الفهرس 
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Abstract
This prospective study was carried out on 51 eyes of 31 patients having KC selected from patients attending the ophthalmic outpatient clinic of Mansoura Ophthalmology Center during the period from March 2010 to February 2011. The aim of the study was to evaluate the efficacy and safety of CXL in reducing progression and in improving visual acuity of KC cases.
After history taken, preoperative detailed ophthalmologic examination was performed including UCVA, BCVA, slit lamp biomicroscopy, refraction and fundus examination. The following investigations were done:
• Corneal Topography ( Wavelight -ALLEGRO Topolyzer).
• Central corneal thickness measurement using specular microscopy.
• Central endothelial cell density measurement using specular microscopy.
Corneal cross linking using UVA light and riboflavin (Ricrolin®) was done for all cases. After topical anesthetic eye DROPs administration, the epithelium was mechanically removed within the central 8 mm diameter area using a Beaver blade. Next, riboflavin 0.1% was applied every 3 minutes for 30 minutes until the stroma was completely saturated and aqueous stained yellow. Then the cornea was irradiated with UV-A light at 370 nm for 30 minutes. During the treatment, riboflavin solution was applied every 5 minutes to saturate the cornea and DROPs of BSS every 2 minutes to moisten the cornea. After the treatment, the cornea was irrigated with 20-ml BSS and an antibiotic DROP was instilled (moxifloxacin hydrochloride). Contact lens was placed after the treatment.
All cases were followed up for one year postoperatively. Follow-up was first done after one day, 3 days for contact lens removal, then after one week for prescription of topical steroid-antibiotic (Tobramycin and Dexamethasone ) and one month for assessment of corneal haze. Uncorrected visual acuity, BCVA, refractive, topographic changes, pachymetery, and endothelial count were recorded at 3,6,12 months using:
• Corneal Topography ( Wavelight -ALLEGRO Topolyzer)
• Specular microscopy for endothelial cell density and central corneal thickness measurement.
• Anterior segment photographing using Sony digital camera attached to the slit lamp.
There was a statistically significant improvement in UCVA from the preoperative values (P < 0.05). None of the eyes lost lines of the preoperative UCVA. Eight eyes (15.5%) maintained the preoperative UCVA; twenty seven eyes (53%) gained one line, ten eyes (19.5%) gained two lines and six (12%) eyes gained three to four lines.
Forty three eyes of the 51 eyes (84%) evaluated at one year, experienced at least a gained of 1–4 lines of BCVA. Eight of the 51 eyes (16%) experienced no change in BCVA. There was no statistically significant change from the 6 months examination values and one year values (P > 0.05).
The cylinder values at 1-year examination were statistically significantly less than the values preoperatively, while there was no statistically significant change from the preoperative values and 3 months values.
The K value at the apex decreased (statistically significant) from pre-operative to 1-year evaluation. In the one year, there were no statistically significant changes in K readings, compared to six months records, denoting the short term stability of the topographic changes at one year. Progression of corneal steepening from the preoperative value was not observed in any of the treated eyes.
One-year evaluation showed the pachymetry to increase gradually but still there was a significant reduction in pachymetry than preoperative values.
The difference between the baseline endothelial cell count and one year after the procedure was not statistically significant, indicating that CXL did not induce endothelial damage during follow-up.
Sight threatening complications were not recorded in this study. All eyes developed diffuse stromal haze that cleared in 50 eyes (98 %) within 1 month and within 6 weeks in only one eye (2 %).