Direct Ophthalmoscopy

I.    Parts of Direct Ophthalmoscope
  A.    On/Off Rheostat
  B.    View aperture / Lens power indicator
  C.    Pupil size:  large / small
  D.    Auxiliary controls:  Red-free filter, Fixation target, Slit beam

II.   Procedure
  A.    Use Dr. OD on Pt. OD and Dr. OS on Pt. OS
    i.    Corrections not used unless very high refractive errors or
          astigmatism present
  B.    Initially set power at +8 to +12 diopters
  C.    Find red reflex of fundus
  D.    Move in/out to focus on cornea and lens structures
    i.    Look for opacities in media:  scars, dots, cataracts
    ii.   Parallax movement -- retro illumination
  E.    Reduce plus to move into vitreous
    i.    Look for opacities in media:  floaters
    ii.   Change positions and focus as power is reduced slowly
  F.    Reduce plus to focus on fundus
    i.    Knuckles should touch cheek of Pt to stabilize
    ii.   Look for arteries or veins
      a.    Bifurications point direction to disc
    iii.  Expect OHN to be seen when you are about 15 degrees temporal
  G.    From OHN follow course of arteries and veins
    i.    Follow each bifurication
    ii.   Look between vessels
    iii.  Change Pt. gaze to view different quadrants

III.  Observations and Recording
  A.    Expected, Abnormal and Pathological findings

  B.    Optic Nerve Head (ONH)
    i.    shape:  oval slightly longer in vertical direction
      a.    Abnormal:  Excessive tilting from the vertical
    ii.   C/D ratio (h/v):  decimal value of size of cup to OHN
      a.    Whites:  .3/.3       Blacks:  .5/.5
      b.    Abnormal:  Values that approach or exceed .6 (or .7)
    iii.  Cup depth:  flat, moderate (sloping margins), deep (steep margins)
      a.    3.00 DS = 1 mm depth (may see darker color of lamina cribrosa)
      b.    Abnormal:  Bean-pot cupping or bearing of tissue around
            vessels at cup margins
    iv.   Color:  Evenly pink
      a.    Abnormal:  Excessively pale
    v.    Margins
      a.    Distinct:  sharp, easily distinguished
      b.    Indistinct:  difficult to tell where OHN starts/stops
        1.    ONH can be seen in detailed, sharp focus -- just blended
              color and pigment
        2.    Reserve BLURRY margins for times when no change in focus
              clear image
      c.    Note crescents:  RPE, Choroidal, Scleral
    vi.   SVP  (Spontaneous Venous Pulsation)
      a.    found in 80% of patients
      b.    homeostatisis between BP and IOP
  C.    A/V ratio and Crossings
    i.    A/V = 2/3 or 3/4
      a.    Check this beyond first bifurcation (about 2 DD from ONH)
    ii.   Arterial reflex
      a.    reflex is expected to be 1/2 or less of vessel width
    iii.  Tortuosity:  Even course of vessels away from disc
    iv.   Crossing of arteries and veins
      a.    nicking or banking
    v.    Check fundus with red-free filter 
      a.    look for both vessel and pigmentation changes
    vi.   Abnormal:
      a.    Excessive tortuosity
      b.    Nicking or Banking or vessel changes
      c.    A/V ratio of 1/2 or less
      d.    Widening of arterial reflex or changes in reddish color to
            white or copper

  D.    Macula
    i.    Darker area of pigmentation
    ii.   Usually uniform in coloration or may appear grainy
    iii.  Abnormal:  Uneven, mottled coloration
    iv.   Fovea
      a.    Reflex changes with age (Graded:  0 to 4)

  E.    Fundus color
    i.    Even pigmentation
    ii.   Light pigmentation:  choroid visible
    iii.  Tesselated or Tigroid:  extra dark streak of pigment
    iv.   Abnormal:  Distinct or indistinct specific areas of pigmentation 
          changes

  F.    Fundus structure
    i.    No breaks, holes, tears or detachments
    ii.   No hemorrhages or exudates
      a.    check with red-free filter
    iii.  Abnormal:  Holds, breaks, tractions, detachments or elevations

  G.    Media recorded as clear if no obvious opacities seen
    i.    Includes from cornea to fundus
      a.    cornea, aqueous chamber, lens, vitreous, fundus
      b.    sometimes see Mittendorf dot on back side of lens (normal)
    ii.   Vitreous
      a.    normally clear or with few floaters
      b.    Abnormal:  Tractions, Asteroid Hyalosis, Canal or Cloquet
    iii.  Abnormal:  Cataracts, corneal scars, opacities along visual axis
      a.    Cloudy

  H.    Record normals and abnormals until checkout doctor can tell you know
        the difference
    i.    Draw what you see in the proper quadrant or location in the eye
    ii.   Be knowledgeable about anterior and posterior position