Vitreous Chemistry Analysis
Condition: Normal Volunteers
Study type: Observational

Summary: 
      The aim of this study is to expand the understanding of the vitreous, its solute chemistry,
      and the normal relationship of that chemistry to the chemistry of the systemic circulation in
      humans.

      Sample human vitreous from patients undergoing vitrectomy surgery and compare to results of
      metabolic chemistry panel from subject.

      Allow the research team to extract .2ml sample of the .5ml - 1.0ml vitreous that is normally
      extracted during a routine undiluted vitreous biopsy, a standard procedure performed for
      various indications. Blood draw for metabolic chemistry panel (1-2 ml).
    

Detailed description: 
      The proposed method for obtaining antemortem vitreous samples is during an otherwise
      scheduled vitrectomy surgery that is being performed for a medically necessary indication.
      Virectomy surgery is a commonly performed eye surgery during which the vitreous humor is
      removed from the eye. Three ports are created through the sclera for access into the eye. One
      port is for a light to provide illumination for visualization, one port is for the vitrector,
      which simultaneously aspirates the vitreous and cuts its intrinsic fibers, and one port is
      for an infusion line which keeps the eye inflated with saline as the vitreous humor is
      removed. typically the aspiration is performed automatically by the vitrectomy machine. For
      an undiluted vitreous biopsy, which is standard procedure performed for various indications,
      the technique must be slightly modified. In particular, the infusion line is not turned on
      initially to avoid diluting the specimen with saline fluid. The vitrector aspiration line is
      connected to a syringe instead of the vitrectomy machine, and the syringe is used to both
      manually provide the aspiration and to collect the undiluted specimen. As soon as an adequate
      volume is collected, the infusion line is turned on and the aspiration line is reconnected to
      the vitrectomy machine. Volumes of 0.5 to 1.0 ml are routinely collected with this technique.

      Subjects will be enrolled from adult patient already undergoing vitrectomy surgery for
      various retinal conditions. Only one eye per subject will be enrolled and the enrollment
      target for the first year is 50 subjects.

      Specimens would be obtained during the subject's otherwise planned vitrectomy. The vitrectomy
      would be started in the usual way, except that the standard modifications would be made for
      an undiluted vitreous biopsy as discussed above. A 0.2 mL sample would be obtained during the
      vitreous biopsy. This is the smallest sample the hospital laboratory can analyze and is
      smaller than what is typically obtained during an undiluted vitreous biopsy.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Ophthalmology Clinic
      
Biospecimen description: 
      Vitreous fluid whole blood
    
Keywords: Virectomy