Abstract
Abstract: :
Purpose:: To evaluate the changes in elevation topography and induced astigmatism in soft contact lens wearers. Methods:We designed a prospective study from March to September 2001 at Fundación Hospital «Nuestra Senora de la Luz» in which included 10 patients (20 eyes) that wear soft contact lens for at least one year and from 10 to 18 hours daily. A corneal topography (ORBSCAN II) was made at the first day, 2 and 4 weeks after contact lens removal. The difference in central elevation, central pachymetry, and posterior elevation were evaluated using the T student statistical test, and vector analysis was made with Visual Basic, Microsoft Excel and Paint software. Results:Anterior elevation map revealed that 45% of the patients had a reduction of at least 0.14 microns between the first day and 4th week after contact lens removal and 90% of these patients had an increase at the 2nd week of contact lens removal. Pachymetry revealed that 45% of patients had a reduction of at least 30 microns between the first day and 4 weeks after contact lens removal and the posterior elevation topography revealed that 55% of the patients had a reduction of 0.14 microns in central elevation at the 4 weeks soft contact lens removal. Vector analysis revealed an induced astigmatism of -0.85 x 171o at the 2nd week, and of -0.31 x 153o at the 4th week. There was no statistically significance (p=0.22687579). Conclusion:Soft contact lens still produce changes after 4 weeks of removal, which could be an important factor in the predictability of any refractive surgery.
Keywords: 367 contact lens • 599 topography • 325 astigmatism