1. CORNEAL PERFORATION AFTER CROSSLINKING TREATMENT FOR KERATOCONUS
G. PAGANONI – P. RAMA
SAN RAFFAELE SCIENTIFIC INSTITUTE
MILAN
Authors have no financial interest

2. ABSTRACT
A 32-year-old man with keratoconus developed corneal melting five days after CXL. Corneal scraping was positive for Acanthamoeba. Due to corneal perforation a large therapeutic keratoplasty was performed. Although considered a safe procedure this case emphasizes the potential risks involved in CXL. We discuss the potential effects of deepithelialization, contact lens placement, topical NSAIDs and anesthetics instillation, and the possible role of apoptosis and denervation when performing CXL.

3. PATIENT 32-year-old man good general health
bilateral keratoconus since 1993
CL discontinued due to intolerance
visual acuity worsened in left eye in the last year
keratoconus progression confirmed by 2 consecutive topography tests
optical pachymetry > 400 μm
no other ocular pathology

4. CXL PROCEDURE February 2008: CXL (Siena Eye Cross protocol)
9 mm epithelial removal
15 minutes riboflavin (Ricrolin) instillation
30 minutes UVA irradiation (CBM VEGA – CSO)
riboflavin instillation every 2' during irradiation
Medication with:
ofloxacin drops x3
flurbiprofen drops x4
artificial tears
BANDAGE CONTACT LENS

5. DAY 1
patient noticed redness and conjunctival discharge
rinsed his eyelids with TAP WATER to remove secretions
referred to ophthalmologist: was added levofloxacin x4
DAY 3
Corneal involvement with opacification and ulceration
Therapy prescribed:
ofloxacin x5
levofloxacin each hour
flurbiprofen x3
chloramphenicol + betamethasone ointment x4
ceftriaxone i.m. 4 g/day
prednisone p.o. 25 mg/day
DAY 5
Condition worsened
Hospitalization and conjunctival flap scheduled

6. DAY 6 Patient referred to San Raffaele Hospital, presented with:
severe inflammation
subtotal epithelial defect
corneal ectasia
corneal infiltrate and opacification
ulceration and melting

7. Smears were positive for Acanthamoeba
Corneal scrapings for bacteria, fungi, Acanthamoeba and herpes virus performed
Smears were positive for Acanthamoeba
Cultures resulted successively negative for all microorganisms
Prescribed therapy:
acyclovir 800 mg x3/day
ceftazidime i.m. 1 gr x2/day
levofloxacin every 2 hours
hexamidine every 2 hours
PHMB every 2 hours

8. DAY 11 Corneal perforation occurred Therapeutic 10 mm PK performed
Histology of the corneal button showed loss of Bowman and Descemet membranes, stromal necrosis and severe granulocytic infiltrate
No Acanthamoeba, bacteria and fungi found

9. ACANTHAMOEBA Can provoke inflammation, melting and corneal perforation
A pre-existing Acanthamoeba keratitis seems unlike: patient did not wear CL before CXL
Soft CL contamination with tap water is a well known risk factor
Acute infections are possible
BUT:
Rapid progression of corneal melting is unusual even after PRK
Wagoner: “Acanthamoeba keratitis after photorefractive keratectomy” JCRS 2002

10. ETIOLOGY OF CORNEAL MELTING
Remain uncertain
Sings of bacterial infection were referred since post-op day1
BUT:
No bacteria, fungi nor herpes found on smears and cultures
Only Acanthamoeba was present in smears
Histology was negative
Possible risk factor are:
infections (bacteria – Acanthamoeba)
epithelial debridement
use of topical NSAIDs
corneal toxicity from topical anesthetics
denervation
keratocyte apoptosis?

11. SUMMARY
A presumed bacterial infection, in association with the lack of integrity of the epithelium, denervation and keratocyte apoptosis secondary to UVA irradiation, the frequent instillation of topical anesthetics during the procedure, NSAIDs instillation and Acanthamoeba infection may have led to the activation of multiple noxious mechanism that caused ulceration and corneal melting.

12. CONCLUSION
A risk of microbial keratitis exist in CXL due to epithelial defect.
The post-operative use of bandage contact lens and NSAIDs (not contempled in the original treatment) should be well evaluated.
The role of denervation and keratocyte apoptosis following CXL has still to be investigated.