached to a 5 ml air filled syringe better screw locked
The blunt cannulae

available: fogla, tan,….

27 gauge blunt tip flattened cannula with a bottom port
lamellar track should be created using pointed dissector or sharp needle

Big bubble formation
The bubble Canula
Difficulties during big bubble formation
Perforation of DM
Use blunt cannula

A drop of viscoelastic on the cornea to enhance visualization of the depth

Use the air bubble in the AC as a reference plane (as in melles technique)

Inject air gently
Horizontal air dissection
Depth of trephination

Design of cannula: bevel down

Cannula place in the posterior third of stroma

Stop air injection once big bubble reaches the trephination groove
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