Abstract
Purpose: :
Theoretical calculations on IOL optics demonstrate superior visual acuity and contrast sensitivity achieved by spherical aberration correcting optics. According to the same calculations a disadvantage of this optic design is a lower focal depth. This study was performed to validate these theoretical findings clinically.
Methods: :
Six aberration-free IOL types (Acritec, Bausch&Lomb, Domilens, Corneal, Rayner, T.med), five aberration-correcting IOL types (Acritec, AMO, Alcon, Hoya, Zeiss) and one contol IOL (Alcon SA60AT) were tested. 30 IOLs per type were implanted in 195 patients intraindividually randomized. Contrast sensitivity was determined by FACT analysis under photopic and scotopic conditions. Focal depth was detected by defocusing best corrected visual acuity +/- 2.5 D in 0.5 D steps.
Results: :
Aberration-correcting IOLs showed the best visual acuities, 0.91 in average, followed by aberration free IOLs (0.89) and the control group (0.88). In contrast to theoretical findings no significant differences in focal depth were proven clinically. Aberration-correcting IOLs showed a significantly improved contrast sensitivity in scotopic vision. However, no significant differences were detected between the other two groups. Analogous tendencies were found under photopic conditions but differences were much smaller here.
Conclusions: :
The sharp focus of an aberration-correcting IOL results clinically in an excellent visual acuity and in improved contrast sensitivity especially pronounced under scotopic conditions. The human visual system seems to enable eye and cortex to compensate for the slight theoretical disadvantage in focal depth.
Clinical Trial: :
Ethics commitee of Saarland, No. 74/07
Keywords: intraocular lens • contrast sensitivity