title: Phenotypes of orthostatic blood pressure behaviour and association with visual acuity.
abstract: BACKGROUND
  Manifestations of neurocardiovascular instability (NCVI), including orthostatic hypotension (OH) orthostatic hypertension (OHTN) and impaired blood pressure variability (BPV), have been associated with cardiovascular (CV) events. The eye is highly vascular and we propose an ideal target end organ to investigate pathological implications of NCVI.
  
  
  OBJECTIVE
  To identify and define clinically applicable phenotypes of orthostatic blood pressure (BP) behaviour, analogous to OH, OHTN, and orthostatic BPV and to investigate their relationship to vision.
  
  
  METHODS
  Wave one data from the Irish Longitudinal Study on Ageing (TILDA) were used. Orthostatic BP (OBP) phenotypes were identified and defined from beat-to-beat BP data, measured by digital photoplethysmography during an active stand (AS) lasting 110 s (s). Visual acuity (VA) was assessed using the Early Treatment Diabetic Retinopathy Study (EDTRS) LogMAR chart. The relationship between OBP phenotypes and VA in 4355 adults aged ≥50 years was investigated through multivariate linear regression models.
  
  
  RESULTS
  There was a wide fluctuation in the prevalence of OH and OHTN up to 20 s after standing. After 30 s, four distinct OBP phenotypes were identified: in 70 % BP stabilised to within 20/10 mmHg of baseline BP, 4 % had persistent OH, 2 % had persistent OHTN and 25 % had exaggerated orthostatic blood pressure variability BPV. Systolic BPV was associated with worse VA (P = 0.02) as was diastolic BPV (P = 0.03), following adjustment for demographics, health behaviours, self-report eye diseases and diabetes, uncorrected refractive error, objective hypertension and antihypertensives.
  
  
  CONCLUSIONS
  The hypothesis that NCVI may independently modulate CV risk is supported the independent association of exaggerated BPV and worse VA.
authors.affiliation: Department of Medical Gerontology, School of Medicine, Trinity College Dublin, Trinity Centre for Health Sciences, St James's Hospital, Old Stone Building, James's Street, Dublin 8, Ireland. nibhuacb@tcd.ie.
authors.forename: Bláithín
authors.initials: B
authors.lastname: Ní Bhuachalla
authors.affiliation: The Irish Longitudinal Study on Ageing (TILDA), Trinity College Dublin, College Green, Lincoln Gate, Dublin 2, Ireland. Christine.McGarrigle@tcd.ie.
authors.forename: Christine A
authors.initials: CA
authors.lastname: McGarrigle
authors.affiliation: Macular Pigment Research Group, Vision Research Centre Carriganore House, Waterford Institute of Technology, Waterford, Ireland. kakuffo@wit.ie.
authors.forename: Kwadwo Owusu
authors.initials: KO
authors.lastname: Akuffo
authors.affiliation: Department of Research and Development, National Institute of Health Research Biomedical Research Centre at Moorfields Eye Hospital National Health Service Foundation Trust and UCL Institute of Ophthalmology, London, UK. Tunde.Peto@moorfields.nhs.uk.
authors.forename: Tunde
authors.initials: T
authors.lastname: Peto
authors.affiliation: Macular Pigment Research Group, Vision Research Centre Carriganore House, Waterford Institute of Technology, Waterford, Ireland. sbeatty@wit.ie.
authors.forename: Stephen
authors.initials: S
authors.lastname: Beatty
authors.affiliation: Department of Medical Gerontology, School of Medicine, Trinity College Dublin, Trinity Centre for Health Sciences, St James's Hospital, Old Stone Building, James's Street, Dublin 8, Ireland. rkenny@tcd.ie.|The Irish Longitudinal Study on Ageing (TILDA), Trinity College Dublin, College Green, Lincoln Gate, Dublin 2, Ireland. rkenny@tcd.ie.
authors.forename: Rose Anne
authors.initials: RA
authors.lastname: Kenny
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007024:Hypotension, Orthostatic / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D007494:Ireland / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D014792:Visual Acuity / Q000502:physiology*
keywords: Blood pressure variability; End-organ damage; Eye; Orthostatic hypertension; Orthostatic hypotension; Visual acuity