title: The ocular pulse amplitude as a noninvasive parameter for carotid artery stenosis screening: a test accuracy study.
abstract: OBJECTIVE
  To investigate a potential correlation between the ocular pulse amplitude (OPA; i.e., the intraocular pressure difference between the systolic and diastolic phases of the heartbeat) and the severity of carotid artery stenosis (CAS) and to test its role as a screening parameter for CAS during routine ophthalmic examination.
  
  
  METHODS
  Test accuracy study.
  
  
  METHODS
  Patients referred for color duplex ultrasound examination of the extra- and intracranial cerebral arteries were enrolled consecutively.
  
  
  METHODS
  We measured OPA on both eyes by dynamic contour tonometry. Multivariate analyses were performed with risk factors for CAS (age, total cholesterol, low-density lipoprotein, and triglycerides) to compare the diagnostic value of OPA measurements with other non- or minimally invasive screening parameters.
  
  
  METHODS
  The difference between OPA measurements in patients with no (<50%) and patients with severe CAS (>70%) as well as the value of OPA measurements to predict the severity of CAS taking further risk factors of CAS into consideration.
  
  
  RESULTS
  One hundred thirty-four eyes of 67 patients (25 women, 42 men) with a mean age of 67±13 years (range, 25-87) were included. The means of the OPA values of those patients showing no CAS (<50%) differed significantly (P = 0.036) from those with a stenosis of ≥70%. The multivariate model produced a statistically significant odds ratio (0.46; P = 0.007) for CAS of ≥70%.
  
  
  CONCLUSIONS
  The results of the present study provide proof of principle that the OPA is reduced in patients with CAS and may be used as a noninvasive, inexpensive, readily available, and unconfounded screening parameter to detect CAS and possibly to reduce the incidence of stroke.
  
  
  BACKGROUND
  The authors have no proprietary or commercial interest in any of the materials discussed in this article.
authors.affiliation: University Hospital Zurich, Department of Ophthalmology, Zurich, Switzerland. pascal.knecht@usz.ch
authors.forename: Pascal B
authors.initials: PB
authors.lastname: Knecht
authors.forename: Moreno
authors.initials: M
authors.lastname: Menghini
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: Ralf W
authors.initials: RW
authors.lastname: Baumgartner
authors.forename: Klara
authors.initials: K
authors.lastname: Landau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002784:Cholesterol / Q000097:blood; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D014065:Tonometry, Ocular; D014280:Triglycerides / Q000097:blood; D018616:Ultrasonography, Doppler, Duplex
chemical_list: D014280:Triglycerides; D002784:Cholesterol