Instructional course IC 1

Corneal cross linking therapy:

Operative techniqueAuhor: Kristina Mikek, Slovenia

Co. Authors :    Carina Koppen, Belgium   Zoltan Nagy, Hungary   David O Brart, UK

Preoperative assessment

Patient counseling

The role of epithelial removal

Riboflavin dosage regimens

UVA exposure regimens

UV lamps and calibration

Postoperative care and follow up

Complications

K. Mikek

Process of corneal cross linking

Patient is referred to your service

Preoperative diagnosis

Decision on therapeutic intervention

Treatment procedure

Corneal cross linking therapy

Post operative follow up visits

K. Mikek

Preoperative diagnosis

• Measurements performed outside of your ophthalmology department and/or refractive changes given from the patient can not serve as a basis for a treatment decision

• Before final decision for cross linking treatment some check up examinations – depends on progression of the disease

• Family history of keratoconus or progression of keratoconus

K. Mikek

Preoperative examination

Rigid contact lenses must be removed for at least 2 weeks to achieve reasonable measurements of the cornea

Most patients with keratoconus who came for the treatment don’t wear contact lenses because they have problems with them

K. Mikek

Preoperative examination

Refraction

Visual acuity

Slit lamp examination (cornea, lens and retina)

Specular microscopy – morphology of endothelial cells and density

Corneal topography and Sheimpflug imagesCorneal thickness map

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Is the patient for cross linking treatment?

Progression of ectasia verified by corneal topography – change of max K by > 1 Dpt

Age of the patient – corneal changes?

Can the patient expect any benefit from corneal cross linking treatment – CL tolerance, visual performance?

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Is the patient for cross linking treatment?

Are there any risk factors that might lead to unpleasant healing responses and complications after treatment – rheumatism, keloid formation, pregnancy, dry eyes…?

Is the corneal thickness suitable for treatment, do I have to swell the cornea?

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What we have to explain to the patient before treatment?

Postoperative follow up time and hazy vision in the first 1 to 2 weeks after the cross linking treatment

Some pain and photophobia on the day of surgery

Results of stability statistically proven on the long term

Based on the preoperative examination:

Real expectation regarding the visual acuity (do not promise to the patient!)

K. Mikek

Treatment procedure

K. Mikek

Treatment procedure

Topical anesthetic eye drops and pilocarpin at the time of surgery

Partial epithelium removal – abrasio (diameter 8 to 9mm)Brush, 20% of ethanol, lines or punctures in the

epithelium

Applying riboflavin 1 drop every 2 min for 30 min

Slit lamp inspection – blue light: staining of the anterior chamber

Start UV- illumination with UV cross linking device: 1 drop of Ribo every 2 min for 30 minK. Mikek

Treatment procedure

At the end of surgery therapeutic contact lens is placed on the surface of the cornea

Eye drops at the end of surgery:0,1 % prednisolonCiprofloxacin

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Postoperative treatment:

0,1% prednisolon 3 times/day

Ciprofloxacin 4 times/day

Artificial tears hourly

Besides this:

Pain killers - among these Lyrica, which helps the most

Removing of the contact lens:

3rd postoperative day

K. Mikek

Treatment procedureBased on animal experimental studies and clinical

studies the following parameters are the most appropriate for maximal safety of cross linking treatment:

Corneal deepithelization (diameter 8 to 9 mm)

0,1% riboflavin in 20% dextrane – swelling the cornea if the corneal thickness after abrasio is less than 400 microns with riboflavin hypotonic solution!

3mW/cm2 at 365 nm for 30 minK. Mikek

Cross linking – cause of actionRiboflavin diffusion

UV –light illumination and absorption

Formation of oxygen radicals

Chemical reactions and cross link formation

Changes of the biomechanical properties of the cornea

M.Mrochen, IV.international congress of corneal cross-linking, 2008K. Mikek

Background of corneal cross linking

Molecular level – collagen molecules

Microscopic level – collagen fibrillae of linked collagen molecules

Tissue level – collagen lamellae – parallel arrangement of the fibrillae

Organ level – cornea –arrangement of interlaced collagen lamellae

M.Mrochen, IV.International Congress of Corneal Cross-linking, 2008

K. Mikek

ComplicationsDelayed corneal reepithelization

Drop of the therapeutic CL out of the treated eye and infection

Corneal endothelium cell damage – in thin corneas

Keratouveitis

Very seldom severe corneal haze

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Conclusions

Corneal collagen cross-linking is now the only treatment which could stop the progression of keratoconus or iatrogenic ectasia of the cornea

Complications rate of the treatment is low and mostly treatable or not affecting the visual acuity:

With careful counseling of the patients before treatment and following the guidelines for cross linking treatment !

K. Mikek

Thank you.

kmikek@morelaokulisti.siwww.morelaokulisti.si

K. Mikek