The extent of the neuro-ophthalmic examination varies depending on the patient’s complaints, but parts of it should always be performed in detail in selected neurologic disorders, and some parts of the neuro-ophthalmic examination should be systematically performed in most neurologic and systemic diseases. For example, in a patient with an occipital infarction, evaluations of visual acuity, color vision, and formal visual fields are the most important. A patient with known multiple sclerosis needs a thorough examination, because all functions involved in the visual system may be affected. In a patient complaining of diplopia or with anisocoria, formal visual field testing is usually not necessary, whereas all patients with raised intracranial pressure and papilledema should have formal visual field testing, even when they have no visual symptoms.

Most examination techniques detailed here are best performed with appropriate tools in a neuro-ophthalmologist’s or ophthalmologist’s office. However, a basic neuro-ophthalmic examination (including evaluation of the vision, pupillary function, ocular motility, and funduscopy) can be performed at the bedside, in the emergency room, or in a neurologist’s office with only very few tools (see ▶ Table 1.1 for a list of required tools).

The examination usually follows a specific order, as given in the following discussion (e.g., you have to examine the visual acuity before flashing light into the eyes; the pupils need to be examined before drops are placed in the eyes; funduscopic examination is the last part of the examination).

1.1 Visual Acuity

In examining the patient’s visual acuity, each eye is tested separately (▶ Fig. 1.1). Visual acuity is measured with the patient’s corrective lenses or a pinhole (▶ Fig. 1.2). There are two types of visual acuity tests: distance and near.

Distance visual acuity is tested as follows (▶ Fig. 1.1 and ▶ Fig. 1.2):

1. 
   

   Place a Snellen chart at 20 feet.

   
   
2. 
   

   Record the smallest letters read by the patient with each eye (e.g., “20/20 right eye with correction; 20/25 left eye with pinhole”).

   
   
3. 
   

   If the patient cannot read the largest letter, visual acuity is less than 20/400 and is recorded as “count fingers,” “hand motion,” “light perception,” or “no light perception.”

The pinhole is an opaque panel perforated with one or more holes 1.0 to 1.5 mm in diameter. The holes restrict incoming light rays to a narrow path that bypasses refractive irregularities and presents a single, focused image to the fovea of the retina. Refractive errors and visual loss from cataracts improve with a pinhole. If visual acuity cannot be improved with a pinhole, then other media opacities, optic nerve disease, maculopathy, or amblyopia is likely the cause of visual loss. The test may be unreliable with young children, the elderly, and cognitively impaired individuals.

Near visual acuity is tested as follows (▶ Fig. 1.3 and ▶ Fig. 1.4):

1. 
   

   Hold a near card at 14 inches from the patient. The patient should be tested with reading glasses (or a +2.00 or +3.00 lens) if he or she is older than age 50 (because of presbyopia).

   
   
2. 
   

   Record the smallest letters or numbers read by the patient with each eye (e.g., “J1+ right eye with correction; J1 left eye with correction”).

   
   
   
   

   

   
   

   Fig. 1.3 Near vision is tested using a near card held at 14 inches from the patient. It must be tested with the patient’s correction for near vision. Most patients older than age 50 will use a +2.00 or +3.00 lens to read.

   
   
   
   

   

   
   

   Fig. 1.4 The near card uses numbers or letters. It is usually measured in Jaeger numbers (J1+ corresponds to 20/20, J16 to 20/200).

1.2 Color Vision, Color Saturation

Color vision can be assessed by several methods, and each eye is tested separately. The purpose of color vision testing is to detect acquired unilateral or bilateral color loss, which occurs most commonly with maculopathies, optic neuropathies, chiasmal disorders, and, more rarely, bilateral occipital lesions.

The Ishihara pseudoisochromatic and the Hardy-Rand-Rittler (HRR) color plates are routinely used (▶ Fig. 1.5). The number of plates correctly identified with each eye is recorded (e.g., “14/14 Ishihara color plates right eye; control only left eye”). The control plate can be read by patients with a visual acuity of at least 20/400. Some patients with dementia and simultagnosia may have difficulty using these plates.

When color plates are unavailable, the difference in color perception between the two eyes may be identified using a red object (e.g., the top from a bottle of dilating drops) (▶ Fig. 1.6). Even with normal color plate testing, the patient may recognize a color difference in a red bottle top alternately presented to each eye. The patient should be asked to quantify the red desaturation (percentage of normal).

1.3 Contrast Sensitivity

Contrast sensitivity is another measure of visual function and is often abnormal in patients with optic neuropathies. Patients with maculopathies and cataracts also often have decreased contrast sensitivity. It is not tested in all patients but is useful in patients with visual complaints and an otherwise normal examination. It is also used as a measure of visual function in numerous clinical trials, especially multiple sclerosis trials. The test uses a chart with letters or stripes represented in various shades of gray.

1.4 Photostress Recovery Test

Photostress recovery is used to differentiate between macular disease and optic neuropathy. The principle underlying this test is that recovery of retinal sensitivity following exposure to a bright light is based on regeneration of visual pigments that were bleached during exposure to light. A delay in this process occurs in diseases affecting the photoreceptors and is independent of the neural pathways.

Each eye is tested separately:

1. 
   

   Measure the best corrected visual acuity in each eye.

   
   
2. 
   

   Have the patient look directly into a bright light held a few centimeters from the eye for 10 seconds.

   
   
3. 
   

   Record the time taken for the visual acuity to return to within one line of the best corrected visual acuity.

Most normal patients will have a recovery time of less than 30 seconds, which is symmetric between the two eyes. Macular diseases (but not optic neuropathies) often cause a prolongation in the photostress recovery time. This is particularly useful for unilateral or subtle macular diseases.

1.5 Amsler Grid

The Amsler grid is very useful in detecting macular abnormalities as a cause of visual loss (▶ Fig. 1.7a).

Each eye is tested separately, and the patient is asked to fixate on a central point in a square grid of lines and to draw any area in which the lines disappear or are broken, warped, double, or curved (▶ Fig. 1.7b).

Patients with maculopathy often see the straight lines as curved (metamorphopsia) (▶ Fig. 1.7c).

1.6 Stereo Vision

Stereo vision is tested on a specific book (Titmus test) with both eyes open and polarized glasses placed on the patient’s reading corrective lenses. This book shows animals and circles that are seen in stereo with the polarized glasses (▶ Fig. 1.8).

Stereopsis requires binocular vision. Therefore, the presence of stereopsis indicates at least some vision in each eye. This test is very helpful when nonorganic visual loss is suspected.

Stereopsis can be quantified and correlated with visual acuity (▶ Table 1.2).

1.7 Eyelid Examination

An eyelid examination includes evaluation of the following:

• 
  

  Position of the eyelids

  
  
  
  
  • 
    

    Ptosis (droopy eyelid)

    
    
  • 
    

    Retraction

  
  
• 
  

  Lid function

  
  
• 
  

  Swelling

  
  
• 
  

  Mass

In normal individuals, the upper lid covers the superior 1 to 2 mm of the iris, while the lower lid just reaches the inferior aspect of the iris (▶ Fig. 1.9). Examination of the eyelids (▶ Fig. 1.10 and ▶ Fig. 1.11) includes measurements of the following:

• 
  

  Palpebral fissure: distance between the upper and lower eyelid in vertical alignment with the center of the pupil (normal 9–12 mm)

  
  
• 
  

  Margin reflex distance (normal 4–5 mm)

  
  
  
  
  • 
    

    Marginal reflex distance-1 (MRD-1): distance between the center of the pupillary light reflex and the upper eyelid margin with the eye in primary gaze

    
    
  • 
    

    Marginal reflex distance-2 (MRD-2): distance between the center of the pupillary light reflex and the lower eyelid margin with the eye in primary gaze

  
  
• 
  

  Levator function: distance the eyelid travels from downgaze to upgaze while the frontalis muscle is held inactive at the brow. A measurement of greater than 10 mm is considered excellent, whereas 0 to 5 mm is considered poor.

For more information on disorders of the eyelid, see Chapter ▶ 17.

1.8 Orbital Examination

An orbital examination includes the following:

• 
  

  Inspection of the patient’s external appearance:

  
  
  
  
  • 
    

    Orbital deformations

    
    
    
    
    • 
      

      Hypo- or hypertropia of the globes

    
    
  • 
    

    Abnormal position of the eyes within the orbits

    
    
    
    
    • 
      

      Proptosis (eye bulging out of the orbit)

      
      
    • 
      

      Enophthalmos (eye sinking into the orbit)

    
    
  • 
    

    Periorbital soft tissues

    
    
    
    
    • 
      

      Swelling

      
      
    • 
      

      Redness

      
      
    • 
      

      Hematoma

      
      
    • 
      

      Mass

  
  
• 
  

  Palpation of the orbital rims

  
  
• 
  

  Resistance to retropulsion of the eyes

  
  
• 
  

  Auscultation of the orbital contents (for a bruit)

Proptosis can be measured with the Hertel exophthalmometer (▶ Fig. 1.12) and on neuroimaging (▶ Fig. 1.13). Deformations (▶ Fig. 1.14) and disease (▶ Fig. 1.15) cause various orbital syndromes. For more information on orbital syndromes, see Chapter ▶ 14.

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