II. Anatomy

  1. See Retinal Anatomy
  2. Optic Disc (Optic Nerve Head, Optic Papilla)
    1. Pink to white oval disc at the posterior globe where the Retinal Ganglion cell axons exit the eye and form the Optic Nerve
    2. This portion of the Retina is devoid of light sensitive photoreceptors
  3. Optic Cup (Physiologic Cup)
    1. Funnel shaped depression at the center of the optic disc
    2. Paler than the surrounding Neuroretinal Rim
    3. In Glaucoma, the cup enlarges (cupping) as the rim thins, resulting in an increased cup to disc ratio (>0.3)
  4. Neuroretinal Rim
    1. Outer, pink portion of the optic disc that surrounds the Optic Cup
    2. Neuroretinal Rim contains nerve fibers and glial cells
    3. Injury to the Retinal axons of the results in cell loss and thinning of the rim
    4. Glaucoma-related pressure induces Retinal axon injury and Neuroretinal Rim thinning

III. Preparation: Pupil Dilation

  1. See Mydriatics
  2. Tropicamide 0.5% - 1% (Mydriacyl)
    1. Onset: 20-40 minutes
    2. Duration: 4-8 hours in most cases (may last as long as 24 hours)
    3. Blue eyes more sensitive, lasts longer
    4. Start with 0.5% concentration
  3. Phenylephrine hydrochloride 2.5% (Ak-Dilate, Mydfrin)
    1. Onset: 30-60 minutes
    2. Duration: 3-5 hours
  4. Contraindications to dilation
    1. Shallow anterior chamber OR angle-closure Glaucoma
      1. Diagnostic exam Mydriatic use is safe (see Mydriatic)
    2. Following pupillary signs after Head Injury
    3. Iris supported intraocular lens implantation
      1. (square/hexagonal pupil 'sputnik')

IV. Exam: Protocol

  1. Red Reflex
  2. Optic Disc
    1. Clarity of disc (evaluation for Papilledema)
    2. Cup Disc Ratio
      1. Ratio of horizontal diameter of the cup to disc
      2. Abnormal Cup to Disc Ratio >0.3 to 0.5 suggests Glaucoma
  3. Retinal Circulation
    1. Venous pulsations
  4. Macula
  5. Retinal Background

V. Findings

  1. Increased Intracranial Pressure
    1. Papilledema
    2. Absent venous pulsations
  2. Vitreous Hemorrhage
    1. Retina with overlying reddish haze
    2. Black Reflex
  3. Macular Degeneration
    1. Gray-Green sub-Retinal membrane
  4. Retinal Artery Occlusion
    1. Retina appears pale-gray due to Retinal edema
    2. Central Macula (fovea) with cherry-red spot on white-yellow background
    3. Constricted arterioles
    4. Box-Carring of Retinal vessels
      1. Retinal vessels with interrupted columns of blood appear as train box cars
    5. Hollenhorst Plaques (emboli)
      1. "Glistening orange yellow flakes"
      2. Represent fragmented emboli at arteriole bifurcation
  5. Retinal Vein Occlusion
    1. Optic disc edema
    2. Retinal veins with tortuous dilation
    3. Blood streaked Retina (esp. in ischemic type)
      1. Diffuse Retinal Hemorrhages radiating from optic disc ("Blood and thunder Retina")
  6. Glaucoma
    1. General
      1. Focal thinning of neural rim
        1. Nerves at edge of cup and edge of disc
        2. Thinning seen at temporal (lateral) disc margin
      2. Superficial Hemorrhage overlying disc edge
      3. Cloudy Cornea (acute Glaucoma)
    2. Diagnostic changes
      1. Symmetrically enlarged cup-to-disc ratio >0.5 or
      2. Cup-to-disc ratio difference between eyes >0.2 or
      3. Significantly asymmetric cup in one eye
  7. Diabetic Retinopathy
    1. Nonproliferative Retinopathy
      1. Retinal veins dilated
      2. Cotton Wool exudates or spots
      3. Hard exudates
      4. Macular edema
      5. Intraretinal Hemorrhages
      6. Microaneurysms
    2. Proliferative Retinopathy
      1. Neovascularization
      2. Preretinal Hemorrhages
      3. Vitreous Hemorrhages
      4. Vascular fibrosis
  8. Subarachnoid Hemorrhage
    1. Blood in center of disc
  9. Methanol Intoxication
    1. Choked disc with engorged veins

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