title: Quantification of topological changes in retinal vascular architecture in essential and malignant hypertension.
abstract: OBJECTIVE
  Grading of hypertension severity by fundoscopic appearance is difficult and inaccurate. We investigated whether essential hypertension (EHT) and malignant phase hypertension (MHT) were associated with quantifiable abnormalities of the topology and architecture of the retinal circulation.
  
  
  METHODS
  The topology and architecture of the retinal microvasculature were compared in images from 20 normotensive subjects, 20 patients with EHT and 20 patients with MHT. Digitized retinal photographs were analysed by a novel multiscale image analysis method using a semi-automated program to quantify geometrical and topological properties of arteriolar and venular trees.
  
  
  RESULTS
  EHT was associated with an increase in the arteriolar length-to-diameter ratio (P < 0.01). There were also alterations in arteriolar topology indicative of rarefaction, including a marked reduction in the number of terminal branches in EHT (P < 0.01). These changes in the arteriolar network were exaggerated in MHT and there was also increased venular tortuosity and venular rarefaction in MHT compared with normotensive subjects.
  
  
  CONCLUSIONS
  Hypertension is associated with marked topological alterations in the retinal vasculature, and quantification of these changes may be a useful novel approach to the assessment of target organ damage in hypertension.
authors.affiliation: Clinical Pharmacology, NHLI Division, Faculty of Medicine, Imperial College London, UK. a.hughes@imperial.ac.uk
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.forename: Elena
authors.initials: E
authors.lastname: Martinez-Perez
authors.forename: Abu-Sufian
authors.initials: AS
authors.lastname: Jabbar
authors.forename: Assif
authors.initials: A
authors.lastname: Hassan
authors.forename: Nick W
authors.initials: NW
authors.lastname: Witt
authors.forename: Paresh D
authors.initials: PD
authors.lastname: Mistry
authors.forename: Neil
authors.initials: N
authors.lastname: Chapman
authors.forename: Alice V
authors.initials: AV
authors.lastname: Stanton
authors.forename: Gareth
authors.initials: G
authors.lastname: Beevers
authors.forename: Roberto
authors.initials: R
authors.lastname: Pedrinelli
authors.forename: Kim H
authors.initials: KH
authors.lastname: Parker
authors.forename: Simon A McG
authors.initials: SA
authors.lastname: Thom
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D006801:Humans; D006973:Hypertension / Q000473:pathology*; D006974:Hypertension, Malignant / Q000473:pathology*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D012171:Retinal Vessels / Q000473:pathology*