title: [Comparative prospective study of 14% and 67% duty cycles of the ultrasound power with WhiteStar in the phacoemulsification cataract surgery using the nuclear preslice technique].
abstract: OBJECTIVE
  To compare the 14% and 67% duty cycles of ultrasound power, continuous module, manual pulse control in the Sovereign phacoemulsification system with WhiteStar power modulation for cataract surgery. The phacoemulsification nuclear preslice technique was used to evaluate effective ultrasound time, ultrasound percentage, salt solution amount and endothelial cell loss.
  
  
  METHODS
  This was a prospective and comparative clinical trial in 32 patients (38 eyes) with senile nuclear cataract NO3 NC3 and NO4 NC4 (LOCS III) divided into two groups: A and B. To perform the cataract surgery phacoemulsification with nuclear preslice technique, manual pulse control was used; for group A with 14% duty cycle (n=21) and group B with 67% duty cycle (n=17). Both groups were subdivided according to crystalline opaque level in two subgroups. Preoperative measures included complete ophthalmologic examination, biometry, pachymetry and specular microscopy and 3 months after surgery specular microscopy.
  
  
  RESULTS
  The surgeries that were used with the 67% duty cycle had significantly more ultrasound effective time than the 14% group in more dense cataracts. The ultrasound percentage in the 67% duty cycle, in different cataract densities, was significantly higher than in the 14% duty cycle. There was no difference in the salt solution amount used in the surgeries. There was no statistically significant difference of endothelial cell loss between both ultrasound cycles. There was a statistically significant correlation between the endothelial cell loss and the variables: ultrasound effective time (EPT) and salt solution amount used in surgeries in both cycles.
  
  
  CONCLUSIONS
  This clinical trial showed less effective time of ultrasound and ultrasound percentage in the 14% duty cycle for more dense cataracts. The salt solution amount used and the endothelial cell loss were the same in both cycles. The ultrasound effective time and the salt solution amount used in the surgery were correlated to endothelial cell loss.
authors.affiliation: Universidade de Brasília, Brasília, DF, Brasil. pereiraa@terra.com.br
authors.forename: Antonio Eduardo
authors.initials: AE
authors.lastname: Pereira
authors.forename: Ana Cláudia Alves
authors.initials: AC
authors.lastname: Pereira
authors.forename: Marcos Pereira
authors.initials: MP
authors.lastname: Avila
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification / Q000009:adverse effects / Q000379:methods*; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods