Ординатура / Офтальмология / Английские материалы / Field of Vision A Manual and Atlas of Perimetry_Barton, Benatar_2003

HISTORY AND EXAM

After a seizure causing a single-car accident, a right frontal oligodendroglioma was found in this 38-yr-old trucker. He complained of “purple haze” to his vision OD after biopsy. Acuity was slightly reduced at that time, but imaging did not show optic nerve compression. Over the next 18 months, his vision became more persistently blurry OD,

but the purple haze disappeared. Acuity was 20/400 OD and 20/20 OS. There was a large RAPD and temporal optic disk pallor OD. His behavior was disinhibited with a cheerful lack of concern about his problems.

DISCUSSION

Field description: Central scotoma with inferior nasal step and superior arcuate defect OD.

Localization: Optic nerve.

Pathology: Compressive optic neuropathy.

Confrontation testing showed a central scotoma OD to finger motion. Other features: Frontal disinhibition.

The patient has a large central defect above the horizontal meridian merged with a large inferior scotoma that respects the nasal horizontal meridian. In addition, there is a subtle superior arcuate defect that arches more peripherally than the inferior defect to gen-

erate a second nasal step defect at the 30° mark, and creating a shallow superior valley above the blind spot to the I2e isopter. Thus, he has damage to the papillomacular and both superior and inferior arcuate nerve fiber bundles.

MRI showed a large frontal tumor (see axial FLAIR image) with inferior mass effect, seen on the coronal T1-weighted image (note the location of the normal optic nerve on the other side, arrow). Although intracranial compression of the optic nerve is often from below by parasellar tumors, compression from cerebral tumors above can also occur. Alterations in behavior with either social disinhibition or abulic states may be present, due to frontal lobe dysfunction.

HISTORY AND EXAM

For 3 years this 44-yr-old woman had proptosis and progressive visual loss OS. She had occasional bifrontal or retro-orbital headaches. Acuity without correction was 20/20 OD and count fingers OS, improving with +.62 sphere to 20/200 and with pinhole to

20/70. There was an RAPD OS. Ishihara color scores were 14/14 OU. Fundoscopy showed choroidal folds and mild optic disk pallor OS. She had 7 mm of proptosis, without lateral displacement of the globe. There was mild limitation of abduction OS.

DISCUSSION

Field description: Cecocentral scotoma OS.

Localization: Intraorbital optic nerve.

Pathology: Compressive optic neuropathy and refractive change.

Confrontation fields were full to finger counting.

The patient has a large central field defect with reduced acuity. While she has an RAPD and disk pallor, suggesting some element of compressive optic neuropathy, she has impressive choroidal folds, much like this fundus picture from another patient. These

findings, along with the improved acuity with plus lenses and pinhole, indicate that part of her visual defect is refractive in origin (101). This is due to compression of the posterior globe by a mass pushing the retina anterior to the plane of focus, inducing a hyperopia. This is typical of intraconal tumors, whereas extraconal tumors induce an astigmatism related to their asymmetric distortion of the globe. Her T1-weighted MRI showed a large enhancing intraconal mass, which resection confirmed to be a cavernous hemangioma (102). She recovered well with improvement in acuity to 20/40 (20/30 with pinhole) and marked shrinkage of the scotoma.

DISCUSSION

Field description: Bilateral inferior nasal defects OU.

Localization: Bilateral optic nerve.

Pathology: Superficial optic disk drusen.

Disk drusen are hyaline concretions that either aggregate on the surface of the disk or are buried beneath its surface. Superficial drusen appear as irregular, shiny, yellowish white clusters of granules that autofluoresce (103), as shown in the photo taken using the filters for fluorescein angiography (but without injection of fluorescein). Buried drusen may be confused with papilledema, but differ in the following ways:

1.The central portion of the disk is most elevated, with lack of a central cup.

2.The disk is not hyperemic, and the elevation does not involve the surrounding retina.

3.The vessels overlying the disk are not obscured but, rather, may have anomalous branching patterns.

Orbital ultrasound or CT scan can help confirm buried drusen by showing the calcifications at the optic disk.

Visual field defects are noted in 70% of patients with optic disk drusen, most frequently enlargement of the blind spot and inferior nasal defects (104), as in this patient. These defects tend to be static or slowly worsen over months to years (105), suggesting a compressive mechanism of visual loss, but some patients have sudden onset of defects with superimposed disk edema or retinal pallor, indicating an ischemic effect. Optic disk drusen may make the disk vulnerable to vascular compromise, much as the crowded “disk at risk” does (see Case 34).

With filters

HISTORY AND EXAM

This 35-yr-old woman came to the emergency room after 3 days of episodic diplopia. With reading, letters would suddenly double, and at other times they seemed to disappear. While looking across the room, sudden vertical steps would appear in windowsills and

door frames. She denied any visual loss. Acuity was 20/20 OU, but she often omitted the right half of lines with her right eye and the left half with her left eye. Ishihara color scores were 12/14 OU. There was no RAPD. Fundoscopy showed bilateral optic disk pallor.

DISCUSSION

Field description: Complete bitemporal hemianopia.

Localization: Optic chiasm.

Pathology: Pituitary macroadenoma.

Other features: Hemifield slide.

The patient’s fields correspond to the classic cartoon of complete loss of both temporal fields, which, like all classic signs, is the exception rather than the rule, as partial temporal field loss is more common than complete hemianopia. Coronal T1-weighted MRI showed a large enhancing pituitary adenoma that was nonsecreting. Three months after surgery her fields had improved to nearly normal with mild residual depression in the superior temporal fields (shown this page).

Her visual complaints represent an unusual phenomenon called hemifield slide (106). Normally, apart from the monocular temporal crescents, all points in the visual field of one eye have a corresponding location in the field of the other eye. This visual corre-

spondence can serve to anchor the eyes together, to maintain a stable fused single image of the world. With complete bitemporal hemianopia, no point in the visual field has binocular representation. Slight drifts in eye alignment may emerge. If they cross transiently, a vertical gap in the middle will

develop, causing letters and stimuli in the midline to disappear. If they drift apart, in an exotropic direction, the remaining nasal fields will overlap in the midline, causing a temporary doubling for stimuli at the midline. If they drift vertically, a step defect will appear. One can easily imagine the resulting confusion during reading.

HISTORY AND EXAM

This 50-yr-old man came to the emergency room 2 months earlier with a sudden severe headache. MRI showed a tumor, which was resected. Afterward he noted blurred vision OD and vertical diplopia, from a right III nerve palsy. Visual acuity was 20/25 OU

and color vision was normal. There was no RAPD and optic disks were normal. He had an exotropia worse in left gaze and a small right hypertropia. The rest of the neurologic examination was normal.