| المستخلص: |
Aim: to evaluate visual outcome and corneal aberrations in keratoconic patients underwent corneal collagen cross-linking using the Sirius Scheimpflug analyzer. Methods: This was descriptive, cohort and retrospective hospital based study, it was conducted at Alzarga Eye Center, Khartoum, Sudan. Data was collected from the records of cornea's clinic. The study was included 54 keratoconic eyes of 40 patients underwent corneal collagen cross linking (CXL) 14 of them in both eyes. All patients operated by one surgeon in period from December 2016 to October 2018. The eyes were saturated with riboflavin solution and were subjected for 30 minutes to ultraviolet -A (UV-A) light with irradiance of 3mW/cm2. Effectiveness of the CXL was assessed by measuring uncorrected visual acuity, manifest refraction, corneal astigmatism, corneal curvature, central corneal thickness, and corneal aberrations by the Sirius Scheimpflug analyzer. All measurements were taken prior to the CXL and 3, 6 and 12 months after CXL. Data obtained were statistically analyzed and compared using statistical package for social science (SPSS-20) and refractive error analyzed by astigmatic decomposition methods. Results: the mean age was 20.05 ± 4.77 years (ranged: 13 - 34 years). There was a significant increase in uncorrected visual acuity (0.15±0.19) preoperatively to (0.24±0.27), (0.30±0.24) and (0.45±0.35) after 3, 6, and 12 months respectively (P<0.001). Mean of spherical refractive error was -12.44±5.31 Diopter (D) preoperatively and -11.07±5.39 D, -8.63±5.45 D and -8.46±4.52 after 3, 6, and 12 months respectively of CXL (P<0.001). The study revealed that CXL significantly decreased ocular astigmatism (P<0.001). It was -7.92±3.73 D preoperatively and -6.87±3.41, -5.07±3.76 and -6.01±3.97 after 3, 6, and 12 months respectively. The corneal curvature flattened and decreased significantly by an average of 1.35 D, 1.93 D and 2.02 D after 3, 6 and 12 month respectively (p˂ 0.001). The central corneal thickness significantly decreased after CXL (p˂ 0.001) by an average of 16.5 μm, 26.83 μm and 46.83 μm3, 6 and 12 month respectively. Anterior corneal aberration pre CXL was decreased from 0.25±0.20 μm/mm2 to 0.24±0.17 μm/mm2, .22±.15 μm/mm2 and 0.21±0.11 μm/mm2 after 3, 6 and 12 months respectively of CXL. Posterior corneal aberration pre CXL was increased from 0.62±0.66 μm/mm2 to 0.65±0.70 μm/mm2, 0.70±2.81 μm/mm2 and 0.85±1.35 μm/mm2 after 3, 6 and 12 months respectively of CXL. Corneal astigmatism decreased from -4.54±2.96 D preoperatively to -4.09±3.01 D, -4.41±2.61 D and -4.51±3.12 D after 3, 6, and 12 months respectively. Conclusion: Corneal collagen cross linking is effective to arrest progression of keratoconus. It increased visual acuity, flattening of corneal curvature, and decreased spherical and astigmatic errors. It also reduced corneal astigmatism, corneal aberrations and keratoconus symmetry index front.
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