High-frequency-ultrasound Annular Arrays for Ophthalmic Imaging
Condition: Posterior Vitreous Detachment
MeSH terms: Vitreous Detachment
Study type: Observational

Summary: 
      The objective of this research is to improve the care of ocular disease and disorders, in
      particular the changes in the eye associated with diabetes, by providing clinicians with
      dramatically improved ultrasonic images of the entire eye. The research combines advanced
      high-frequency, high-resolution ultrasonic annular arrays transducers with new processing
      techniques designed to overcome several limits that have been reached with conventional
      high-frequency ultrasound systems. We propose that diagnosis of eye diseases using annular
      arrays can be more effective than the conventional ultrasound images by at least 50%; i.e.,
      that for every 2 posterior vitreous detachments detected conventionally, 3 will be detected
      with the annular arrays.
    

Detailed description: 
      In this study, we will deploy annular-array systems and assess their experimental and
      clinical utility for ophthalmic imaging. We hypothesize that a 20-MHz annular array will
      detect posterior vitreous detachment (PVD) more reliably than a conventional single element
      ultrasound system. Clinically, we will test the hypothesis that 20-MHz annular arrays improve
      detection of PVD, an important risk factor for disease progression in diabetic retinopathy.
      Diabetic retinopathy is the leading cause of blindness in the working population (25 to 65
      years) and the third major cause of legal blindness in the U.S.

      We propose to carry out a study of 30 human subjects, aged 60 years or above, in whom PVD is
      likely to be present as a consequence of normal aging. The study will compare the ability to
      detect PVD using a commercial ophthalmic ultrasound system equipped with 10- and 20-MHz
      sector scan probes (Cinescan A/B-S, Quantel Medical), and OCT (OCT/SLO, Ophthalmic
      Technologies, Inc.), and the 20-MHz annular array. The annular array will be used with
      synthetic focusing and simulated single-element mode. The end point will be the fraction of
      eyes in which the PVD is visualized with each technique. This comparison is designed to
      demonstrate the improvement in our ability to visualize this pathologic entity using the
      advanced signal processing modes to be explored in this study. PVD can represent a risk
      factor for retinal detachment and retinal neovascularization in diabetics and localization of
      vitreoretinal traction points may be crucial for management. The present study, however, is
      limited to visualization of PVD in older normal subjects, about 75% of which would be
      expected to have PVD present. Thus, our aim is purely to develop an improved imaging modality
      rather than demonstrating its clinical efficacy in management of diabetic retinopathy or
      other ocular diseases.

      The imaging technologies that we are developing could potentially result in patents or other
      intellectual property, which would be managed by the Cornell Research Foundation and
      Riverside Research Institute. This is alluded to in the consent form for the sake of
      completeness.
    

Intervention name(s): Ultrasound examination
Intervention type(s): Procedure
Intervention description(s): Immersion Ultrasound Exam: In the immersion technique, the patient lies down on the examination table. A steridrape with a central aperture is used to form a water-tight seal around the eye. After installation of 2 drops of 0.5% proparacaine HCl, a wire lid speculum is used to hold the patient's lids open. Warm 0.9% sterile saline solution is then used to create a waterbath about 1/2 inch deep to provide acoustic coupling between the transducer and the eye. The transducer (either the 10- and 20-MHz sector scan probe or the annular array) is placed in the waterbath, but does not touch the eye.
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Ophthalmology practice
      
Keywords: annular array ultrasound; ophthalmic ultrasound; posterior vitreous detachment (PVD)