Recent developments in corneal surgery

Dr Laurie Sullivan FRANZCO
Corneal Clinic, RVEEH
Bayside Eye Specialists, Brighton
100 Victoria Parade, East Melbourne
Lasersight

Background of Corneal
Transplantation
The first cornea transplant was performed in
1905, by Eduard Zirm – sutures over the graft
– 1 of 2 eyes survived!
Operating microscopes have enabled us to get a
better view of the surgical field
Advances in materials enabled us to use nylon
sutures finer than a human hair
The development of synthetic corticosteroids
has enabled inhibition of rejection
In Australia, approximately 1,500 grafts are
performed each year (20% are for keratoconus)
Dr Laurie Sullivan 2008 www.baysideeyes.com.au

Why was Lamellar Corneal
Transplantation out of favour for
decades?
Because the eyes did not see well after
surgery.
Interface irregularities between the two stromal
surfaces produce light scatter causing poor acuity.
Full thickness transplants were much better optically
(although the problems of regular and irregular
astigmatism still remained).

Previous model of lamellar keratoplasty

Why has lamellar grafting made such
a huge comeback?
Because they see better than
they did previously
A lamellar graft is structurally
stronger than a PK.
Rejection is less

Evidence?

Trans Am Ophthalmol Soc. 2007 December; 105: 530–563.
ENDOTHELIAL KERATOPLASTY: CLINICAL OUTCOMES IN THE TWO YEARS FOLLOWING
DEEP LAMELLAR ENDOTHELIAL KERATOPLASTY. (AN AMERICAN OPHTHALMOLOGICAL
SOCIETY THESIS) Mark A. Terry, MD Trans Am Ophthalmol Soc. 2007 December; 105
Purpose: To evaluate the clinical outcomes of deep lamellar endothelial keratoplasty
(DLEK) for the treatment of endothelial dysfunction.
Methods: A prospective series of 79 eyes that underwent DLEK was evaluated.
BSCVA, astigmatism, and central endothelial cell density (ECD) were measured
preoperatively and at 6, 12, and 24 months.
Results: Data was available on 78 eyes (99%) at 6 months, 77 eyes (97%) at 1 year,
and 79 eyes (100%) at 2 years.
Mean BSCVA preoperatively of 20/71 improved to 20/42 by 6 months and remained
stable. BSCVA of 20/40 or better was present in 60% of eyes at 6 months,
74% of eyes at 1 year, and 79% of eyes at 2 years. Astigmatism preoperatively
was .91 ±.78 diopters and was unchanged by surgery over time .
The mean donor ECD preoperatively was 2819 ± 225 cells/mm2
, and this decreased
by 26% at 6 months (2095 ± 380), 3% fewer at 1 year (2009 ± 393), and 17% fewer
at 2 years (1536 ± 547).
Complications included one primary graft failure and 4 graft dislocations.
Conclusions
DLEK provides improved vision and minimal refractive
astigmatic change, but progressive ECD decrease over time
is of concern.

Am J Ophthalmol. 2007 Feb;143(2):228-235.
Quality of vision and graft thickness in deep anterior
lamellar and penetrating corneal allografts.
Ardjomand N, Hau S, McAlister JC, Bunce C, Galaretta D, Tuft SJ, Larkin DF.
Cornea and External Diseases Service, Moorfields Eye Hospital
PURPOSE: To compare visual function after deep anterior lamellar keratoplasty
(DALK) with visual function after penetrating keratoplasty (PK) for keratoconus.
DESIGN: Retrospective case series. METHODS: 32 eyes with DALK or PK for
keratoconus were analyzed for visual quality after suture removal. Total and
residual stromal thickness after DALK was measured using OCT and correlated to
visual quality. RESULTS: Eyes after PK had better visual acuity than eyes after
DALK (P = .018). Subgroup analysis revealed that DALK Eyes with a recipient
corneal bed thickness of <20 microm had visual acuities similar to eyes with
a PK, whereas those with a recipient thickness of >80 microm had a significantly
reduced visual acuity (P = .0009). Contrast sensitivity was similar in DALK and PK
eyes. There was no significant difference in HOAs between eyes with DALK or PK.
CONCLUSIONS: These data suggest that the main parameter for good visual
function after DALK for keratoconus is the thickness of residual recipient stromal
bed. An eye with a DALK with a residual bed of <20 microm can achieve a similar
visual result as a PK.

“Endothelial Keratoplasty”
(DSAEK, DMEK)
Why remove the full thickness of the
cornea if you only need to replace the
endothelium?

Indications
Endothelial disease
Fuch’s dystrophy, PPD
Pseudophakic bullous keratopathy (PBK)
Other endothelial failure (AACG, PXF)
The eye should be pseudophakic (AC manipulation
during surgery would cause cataract). Surgery can
be combined with cataract and IOL.

DSAEK

DSAEK
Remove host Descemet’s membrane
Replace with lenticle of donor Descemet’s
membrane and posterior stroma (100 to 150 µm)
prepared using a microkeratome to dissect anterior
stroma
Air bubble to hold in place
No corneal sutures, minimal astigmatism

Postop DSAEK vs PK

DSAEK
Main benefit is relatively rapid rehabilitation
1 to 2 months compared to 3 to 12 months for PK
Better structural integrity than PK
No sutures, less astigmatism, fewer visits
The issue of the interface remains, with lower
BCVA the PK → DMEK?
?Ideal patient a little old lady from the country
Dr Laurie Sullivan 2008
www.baysideeyes.com.au

DSAEK POD1
Bubble behind pupil Dilated, postured

DSAEK
Main disadvantages:
Lower BCVA than PK
Shorter survival of transplanted tissue (endothelial
trauma during insertion)?
1-10% postoperative interventions for detached and
displaced donor lenticles, pupil block
All improving with new techniques and instruments,
larger incisions, rolling of donor lenticles
“Endothelial transplantation” (ET, DMEK)
Transfer endothelium and Descemet’s membrane only
– NO stroma – less interface opacity

DSAEK Dislocation
Day 2 postop

Femtosecond Laser for
Penetrating Keratoplasty
Intralase was introduced initially
to produce LASIK flaps
Intralase can produce complex,
complementary donor and host
wound profiles
“Intralase Enabled Keratoplasty” =
IEK

Top Hat Shape
•

Top Hat Shape
• Provides large endothelial surface transplantation
• Uniform anterior refractive surface
• Also true for other shapesDr Laurie Sullivan 2008 www.baysideeyes.com.au

Valve-Sealing Edge Design
Suture
Not Tight
Intraocular Pressure
Prevents Leakage

ZigZag Shape
• Hermetic wound seal
• Angled edge provides
smooth transition between
host and donor

Anterior Lamellar
Keratoplasty
DALK = Deep ALK
“Stroma-only” keratoplasty
Remove all host corneal stroma, leaving only
endothelium and Descemet’s membrane
Less host stroma means less interface haze
Cannot be rejected
2 main techniques
Melles’ direct dissection (difficult)
Anwar’s Big Bubble (easier)

DALK Indications
Eyes with healthy endothelium
Keratoconus, anterior scars, dystrophies
Severe atopy
Eyes at high risk for endothelial rejection inc
large diameter grafts (Pellucid, Keratoglobus)
Unreliable patients, trauma risk (young males)
Down’s syndrome
Now my preferred option for KCN

DALK results
Slightly longer, more difficult surgery (learning)
VA equivalent to PK if stroma < 20 microns
No better for astigmatism results
Slightly earlier suture removal
Can still have wound and suture problems,
infection
May need to reinject air bubble into AC in the 1st
week

DALK Postop Day 1 & 2

Suture related keratitis – no
rejection

Keratoconus and Corneal
Collagen Crosslinking
Q. Why does keratoconus stabilise?
Q. Why do corneas become “stiffer” with age?
A. Increased collagen crosslinking - ?related to lifelong
UV exposure.

“Corneal Collagen
Crosslinking With Riboflavin”
= C3R = CXL
Keratoconic corneas show less crosslinking of
collagen fibrils than normals
This may cause decreased resistance to stretch
Treatment with UVA light can promote collagen
crosslinking (as seen in the ageing cornea)
Riboflavin is a very good photosensitiser to UVA

C3R/CXL - the treatment
Like PRK
8mm epithelial debridement (similar to PRK)
Sore eye
Blurry(er) vision for a week
Risk of infection
2- 4 weeks out of RGP CL
Stroma is soaked with riboflavin drops every 5
minutes
30 minutes of UVA light exposure (3.5 Mw/mm2)
under an operating microscope
Padded (or bandage SCL), ointment, antibiotics,
steroids, lubricants

ICOR UVA diode system

Results of C3R Treatment
Slows or stops progression of KCN
Some reversal (flattening) in 25%
Maybe better spectacle corrected vision
Consequences:
? Longer duration of tolerability, fittability of rigid
contact lenses?
? Fewer transplants?

C3R long term
Duration of effect? – may need repeat treatment at 5
or 10 years – not so far (6years follow up for the
initial Dresden cohort)
??Long term adverse effects (later OSSN / CIN,
endothelial failure?)

Intracorneal ring segments
(ICRS)
Intacs
Ferrara rings
Originally designed to treat low
myopia, but less accurate than
excimer laser
Now having a second life in milder
KCN

Intacs

ICRS: how they work
The ring segments
flatten the cornea
similarly to the way
you can flatten the
top of a tent by
pushing on the sides.

Intacs for KCN – who can
benefit?
Mild to moderate keratoconus
Decreased SCVA
A single segment inserted below the cone may
give better results than 2 segments
?May be combined with C3R to “set” the cornea
in the new shape

Keratoconus management -
Then
Glasses → RGP contact lenses → Corneal
Transplant (penetrating)
Then: glasses 70%, RGP 20%, nothing
5 -10%
LASIK/PRK, 12 months after suture removal – if
BSCVA is reasonable. Not good for irregular
astigmatism.

Keratoconus management -
Now
Consider C3R/CXL at diagnosis or if progressing
Intacs segments may keep patients in glasses
longer (but results are not dazzling in my
experience)
DALK is becoming a more popular corneal
transplant option (“Big Bubble” technique)
Gls, RGP, laser as before

Summary
The field of corneal transplantation is evolving rapidly
Techniques and technology seem to be leading the way
Stand by for updates even in the next few months
DALK Video 2:29 If time permits

DALK Video 2:29
If time permits

Recent developments in corneal surgery

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