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At least 109 records · Page 6Linked to original sources
PubMed2006

Long-term evaluation of eccentric viewing spectacles in patients with bilateral central scotomas.

PURPOSE: Yoked prism spectacles (eccentric viewing spectacles [EVS]) facilitate eccentric viewing in patients with bilateral central scotomas. This study was conducted to evaluate the long-term success and patient satisfaction of this type of low-vision aid. METHODS. In this retrospective cross-sectional study, we reviewed the low-vision rehabilitation records of all patients who received EVS since 1993. With an 18-item survey, 191 patients were questioned about the wearing characteristics, advantages, and disadvantages of the EVS. Descriptive and nonparametric statistics were applied to compare regular users with those persons who no longer use the EVS. RESULTS: The response rate was 83.2% and the average follow-up time was 4.5 years. Forty percent of all patients still used the EVS. The main disadvantages of these spectacles, mentioned mainly by the nonusers, included the heavy weight (41%), perception of curved lines (46%), dizziness during walking (46%), and poor cosmetic appearance (25%). Many successful long-term users considered the EVS suitable for home activities (86%) and walking in the street (70%) and reported that this device reduced eccentric viewing (77%), created better vision in the center of their visual field (67%), and helped with recognition of objects and faces (64%). CONCLUSIONS: The prescription of EVS aids eccentric viewing in patients with dense central scotomas. Although associated with a number of disadvantages and side effects, 40% of the patients continued to use EVS. The results of this study indicate that patients who experience difficulties with eccentric fixation are most likely to benefit from these low-vision aids. A thorough explanation of the advantages and disadvantages of the EVS is important to prevent unnecessary disappointments.

Adult↗
PubMed1993

Effects of light scatter, defocusing, mean luminosity, contrast, and central scotoma on the PVER amplitude-check size function curve.

We analyzed the effects of various stimulus parameters, ie, light scatter, defocusing, mean luminosity, contrast, and central scotoma, on the normal pattern reversal visual evoked response (PVER), amplitude-check size function curve in six normal subjects. The steady-state PVER was recorded with five check sizes ranging from 160 to 10 min in 1-octave increments. The PVER amplitude, especially with the smaller check sizes, was markedly decreased by light scatter induced by acrylic sheets. The function curve quickly changed to a low pass filter shape when +2.0 diopters of defocus were added, with the decrease most marked in the small check sizes. When the mean luminosity was decreased, the function curve maintained its normal inverted-U shape up to 5 cd/m2, but the shape flattened with lower luminosity. Amplitude decreases were seen with all check sizes in low luminosity. With contrast changes from 95 to 24%, the function curve maintained its normal shape, but with slightly reduced amplitudes. The amplitude decrease was moderate even with the lowest contrast. With a two-degree central scotoma, the PVER amplitude was reduced more with the smaller than the larger check sizes. The function curve became somewhat flatter, with its peak shifting to the larger check sizes. Results indicated that the shape of the PVER amplitude-check size function curve changes in response to different modes of stimulation.

Adult↗
PubMed2004

Can fixation instability improve text perception during eccentric fixation in patients with central scotomas?

BACKGROUND: Oculomotor behaviour was investigated in 14 patients with central scotomas from age related macular degeneration (AMD) or Stargardt's disease. A scanning laser ophthalmoscope (SLO) was used to project letters and words onto the retina and to assess fixation behaviour. Five patients reported while deciphering letters that they needed to "move their eye" to prevent the image from vanishing. The observation of the SLO fundus images revealed that the gradual disappearance of the stimulus did not result from a transient projection of the word in the lesion. This prompted the authors to investigate, in an experimental setting, whether purposeful changes in fixation position could improve the perception of an eccentrically fixated text stimulus. METHODS: Twenty normal subjects were asked to alternate fixation, every three to four seconds, between two vertically aligned dots, spaced 10 degrees apart, and to report any changes in the perception of a laterally located letter, 1.5 degrees in height, 7 degrees apart and equidistant between the two fixation spots. RESULTS: Nineteen subjects reported a transient refreshment of the letter image immediately after the realisation of a saccade. Improved perception lasted approximately a second. With persistent fixation, they noted a rapid fading effect that reduced letter recognition. CONCLUSION: These observations suggest that ocular instability during eccentric viewing can have a functional advantage, probably related to counteracting Troxler's phenomenon. In addition to alternating between PRLs, it appears that saccades related to fixation instability might be valuable and improve text perception in individuals with a central scotoma and eccentric fixation. This possibility should be taken into consideration when conducting visual rehabilitation procedures.

Adult↗
PubMed1999

Full text reading with a central scotoma: pseudo regressions and pseudo line losses.

AIMS: To investigate the reading strategy of a patient with central scotoma, using several preferred retinal loci (PRL). METHODS: A 47 year old man with Stargardt's disease was asked to decipher texts projected onto his retina using a scanning laser ophthalmoscope. A recording of the fundus image, on which the projected texts were superimposed, was analysed frame by frame. RESULTS: The subject used a combination of three PRL, located above the scotoma and laterally to the left and right of it. He first used his left PRL to search for the beginning of a line, then switched to his right PRL, thus performing an apparent regression which was called "pseudo regression", to read the line with successive rightward saccades. To decipher a particularly difficult word, he switched to his upper PRL, showing an apparent line loss which was called ("pseudo line loss"), and then used his three PRL in combination. CONCLUSION: The patient used a complex, well structured reading strategy. These data showed that backward saccades and unexpected line losses, hitherto thought to be inappropriate and uneconomical, may in fact represent purposeful changes of PRL. It is thought that this is the first structured reading behaviour ever identified in such a condition. Such adaptive oculomotor behaviour should be taken into account when considering rehabilitation procedures.

Eye Movements↗
PubMed1986

[Vision aids for patients with senile exudative macular degeneration. Comparison of spontaneous fibrovascular scars and scotomas induced by photocoagulation].

Aging exudative macular degeneration frequently results in a fibrovascular scar which entails the loss of central vision. This scar implies an often large and deep scotoma which makes it very difficult for the patient to be fitted with low-vision aids. A Goldmann static perimetry study of retinal sensitivity in the treated areas showed that krypton laser at liminar doses does not induce deep scotomas.

Aged↗
PubMedDate not supplied

Evaluation of amblyopic scotoma by electrophysiological examinations and computerized perimetry.

To evaluate amblyopic scotoma and the most affected neural cells in suppressive phenomena, eight patients with deep amblyopia from strabismus (visual acuity of the amblyopic eye between 4/50 and 2/10) underwent a pattern electroretinogram (PERG), pattern visual evoked potential (VEP), and event-related potential (ERP) from visual stimuli, and computerized perimetry. The results of stimulation of the amblyopic eye, the leading eye and the leading eye penalized by Ryser filters were compared statistically. Computerized perimetry was used to quantify the depth and amplitude of the amblyopic scotoma. All electrophysiological potentials were reduced in amplitude and the implicit times of VEP and ERP were longer when stimulating the amblyopic eye compared to the leading eye. Only in PERG the penalization induced major changes. Our data suggest that the important suppressive phenomena present in the squint amblyopic eye involve not only the occipital cortex, but also the cognitive areas.

Adolescent↗
PubMed2006

A technique to train new oculomotor behavior in patients with central macular scotomas during reading related tasks using scanning laser ophthalmoscopy: immediate functional benefits and gains retention.

BACKGROUND: Reading with a central scotoma involves the use of preferred retinal loci (PRLs) that enable both letter resolution and global viewing of word. Spontaneously developed PRLs however often privilege spatial resolution and, as a result, visual span is commonly limited by the position of the scotoma. In this study we designed and performed the pilot trial of a training procedure aimed at modifying oculomotor behavior in subjects with central field loss. We use an additional fixation point which, when combined with the initial PRL, allows the fulfillment of both letter resolution and global viewing of words. METHODS: The training procedure comprises ten training sessions conducted with the scanning laser ophthalmoscope (SLO). Subjects have to read single letters and isolated words varying in length, by combining the use of their initial PRL with the one of an examiner's selected trained retinal locus (TRL). We enrolled five subjects to test for the feasibility of the training technique. They showed stable maculopathy and persisting major reading difficulties despite previous orthoptic rehabilitation. We evaluated ETDRS visual acuity, threshold character size for single letters and isolated words, accuracy for paragraphed text reading and reading strategies before, immediately after SLO training, and three months later. RESULTS: Training the use of multiple PRLs in patients with central field loss is feasible and contributes to adapt oculomotor strategies during reading related tasks. Immediately after SLO training subjects used in combination with their initial PRL the examiner's selected TRL and other newly self-selected PRLs. Training gains were also reflected in ETDRS acuity, threshold character size for words of different lengths and in paragraphed text reading. Interestingly, subjects benefited variously from the training procedure and gains were retained differently as a function of word length. CONCLUSION: We designed a new procedure for training patients with central field loss using scanning laser ophthalmoscopy. Our initial results on the acquisition of newly self-selected PRLs and the development of new oculomotor behaviors suggest that the procedure aiming primarily at developing an examiner's selected TRL might have initiated a more global functional adaptation process.

Aged↗
PubMed2002

Junctional scotoma in giant cerebral aneurysm.

A brain lesion located at the lateral side of the sella turcica can produce a junctional scotoma by compressing the ipsilateral optic nerve and the contralateral inferonasal nerve fiber. This study reports a female patient with a junctional scotoma caused by a cerebral aneurysm. At the initial visit, she complained of visual disturbance in both eyes and the right optic disc was atrophied. The visual field showed right blindness and left superotemporal quadrantopsia. A brain CT indicated an approximately 3 cm sized brain mass located superolateral to the sella turcica. The brain MRI showed the lesion to be more like an aneurysm than a pituitary adenoma. Therefore, 4 vessels angiography was done, and this lesion was confirmed to be a sellar variant of an aneurysm located at the right carotid siphon. Like a tumor of the optic chiasm, a cerebral aneurysm can cause visual disturbance and visual field defects. Therefore, an early differential diagnosis is important because the prognosis and treatment of an aneurysm differ.

Aged↗
PubMed2002

[Aneurysm of the anterior cerebral artery disclosed by unique hemianopic scotoma].

We report the case of a 47-year-old man with an aneurysm of the anterior cerebral artery revealed by lateral homonymous hemianopic non congruent scotoma. The aneurysm was successfully treated with interventional radiology procedures. In 10p. cent of cases, intracranial aneurysms present prior to their rupture with headache or neuro-ophthalmological symptoms and signs. Isolated visual field defects are rare, and isolated compression of the optic tract is extremely unusual. Although rare, the development of a non-congruent controlateral homonymous hemianopic scotoma is highly suggestive of optic tract compression, and can be explained by the somatotopy of the fibers within the optic tract.

Anterior Cerebral Artery↗
PubMed1992

Visual acuities and scotomas after one week levodopa administration in human amblyopia.

The authors previously showed that a single dose of levodopa improves the contrast sensitivity and decreases the size of fixation point scotomas in amblyopic patients. In the present study, they investigated the effect of levodopa after 1 wk of daily administration using a cross-over, double masked design. The decrease of fixation point scotomas was confirmed with automatic static perimetry. An improvement of visual acuity occurred in 70% of the patients after 1 wk of levodopa administration compared to only 22% in the authors' previous study using one single dose. The improvements in visual acuities and visual fields persisted even after the levodopa administration was completed.

Administration, Oral↗
PubMed1990

Normal gray scale displays in the presence of arcuate scotomas in automated threshold perimetry.

In 2.4% of visual fields and 10.4% of eyes with well-established early glaucoma, a normal gray-scale display was present despite an arcuate scotoma on pattern-deviation display in the same central threshold visual-field printout (30-2 single-field analysis program, Humphrey Field Analyzer). Also, the pattern-deviation probability plot highlighted the presence and significance of the arcuate scotoma. To my knowledge these findings have not been previously reported in the literature. In suspected glaucoma or early glaucoma, visual-field analysis based on the gray-scale display alone can be misinterpreted. In this population, the defect-depth or pattern-deviation displays should be examined before any diagnostic or therapeutic decision is made.

Adult↗
PubMed1990

Effect of levodopa on contrast sensitivity and scotomas in human amblyopia.

The neurotransmitter dopamine (DA) is involved in several visual functions. Visual deprivation decreases retinal DA concentration in chickens and monkeys. In animals with deprivation amblyopia, several studies suggest that neurotransmitters are involved in visual-cortical plasticity and can restore partial visual acuity in adult cats. We investigated in a cross-over, double-masked study the influence of levodopa on contrast sensitivity and binocular suppression in human adult strabismic and amblyopic patients. After one single administration of levodopa, a significant increase in contrast sensitivity and decrease of the size of the fixation point scotoma was found. No changes could be detected after placebo administration. Levodopa did not induce changes in contrast sensitivity in the dominant eyes of the patients or in normal subjects. In conclusion, we found a short-term effect of levodopa on contrast sensitivity and fixation point scotomas in amblyopic eyes of adult patients.

Adult↗
PubMed1989

[The significance of the phenomenon of dynamic disadaptation scotoma in the early diagnosis of macular dystrophies].

Examinations of 202 patients (337 eyes) with different forms of macular dystrophies, such as idiopathic flat detachment of the retina in the macular area, central sclerotic dystrophy of the retina, tapetoretinal macular degeneration, outcome of local inflammation of pigmented epithelium, post-traumatic central chorioretinitis, etc., allowed to receive data confirming high information value of a method based on the phenomenon of dynamic scotoma of disadaptation as compared with examinations on the Amsler's grid and campimetry. Thus, metamorphopsias were revealed on the Amsler's grid in 193 eyes (57%), changes by means of campimetry--in 171 eyes (51%), while dynamic scotoma disadaptation was revealed in 337 eyes (100%). The method is most effective at early stages of the disease because it allows to reveal it in the presence of high visual acuity and negative data of the Amsler's grid and campimetry.

Dark Adaptation↗
PubMed1986

Acute, severe, symmetric visual loss with cecocentral scotomas due to olfactory groove meningioma.

Cecocentral scotomas are a hallmark of toxic, metabolic, and hereditary optic neuropathies, but are rarely associated with compressive processes. Acute visual loss due to a compressive optic neuropathy by a benign tumor is unusual unless intratumoral hemorrhage or infarction occurs. A case of acute, severe, remitting, symmetrical visual loss with cecocentral scotomas, initially thought to be of toxic etiology, proved to be due to a typical suprasellar meningioma originating in the olfactory groove. A history of olfactory disturbance with visual loss should prompt neuroradiologic investigation despite atypical neuro-ophthalmic features.

Adult↗
PubMed1984

Cecocentral scotomas in gliomatosis cerebri.

A previously healthy 69-year-old white male presented with slowly progressive, painless loss of vision in both eyes. Bilateral cecocentral scotomas were found, and this was his only chief complaint for 9 months. Signs of progressive neurologic dysfunction ensued, and the patient was followed through a complete neuropathologic study at postmortem examination. To our knowledge, this is the only reported instance of pathologically confirmed gliomatosis cerebri with an initial presentation of bilateral chronic cecocentral scotomas.

Aged↗
PubMed1978

Monocular performance of functional amblyopes: another look at the scotoma hypothesis.

The traditional scotoma hypothesis for functional amblyopia is modified to state: whereas the central visual field of a normal visual system and that of an organic amblyope become increasingly scotomatous as light level is decreased from high to low photopic levels, the reverse is true for the central field of a functionally amblyopic visual system. An attempt is made to show how this hypothesis provides a unifying explanation for several seemingly different visual performances observed in functional amblyopes. The paper deals with (1) field inhomogeneities and threshold measures, and (2) threshold changes with light adaptation level. Implications of the modified scotoma hypothesis are discussed for (1) the neutral-density-filter test to distinguish functional from organic amblyopia, (2) the reduced CFF threshold for amblyopic eyes, (3) expectations of stereopsis for amblyopes, and (4) possible mechanisms for amblyopia.

Amblyopia↗
PubMed1994

Fluctuations of visual field interpretation related to cluster and scotoma analysis by one interpreter.

A total of 189 numerical printouts of the visual fields of 189 eyes of individuals either suspected of or verified as having glaucoma and displaying varying degrees of glaucomatous visual field damage were analyzed by one expert interpreter. The amount of clusters (or scotomas) was counted and delineated in each visual field under both a more stringent and a more liberal criterion. The interpretations of the visual fields differed significantly in both groups, as did the subjective certainty the interpreter allotted to his assessment. In the group of certain decisions, only 144 defects were assessed as opposed to 364 when a more stringent rather than a more liberal criterion was adopted. In uncertain cases, a reverse trend was observed, since only 11 as opposed to 324 defects were assessed when a more liberal rather than a more stringent criterion was adopted. Both trends may be explained by an increase in sensitivity at the expense of specificity (i.e., a change in the receiver-operating characteristic of the expert when the latter is pressed to change the criterion in a subjective cluster or scotoma assessment task). The ambiguity of the task and the difference in the criterion adopted by the interpreter significantly influences the assessment of normality and pathology, in particular its extent and spatial distribution.

Adult↗
PubMed1993

Evaluation of numerical displays of visual field data by human observers--the definition of scotomas and clusters by human interpreters.

Numerical printouts of 23 visual field examinations performed with glaucoma program G1 were analyzed by 3 perimetrists. The task consisted of defining the existence of clusters or scotomas. Considerable discrepancy with regard to the existence or the size of clusters and/or scotomas was found among the three perimetrists. The median difference in number of clusters as compared for each pair of interpreters was found to differ from zero at a significance level of 5% (Wilcoxon's signed-rank nonparametric test). These findings suggest that the interpretation of a visual field status by human observers will always remain subjective and to a large extent contradictory. This situation calls for the implementation of interpretative computer software to supplement the currently available algorithms.

Adult↗