The aim of this study was to compare the anatomical and clinical outcomes of cataract surgery on lenses with moderate and severe nuclear hardness by pulse mode phacoemulsification with different frequencies.

127 patients with moderate and severe lens hardness were recruited; (69 with moderate and 58 with severe nuclear hardness). Patients were randomly assigned into one of these two groups: Group 1 who were operated with frequency 10 and group 2 operated with frequency 60 pulses per second (pps) (63 and 60 patients, respectively). Best corrected visual acuity (BCVA), endothelial cell count, corneal edema, central corneal thickness (CCT) and effective phaco time (EPT) were evaluated according to a fixed timetable.

The results of this study showed a statistically significant relation between lens hardness and the final anatomical and visual outcomes; patients with moderate lens hardness had better BCVA (p<0.001), less endothelial cell loss (p=0.034) and shorter Effective phaco time (EPT) (p<0.001). EPT was shorter in group operated with 10 PPS phacoemulsification (p=0.18).Applied frequency also had a statistically significant effect on clinical outcomes; patients operated with frequency of 10 pps had better BCVA (p<0.001) and less corneal edema (p<0.001). CCT was only related with time and increased during the study course from each follow up visit to the other.

The surgical, anatomical and visual outcomes with respect to endothelial cell loss and improvement in visual acuity was better in cases with moderate nuclear hardness and also effective phaco time was shorter in this group. The use of pulsed-phacoemulsification of 10 pps was accompanied with better outcomes including visual acuity improvement, less corneal edema and shorter effective phaco time.