title: Interobserver variability of an open-source software for tear meniscus height measurement.
abstract: OBJECTIVE
  Different values of the lower tear meniscus height (TMH) can be obtained depending on the method and technique of measurement employed. The aim of this study was to analyse the interobserver variability of a method for measuring TMH by using an open source software.
  
  
  METHODS
  On a group of 176 subjects, two videos of the central lower tear meniscus, first under slit-lamp illumination and ten minutes later under Tearscope illumination, were generated by a digital camera attached to a slit-lamp. Images were extracted from each video by a masked observer. Two further observers measured in a masked and randomized order the TMH in each illumination method by using an open source software based on Java (NIH ImageJ). TMH was measured from the lower lid to the upper limit of the tear meniscus for both slit-lamp (TMH-SL) and Tearscope (TMH-Tc) illumination methods. Subsequently, in different order, observers assigned a four-grading and a healthy/abnormal subjective classification to each central meniscus.
  
  
  RESULTS
  No significant differences were found between the TMH measurements obtained by both investigators in slit-lamp or Tearscope image datasets (t-test; both p≥0.136). When comparing TMH measurements stratified by grade, only interobserver significant differences were observed for grades 3 and 4 with silt-lamp (t-test; both p≤0.009). Significant differences on TMH results between subjective subgroups were observed for both illumination techniques (ANOVA, all p≤0.045).
  
  
  CONCLUSIONS
  This study showed a useful tool to objectively measure TMH by photography.
authors.affiliation: Departamento de física aplicada (Grupo de Optometría GI-2092), Universidade de Santiago de Compostela, Campus vida s/n, Santiago de Compostela 15782, Galicia, Spain. Electronic address: hugo.pena@rai.usc.es.
authors.forename: Hugo
authors.initials: H
authors.lastname: Pena-Verdeal
authors.affiliation: Departamento de física aplicada (Grupo de Optometría GI-2092), Universidade de Santiago de Compostela, Campus vida s/n, Santiago de Compostela 15782, Galicia, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Garcia-Resua
authors.affiliation: Departamento de Computación (Grupo VARPA), Universidade da Coruña, Campus de Elviña s/n, A Coruña 15071, Galicia, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Barreira
authors.affiliation: Departamento de física aplicada (Grupo de Optometría GI-2092), Universidade de Santiago de Compostela, Campus vida s/n, Santiago de Compostela 15782, Galicia, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Giraldez
authors.affiliation: Departamento de física aplicada (Grupo de Optometría GI-2092), Universidade de Santiago de Compostela, Campus vida s/n, Santiago de Compostela 15782, Galicia, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Yebra-Pimentel
mesh_terms: D000293:Adolescent; D000328:Adult; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066167:Slit Lamp; D000072776:Slit Lamp Microscopy / Q000295:instrumentation / Q000379:methods*; D012984:Software; D012986:Software Validation; D013666:Tears / Q000166:cytology* / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: ImageJ software; Slit-lamp; Tear film; Tear meniscus height; Tearscope