Ординатура / Офтальмология / Английские материалы / Clinical Neuro-ophthalmology A Practical Guide_Schiefer, Wilhelm , Hart_2007

Outside of the central 30° of field: λ No correction

Within the central 30° of field:

λSufficient correction for the test distance, depending on the cupola radius of the perimeter

λLenses with very narrow rims

λCorrection for astigmatic errors of one full diopter or more

Near addition for patients starting at ages 35 to 40 years (in case of a cupola radius of 33 cm):

λAge 35 to 50 years: use an addition of +1 diopter sphere

λAge 50 to 60 years: use an addition of +2 diopters of sphere

λAge over 60 years: use an addition of +3 diopters of sphere

pervision by means of a telescopic sight or video monitor. It would be ideal to document the quality of fixation during each presentation of the stimulus. During automated examinations, an indirect form of control for fixation is the use of so-called catch trials. This is done by presenting suprathreshold stimuli into the center of the previously mapped physiologic blind spot (the so-called Heijl-Krakau method). This strategy is of limited use when the blind spot is significantly enlarged or when the determination of the blind spot location is inaccurate.

!Note

The physiologic blind spot can in general serve as a reference scotoma or criterion of the test’s validity: If it cannot be detected and documented as an absolute scotoma, the validity of the examination’s findings will be markedly reduced.

An alternative type of automated fixation monitoring uses random presentations of stimuli that are minimally suprathreshold at the center of the field. The patient can see these presentations only if he/she is truly maintaining central fixation. An inaccurate determination of the threshold at fixation can of course produce invalid results when using this method.

Detection of False-Positive Responses

To test for false-positive responses several exclusively auditory stimuli can be presented during the course of the examination. These are meant to detect reflex responses that are not truly visually dependent. Frequent false-positive

responses indicate a risk of underestimating the depth or area of depressed visual sensitivity, and to detect significant areas of visual

-Negative Responses

responses (instances of failure to stimuli), strongly suprathreshpresented at various locations within the prior determinations of threshold have

. A high number of such falsely suggests marked variations in the paconcentrate or in the visual field perfor-

mance itself, and could lead to an overestimation of the size of a scotoma, or even produce a false indication of visual field loss.

Usually, about 10 to 15% of stimulus presentations are divided evenly among the catch trials and the trials of false positive and false negative responses.

• Pearl

Visual field test results are of limited value when any one of the three types of controlling trials produces faulty responses in 20% or more of its presentations.

Display of the Test Results

To make best use of the test results, it is particularly important that all of the test data are documented, including the optical correction used, the acuity of the eye with best correction, the results of catch trials (see above), and the time and duration of the test. For automated threshold static perimetry, the results of stimulus presentation within the physiologic blind spot, as well as in the area immediately surrounding the blind spot, should be provided, if this area can fulfill its important role as a reference scotoma (see above).

Isolated grayscale plots of the results are inadequate, since the borders of scotomas are interpolated in such plots, can frequently yield inaccurate impressions, and can even mask the presence of clinically significant defects. For this reason the location of all points in the pattern of test objects should be overlaid on the grayscale plots

• Pearl

Preferably, the presentation of the data for both eyes should be shown side by side for simultaneous viewing (the left eye’s field on the left and the right eye’s field on the right) – exactly as seen by the patient.

Poster 4.2

Chapter 4 U. Schiefer, J. Schiller, W. Hart

Compendium of Visual Field Defects

and Their Differential Diagnosis

Normal perimetric findings

λ Normal peripheral isopters plotted with the III/4e test object of the Goldmann perimeter:

temporal > 90°, nasal 60°, superior 50°, inferior 60° λ Physiologic blind spot:

eccentricity 14°, horizontal diameter 6°, vertical diameter 10°;

2/5 above the horizontal meridian, 3/5 below the horizontal meridian

Poster 4.2

Poster 4.1

4.9 Hemianopsias

!Note

Every hemianopic visual field defect indicates chiasmal or postchiasmal disease until proven otherwise. When first discovered, such defects require immediate investigation, on a semiemergent basis, by means of CT or MRI imaging

4.9.1 Monocular hemianopsia (rare)

λ A prechiasmal process, e.g., optic nerve compression posterior to the optic canal

λ Paraneoplastic retinopathy

λ Functional disorder, exaggeration, malingering

Additional testing, when indicated:

λ Swinging flashlight test

λ Color vision testing for hue discrimination and saturation sensitivity (pseudoisochromatic plates, such as the Ishihara series, and/or color sorting tests, such as the Farnsworth D15)

λ Fundoscopy of the optic disc and the nerve fiber layer of the retina

λ Ocular motility

λ Trigeminal nerve function λ MRI/CT

λ Electrophysiological testing (VEP)

λ Endocrine testing, e.g., for hyperprolactinemia, panhypopituitarism

see also Animation 3.2

4.9.2 Binocular hemianopsias

4.9.2.1 Bitemporal hemianopsia

A complete bitemporal hemianopsia, which is relatively uncommon, may cause the so-called hemifield slide phenomenon – see Chaps. 2, 15, and 22.

(Complete bitemporal hemianopsias cause a loss of all binocular vision, with each eye seeing only its nasal hemifield. In the absence of binocular sensory input to fusional vergence movements, the eyes will adopt positions dictated by the mechanics of the ocular and orbital tissues)

Chiasmal disorders – see Chap. 12

λSpace-occupying lesions, e.g.:

–Pituitary adenoma

–Optic nerve tumor

–Meningioma

–Aneurysm

Inflammatory disorders, e.g.:

λMultiple sclerosis, atypical retrobulbar optic neuritis – see Chap. 8

λWegener’s granulomatosis

λAbscess

Vascular disorders, e.g.:

λPitutiary apoplexy

λVascular malformations

λCavernous sinus disease – see Chapter 10

λRadiation neuropathy

λTrauma

Additional testing, when indicated:

λ Please refer to section 4.9.1 in this compendium

see also Animation 3.2