title: Universal opacity standard for Scheimpflug photography.
abstract: OBJECTIVE
  To develop a universal standard for comparison of the results from different studies using Scheimpflug photography.
  
  
  METHODS
  A suspension including polystyrene spheres was selected as the universal standard. The polystyrene suspension was diluted into 10 concentrations by adding spectroscopic quality water. An artificial eye chamber was designed to hold the diluted suspension for photography. Each concentration was photographed by both a Topcon SL-45 slit-lamp camera and a Nidek EAS-1000 system. The intensity of back-scattered light was analyzed statistically.
  
  
  RESULTS
  The relationship between the concentration of the polystyrene suspension and the internal gray scale step within the Topcon SL-45 camera can be described by a second-order polynomial. The relationship between the concentration of the polystyrene suspension and the measurement of the Nidek EAS-1000 system can also be expressed by a second-order polynomial. The relationship between the Topcon SL-45 camera and the Nidek EAS-1000 system is linear.
  
  
  CONCLUSIONS
  The results of lens nuclear opacity measured with different Scheimpflug cameras can be compared using the method established in the study. The linear relationship between the Topcon SL-45 and Nidek EAS-1000 systems can be used to convert measurements from one system to the other.
authors.affiliation: Research Laboratory, St. Erik's Eye Hospital, Karolinska Institutet, Stockholm, Sweden. wen@brain.ste.ki.se
authors.forename: W
authors.initials: W
authors.lastname: Qian
authors.forename: P
authors.initials: P
authors.lastname: Söderberg
authors.forename: E
authors.initials: E
authors.lastname: Chen
authors.forename: B
authors.initials: B
authors.lastname: Philipson
mesh_terms: D000867:Anterior Chamber; D002386:Cataract / Q000145:classification* / Q000473:pathology; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards*; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology; D008027:Light; D008863:Microspheres; D008953:Models, Anatomic; D010781:Photography / Q000592:standards*; D011137:Polystyrenes; D012542:Scattering, Radiation
chemical_list: D011137:Polystyrenes