title: Non-Invasive Detection of Anaemia Using Digital Photographs of the Conjunctiva.
abstract: OBJECTIVE
  Anaemia is a major health burden worldwide. Although the finding of conjunctival pallor on clinical examination is associated with anaemia, inter-observer variability is high, and definitive diagnosis of anaemia requires a blood sample. We aimed to detect anaemia by quantifying conjunctival pallor using digital photographs taken with a consumer camera and a popular smartphone. Our goal was to develop a non-invasive screening test for anaemia.
  
  
  METHODS
  The conjunctivae of haemato-oncology in- and outpatients were photographed in ambient lighting using a digital camera (Panasonic DMC-LX5), and the internal rear-facing camera of a smartphone (Apple iPhone 5S) alongside an in-frame calibration card. Following image calibration, conjunctival erythema index (EI) was calculated and correlated with laboratory-measured haemoglobin concentration. Three clinicians independently evaluated each image for conjunctival pallor.
  
  
  RESULTS
  Conjunctival EI was reproducible between images (average coefficient of variation 2.96%). EI of the palpebral conjunctiva correlated more strongly with haemoglobin concentration than that of the forniceal conjunctiva. Using the compact camera, palpebral conjunctival EI had a sensitivity of 93% and 57% and specificity of 78% and 83% for detection of anaemia (haemoglobin < 110 g/L) in training and internal validation sets, respectively. Similar results were found using the iPhone camera, though the EI cut-off value differed. Conjunctival EI analysis compared favourably with clinician assessment, with a higher positive likelihood ratio for prediction of anaemia.
  
  
  CONCLUSIONS
  Erythema index of the palpebral conjunctiva calculated from images taken with a compact camera or mobile phone correlates with haemoglobin and compares favourably to clinician assessment for prediction of anaemia. If confirmed in further series, this technique may be useful for the non-invasive screening for anaemia.
authors.affiliation: Wellington School of Medicine, University of Otago, Wellington, New Zealand.|Malaghan Institute of Medical Research, Wellington, New Zealand.
authors.forename: Shaun
authors.initials: S
authors.lastname: Collings
authors.affiliation: Sensing and Automation Group, Callaghan Innovation, Lower Hutt, New Zealand.
authors.forename: Oliver
authors.initials: O
authors.lastname: Thompson
authors.affiliation: Sensing and Automation Group, Callaghan Innovation, Lower Hutt, New Zealand.
authors.forename: Evan
authors.initials: E
authors.lastname: Hirst
authors.affiliation: Photography Department, Capital & Coast District Health Board, Wellington, New Zealand.
authors.forename: Louise
authors.initials: L
authors.lastname: Goossens
authors.affiliation: Wellington Blood & Cancer Centre, Capital & Coast District Health Board, Wellington, New Zealand.
authors.forename: Anup
authors.initials: A
authors.lastname: George
authors.affiliation: Malaghan Institute of Medical Research, Wellington, New Zealand.|Wellington Blood & Cancer Centre, Capital & Coast District Health Board, Wellington, New Zealand.|Department of Pathology & Molecular Medicine, University of Otago Wellington, Wellington, New Zealand.
authors.forename: Robert
authors.initials: R
authors.lastname: Weinkove
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000175:diagnosis*; D003228:Conjunctiva / Q000473:pathology*; D003430:Cross-Sectional Studies; D004890:Erythema / Q000473:pathology; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D015588:Observer Variation; D010167:Pallor / Q000473:pathology; D010781:Photography / Q000379:methods*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D000068997:Smartphone
chemical_list: D006454:Hemoglobins