Seite 1

Corneal Crosslinking (CXL)

beyond keratoconus

Theo Seiler

Institut für Refraktive und Ophthalmo-Chirurgie (IROC )

and

University of Zürich

Seite 2

• Definition of CXL During CXL radicals create new chemical bonds

between neighbouring molecules

facts

Seite 3

cornea

Seite 4 Nach Hayes S, PLoS One 2013;8(1)

cornea

Seite 5

1. Biomechanical action

2. Biochemical action

3. Cytotoxic action

4. Refractive action

Seite 6

• Definition of CXL During CXL radicals create new chemical bonds

between neighbouring molecules

• Biomechanical action Human corneal stroma becomes a factor of 4 stiffer

(= less elastic)

facts

Seite 7

0

2

4

6

8

10

12

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

strain/%

str

es

s With CXL

Without CXL

biomechanical result

Seite 8

Clinical results Stability:

1y

post-op

9y

post-op

4y

post-op

pre-op

Seite 9

1. Biomechanical action

2. Biochemical action

3. Cytotoxic action

4. Refractive action

Seite 10

• Definition of CXL During CXL radicals create new chemical bonds

between neighbouring molecules

• Biomechanical action Corneal stroma becomes a factor of 4 stiffer (= less

elastic)

• Biochemical action Corneal stroma becomes a factor of 2 more resistant

against digesting enzymes

facts

Seite 11 Nach Hayes S, PLoS One 2013;8(1)

biochemical result

Seite 12

Klin Monbl Augenheilkd. 2000;217:190-3 Irradiation of cornea with ultraviolet light and riboflavin

administration as a new treatment for erosive corneal

processes Schnitzler E, Spörl E, Seiler T.

Dresden study reporting CXL in 4 eyes with corneal

melting not responding to conventional therapy

In 3 out of the 4 cases the melting halted, 1

needed PKP à chaud

Seite 13

Seite 14

Visus 0.4p Visus 0.7

Seite 15

Extrazelluläre

Matrix Abbau

(keratozyten,

Enzyme)

Synthese

(Keratozyten)

CXL

Seite 16

1year after CXL

reverse melting

Seite 17

1. Biomechanical action

2. Biochemical action

3. Cytotoxic action

4. Refractive action

Seite 18

• Definition of CXL During CXL radicals create new chemical bonds

between neighbouring molecules

• Biomechanical action Corneal stroma becomes a factor of 4 stiffer (= less

elastic)

• Biochemical action Corneal stroma becomes a factor of 2 more resistant

against digesting enzymes

• Cytotoxic action 300 microns deep keratocytes (germs) are killed

facts

Seite 19

cytotoxicity

Confocal microscopy as parameter

Seite 20

zytotoxische Wirkung

Seite 21

zytotoxische Wirkung

Seite 22

4 months after

LASIK with DLK+4

interface floating

twice, antibiogram

negative

maximal antibiotic,

antifungal, and

steroid therapy

EDTA-therapy

ineffective

zytotoxische Wirkung

Seite 23

5 days after CXL

standard

antibiotic-steroid

therapy

3 months later

deep lamellar

keratoplasty

zytotoxische Wirkung

Seite 24

zytotoxische Wirkung

Graefes Arch Clin Exp Ophthalmol. 2012;250:95-102 UVA-riboflavin photochemical therapy of bacterial keratitis: a pilot study

Makdoumi K, Mortensen J, Sorkhabi O, Malmvall BE, Crafoord S

Seite 25

1. Biomechanical action

2. Biochemical action

3. Cytotoxic action

4. Refractive action

Seite 26

male, 24 years

BSCVA 20/30 with

-1.25cyl-2.0/85

pachymetry 520 µm

post. elev. 53 µm

Customized CXL

Seite 27

Customized CXL

Seite 28

Customized CXL

Seite 29

Customized CXL

Seite 30

Summary

Besides the well-known biomechanical action

of CXL for keratoconus, there are 3 more

actions to consider:

• The biochemical action to stop melting

• The cytotoxic action to kill bacteria, fungi,

and viruses

• The flattening effect to create myopia

correction