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PubMed1995

Visual scotoma and visual afterimages: some evidence that the perceived visual afterimage may not be a purely retinal phenomenon: a single case study.

Observations of the differential appearance and behaviour of a deliberately induced visual scotoma and a patterned visual afterimage are reported. Although a retinal scotoma behaves like a visual afterimage in some ways, there are sufficient differences to suggest that the perceived visual afterimage may not be just the simple consequence of prolonged retinal stimulation.

Afterimage↗
PubMed1995

Visual acuities and scotomas after 3 weeks' levodopa administration in adult amblyopia.

BACKGROUND: Previous studies have shown that both a single dose of levodopa and a 1-week administration of levodopa improve visual functions in adult amblyopic patients. In the present study, we investigated the effect of increased dosage and duration of levodopa on amblyopes' visual functions. METHODS: Visual acuity and visual fields were examined before and after 3 weeks of daily administration of levodopa/carbidopa as well as 1 month and 2 months after completion of drug therapy in a double masked-design. RESULTS: A significant increase in visual acuities and a decrease in fixation point scotomas were found. Changes were of comparable dimension to those found after 1 week of levodopa administration. Improvement of visual functions persisted 2 months after the levodopa/carbidopa administration was completed. CONCLUSION: The present study confirms previous findings of improvement in visual function in amblyopia after levodopa/carbidopa administration. However, increasing the dosage and the duration of levodopa did not enhance the effect in adults.

Administration, Oral↗
PubMedDate not supplied

Topographical reproducibility of small scotoma using computerised dynamic fixation target.

The computer assisted dynamic fixation technique uses the patient's eye movements to locate the test stimulus in the central visual field in relation to a randomly meandering fixation target. The patient looks at the moving fixation target on a high resolution monitor and tries to keep it inside a circle using a joystick. The stimuli are presented at predetermined locations in a seemingly random manner and the awareness of the stimuli is registered by the patient pressing the joystick button. That novel fixation maintenance technique has been combined with suprathreshold static light offset (dark-on-bright-light decrement) stimuli created on a cathode ray tube and used in mapping of the physiological blind spot in 10 healthy eyes. Each eye was examined twice with the same test program in order to document the repeatability of the results. On two consective tests, the physiological blind spot measured an average of 5.7 degrees horizontally and 6.4 degrees vertically, using 15% (17 dB) contrast, 16 mm2, single intensity offset stimuli. The moving eye method and the light offset stimuli, on repeated testing, yielded an average topographical reproducibility rate of 73% in mapping of the scotomas, with an average of 1.4 degrees and 0.6 degree variability in the vertical and horizontal dimensions of the blind spot respectively.

Adult↗
PubMed1995

A computer and video display based system for training eccentric viewing in macular degeneration with an absolute central scotoma.

A new approach designed to establish the most suitable area for eccentric viewing and to teach and train patients with severe age-related macular degeneration (AMD) to use the eccentric viewing technique is described. Using a computer and video display based system, as well as software written specifically for this purpose, we investigated and trained ten consecutive patients with AMD. The patients were 80.1 + or - 5.6 years old, on average. All of them had an absolute central scotoma. Mean visual acuity was 0.035 + or - 0.016. After 30 min of testing, instruction and reading on the screen, followed by 2.6 + or - 0.69 one-hour training sessions, on average, with the low vision therapist, reading newspaper and book texts with the aid of hyperoculars or aplanatic systems and a very short reading distance, the patients achieved a reading speed of 58.9 + or - 19.7 words/min, significantly (p<0.001) higher than the initial speed when reading on the screen, 11.5 + or - 4.5 words/min.

Aged↗
PubMed1977

[Results of objective accommodation determination in eyes with alternating functional central scotoma (alternating strabismus) (author's transl)].

Objective determination of monocular accommodation in young eyes revealed a different behaviour in strabismus alternans from that in normal binocular vision. This manifested itself by strongly differing individual responses, less correct values in physiological and unphysiological accommodation tests, and different reactions on hindering clear vision that cannot be compensated by refraction changes. The possibility of central scotoma, persisting during fixation and varying in density, occurring in alternating strabismus, is discussed.

Accommodation, Ocular↗
PubMed2005

[Correlation between glaucomatous hemifield scotomas and measurements of nerve fiber layer thickness using scanning laser polarimetry].

BACKGROUND: The purpose of the present study was to investigate wether a reduction of the retinal nerve fiber layer (RNFL) in patients with hemifield scotoma can be measured with scanning laser polarimetry and wether regional RNFL parameters can be correlated with the corresponding visual field indices. PATIENTS AND METHODS: We included one eye from each of 40 normal subjects and one eye from each of 40 glaucoma patients. Automated perimetry was performed and the RNFL was analyzed. RESULTS: HMD values obtained by white-white (W/W) and blue-yellow (B/Y) perimetry failed to correlate significantly with most of the corresponding RNFL parameters obtained with the GDx. Significant correlations were only shown for the inferior HMD (W/W and B/Y) and the superior ratio, superior average, and deviation superior. Furthermore, we found a high correlation between differences of upper and lower GDx parameters and differences of upper and lower visual field indices of W/W and B/Y perimetry. CONCLUSIONS: Scanning laser polarimetry can detect differences in RNFL sectors in patients with functional hemifield differences and carries the potential to detect changes in RNFL thickness at an early stage.

Diagnosis, Differential↗
PubMed2004

Distribution of scotoma pattern related to chiasmal lesions with special reference to anterior junction syndrome.

PURPOSE: To evaluate pathogenetic mechanisms and frequency distribution of visual field defects (VFDs) in patients with chiasmal lesions. Secondly, to reconsider the existence of "Wilbrand's knee" as far as referable to the anterior junction syndrome. METHODS: Consecutive visual field records related to chiasmal lesions were retrieved from the Tuebingen Perimetric Database. In all cases, at least one eye was examined with the Tuebingen Automated Perimeter using a standardized grid of 191 static targets within the central 30 degrees visual field, and a threshold-related, slightly supraliminal strategy. VFDs were classified according to standard neuro-ophthalmological categories. RESULTS: Results from 153 consecutive patients (65 male, 88 female) were evaluable. The majority (65%) of chiasmal lesions was due to pituitary adenoma, followed by craniopharyngioma (12%), astrocytoma (9%), and meningioma (8%). Vascular lesions in this region occurred rarely (2%). Three per cent of all patients had no final diagnosis. The majority (22%) of scotomas was attributable to involvement of the temporal hemifield in both eyes, with true bitemporal hemianopia being a very rare event (1%). Anterior junction syndrome, characterized by advanced visual field loss affecting the visual field centre in one eye and (possibly subtle) defects respecting the vertical midline in the fellow eye, was the second most frequent classifiable VFD (13%). Homonymous hemianopic VFDs occurred in 11% of all cases. Nine per cent of all patients exhibited monocular VFDs which did not respect the vertical midline, whereas in 3% of the subjects the monocular VFDs did not cross the vertical meridian. Binasal defects and posterior junction syndrome also occurred seldom (< 1%). Nineteen per cent of all visual field records of patients with chiasmal lesions had results, which could not be classified unequivocally, and an identical portion was rated normal. CONCLUSION: In patients with chiasmal lesions, incomplete involvement of the temporal hemifields in both eyes was the most frequent event (22%), followed by anterior junction syndrome (13%). The latter entity at least clinically indicates the proximity of the pre-chiasmal ipsilateral optic nerve and decussating fibres emanating from the inferior nasal hemiretina of the fellow eye. However, this cannot provide conclusive evidence for the existence of anterior Wilbrand's knee.

Adolescent↗
PubMed2005

Peculiar arcuate scotoma in pathologic myopia--optical coherence tomography to detect peripapillary neural tissue loss over the disc crescent.

BACKGROUND: Optical coherence tomography (OCT) was used to detect peripapillary neural tissue loss (PPNTL) over the disc crescent in pathologic myopia. The retinal neural tissue loss located inside the disc crescent in pathologic myopia is a newly recognized fundus lesion. METHODS: Review of ten eyes of ten patients with peripapillary yellowish-white retinal lesions who underwent OCT for evaluation of the nature of PPNTL in pathologic myopia. OCT, fluorescein angiography, automated visual fields, axial length measurement with ultrasound A scan, and ultrasound B scan were performed. RESULTS: Ten eyes of ten patients were identified during a 14-year period to have findings characteristic of PPNTL. The mean age of the patients was 46 years. They were followed up for an average of 9 years. The mean spherical equivalent correction was -10.50 diopters (D) (range -6.0--16.0 D). The mean axial length was 28.6 mm (range 26.30-31.50 mm). In each case, OCT showed a complete retinal discontinuity in the PPNTL lesion. Automated visual field examination showed corresponding arcuate scotoma. During the follow-up period, the inner retina layer of the retinal defect margin was elevated by posterior hyaloid and partial retinal detachment developed in one eye. CONCLUSIONS: PPNTL in pathologic myopia is a relatively asymptomatic, yellowish-white peripapillary retinal discontinuity. Recognition of this lesion is important because the visual field defect may mimic glaucomatous changes owing to the loss of nerve fiber layer. Progressive partial retinal detachment may ensue as one of the complications of the peripapillary lesion.

Adult↗
PubMed1989

Increase of the short-term fluctuation of the differential light threshold around a physiologic scotoma.

Because determination of the differential light threshold of a visual field is a psychophysiologic test, the results can be subject to variation. This scatter measured during a single examination is usually called the short-term fluctuation. Increases of the short-term fluctuation were thought to occur primarily in abnormal visual fields; however, we found an increase of the short-term fluctuation in normal visual fields when the measurements were made at the border of a physiologic scotoma, such as the blind spot. These results suggest that an increase of the short-term fluctuation may be mainly related to measurements done with any static perimeter at the border of a depression of the island of vision.

Adult↗
PubMed2006

Bilateral ring scotomas following laser in situ keratomileusis.

A 53-year-old white man who had a history of transient ocular hypertension had bilateral laser in situ keratomileusis (LASIK) for myopia. Subsequent computerized static perimetry revealed bilateral, persistent, repeatable midperipheral ring scotomas. The pre-LASIK visual fields were within normal limits, and the optic discs appeared stable and not diagnostic for glaucomatous optic neuropathy. A comprehensive baseline data set before laser refractive surgery aids subsequent assessment of individuals at high risk for developing glaucoma.

Functional Laterality↗
PubMed2001

Peripheral homonymous scotomas from a cavernous angioma affecting fibers subserving the intermediate region of the striate cortex.

PURPOSE: To report the case of a pure peripheral homonymous visual field defect and to delineate the representation of the visual field on the striate cortex. METHODS: Observational case report. Neuro-ophthalmologic and neuroimaging assessment of a patient with a cavernous angioma of the right parieto-occipital lobe. RESULTS: The patient had left homonymous scotomas located 40 degrees to 60 degrees from the vertical meridian. Neuroimaging indicated that the lesion was affecting the optic radiations at their termination in the intermediate portion of the striate cortex or the striate cortex itself. CONCLUSION: Homonymous field defects are typically located within 10 degrees of fixation. This patient had a peripheral homonymous field defect from damage to the intermediate striate cortex. Correlation of the neuroimaging findings in this case with the most commonly used maps of the representation of the visual field on the striate cortex suggests that none of the maps correctly predicts the location or extent of lesions that affect the intermediate portion of the cortex.

Adult↗
PubMed1999

Incongruous homonymous hemianopic scotoma.

We report a patient presenting with incongruous homonymous hemianopic scotoma due to infarction in the territory of the lateral posterior choroidal artery. Imaging studies showed that the patient had a fresh infarct in the lateral geniculate body causing this unusual visual field defect.

Aged↗
PubMedDate not supplied

An unusual junctional scotoma.

A 28-year-old woman presented with painful unilateral left visual loss, impaired color vision, left afferent pupillary defect, and normal ocular fundus. Although optic neuritis was first suspected, visual fields disclosed a junctional scotoma related to chiasmal demyelination, due to a probable multiple sclerosis.

Adult↗
PubMed2005

[Adaptation to central scotoma. Part I. Eccentric fixations].

Among the different means to adapt to central scotoma is eccentric fixation in several zones, the most documented and best-known phenomenon. After anatomic destruction of the macula, one area of the perifoveal retina may become the new oculomotor reference. This area is referred to as the preferred retinal locus (PRL). Scanning laser ophthalmoscopy greatly facilitated the analysis of these preferred retinal loci. However, the mechanisms involved in establishing the PRL remain insufficiently known. Furthermore, there may be several PRLs, which differ depending on the fixated target. PRL stability may also differ greatly among patients. The present review analyzes published data on the location of the preferred retinal loci, their number, and the factors that favor their occurrence. Methods to study the PRL and the relationship of the PRL with the visual cortex are also analyzed.

Adaptation, Physiological↗
PubMed2006

[Adaptation to central scotoma. III. Visual hallucinations and Charles Bonnet syndrome].

Patients with low vision due to central scotoma may experience complex visual hallucinations, referred to as Charles Bonnet syndrome. The present review reports the current literature on this syndrome and details its frequency, predisposing circumstances, the nature of the hallucinations, and treatments. It also reports the possible occurrence of the syndrome immediately after macular treatments using laser photocoagulation and photodynamic therapy. Patients should be reassured when they experience this syndrome, which is not severe but may be the cause of patient concern.

Adaptation, Physiological↗
PubMed1997

[Scotomas: assessment by the patient and by the physician. There's nothing to see].

Contrary to long-held beliefs, plasticity occurs in the adult cerebral cortex, and allows the brain to adapt to background modifications or to damage of the nervous system. Cortical changes occurring following focal visual deafferentation modify visual perception, by filling in visual field defects with information from the area surrounding the scotoma. This causes affected subjects to ignore or underestimate their defects. With visual field defects, cortical plasticity also causes distortion in spatial perception. In ophthalmological daily practice, the effects of cortical plasticity are prominent, but are usually unrecognized. They result in unawareness of field defects following retinal photocoagulation, and cause delay in recognizing visual field defects, they e.g., in early stages of simple chronic glaucoma. In addition affect the results of some procedures for testing the visual field, and increase patients' difficulty in coping with activities in everyday life. It is important to introduce into clinical practice the concept of dissociation between actual and perceived defects in the visual field, resulting from the filling-in process. It can be demonstrated using a "double Amsler grid test".

Adult↗
PubMed1990

The anatomical basis of the caecocentral scotoma. New observations and a review.

It is shown that the 'papillomacular bundle' of optic nerve fibres, although a concept discussed frequently in the clinical literature, lacks a clear anatomical definition. It is suggested that the explanation for this is that the 'bundle' was originally described in autopsy studies of toxic amblyopia, not normal anatomy. The optic nerve fibre projection and vascular architecture of the caecocentral region of the retina is described. These anatomical features are discussed in relation to a number of possible anatomical explanations for the fact that a caecocentral scotoma is the characteristic field defect found in toxic amblyopia. We have been unable to identify a distinct anatomical feature which might explain this vulnerability but suggest that the problem has not as yet been clearly addressed by anatomists.

Amblyopia↗
PubMed1994

Optic neuritis. Differential losses of luminance and chromatic function near a scotoma.

Visual sensitivity to achromatic and chromatic stimulus flashes was determined at sites just inside, on the boundary and just outside scotomata in 11 patients with recovered optic neuritis. The colour of the flashes and the size of the steady background on which they appeared were such that detection was more likely to be mediated by either the large-diameter, magnocellular fibres or the small-diameter, parvocellular fibres of the anterior visual pathway. The spacing of the test sites ranged from 0.5 degrees to 4 degrees visual angle, depending on the shape and location of the scotomata. The greatest differences in sensitivity were between sites just inside and just outside the scotoma and in response to achromatic stimuli more likely to involve the magnocellular fibres. This effect may be due to the size of magnocellular fibres or to their relatively smaller numbers.

Adult↗