Automatic Image Analyzer to Assess Retinal Vessel Caliber
Condition: Cardiovascular Risk Factor
Study type: Observational

Summary: 
      The objective of this work is the development and validation (reliability and validity) of
      the Automatic image analyzer to assess it retinal vessel caliber (ALTAIR) platform to analyze
      and validate its utility in different clinical settings.

      Methods / Design Design : In the first phase , will be a cross- sectional study and a second
      phase will be a prospective observational study with annual follow-up for 4 years. The study
      will be conducted in primary care including 386 subjects. Main measurements: blood pressure,
      carotid intima-media thickness using carotid ultrasound , central blood pressure and wave
      velocity pulse by SphygmoCor system, Cardio-ankle vascular index (CAVI) by VASERA® VS1500 ,
      evaluation of hypertrophy ventricular using a digital ECG and renal injury . Retinal vascular
      evaluation will be done by a non-mydriatic TOPCON TRCNW200 getting focused papilla, nasal and
      temporal and developed by software images automatically calculate the thickness of the
      retinal vessels , the arteriovenous index, the vascularized area and branching pattern . For
      validation software retina intra and inter - observer variability , the correlation of the
      tool measurement with AVindex , and concurrent validity with parameters of vascular structure
      and function and target organ damage and association analysis will analyze the different
      parameters of the estimated retina and evolution or appearance of new lesions in the target
      organs.

      Discussion The validation of the tool contribute to the analysis of retinal vessels improved
      reliability by reducing the intervention of the observer and further validate the use of more
      information than the previously used , especially surface vascularization and vessel
      branching patterns .
    

Detailed description: 
      Design and setting In the first phase, will be an observational descriptive study, with the
      primary objective of validating the instrument developed. Later, in a second phase will be a
      prospective observational study, with annual follow-up for 4 years. The study will be
      conducted in the field of primary care.

      The study population will be subject 30 to 75 years with a cardiovascular risk factor defined
      by the European Hypertension Guide 2013 and does not meet any of the defined exclusion
      criteria: patients who can not comply with the requirements of the protocol due to mental and
      / or cognitive impairment, no partners, educational and understanding limitations and severe
      comorbidity that would endanger his life in the next 12 months. By consecutive sampling of
      all patients referred to the research unit for assessment of cardiovascular risk, their
      participation is requested from those who meet the inclusion criteria and have no reason for
      exclusion to the size of the estimated sample.

      Sample size was estimated to detect a correlation coefficient between velocity and the pulse
      wave parameters retinal 0.15, alpha risk of 0.05 and a beta risk of 0.20, and an estimated
      loss by difficulty technical or abandonment of monitoring 10%, so 386 subjects, who will be
      included in the study required.

      Software Validation retina For validation of the retina software Follow these steps after a
      previous training of evaluators who will make the evaluation of the images . 1 - intra-
      observer variability . Assessing the repeatability of the measurement, an operator must
      measure the same picture in the same individual, at least twice. To do this, an operator will
      evaluate 100 images of a random subsample of 50 patients with a gap of one week between the
      two embodiments . In this case , the operator and the images analyzed are the same on both
      days and will not have information on the previous assessment . 2 - inter-observer
      variability . To assess the reproducibility of the measurement system , a new operator,
      different from phase 1, evaluated the same 100 images previously analyzed . This operator
      will ignore the results that have been obtained in the previous phase. The two operators have
      the same experience in the field and in the use of software , in addition, both receive the
      same previous training. 3.- And with retina developed software program provides the results
      on the evaluation of arterial / venous , thickness of the vein and the artery index. To
      assess the degree of agreement between the two methodologies (AVindex ) valuation of 100
      images were made with the two tools . In this way, we can show that the new method and
      provides the same results improves daily practice having more objective and faster processing
      of results. 4.- The validity of the measurement was analyzed in the total sample, 386 and 772
      subjects fundus , analyzing the relationship of the results to the carotid intima-media
      thickness as a measure of vascular structure , the speed of the pulse wave as measure of
      vascular function and arterial stiffness gold standard (arterial stiffness ) in Cardio Ankle
      vascular Index , renal function , and electrocardiographic parameters estimated with the
      Framingham cardiovascular risk. 5.- also the association of the different parameters of the
      estimated retina and evolution or appearance of new lesions in target organs and
      cardiovascular monitoring of patients during the four years of the second phase of this
      project will be analyzed events
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        386 subjets of 30 to 75 years
      
Keywords: Vascular stiffness, retinal vessels, target organ damage