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At least 73 records · Page 4Linked to original sources
PubMed1999

Reading with simulated scotomas: attending to the right is better than attending to the left.

Persons with central field loss must learn to read using eccentric retina. To do this, most adopt a preferred retinal locus (PRL), which substitutes for the fovea. Patients who have central field loss due to age-related macular degeneration (AMD), most often adopt PRL adjacent to and to the left of their scotoma in visual field space. It has been hypothesized that this arrangement of PRL and scotoma would benefit reading. We tested this hypothesis by asking normally-sighted subjects to read with the left or right half of their visual field plus 3.2 degrees in the contralateral field masked from view. Letter identification, word identification, and reading were all slower when only the information in the left visual field was available. This was primarily due to the number of saccades required to successfully read to stimuli. These data imply that patients would be better off with PRL to the right of their scotoma than to the left for the purposes of reading.

Eye Movements↗
PubMed1986

The nasal junction scotoma in giant aneurysms.

Thirteen giant aneurysms in ten patients were retrospectively reviewed. Careful visual field testing of both peripheral and central fields revealed an ipsilateral nasal scotoma in 7 of the 13 aneurysms (54%), or six of the ten patients. A review of 47 giant carotid aneurysms reported in the literature revealed 16 ipsilateral nasal scotomas (34%). The more common intraocular causes of ipsilateral nasal field defects were excluded by careful funduscopic examination. In the absence of intraocular pathologic characteristics, an ipsilateral nasal junction scotoma should alert the clinician to suspect the presence of an otherwise silent internal carotid artery aneurysm.

Adult↗
PubMed2005

[Adaptation to central scotoma. Part II. Perceptual filling-in phenomenon].

The visual cortex may reorganize after occurrence of a scotoma. Different experimental studies have shown that there is an attempt to minimize the impact of the scotoma, the missing information being filled-in by surrounding information. The clinical consequences of this filling-in phenomenon have been extensively studied by Safran and co-workers. The present review summarizes the current literature on this phenomenon and its clinical consequences. Furthermore, the authors present their own experience with the filling-in phenomenon in patients with age-related macular degeneration. Their study shows that, with few exceptions, the phenomenon only occurs in patients with bilateral central scotoma, in their better eye.

Adaptation, Physiological↗
PubMedDate not supplied

Perceptual filling-in at the scotoma following a monocular retinal lesion in the monkey.

Although no visual inputs arise from the blind spot, the same visual attribute there as in the visual field surrounding the blind spot is perceived. Because of this remarkable "perceptual filling-in," a hole corresponding to the blind spot is not perceived, even when one eye is closed. Does the same phenomenon occur in the case of a scotoma in which visual inputs are lost postnatally due to a retinal lesion? We report that it did: in the macaque monkey, behavioral evidence for filling-in at a scotoma produced by a laser-induced monocular retinal lesion was obtained. The visual receptive fields of neurons in the primary visual cortex (V1) in and around the representation of the visual field corresponding to the scotoma were also mapped, and no clear difference between the retinotopic organization of this part in V1 and that found in the normal visual field was found. Also, perceptual filling-in was found to occur only two days after the lesion. These findings suggest that the normal visual system possesses a mechanism that yields filling-in when some part of the retina is damaged, and that such a mechanism requires no topographical reorganization in V1.

Animals↗
PubMed1999

Manifestation of scotomas created by transcranial magnetic stimulation of human visual cortex.

Reduced visual performance under transcranial magnetic stimulation (TMS) of human visual cortex demonstrates suppression whose spatial extent is not directly visible. We created an artificial scotoma (region missing from a visual pattern) to directly visualize the location, size and shape of the TMS-induced suppression by following a large-field, patterned, visual stimulus with a magnetic pulse. The scotoma shifted with coil position according to known topography of visual cortex. Visual suppression resulted in pattern-dependent distortion, and the scotoma was filled in with temporally adjacent stimuli, suggesting spatial and temporal completion mechanisms. Thus, perceptual measurements of TMS-induced suppression may provide information about cortical processing via neuronal connections and temporal interactions of neural signals.

Humans↗
PubMed1987

Residual vision in a scotoma. A follow-up study of 'form' discrimination.

This study is a follow-up of a patient, D.B., who was reported (Weiskrantz et al., 1974) to be able to discriminate between simple visual forms within the scotoma caused by a lesion in calcarine cortex. Among other capacities, he was able to discriminate between lines of different orientation in the frontal plane. Given the reported deficits for form discrimination but a high sensitivity for orientation discrimination in primates without striate cortex, the question arises whether D.B.'s apparent 'form' discrimination arises from an ability to discriminate the orientations of components of the figures. It is shown in the first experiment, by using the optic disc as a control, that his ability to detect stimuli in his scotoma cannot be due to stray light falling upon the intact field. Next, his ability to discriminate orientations is confirmed, and an orientation threshold determined. A range of form discriminations is presented varying in degree of orientation cues of their components. It is confirmed that he can discriminate those forms originally studied, in which such differences are large, but not when orientation cues are small or minimal. Finally, his ability to compare two forms both projected within his scotoma is examined. Even when the components of the two forms have large orientation differences and are highly discriminable when presented successfully, D.B. appears to be unable to make a 'same-different' comparison when both are presented simultaneously. The evidence is interpreted against D.B.'s having a residual capacity for form discrimination.

Follow-Up Studies↗
PubMed1998

Location and stability of a newly established eccentric retinal locus suitable for reading, achieved through training of patients with a dense central scotoma.

Six patients, median age 71 years, with a dense central scotoma in one eye and a median visual acuity of 0.06 (20/330) in the same eye, were all (100%) shown by means of fundus photography including a fixation target to preferably use an unfavorable retinal locus for fixation, i.e., within the lesion (scotoma). None of the patients was able to read novel text with the affected eye. A computer and video display system were used to determine the most suitable area above or below the visual field scotoma (below or above the retinal lesion) for reading and the magnification needed at this eccentricity. The same setup was also used for an introductory training in reading single words as well as scrolled text with the aim of establishing a preferred retinal locus (PRL) at a favorable, eccentric position, the trained retinal locus (TRL). Thereafter, the patients were provided with strong positive lenses (median power, 40 D) for reading printed text at a very short reading distance (median, 2.5 cm), first single words, above and below which help lines were printed to facilitate eccentric fixation, and finally, novel text. The total training time was 4 to 5 h. Thereafter, fundus photography showed that five of the patients (83%) used their TRL as their PRL. Reading speed was 71 words per minute (median). Our results seem to indicate that an eccentric PRL favorable for effective reading can be established through training and that a fairly low number of training sessions is required.

Aged↗
PubMed1988

The effect of a foveal scotoma on the visual lobe.

One-dimensional visual lobes representing the detectability of a small bright target on an unstructured background were measured at several contrast levels, both with and without an artificial foveal scotoma. The effect of the scotoma on the lobe is shown to be restricted to the area of the retina covered by the scotoma, and detection ability is unaffected outside this area.

Adult↗
PubMed2000

Coffee and doughnut maculopathy: a cause of acute central ring scotomas.

AIMS: To report the clinical features of five patients with non-progressive central ring scotomas of acute onset associated with excellent retained visual acuity. METHODS: Complete neuro-ophthalmological examinations were performed. Visual fields were performed by tangent screen, Goldmann, or Humphrey perimetry. In some cases further testing was carried out including fundus photography, fluorescein angiography, ERG, VEP, and neuroimaging. RESULTS: The patients were three women and two men whose ages ranged from 25 to 57 years. Four patients were heavy caffeine consumers while the fifth patient experienced an episode of hypotension. Vision loss was acute in all cases. The onset of vision loss was bilateral/simultaneous in three cases, bilateral/sequential in one case, and unilateral in one case. All affected eyes retained visual acuities of 20/25 or better. Colour vision was subnormal in three of four cases. Visual field defects were characterised by a central ring scotoma having an outer diameter less than 10 degrees. Fundus examination demonstrated temporal optic nerve pallor in three patients (five of 10 affected eyes) and reddish, petaloid macular lesions in one patient. Good visual acuity was maintained for the duration of follow up in all five patients. CONCLUSION: Central ring scotomas with excellent retained visual acuity may present as an acute, bilateral syndrome in patients who are heavy caffeine consumers. The configuration of visual field loss and its location, combined with the presence of temporal pallor in five eyes, suggest that the defect localises to the inner layers of the macula. While these cases could be considered an expansion of the clinical spectrum of acute macular neuroretinopathy, some may represent a distinct entity.

Adult↗
PubMed1997

Pituitary adenoma revealed by paracentral junctional scotoma of traquair.

The term junctional scotoma of Traquair is used to describe a unilateral temporal visual field defect due to pathology of the ipsilateral optic nerve where it joins the chiasm. We report a 26-year-old woman who presented with blurred vision of her left eye. Examination revealed visual acuity of 20/20 OU, AO-HRR color plates 6/6 OD and 4.5/6 OS, and a 0.3 log unit relative afferent pupillary defect on the left side. Computer and Goldmann perimetry revealed a normal visual field OD and a paracentral temporal scotoma OS. Magnetic resonance imaging scan disclosed a sellar mass, expanding mainly into the left suprasellar area. Laboratory findings and pathological studies were consistent with a prolactin-secreting pituitary adenoma. While involvement of the temporal visual field in only one eye (junctional scotoma of Traquair) is found in about 10% of patients with pituitary adenoma, involvement of only the paracentral temporal visual field in one eye is rare (1-2%). Recognition of this rare syndrome is important because careful visual field analysis discloses a vertical step and helps to avoid misdiagnosing optic neuritis.

Adult↗
PubMed2000

[The influence of experimental scotoma on multifocal electroretinogram].

PURPOSE: To detect the sensitivity and the repeatability of multifocal electroretinogram (mfERG). METHOD: The effects of experimental absolute and relative scotomas on mfERG with 103 hexagons were observed on 8 normal eyes. The scotomas were produced by simultaneous and multi located masks on the hexagons of the screen in 6 different locations with black paper, and the neutral filters of 0.3 and 0.6 log unit. The repeatability was evaluated by analysis the data from 5 unmasked hexagons in 4 successive tests. RESULTS: When the hexagons were 1/2 or wholly masked with the black paper and the two kinds of the filters, the amplitudes of N1 and P1 waves in these areas were significantly decreased as with the reduced transferability of light. When the hexagon was 1/3 masked, there were no significant differences between the different kinds of mask and the unmasked control. There were no significant changes in the datas from the selected unmasked hexagons in the 4 successive recordings. CONCLUSION: mfERG is an unique sensitive visual electrophysiological test with high sensitivity and good repeatability. When 103 hexagons stimulating pattern is used, it could detect the scotoma larger than 1/3 of each hexagon.

Adult↗
PubMed2005

The influence of artificial scotomas on eye movements during visual search.

PURPOSE: Fixation durations are normally adapted to the difficulty of the foveal analysis task. We examine to what extent artificial central and peripheral visual field defects interfere with this adaptation process. METHODS: Subjects performed a visual search task while their eye movements were registered. The latter were used to drive a real-time gaze-dependent display that was used to create artificial central and peripheral visual field defects. Recorded eye movements were used to determine saccadic amplitude, number of fixations, fixation durations, return saccades, and changes in saccade direction. RESULTS: For central defects, although fixation duration increased with the size of the absolute central scotoma, this increase was too small to keep recognition performance optimal, evident from an associated increase in the rate of return saccades. Providing a relatively small amount of visual information in the central scotoma did substantially reduce subjects' search times but not their fixation durations. Surprisingly, reducing the size of the tunnel also prolonged fixation duration for peripheral defects. This manipulation also decreased the rate of return saccades, suggesting that the fixations were prolonged beyond the duration required by the foveal task. CONCLUSIONS: Although we find that adaptation of fixation duration to task difficulty clearly occurs in the presence of artificial scotomas, we also find that such field defects may render the adaptation suboptimal for the task at hand. Thus, visual field defects may not only hinder vision by limiting what the subject sees of the environment but also by limiting the visual system's ability to program efficient eye movements. We speculate this is because of how visual field defects bias the balance between saccade generation and fixation stabilization.

Adult↗
PubMed1987

Scintillating scotoma as the first symptom of systemic lupus erythematosus.

We reported a case where scintillating scotoma was the first and only symptom of systemic lupus erythematosus. The patient was diagnosed as having classic migraine and was given cafergot and phenytoin with no effect. During this treatment, severe myocardial infarction occurred and SLE was found to be the underlying disease responsible for scintillating scotoma. Scotoma attacks disappeared by steroid treatment but his general condition remained poor.

Adult↗
PubMed1985

Junction scotoma and involvement of the optochiasmal junction.

In two patients, ipsilateral central scotoma and contralateral superior temporal hemianopic field defect indicated involvement of the junction of the optic nerve and chiasm, the optochiasmal junction. In both cases, computed tomography and carotid angiography confirmed mass lesions at this location. After surgical removal of a parasellar tumor in one case, we found that the optic nerve and the anterior part of the optic chiasm were compressed upwards. The previously reported examples of these perimetric findings are reviewed and compared with those of our cases. We concluded through this study that the characteristic combination of visual field defects, namely central or paracentral scotoma on the involved side and superior temporal field defect on the uninvolved side, should be termed junction scotoma.

Adult↗
PubMed1980

Traumatic bilateral homonymous hemianopic scotomas.

A patient is presented who received a gunshot wound that injured both occipital poles. It resulted in a central scotoma that was due to the combined effect of both right and left homonymous hemianopic scotomas. A 15 degrees wedge of retained, functioning, central field permitted the retention of 20/20 visual acuity. This case illustrates the point that only a small portion of the central fixation area need to be retained in order to maintain normal central visual acuity. We stress the diagnostic significance of vertical steps demonstrated with central scotomas as an indication that the field defect is due to retrochiasmal disease rather than bilateral macular or optic nerve disease.

Adolescent↗
PubMed1997

[Localized glioma in the occipital lobe manifesting as scintillating scotoma: case report].

An 11-year-old female presented with headache in May 1993. Magnetic resonance (MR) imaging disclosed a small lesion (9 mm in diameter) in the left occipital lobe. No treatment was performed because the lesion was small. She subsequently developed frequent episodes of scintillating scotoma in the right visual field eleven months later. MR imaging eleven months after the first MR imaging showed the lesion had enlarged to 14 mm in diameter. Preoperative surface electroencephalography (EEG) detected no spike waves. The diagnosis was localized glioma. The mass was totally removed by gyrectomy in December 1994. Intraoperative cortical EEG demonstrated spike waves which disappeared after tumor removal. The histological diagnosis was pleomorphic xanthoastrocytoma. No postoperative neurological deficit was recognized, and scintillating scotoma and headache disappeared. Postoperative stereotactic radiosurgery was performed. The scintillating scotoma was caused by the tumor, because the spike wave and phase reversal were detected by the intraoperative cortical EEG. Intraoperative EEG is useful for the diagnosis of epilepsy caused by tumor. Sulcotomy and gyrectomy are the optimal surgical treatments for epilepsy caused by a localized glioma.

Astrocytoma↗
PubMed1996

[Effect of fast alternating eye covering on formation of binocular vision in strabismus treated with a localization method. II. Evaluation based on the behavior of functional scotomas].

The authors have examined the behaviour of functional scotomas in the squinting eye in children treated on the static apparatus modelled after the Starkiewicz alteroobturator. They examined 25 children at the age of between 8 and 14 years with convergent squint with macular fixation. Visual acuity of the master eye was equal 1.0 and in the of the squinting eye from 0.4 do 0.8 in correction. The angle of squint was equal from +4 degrees to +26 degrees. The patients were treated in accordance with the localization method-stage II/III. Children were practising on the apparatus 2 x 7-10 minutes for 5 days. In 12 children out of the 25 under examination the functional scotomas were of the same size after exercises, and in 12 children it decreased from 12% to 40%, on average 24.8%. In 1 child the functional scotoma absolutely disappeared.

Adolescent↗
PubMed1998

Peripheral scotoma associated with chronic ethmoidal sinusitis. A case report and review of the literature.

Diseases of the paranasal sinuses may cause visual disturbances, especially diminished visual acuity and visual field defects, by affecting the optic nerve. We report the unusual case of a female patient with unilateral peripheral, quadrantic scotoma and concomitant chronic ethmoidal sinusitis. Visual acuity was not diminished. Despite extensive diagnostic examinations no other cause of the scotoma could be evaluated. As conservative therapy had been unsuccessful, endonasal pansinus operation was performed. Upon surgery, nearly all ethmoidal cells appeared to be filled with polypous mucosa. The sphenoid sinuses, however, contained air. In contrast, pre-operative CT scans had shown only a slight opacity of the ethmoid bone. Already two weeks after surgery a reduction in size of the scotoma could be noted. In addition to this case report, possible causes of visual field defects due to inflammatory diseases of the paranasal sinuses are discussed. In cases of unilateral visual field reduction associated with symptoms of chronic paranasal sinusitis, early operative exploration of the paranasal sinuses should be considered after exclusion of other possible causes, even if radiological findings do not warrant such a procedure.

Adult↗