Neurosurgery notes/Anatomy/Sensory/Visual/Eye assessment

Eye assessment

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Relative afferent pupillary defect (RAPD)

  • Will be present with a monocular optic neuropathy or with bilateral optic neuropathies affecting the eyes asymmetrically
  • Do not cause the pupils to be unequal in size; Unequal pupils (anisocoria) are caused by efferent disorders.

Pupillary examination

  • Efferent defect
      • In Dark room
        • The smaller pupil is the diseased one:
          • Horner disease → lack of sympathetic innervation → Pupil cannot dilate
      • In Light room
        • The larger pupil is the diseased one:
          • Adie pupil/surgical CN3 palsy → lesion in ciliary ganglion → Parasympathetic dysfunction → Unilateral fixed and dilated pupil
          • In light room more dilated eye
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  • Afferent defect
    • Swing light test: swing directly while asking patient to see something far to removed convergence related pupillary constriction

Acuity assessment

  • Snellen chart
  • When a patient has vision reduced to the level of "counting fingers," this represents severe vision loss. In these cases, it is important to check for a relative afferent pupillary defect (RAPD), as this test helps localize whether the vision loss is due to a problem in the optic nerve or severe retinal disease in one eye
Mono-ocular deficit
  • Transient visual obscuration's consist of episodes of brief loss of vision in one or both eyes, often provoked by bending down, lasting only seconds. These are common with papilledema from raised intracranial pressure
  • Amaurosis fugax: Transient monocular vision loss, a thromboembolic phenomenon.
  • Idiopathic demyelinating optic neuritis causes decline in monocular vision over several days accompanied by pain with eye movement, with subsequent recovery over several weeks.
  • Gradual, relentless decline in vision suggests a compressive mechanism (e.g., aneurysm or tumor)

Visual field testing

  • Confrontation
    • Do 4 quadrants with colour as a fast check
    • Do blind spot check with red pin as blind spot increases with papillodema
    • Absolute and relative scotoma
      • Red hat pin
        • Relative scotoma
        • Magnocellular pathways
      • White hat pin
        • Absolute scotoma
        • Parvocellular pathways
  • By perimetry with a tangent screen
    • Use the small red stimulus since desaturation of colour is an early sign of chiasmal compression
    • Types
        • Goldman perimetry
        • 160 degree testing
        How to interpret visual fields | Practical Neurology
        A diagram of a radar AI-generated content may be incorrect.
        This the left visual field.
        The blind spot is incoorporated into the Superior temporal and nasal quadranopia.
        Together with the right eye. The patient has a Right homonymous heminanopia that is incongruent (i.e. one is upper and one is lower quadrant)
        Goldman Perimetry - American Academy of Ophthalmology
        A diagram of a radar AI-generated content may be incorrect.
        The red line is the inner isomere.
        Blue line is the outer isomere.
        The 3 lines have different light intensity and light size.
        This image is of the right eye visual field as the n shaped blind spot is on the temporal side (the right side here)
        Automated Humphrey perimeter
        • HVF requires good patient cooperation to be valid
          • False negative: asleep
          • False positive: trigger happy
        • Central 60 degree
        • Has SD results
         
        Humphrey visual field analyser - Wikipedia
        a Eos Sr-qLe Fixate. Fixatim T*get Fixatim Losses: False POS Errors: False NEG Em's: Test Ck.ratm: Fig. Artarrs's Spot 12% White 3' asb SITA.Stardard GHT: pso: I esl Outside Normal L•mitS 828 dB 0.5% Pe2% Fixatim Monit«. Fintim F Los•: False POS Errors: F "e NEG Test .3 .2 .2 Total V. Biirxj Spot 5% Vesux Acuty: White 31.5 asb SITA.Star•dMd Anny•: VFI•. C)utside Normal omits 0 Q 3 Humphrey 24-2 SITA-Standard visual field test loss, conduced two days after MRF tests result for patient's left (a) and right (b) eyes, confirming a dense superior bitemporal field
        Humphrey visual field of patient’s left (A) and right (B) eyes.
        Humphrey field A is left eye and B is right eye.
        See Pituitary eye assessment
  • Estermann driving standards

Colour vision

  • Ishihara chart:
    • If can rad will have half of normal acuity
  • Recovers last

Optic disc assessment

  • Normal fundoscopy
      • Arteriovenous ratio and papilledema based hybrid decision support system for detection and grading of hypertensive retinopathy - ScienceDirect
      Arteriovenous ratio and papilledema based hybrid decision support system for detection and grading of hypertensive retinopathy - ScienceDirect
      • The macula is the center portion of the retina that produces even sharper vision with its rods and cones.
      • The fovea is the pit inside the macula with only cones, so vision can be at its sharpest.
      Fundoscopic photographs of the right eye (a) and left eye (b) of Patient 1. The fundoscopic photographs of Patient 1 revealed bilateral enlarged disc cupping of the optic nerves with sectorial excavation and reduction of the neural rim in the left eye
      The A image is the right eye, The B image is the left eye and
      Fundoscopic Exam (Ophthalmoscopy) | Stanford Medicine 25 | Stanford Medicine
  • Conditions seen on fundoscopy
      • Optic disc pathology
      Optic disc oedema
      • Not all disc oedema represents papilledema
      Papilledema
      • Optic disc oedema with documented or strongly suspected raised ICP
      • Due to stasis of axoplasmic flow → swelling of optic nerve axons → optic disc elevation
      • Loss of retinal vessels entering and exiting the optic disc:
        • The normally transparent peripapillary nerve fiber layer gradually opacifies and obscures the retinal vessels.
        • The disc margins become indistinct.
      • The optic disc may become hyperemic as small vessels are dilated, and characteristic splinter haemorrhages may appear at the disc margin in the nerve fiber layer.
      • Papilledema (raised intracranial pressure). Note the substantial blurring of the disc margins, nearly complete obscuration of the vasculature at the disc, peripapillary disc haemorrhages, and white gliosis and cotton-wool spots
      Close-up of a red and white sphere AI-generated content may be incorrect.
      • Takes 48hrs to develop following sustain rise in ICP
      • Last for (Vries 1983)
          • Group
          Longest time to resolution
          Notes
          Tumour removal
          20 weeks
          No consistent relation to severity
          CSF shunt operation
          6 weeks
          Related to severity of papilloedema
      • Does not cause visual blurring or reduction of visual fields unless very severe and prolonged.
      • Stages of papilloedema
        • Axonal transport dysfunction
        • Venous
        • Arterial
      • Differential diagnosis
        • Optic neuritis:
          • Looks the same on fundoscopy
          • ON has Severe loss of vision and tenderness when pressure exerted over the eyes
      • Unilateral papilloedema causes
        • Compressive lesions
          • Orbital tumors
          • Tumours of optic nerve sheath (meningiomas)
          • Optic nerve tumors (optic gliomas)
          • Foster Kennedy syndrome:
            • Compression of the ipsilateral optic nerve by an intracranial mass, often an anterior cranial fossa meningioma (e.g., frontal lobe, olfactory groove, sphenoid wing).
            • Contralateral papilloedema: When the intracranial mass is large enough to inc ICP, contralateral papilledema results.
            • An atrophic optic nerve is no longer able to manifest the optic disc oedema and therefore only contralateral papilloedema is seen.
        • Local inflammatory disorder
        • Demyelinating disease (e.g. multiple sclerosis)
        • Elevated ICP (as in pseudotumor cerebri) with some form of blockage on the normal appearing side which prevents transmission of elevated CSF pressure to that optic disc 4
        • Eye prosthesis (artificial eye)
      • Modified Frisén grading scale for papilloedema
          • Frisén grade
          Description
          Get IMAGES
          0
          Normal optic disc
          Minimal swelling of nasal margin of optic disc
          Nerve fiber layer (NFL) clear
          Vessels not obscurred
          Cup, if present, not obscured
          1
          Minimal papilledema
          230° “C-shaped” swelling of nasal, superior & inferior borders
          Normal (sharp) temporal margin (temporal gap)
          Cup, if present, is maintained
          2
          Low degree of papilledema
          Elevation of nasal margin
          360° disc swelling (circumferential halo)
          No obscuration of major vessels
          3
          Moderate degree of papilledema
          Elevation of entire disc
          360° disc swelling
          Obscuration of ≥1 segment of major blood vessel at disc margin
          Cup may be obscured
          4
          Marked degree of papilledema
          NFL opaque, 360° disc swelling
          Vessels obscured at disc margin, not completely obscured on disc surface
          5
          Severe papilledema
          NFL opaque, 360° disc swelling
          All vessels obscured on disc surface & leaving disc
          Moran CORE | Disc Edema
          Papilledema (Common)
          Acute
          Chronic
          Disc elevation
          Disc hyperemia
          Champagne cork appearance
          Venous distension/tortuosity
          Cotton wool spots
          Pseudodrusen (gliosis and extruded axoplasm)
          Blurred disc margin
          Peripapillary hemorrhages
          Disc atrophy (pale)
          Absent venous pulsations
          ㅤ
          Venous collaterals;Peripapillary subretinal neovascularization
      Conjunctival vessels signs
      • Dilated, tortuous conjunctival vessels may signal a carotid-cavernous fistula
      • Redness concentrated around the edge of the iris may be a sign of intraocular disease such as uveitis or acute glaucoma
      • Redness of the exposed bulbar conjunctiva within the palpebral fissure suggests exposure keratopathy or dry eye

Red reflex

  • Cataract and corneal opacities can be seen in the red reflex, and vitreous haemorrhage (as in Terson’s syndrome in the setting of subarachnoid haemorrhage) will darken or abolish the red reflex

Optical coherence tomography (OCT)

  • Uses light to provide high resolution images of the retina thickness (including the optic disc)
  • Might have some prognostic information
  • Thinning or atrophy of
    • Retinal nerve fibre layer
      • Thins after
    • Ganglion cell complex
      • Thins first before visual field loss
      • Can see ganglion cell thinning first
  • 2 to 3months to see thinning to occur
Pattern deviation Jeong et al: J Neuro-ophthalmol 2016; 36: 152-155

Images