Visual Field Testing

Detecting glaucoma as early as possible requires documenting glaucomatous visual field defects at the earliest possible stage. We know that glaucomatous visual field defects initially manifest themselves in the superior paracentral nasal visual field or, less frequently, in the inferior field, as relative scotomas that later progress to absolute scotomas (Fig. 10.11 a - d).

— Optic disk tomography.

— Optic disk tomography.

Clinical Visual Field Test

Stereometric Analysis OHN:

Disk Area: 2.103 mm2

Cup Area: 0.576 mm2

Cup/Disk Area Ratio: 0.274 Rim Area: 1.527 mm2

Rim Volume: 0.322 mm3

Mean Cup Depth: 0.262 mm Maximum Cup Depth: 0.843 mm

Stereometric Analysis OHN:

Disk Area: 2.103 mm2

Cup Area: 0.576 mm2

Cup/Disk Area Ratio: 0.274 Rim Area: 1.527 mm2

Rim Volume: 0.322 mm3

Mean Cup Depth: 0.262 mm Maximum Cup Depth: 0.843 mm

Fig. 10.9 A laser beam scans the optic disk (ai and a2) to produce a vertical map (b) and horizontal map (c) of the height and depth of the optic disk. The computer then calculates crucial data for the optic disk and presents a stereometric analysis (d).

Clinical Eval Visual Field

Glaucomatous lesions in the optic nerve.

Glaucomatous lesions in the optic nerve.

Optic Nerve Ratio Measurement
Fig. 10.10 The optic disk is sharply demarcated and pale (a sign of tissue atrophy). The optic cup is enlarged and almost completely covers the disk. The blood vessels abruptly plunge into the deep cup, indicated by their typical bayonet-shaped kinks in the image (arrow).

Computerized static perimetry (measurement of the sensitivity to differences in light) is superior to any kinetic method in detecting these early glaucomatous visual field defects. Computer-controlled semiautomatic grid perimetry devices such as the Octopus or Humphrey field analyzer are used to examine the central 30 degree field of vision (modern campimetry; Fig. 10.12).

Reproducible visual field findings are important in follow-up to exclude any enlargement of the defects.

- Overview of glaucomatous visual field defects.

Peripheral optic cup in a temporal and inferior location (with damage to the optic nerve fibers in this area).

Campimetry Visual

Increase in the size of the optic cup with thinning of the vital rim. The lamina cribrosa is visible.

Neuroretinal Rims Thinning

Advanced generalized thinning of the neuroretinal rim with an increasingly visible lamina cribrosa and nasal displacement of the blood vessels.

Neuroretinal Rim Thinning

Total glaucomatous atrophy of the optic nerve: Complete atrophy of the neuroretinal rim, kettle-shaped optic cup, bayonet kinks in the blood vessels on the margin of the optic disk, some of which disappear. The lamina cribrosa is diffusely visible. Only remnants of the atrophic tissue of the optic disk remain. The optic disk is surrounded by a ring of chorioretinal atrophy (glaucomatous halo) due to pressure atrophy of the choroid and lysis of the retinal pigmented epithelium.

Double Disk Margin Fundus Pigmented

Fig. 10.11

Peripheral Scotoma Causes

Narrowing of the peripheral superior paracentral visual field. The insular paracentral scotomas converge and extend to the blind spot.

Further loss of superior nasal visual field. Circumscribed horizontal penetration of the Bjerrum's scotoma into the nasal half of the field of vision. A new inferior nasal scotoma is a sign of a superior temporal nerve fiber lesion.

A small central and peripheral residual field ^^^^^^^^^^^^^ of vision remains. The arc-shaped scotoma has expanded into a ring-shaped scotoma /tY^QS^^ surrounding the focal point. As the focal

XStaJfaCQ point degenerates, the center of vision disappears and only a peripheral residual field of vision remains.

250 10 Glaucoma Thirty degree visual field test for glaucoma screening.

250 10 Glaucoma Thirty degree visual field test for glaucoma screening.

Visual Field Study Test

Fig. 10.12 The central field of vision is examined for scotomas with an automatic perimeter as studies of early glaucoma have shown that the initial defects occur in this area (see Fig. 10.11 a - d). The figure shows the visual field defect in the early stages of glaucoma. The blind spot is slightly enlarged (arrow), and an arc-shaped paracentral Bjerrum's scotoma is present (arrowhead). The standardized examination conditions in automatic perimetry not only permit early detection of glaucoma; the reproducible results also aid in the prompt diagnosis of worsening findings.

Fig. 10.12 The central field of vision is examined for scotomas with an automatic perimeter as studies of early glaucoma have shown that the initial defects occur in this area (see Fig. 10.11 a - d). The figure shows the visual field defect in the early stages of glaucoma. The blind spot is slightly enlarged (arrow), and an arc-shaped paracentral Bjerrum's scotoma is present (arrowhead). The standardized examination conditions in automatic perimetry not only permit early detection of glaucoma; the reproducible results also aid in the prompt diagnosis of worsening findings.

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Responses

  • Caio
    What is "inferior nasalscotoma" ....?
    4 years ago

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