Binocular Indirect Ophthalmoscopy (BIO) (Thanks to Heine for BIO photo)

I.    Purpose
  A.    To view the fundus from the posterior pole to the periphery
  B.    With experience, can view the entire retina
  C.    Provides a minified, high resolution, stereoscopic view of the
fundus
    i.    Able to visualize the "Forest instead of the trees"

II.   Instrumentation
  A.    Viewing Oculars
    i.    Headmount settings:  Straight & Level
    ii.   P.D. setting (very important)
    iii.  Panascopic tilt to spectacle plane
  B.    Illumination
    i.    Light source:  set rheostat at 1/2 power or less to begin  
    ii.   Aperture and filters
      a.    Use larger aperture except on small pupils or when excessive 
            glare cannot be eliminated)
      b.    Use white light (no filter) initially as opposed to filters 
            to alter contrast
    iii.  Mirror: adjusts light to meet visual axis at working distance
  C.    +20 D. lens (or equivalent) (double aspheric lens)
    i.    Magnification:  60D / 20D = 2.5 to 3X mag for BIO
    ii.   VS.             60D / 4  = 15X mag for direct: simple magnifier
    iii.  Focal length:   1 / 20D  = 5.0 cm
    iv.   Working Dist:   16 - 20 inches
  D.     Image produces is real, inverted and reversed: floating in space
between condensing lens and headset

III.  Technique                                
  A.    Recline patient 
    i.    Raise to waist high or slightly lower
    ii.   Adjust patient headrest for comfort
  B.    180 degree technique
    i.    Stand on temporal side of patient
      a.    You will be moving nasal
      b.    Macula will be temporal and you will be moving away
      c.    Macula should be the last area viewed in the BIO procedure
    ii.   Patient to look straight to ceiling (not at your light source)
      a.    Use patient's thumb and alternate eye to position gaze
    iii.  Later, position yourself OPPOSITE the area desired to be seen
  C.    Place +20D lens close to eye and center pupil in lens
    i.    Slowly raise lens while pupil (& red-reflex) fills lens view
      a.    Extend middle finger to stabilize on patient cheek, brow, etc.
      b.    Can also pull lower or upper lid out of the way
      c.    If view goes black or appears inverted, 
            you have moved too far away from the eye
        1.    Reduce focal distance and re-center pupil
        2.    Raise lens slowly again, but to a level a little less high
    ii.   Change working distance slowly (in and out) until fundus is clear
    iii.  Hold lens steady at focal length
      a.    ALIGNMENT is CRITICAL                                         
        1.    Straight line from your pupil into patient's pupil
        2.    +20D lens centered in-line and perpendicular with your axis
      b.    If not fully illuminated, TRY the following LITTLE changes:         
        1.    Adjusting the focal length of the lens SLIGHTLY
        2.    OR adjusting your head tilt 
                 to evenly distribute light onto lens and into pupil
        3.    OR adjust mirror up/down to make 
                 light source and visual axis meet at +20D lens
        4.    OR adjust lens laterally or vertically on plane of face
        5.    OR adjust tilt of +20D lens
        6.    OR check for binocular vision
          a.    close one eye, then the other, to assure eyes seen
                the same view in lens
          b.    Re-adjust headset and PD if both eyes do not see equally
        7.    DO NOT ADJUST ALL OF ABOVE PARAMETERS AT THE SAME TIME: 
              Adjust ONLY ONE parameter at a time
    iv.   Use other hand to raise lid/lashes out of the way 
          or to stabilize hand holding lens
    v.    Limit exposure to BIO light to 30 seconds or less at a time
      a.    Give the patient a chance to blink to refresh tear film
      b.    Use celluvisc or other ocular wetting solution 
            to aid in comfort if extremely photophobic

IV.   90 degree technique
  A.    Not recommended except for scanning far periphery
    i.    OK technique to find problem in eye
    ii.   Must use 180 degree technique to determine elevation
    iii.  Must use 180 degree technique for more advanced procedures 
  B.    Only one eye is being used in extreme gaze:  NOT BINOCULAR
    i.    TWO eyes see better together than each eye individually

V.    Views
  A.    Inverted and Reversed
    i.    When viewing posterior pole to equator, keep 100% filled lens
    ii.   Needs to be STABLE (steady) and FOCUSED (clear)
  B.    As you scan a vessel toward the periphery
    i.    Old retina moves away from top of lens view
    ii.   New retina moves in from bottom of lens view
    iii.  Real temporal retina APPEARS on nasal side of lens
    iv.   Move to quadrants you wish to view (stand opposite)
  C.    Scan along length of vessel as it moves to far periphery
    i.    Posterior arcades stay in posterior pole area near the disc
    ii.   Work toward a normal anatomical landmark
      a.    Vortex veins (VV) and Long ciliary nerves (LCN)
    iii.  Change patient gaze in 20-30 degree increments 
          to produce overlap of fundus views
    iv.   Maintain 100% filled views to equator 
          (VV or start of LCN centered in view)

VI.   Recording
  A.    Draw what you seen in lens you are holding
  B.    Draw in paper that has been inverted
  C.    Draw what you seen onto the quadrant in which you are standing
  D.    Check you interpretation of the fundus with the direct and +90 
    i.    Try to localize any normal anomaly using multiple techniques
    ii.   Try to be accurate in description so that fellow clinician 
          would be able to localize anomaly
      a.    Describe in terms of DD distances or # of vessel splits
      b.    Describe in terms of proper quadrant or clock position
      c.    Describe in terms of normal anatomical occurrences
    iii.  Try to re-acquire any special views seen 
          after moving away to other positions within the eye