1/9/2015
Financial disclosures
Modern Corneal Surgery
• Formerly a paid research scientist for
Alcon Laboratories Inc. (2006)
• Travel and consulting services for Essilor
Laboratories (2010)
• Honoraria from Contact Lens Spectrum for
publication submission (2014)
Derek J. Louie, MSc, OD, FAAO
Clinical Associate Professor, Ophthalmology
Video presented with permission from Winston Chamberlain, MD, PhD
Objectives
Basic corneal anatomy
• Review corneal anatomy
• Understand the variations and indications of
corneal surgery
• Understand when to refer to corneal surgeon for
assessment and treatment
Epithelium & limbal stem cells
Epithelium & limbal stem cells
• Stem cells are necessary for intact and
functioning epithelium
• Epithelial cells migrate from the limbus to
central cornea then are sloughed off
– 5-7 cell layers thick, ~50µm total
• Epithelium acts as barrier tissue to prevent
fluid movement from tears to stroma
• Epithelium is necessary to provide smooth
refractive surface
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Corneal stroma
Corneal endothelium
• Thickest layer of cornea
• Approximately 500µm
• Regular distribution of collagen fibers
produces destructive interference
producing a clear tissue
• Scars happen here
• Monolayer of cells acting as pump to restrict
water into the stroma
• Aqueous leaks across the endothelium to
provide glucose, amino acids and other nutrients
to the cornea
• 2500-3000 cells/mm2 in average adult cornea
– 0.6% decrease/year
• 300-600 cells/mm2 leads decreased barrier
function and possibly edema
• Fuch’s endothelial dystrophy
Reasons for cornea surgery
• Excessive scarring/opacity
• Excessive ectasia/thinning (<200 µm)
• Excessive loss of endothelium/endothelial
function
TYPES OF CORNEAL PROCEDURES
Penetrating Keratoplasty (Conventional)
Penetrating Keratoplasty
PKP or PK
Full thickness keratoplasty
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Approximately 40,000/year in US
~20% rejection/year
Lifetime of risk
Does not require blood/tissue match
May or may not improve vision
– Decrease/remove scar
– Increase thickness
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Suture patterns
Suture Patterns
IntraLase Enable Keratoplasty
• Necessary for most corneal surgery
• Surgeon dependent
• IEK
• Femtosecond Laser Assisted
Keratoplasty– “FLAK”
– Running – single suture and knot
– Interrupted – multiple sutures and knots
– Combo
• Selective removal (or application) may
help alleviate irregularity
– Topography guided removal
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Shapes
Shapes
• TopHat
• Zigzag
• Mushroom
• Christmas Tree
• Standard
• Zig Square
Anterior Lamellar Keratoplasty
• ALK
• Not full thickness
– Bladed or laser options
How a Flap or Free Cap is Created
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Femtosecond Laser Assisted ALK
Deep Anterior Lamellar Keratoplasty
• DALK
• “Big Bubble” – dissection technique
Zigzag incision clear on OCT
Zigzag incision clear on OCT
Zigzag incision clear on OCT
Zigzag incision clear on OCT
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DALK
Tough Case with Multiple RK Incisions
After Surgery
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Endothelial Keratoplasty
• Descemet Stripping and (Automatic)
Endothelial Keratoplasty
• Includes basement membrane
• DSEK and DSAEK
Deep Lamellar Endothelial Keratoplasty
• DLEK
• Usually doesn’t require sutures
• Held in place by air bubble
What about transplanting a single
cell layer ??
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Descemet Membrane Endothelial Keratoplasty
(DMEK)
DMAEK in the Eye Bank
Viscodissection
Limbal Stem Cell Deficiency
Intralase assisted Air dissection
Causes of Limbal Stem Cell Deficiency
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Congential
– Aniridia
– Ectodermal Dysplasia
– Keratitis Ichthyosis Deafness
(KID) Syndrome
– Autoimmune Polyglandular
Syndrome
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Autoimune/Inflammatory
– Stevens Johnson Syndrome
– Ocular Cicatricial Pemphigoid
(Mucous Membrane Pemphigoid)
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Acquired Conditions
– Pterygia
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Drug toxicity/topical medications
Chemical/thermal burns
Herpes Virus
Contact lens
Limbal tumors
Radiation Keratopathy
Sequelae of Mustard Gas
exposure
– Multiple surgeries
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Stem cell deficiency in one eye.
Total or Diffuse
limbal stem cell
deficiency
Partial limbal stem
cell deficiency
Sectoral conjunctival
scraping to remove
conjuctival epithelium
from corneal surface ±
AMT
Poor tear production
and/or keratinized
surface
• KLAL
Allogeneic limbal stem
cell transplant ±
conjunctiva from living
related donor (lrCLAL) with systemic
immunosuppression
OR
Autologous limbal
stem cell transplant
± conjunctiva from
healthy other eye
Keratolimbal Allograft
Allogeneic limbal stem
cell transplant ±
conjunctiva from 1-2
cadaver eyes (KLAL)
with systemic
immunosuppression
Keratoprothesis
Boston K-Pro I or II, AlphaCor,
Oculaid, Osteo-odontokeratoprosthesis
KLAL—Keratolimbal Allograft
Keratolimbal allograft in corneal reconstruction
E M Espana, M Di Pascuale, M Grueterich, A Solomon and S C G Tseng
Boston Keratoprosthesis Type I
56 y.o Farmer – KPRO type I
POM #4--20/30
Pre surgical--Hand Motion
from Eastern Washington with history of bilateral corneal alkali burn
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Boston Keratoprosthesis Type I
58 y.o male
20/4000 --Counting fingers vision at 2 feet
20/25 vision with Scleral Contact Lens
h/o Stevens Johnson Syndrome—Chronic ocular findings
Indications for Boston Keratoprosthesis
• Multiple failed corneal transplants
• Extensive corneal blood vessels
• Total or severe limbal stem cell deficiency
Keratoconus
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Non-Inflammatory corneal ectatic disease
Progressive steepening and thinning
Irregular astigmatism
1:2000 patients
Treatment
– Contact lens
– Penetrating keratoplasty
– Deep anterior lamellar keratoplasty
• Life long risk of rejection (with PK and DALK)
Keratoconus
• 2nd most common reason for cornea surgery
• Full thickness was the only option until ~1015 years ago
• Scleral lenses have help reduce the need for
surgery
• Intra-corneal ring segments (ICRS) can help
with mild corneal irregularity
– INTACS®
• Cross linking maybe the answer
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Intracorneal Ring Segments
INTACS®
• Flatten the steep part of the cornea or
cone to reduce distortions
• Does not stop ectasia or progression
• Made of PMMA
• Intrastromal placement
– Can be femtosecond laser assisted
• Removable
Crosslinking
stiffens the
cornea
365nm
Better Picture?
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Cross-linking
Switzerland
Switzerland
CBM Vega X-- BON OPTIC – ITALY
TECHNIQUE
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Sterile conditions
Topical anesthesia
Debride central epithelium 7-9 mm of cornea.
Treat surface with 0.1% solution Riboflavin (in 10 ml
dextran 20% solution) for 30 minutes starting 5
minutes before the start of irradiation.
• UVA radiation of 365 or 370 nm wavelength for 30 min
TECHNIQUE
• Accelerated cross-linking study
– 15 mW/cm2 for 8 min
– 30 mW/cm2 for 4 min
– 45 mW/cm2 for 2 min 40 sec
– irradiance of 3 mW/cm2 at distance of 1 cm from the
cornea
– dose of 5.4 J/cm2
• Prophylactic antibiotic drops
• Bandage contact lens
• Follow-up visits (1day, 7 day, 1 month, 3 months)
Topographic Changes
Long term stabilization
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METHODS: Four hundred eighty eyes of 272 patients with progressive keratoconus were
included in this long-term retrospective study. The maximum follow-up was 6 years. At the first
and all followup examinations, refraction, best corrected visual acuity (BCVA), corneal
topography, corneal thickness, and intraocular pressure were recorded.
• RESULTS: The analysis included 241 eyes with a minimum followup of 6 months. The steepening decreased significantly by 2.68
diopters (D) in the first year, 2.21 D in the second year, and 4.84 D
in the third year. The BCVA improved significantly (R1 line) in 53%
of 142 eyes in the first year, 57% of 66 eyes in the second year, and
58% of 33 eyes in the first year or remained stable (no lines lost) in
20%, 24%, and 29%, respectively. Two patients had continuous
progression of keratoconus and had repeat crosslinking procedures.
Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol.
2003;135(5):620-7.
J Cataract Refract Surg 2008; 34:796–801
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Nature.com
• In conclusion, in this systematic review and meta-analysis, we found
that CXL may be effective in halting the progress of KC for at least
12 months under certain conditions. The effects of CXL on visual
acuity improvement are also remarkable. With long-term follow-up
(after 18 months post-CXL), a significant decrease in Kave and
MRSE was observed, and BCVA also significantly increased
compared with the pre-CXL values. However, no statistical
difference in CT after CXL was found during long-term follow-up.
Further research from randomized trials is necessary to confirm
these findings.
Other Applications
Post Refractive Surgery Ectasia
Hafezi F, Kanellopoulos J, Wiltfang R et al. Corneal collagen crosslinking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ
keratomileusis. J Cataract Refract Surg. 2007;33(12):2035-40.
Kymionis GD, Diakonis VF, Kalyvianaki M et al . One-year follow-up of corneal confocal microscopy after corneal cross-linking in patients with post laser in situ
Keratosmileusis ectasia and keratoconus. Am J Ophthalmol. 2009;147(5):774-8, 778.
Infectious melting keratitis
Iseli HP, Thiel MA, Hafezi F et al. Ultraviolet A/riboflavin corneal cross-linking for infectious keratitis associated with corneal melts. Cornea. 2008;27(5):590-4.
Bullous Keratopathy
Corneal collagen cross-linking in keratoconus: A systematic review and
meta-analysis, Jul10, 2014. Nature.com
Tian Chunyu, Peng Xiujun, Fan Zhengjun, Zhang Xia & Zhou Feihu
Wollensak G, Aurich H, Wirbelauer C et al. Potential use of riboflavin/UVA cross-linking in bullous keratopathy. Ophthalmic Res. 2009;41(2):114-7.
Ehlers N, Hjortdal J. Riboflavin-ultraviolet light induced cross-linking in endothelial decompensation. Acta Ophthalmol. 2008;86(5):549-51.
Summary
• Multiple corneal surgeries available
• Lamellar keratoplasty has become the approach
to most types of corneal pathology
• Severe corneal disease requires more heroic
intervention
• Femtosecond lasers are fine tuning the surgeon
maneuvers, but can’t do everything
• Familiarity with different corneal procedures is
essential in helping patients make informed
decisions regarding their vision and eye health
Thank you for staying awake
(or at least not snoring…)
louied@ohsu.edu
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