title: Unsupervised machine learning with independent component analysis to identify areas of progression in glaucomatous visual fields.
abstract: OBJECTIVE
  To determine whether a variational Bayesian independent component analysis mixture model (vB-ICA-mm), a form of unsupervised machine learning, can be used to identify and quantify areas of progression in standard automated perimetry fields.
  
  
  METHODS
  In an earlier study, it was shown that a model using vB-ICA-mm can separate normal fields from fields with six different patterns of visual field loss related to glaucomatous optic neuropathy (GON) along maximally independent axes. In the present study, an independent group of 191 patient eyes (66 with ocular hypertension (OHT), 12 with suspected glaucoma by field, 61 with suspected glaucoma by disc, and 52 with glaucoma) with five or more standard visual fields under observation for a mean of 6.24 +/- 2.65 years and 8.11 +/- 2.42 visual fields were evaluated with the vB-ICA-mm. In addition, eyes with progressive GON (PGON) were identified (n = 39). Each participant had a series of fields tested, with each field entered independently and placed along the axes of the previously developed model. This allowed change in one pattern of visual field defect (along one axis) to be assessed relative to results other areas of that same field (no change along other axes). Progression was based on a slope falling outside the 5th and the 95th percentile limits of all slopes, with at least two axes not showing such a deviation in a given individual's series of fields. Fields were also scored using Advanced Glaucoma Intervention Study (AGIS) and the Early Manifest Glaucoma Treatment Trial (EMGT) criteria.
  
  
  RESULTS
  Thirty-two of 191 eyes progressed on vB-ICA-mm by this definition. Of the 32, 22 had field loss at baseline, 7 had only GON, 3 were OHTs and 12 were from the 39 eyes (31%) with PGON. The vB-ICA-mm identified a higher percentage of progressing eyes in each diagnostic category than did AGIS or and the EMGT.
  
  
  CONCLUSIONS
  The vB-ICA-mm can quantitatively identify progression in eyes with glaucoma by evaluating change in one or more patterns of the visual field loss while other areas or patterns remain stable. This may enable each eye to contribute to the determination of whether change is caused by true progression or by variability.
authors.affiliation: Visual Function, Department of Ophthalmology, University of California, La Jolla, 92093, USA. psample@glaucoma.ucsd.edu
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Sample
authors.forename: Catherine
authors.initials: C
authors.lastname: Boden
authors.forename: Zuohua
authors.initials: Z
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Pascual
authors.forename: Te-Won
authors.initials: TW
authors.lastname: Lee
authors.forename: Linda M
authors.initials: LM
authors.lastname: Zangwill
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Crowston
authors.forename: Esther M
authors.initials: EM
authors.lastname: Hoffmann
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
authors.forename: Terrence
authors.initials: T
authors.lastname: Sejnowski
authors.forename: Michael
authors.initials: M
authors.lastname: Goldbaum
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001185:Artificial Intelligence; D003941:Diagnostic Techniques, Ophthalmological; D018450:Disease Progression; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D014786:Vision Disorders / Q000175:diagnosis*; D058609:Visual Field Tests; D014794:Visual Fields