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Paper Information

Journal:   JOURNAL OF CURRENT OPHTHALMOLOGY   2004 , Volume 17 , Number 2; Page(s) 38 To 42.
 
Paper: 

CORNEAL TOPOGRAPHIC CHANGES AFTER LASIK IN MYOPIA AND MYOPIC ASTIGMATISM

 
 
Author(s):  MIRZAEI MOHAMMAD*
 
* ALAVI HOSPITAL, TABRIZ UNIVERSITY OF MEDICAL SCIENCES
 
Abstract: 

Purpose: Evaluation of corneal topographic changes after LASIK with quantitative and qualitative methods.
Materials and Methods: A semiexperimental clinical trial was done in 80 eyes of 41 patients from 1380-1382 (2001-2003) in Tabriz. In this study eyes with myopia and myopic astigmatism undergo LASIK with Nidek EC-5000.Computerized video keratography was made before, 5days after and in the last visit following LASIK with Eye sys corneal analysis system and Holladay diagnostic summary programs. Findings are comparised and differences was analysed with T-test and Wilcoxon statistical methods. Results: Mean age of Patients was 30±10 (SD) Year. Mean duration of follow up was 12 months. Mean level of best corrected visual acuity before operation was 0.1 LogMar (20/25) and mean uncorrected visual acuity after operation in the last visit was 0.2 LogMar (20/30). Mean Level of best corrected visual acuity in the last visit was 0.35 LogMar (20/22).
Mean amount of refractive error before operation in the spectacle plan was -5.75±3 (SD) that reached to -0.35±0.62 (SD) after operation.
Mean amount of corneal asphericity (Q) before operation was -0.105 (min -1.04 and max +0.35) that raised to +1.07 (min +0.01 and max +1.99) in the last visit after LASIK. Mean corneal uniformity index (CUI) before operation was 97.25%, that reached to 85.37% in the last visit after LASIK.
Mean predicted corneal acuity (P.C.A) before operation was 20/14 that reduced to 20/25 in the last visit after LASIK.
Mean decentration of corneal center before and after LASIK in the horizontal axis was 0.03 mm and 0.045 mm (respectively) and in the vertical axis was 0.037mm and 0.024mm (respectively).
Mean amount of effective refractive power before operation was 43.83±1.63 (SD) that reduced to 38.98±2.05 (SD) in the last visit after LASIK.
Topographic profiles after LASIK were: Circular (C) in 53 eyes (66.25%), circular with central bowtie (CCB) in 25 eyes (31.25%) and assymetric bowtie (ASB) in 2 eyes (2.5%).
Conclusion: This study shows that LASIK with Nidek-EC 5000 causes corneal topographic change from prolate to oblate with resultant correction of myopia and myopic astigmatism but, CU index and PCA are reduced after LASIK that causes unwanted effects on visual quality.

 
Keyword(s): TOPOGRAPHY, LASIK, MYOPIA, REFRACTIVE SURGERY
 
References: 
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  Persian Abstract Yearly Visit 79
 
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