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P. C. Serapicos, K. M. Bottós, M. Kurauchi, V. Sakai, P. Schor, W. Chamon, E. Mori, D. Freitas; The Safety and Effectiveness of the Collagen Cross Linking With Riboflavin and Ultraviolet-A Light in Progressive Mild and Moderate Grades of Keratoconus. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5494.
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To assess the effectiveness of collagen cross linking (CXL) in reducing progression of mild and moderate progressive keratoconus.
Prospective longitudinal randomized case-control study including progressive keratoconus cases. Progression was based on increase in the cone apex keratometry of - 0,75 D, alteration of - 0,75 D in the spherical equivalent or increase of the anterior chamber depth on Pentacan, in a period of at least six months. All patients were between 15 and 40 year old. Patients were randomized and allocated in the treated or the control groups. Complete exam before and after the procedure included best corrected visual acuity, refraction, IOP, fundoscopy, imaging exams such as corneal computerized topography, pentacanTM,orbscanTM, ultrasound pachymetry, esthesiometry, endothelial cell count, HRT II system confocal microscopy, optic coherence tomography (VISANTETM), ORA , optic coherence tomography (Stratus OCT) and dynamic contour tonometry . All the exams were repeated 1, 3, 6 and 12 months after the procedure. The cross linking was performed as follows: after topical anesthesia, the epithelial tissue was removed in a 8.0mm diameter area of the central cornea, the 0,1% riboflavin solution was applied every 2 min, for 30 min followed by cornea irradiation with UVA light with a wavelength of 370 nm and an irradiance of 3 mW/cm2. During the irradiation, drops of the riboflavin solution were continuously applied onto the cornea every 5 min.
We have 15 patients included and 2 treated until now, with a mean age of 26,93 ± 8,42 (SD). Preoperatively, the mean K value of the apex is 54,06 ± 4,08 (SD) and the maximum K value is 49,47 ± 2,73 (SD). In the one-month follow-up after the CXL of these two patients, both had improvement of the refraction and BCVA in one line. Comparative pre and postoperative results showed a slight reduction of the cone apex and the maximum keratometry in one patient. Both patients had a higher density of the collagen fibrils of the anterior 250 to 300 µm of the cornea in the 1-month confocal microscopy and a reduction of the central corneal sensitivity at esthesiometry.
These initial results suggest that CXL might be a procedure to stop keratoconus progression. However, a long-term follow up, with more patients is necessary for further conclusions. This study is in progress.
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