Changes in contrast sensitivity functions after photo refractive keratectomy and laser in situ keratomileusis
Aim: To evaluate the visual function in tenus of changes in contrast sensitivity following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).
Materials and Methods: Distant and near contrast sensitivity functions were tested in 36 eyes that had undergone PRK and 31 eyes that had undergone LASIK respectively. Only those eyes that retained pre-operative best corrected visual acuity were included in the study. The pre-operative refractive errors ranged from -1.75 to -7.75 diopters.
Results: Post-operatively, all patients had best corrected visual acuity of 1.0 or better. Contrast sensitivity was reduced in the first few months following the operations. The greatest reduction in contrast sensitivity occurred at the intermediate spatial frequencies. Contrast sensitivity returned to the pre-operative baseline level at 12 months and 6 months following PRK and LASIK respectively.
Conclusion: There is a transient reduction in contrast sensitivity, especially at the intermediate spatial frequencies, after PRK and LASIK. The restoration of contrast sensitivity is faster in those underwent LASIK than PRK.
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