Abstract
Purpose: :
Keratoconus is a disease with gradual stromal thinning and coned formation of the cornea. Corneal transplantation, with a long healing period and unpredictable refractive errors has been the only resolution in the treatment of keratoconus. Today, keratoconus can be treated by the application of the photosensitizer Riboflavin and UV-A light to reorganize collagenous fibres and increase the biomechanical stability of cornea. Complications are very rare.
Methods: :
A 47-year-old patient had uneventful cross-linking to his right eye. Postoperatively the patient was treated with a therapeutic contact lens, topical ofloxacin and diclofenac. Three days after the treatment, he presented with complains of visual deterioration and pain in his right eye. Cross-linking had been performed four weeks before without complications to his left eye.
Results: :
The examinations revealed a visual acuity of finger counting in his right eye and 20/20 in his left eye. Slit lamp biomicroscopy showed conjunctival injection and multifocal stromal opacification of the central cornea. A mycotic keratitis could not be excluded. Therefore the patient was put on topical therapy with voriconazol, gentamicin, ofloxacin and scopolamine and systemic therapy with voriconazol. A smear test revealed isolated staphylococcus aureus sensitive to the antibiotic treatment but no mycosis. After 7 days topical dexamethason was added. Under the therapy the patient showed a slow restitution of visual acuity and inflammation with persisting corneal opacification. After 4 weeks of topical and systemic therapy the patient had a visual acuity of 20/200 in his right eye. With topical dexamethason visual acuity increased to 20/50 after further 6 weeks. A follow-up 3 months after cross-linking showed continuous clearing of the cornea with a visual acuity of 20/30.
Conclusions: :
Intrastromal opacification after cross-linking is a rare complication. Confocal examination shows apoptosis of keratocytes with complete loss of keratocytes in the upper two third of the cornea weeks after the cross-linking procedure. The keratocyte repopulation can take up to four months. Within this time intrastromal opacity occurs in the corneal stroma, resulting in haze and deterioration of visual acuity. In the same way an inhomogene disposition of riboflavin can lead to focal opacification. The occurrence of haze seems to be unpredictable even intraindividually when the same operative and postoperative procedure is applied to both eyes. Differentiation between haze and fungal keratitis can be difficult as they occur within the same time period after surgery and both show a delayed response to local therapy.
Keywords: keratoconus • cornea: stroma and keratocytes • inflammation