title: Potential new diagnostic tool for Alzheimer's disease using a linear discriminant function for Fourier domain optical coherence tomography.
abstract: OBJECTIVE
  We calculated and validated a linear discriminant function (LDF) for Fourier domain optical coherence tomography (OCT) to improve the diagnostic ability of retinal and retinal nerve fiber layer (RNFL) thickness parameters in the detection of Alzheimer's disease (AD).
  
  
  METHODS
  We enrolled AD patients (n = 151) and age-matched, healthy subjects (n = 61). The Cirrus and Spectralis OCT systems were used to obtain retinal measurements and circumpapillary RNFL thickness for each participant. An LDF was calculated using all retinal and RNFL OCT measurements. Receiver operating characteristic (ROC) curves were plotted and compared among the LDF and the standard parameters provided by OCT devices. Sensitivity and specificity were used to evaluate diagnostic performance. A validating set was used in an independent population to test the performance of the LDF.
  
  
  RESULTS
  The optimal function was calculated using the RNFL thickness provided by Spectralis OCT, using the 768 points registered during peripapillary scan acquisition (grouped to obtain 24 uniformly divided locations): 18.325 + 0.056 × (315°-330°) - 0.122 × (300°-315°) - 0.041 × (285°-300°) + 0.091 × (255°-270°) + 0.041 × (225°-240°) + 0.183 × (195°-210°) - 0.108 × (150°-165°) - 0.092 × (75°-90°) + 0.051 × (30°-45°). The largest area under the ROC curve was 0.967 for the LDF. At 95% fixed specificity, the LDF yielded the highest sensitivity values.
  
  
  CONCLUSIONS
  Measurements of RNFL thickness obtained with the Spectralis OCT device differentiated between healthy and AD individuals. Based on the area under the ROC curve, the LDF was a better predictor than any single parameter.
authors.affiliation: Ophthalmology Department, Miguel Servet University Hospital, Zaragoza, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Larrosa
authors.forename: Elena
authors.initials: E
authors.lastname: Garcia-Martin
authors.forename: Maria P
authors.initials: MP
authors.lastname: Bambo
authors.forename: Juan
authors.initials: J
authors.lastname: Pinilla
authors.forename: Vicente
authors.initials: V
authors.lastname: Polo
authors.forename: Sofia
authors.initials: S
authors.lastname: Otin
authors.forename: Maria
authors.initials: M
authors.lastname: Satue
authors.forename: Raquel
authors.initials: R
authors.lastname: Herrero
authors.forename: Luis E
authors.initials: LE
authors.lastname: Pablo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis*; D019540:Area Under Curve; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D016002:Discriminant Analysis; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: Alzheimer's disease; OCT; logistic regression; optical coherence tomography; retinal nerve fiber layer; retinal thickness