title: The Brückner transillumination test: limited detection of small-angle esotropia.
abstract: OBJECTIVE
  To evaluate the sensitivity of the Brückner test in detecting esotropia of 2° to 10° by interocular asymmetry of the red fundus reflex.
  
  
  METHODS
  Single-blinded evaluation of the diagnostic test.
  
  
  METHODS
  Five blinded observers and 20 isometropic orthotropes.
  
  
  METHODS
  Set-up 1 included monocular evaluation of the Brückner reflex test for each eye of 10 subjects. The subjects alternated fixation between an ophthalmoscope light and an eccentric target (2.5°, 5°, 7.5°, and 10°). Set-up 2 comprised simulation of esotropia of 2° to 5°, 7.5°, and 10° by base-in prisms placed in front of both eyes of 20 subjects. The subjects fixated with either their right or left eye. As a control experiment, 0.5° base-in prisms were used.
  
  
  METHODS
  Set-up 1 tested the sensitivity in detecting a change in reflex between central and eccentric retinal illumination. Set-up 2 tested the sensitivity and specificity in detecting asymmetry of the Brückner reflex between the 2 eyes as a dimming of the reflex of the fixating eye in a 2° to 10° simulated esotropia.
  
  
  RESULTS
  In set-up 1, fixation of the ophthalmoscope light owing to foveal dimming was discriminated from fixation of the eccentric target in 98.2% of the trials, regardless of target eccentricity. In set-up 2, esotropia of 2° to 5° was detected in 62% of 100 trials by red reflex asymmetry. Dimming of the reflex in the fixating eye was found in 48% of 100 trials. Esotropia of 7.5° and 10° was detected in 85% and 97% of the trials, respectively. Dimming in the fixating eye was present in 75% and 86% of the trials, respectively. Thirty-six percent of the 300 control tests were false-positives.
  
  
  CONCLUSIONS
  When the eccentric fundus reflex was compared with the central reflex in the same eye, dimming owing to central fixation of the ophthalmoscope was reliably detected. However, comparison of the eccentric red reflex in the strabismic eye with the central reflex in the fixating eye showed that the Brückner red reflex test was not suitable for detecting small angles of squint.
  
  
  BACKGROUND
  The authors have no proprietary or commercial interest in any of the materials discussed in this article.
authors.affiliation: Department of Ophthalmology, Justus-Liebig-University, Giessen, Germany. michael.h.graef@augen.med.uni-giessen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Gräf
authors.forename: Qasem
authors.initials: Q
authors.lastname: Alhammouri
authors.forename: Christian
authors.initials: C
authors.lastname: Vieregge
authors.forename: Birgit
authors.initials: B
authors.lastname: Lorenz
mesh_terms: D000293:Adolescent; D000328:Adult; D003941:Diagnostic Techniques, Ophthalmological; D058453:Emmetropia / Q000502:physiology; D004948:Esotropia / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D009216:Myopia / Q000150:complications; D019721:Ophthalmoscopes; D011237:Predictive Value of Tests; D012025:Reflex, Pupillary; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D055815:Young Adult