Defocus-specific contrast sensitivity

This thesis describes contrast sensitivity measurements that were made in healthy control subjects, in patients who have undergone a cataract operation, and in patients who have been treated with refractive surgery. The study is innovative in that the measurements were performed not only under wellfocused (corrected for refractive errors) conditions, but also with different amounts of defocus. As a result it was possible to discuss depth of focus and, using a theoretical eye model, calculate the spherical and irregular aberrations that are present in the human eye. Such an approach made it practicable to show the differences between healthy control subjects and patients after a cataract extraction. There were also clear differences between the healthy control subjects and the patients who underwent refractive surgery and between the subgroups undergoing different forms of refractive surgery.