title: Discrimination between surgical and nonsurgical nuclear cataracts based on ROC analysis.
abstract: OBJECTIVE
  The aim of this article is to propose a quantitative methodology for determining a criterion to discriminate the nonsurgical nuclear cataract from the surgical one taking into account objective measures of intraocular scattering in patients with good visual acuity (>0.6).
  
  
  METHODS
  Two groups of subjects were taken into account: a control group and a group with nuclear cataracts. At a first stage, eyes belonging to the cataract group were classified into "nonsurgical" and "surgical" cataracts by ophthalmologists at their clinical settings. At a second stage a double-pass instrument was also used to determine the objective scatter index (OSI) at the laboratory. Receiver operating characteristic (ROC) curves were used to analyze OSI values to determine a value able to separate between nonsurgical and surgical cataracts.
  
  
  RESULTS
  We obtained statistically significant differences among the control and both nuclear cataract groups (p < 0.05). ROC curves determined an OSI criterion level (of 2.1) to suggest surgery in nuclear cataracts with an area under curve of 0.83, i.e. with 80% of sensitivity and 80% of specificity.
  
  
  CONCLUSIONS
  ROC analysis allows separating both groups of nuclear cataract, and we determined a value of OSI in nuclear cataract quantification for surgery.
authors.affiliation: Departamento de Luminotecnia, Luz y Visión, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán , Tucumán , Argentina .
authors.forename: Clemente Paz
authors.initials: CP
authors.lastname: Filgueira
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Sánchez
authors.forename: Elisa M
authors.initials: EM
authors.lastname: Colombo
authors.forename: Meritxell
authors.initials: M
authors.lastname: Vilaseca
authors.forename: Jaume
authors.initials: J
authors.lastname: Pujol
authors.forename: Luis A
authors.initials: LA
authors.lastname: Issolio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000145:classification / Q000175:diagnosis*; D002387:Cataract Extraction; D006801:Humans; D007907:Lens Nucleus, Crystalline / Q000473:pathology* / Q000528:radiation effects; D008027:Light; D008875:Middle Aged; D012372:ROC Curve; D012542:Scattering, Radiation; D014792:Visual Acuity; D055815:Young Adult
keywords: ROC analysis; Surgical nuclear cataract; double-pass instrument; objective scattering index