Blindsight in Subjects with Homonymous Visual Field Defects

1999 ◽  
Vol 11 (1) ◽  
pp. 52-66 ◽  
Author(s):  
Heinz Schärli ◽  
Alison M. Harman ◽  
John H. Hogben
Keyword(s):  
Visual Field ◽  
Visual Fields ◽  
Neural Mechanism ◽  
Stray Light ◽  
Visual Field Defects ◽  
Optic Radiation ◽  
Visual Ability ◽  
Choice Tests ◽  
Visual Areas ◽  
Better Than

Brain damage in the visual system can lead to apparently blind visual areas. However, more elaborate testing indicates that some visual ability may still exist for specific stimuli in the otherwise blind regions. This phenomenon is called “blindsight” if subjects report no conscious awareness of visual stimuli but when forced to guess, nevertheless perform better than chance. It has mainly been suggested that secondary visual pathways are responsible for this phenomenon. However, no published study has clearly shown the neural mechanism responsible for blindsight. Furthermore, experimental artifacts may have been responsible for the appearance of the phenomenon in some subjects. In the present study, the visual fields of nine subjects were mapped and residual visual performance was examined in many areas using three different experimental procedures. Artifacts such as stray light or eye movements were well controlled. In addition, confidence ratings were required after each trial in the forced-choice tests. The results show that only one subject with a lesion in the optic radiation had blindsight in two discrete areas of the affected visual field. Spared optic radiation fibers of the main (primary) geniculo-striate visual pathway were most likely to account for this finding.

Arteriovenous malformations in the optic apparatus: systematic literature review and report of four cases

2021 ◽  
pp. 1-11
Author(s):  
Visish M. Srinivasan ◽  
Phiroz E. Tarapore ◽  
Stefan W. Koester ◽  
Joshua S. Catapano ◽  
Caleb Rutledge ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
Visual Function ◽  
Arteriovenous Malformations ◽  
Vascular Malformations ◽  
Visual Fields ◽  
Optic Tract ◽  
Visual Disturbance ◽  
Visual Field Defects ◽  
Subtotal Resection

OBJECTIVE Rare arteriovenous malformations (AVMs) of the optic apparatus account for < 1% of all AVMs. The authors conducted a systematic review of the literature for cases of optic apparatus AVMs and present 4 cases from their institution. The literature is summarized to describe preoperative characteristics, surgical technique, and treatment outcomes for these lesions. METHODS A comprehensive search of the English-language literature was performed in accordance with established Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all published cases of AVM in the optic apparatus in the PubMed, Web of Science, and Cochrane databases. The authors also searched their prospective institutional database of vascular malformations for such cases. Data regarding the clinical and radiological presentation, visual acuity, visual fields, extent of resection, and postoperative outcomes were gathered. RESULTS Nine patients in the literature and 4 patients in the authors’ single-surgeon series who fit the inclusion criteria were identified. The median age at presentation was 29 years (range 8–39 years). Among these patients, 11 presented with visual disturbance, 9 with headache, and 1 with multiple prior subarachnoid hemorrhages; the AVM in 1 case was found incidentally. Four patients described prior symptoms of headache or visual disturbance consistent with sentinel events. Visual acuity was decreased from baseline in 10 patients, and 11 patients had visual field defects on formal visual field testing. The most common visual field defect was temporal hemianopia, found in one or both eyes in 7 patients. The optic chiasm was affected in 10 patients, the hypothalamus in 2 patients, the optic nerve (unilaterally) in 8 patients, and the optic tract in 2 patients. Six patients underwent gross-total resection; 6 patients underwent subtotal resection; and 1 patient underwent craniotomy, but no resection was attempted. Postoperatively, 9 of the patients had improved visual function, 1 had no change, and 3 had worse visual acuity. Eight patients demonstrated improved visual fields, 1 had no change, and 4 had narrowed fields. CONCLUSIONS AVMs of the optic apparatus are rare lesions. Although they reside in a highly eloquent region, surgical outcomes are generally good; the majority of patients will see improvement in their visual function postoperatively. Microsurgical technique is critical to the successful removal of these lesions, and preservation of function sometimes requires subtotal resection of the lesion.

Influence of Carteolol and Timolol on IOP and Visual Fields in Glaucoma: A Multi-Center, Double-Masked, Prospective Study

1992 ◽  
Vol 2 (4) ◽  
pp. 169-174 ◽  
Author(s):  
J. Flammer ◽  
Y. Kitazawa ◽  
L. Bonomi ◽  
B. Mills ◽  
M. Fsadni ◽  
...  
Keyword(s):  
Visual Field ◽  
Prospective Study ◽  
Beta Blockers ◽  
Visual Fields ◽  
Visual Field Defects ◽  
Eye Drops ◽  
Treatment Groups ◽  
Visual Field Damage ◽  
One Year ◽  
Field Defects

The influences of Carteolol and Timolol eye drops on intraocular pressure (IOP) and visual fields were compared in a multi-center, double-masked, prospective study. Two-hundred and forty eyes of 120 patients were initially included in the study, and 142 eyes of 72 patients fulfilled all the criteria for final statistical analysis. Both drugs significantly reduced IOP. The visual fields in both treatment groups did not change during one year of treatment. In both groups some patients improved slightly, and others deteriorated slightly. This indicates that locally applied beta-blockers may efficiently stop further progression of visual field defects in cases with increased IOP and early visual field damage. There was no difference between Carteolol and Timolol in this regard. The side effects were minimal, and there were no differences in their frequency or intensity in the two treatment groups.

Optical Coherent Tomography Predicts Long-Term Visual Outcome of Pituitary Adenoma Surgery: New Perspectives From a 5-Year Follow-up Study

Neurosurgery ◽  
2020 ◽  
Vol 88 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Young Soo Chung ◽  
Minkyun Na ◽  
Jihwan Yoo ◽  
Woohyun Kim ◽  
In-Ho Jung ◽  
...  
Keyword(s):  
Pituitary Adenoma ◽  
Visual Field ◽  
Assessment Tool ◽  
Visual Fields ◽  
Visual Field Defects ◽  
Mean Deviation ◽  
Rnfl Thickness ◽  
Long Term Follow Up

Abstract BACKGROUND Compressive optic neuropathy is the most common indication for transsphenoidal surgery for pituitary adenomas. Optical coherence tomography (OCT) is a useful visual assessment tool for predicting postoperative visual field recovery. OBJECTIVE To analyze visual parameters and their association based on long-term follow-up. METHODS Only pituitary adenoma patients with abnormal visual field defects were selected. A total of 188 eyes from 113 patients assessed by visual field index (VFI) and 262 eyes from 155 patients assessed by mean deviation (MD) were enrolled in this study. Postoperative VFI, MD, and retinal nerve fiber layer (RNFL) thickness were evaluated and followed up. After classifying the patients into normal (&gt;5%) and thin (&lt;5%) RNFL groups, we investigated whether preoperative RNFL could predict visual field outcomes. We also observed how RNFL changes after surgery on a long-term basis. RESULTS Both preoperative VFI and MD had a linear proportional relationship with preoperative RNFL thickness. Sustained improvement of the visual field was observed after surgery in both groups, and the degree of improvement over time in each group was similar. RNFL thickness continued to decrease until 36 mo after surgery (80.2 ± 13.3 μm to 66.6 ± 11.9 μm) while visual field continued to improve (VFI, 61.8 ± 24.5 to 84.3 ± 15.4; MD, −12.9 ± 7.3 dB to −6.3 ± 5.9 dB). CONCLUSION Patients with thin preoperative RNFL may experience visual recovery similar to those with normal preoperative RNFL; however, the probability of normalized visual fields was not comparable. RNFL thickness showed a strong correlation with preoperative visual field defect. Long-term follow-up observation revealed a discrepancy between anatomic and functional recovery.

Reading with Visual Field Defects

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 11-11 ◽  
Author(s):  
S Trauzettel-Klosinski
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Reading Ability ◽  
Reading Speed ◽  
Visual Fields ◽  
Zero Point ◽  
Normal Subjects ◽  
Visual Field Defects ◽  
Video Tape ◽  
Field Defects

The influence of different visual field defects on the reading performance was examined with potential adaptive strategies to improve the reading process in mind. By means of an SLO, the retinal fixation locus (RFL) was determined with the use of single targets and text, and eye movements scanning the text were recorded on video tape. Additionally, eye movements were monitored by an Infrared Limbus Tracker. Visual fields were assessed by the Tübingen Manual and/or automatic perimetry. Normal subjects, and patients with central scotomata, ring scotomata, and hemianopic field defects (HFD) were examined. The main pathological reading parameters were an increase of saccade frequency and regressions per line, and a decrease of reading speed. In patients with field defects involving the visual field centre, fixation behaviour is significant for regaining reading ability. In absolute central scotoma, the lost foveal function promotes eccentric fixation. The remaining problem is insufficient resolution of the RFL, which can be compensated for by magnification of the text. In patients with insufficient size of their reading visual field, due to HFD and ring scotoma, it is crucial that they learn to use a new RFL despite intact foveolar function. Preconditions for reading have been found to be: (1) sufficient resolution of the RFL, (2) a reading visual field of a minimum extent, and (3) intact basic oculomotor function. In patients with visual field defects involving the centre, a sensory-motor adaptation process is required: the use of a new RFL as the new centre of the visual field and as the new zero point for eye-movement coordinates.

Influence of Nifedipine on the Visual Fields of Patients with Optic-Nerve-Head Diseases

1994 ◽  
Vol 4 (1) ◽  
pp. 24-28 ◽  
Author(s):  
A.Z. Gaspar ◽  
J. Flammer ◽  
PH. Hendrickson
Keyword(s):  
Optic Nerve ◽  
Visual Field ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Optic Nerve Head ◽  
Channel Blocker ◽  
Glaucoma Patient ◽  
Visual Fields ◽  
Visual Field Defects ◽  
Channel Blockers

Calcium-channel blockers have long been employed in coronary disease, and recent investigations have indicated their efficacy in improving the visual field in low-tension glaucoma or presumed vasospasm, possibly by enhancing ocular circulation. We evaluated the short-term influence of a typical calcium-channel blocker, nifedipine, on 59 patients with visual-field defects, some with optic-nerve-head pathology (n = 38) and some with normal-appearing optic nerve heads (n = 21). On the average, a statistically significant improvement of 1.2 dB was observed. Different types of patients, however, behaved quite differently. The younger the patient, the greater the improvement. Patients with normal optic nerve heads improved by 1.54 dB, whereas patients with optic-nerve-head excavation improved by only 0.66 dB. No response was observed in patients with anterior ischemic neuropathy. Marked deterioration was noted in one glaucoma patient with low systemic blood pressure. The visual-field changes were observed in the scotomatous and non-scotomatous areas. Thus, the calcium-channel blocker nifedipine can be effective in some selected diseases whose pathogenesis probably involves vascular dysregulation though it may even be contraindicated in others

scholarly journals Visual Field Defect after Cardiac Surgery: The Striking Role of Interdisciplinary Collaboration

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Raffaele Nuzzi ◽  
Carlo Lavia
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
Interdisciplinary Collaboration ◽  
Visual Fields ◽  
Cortical Blindness ◽  
Visual Field Defects ◽  
Ischemic Optic Neuropathy ◽  
Intraoperative Hypotension ◽  
Perioperative Visual Loss ◽  
Vascular Occlusions

Perioperative visual loss (POVL) is a potentially devastating complication that can occur following ocular or nonocular surgery. The leading causes of this disease are retinal vascular occlusions, ischemic optic neuropathies, and cortical blindness. POVL pathogenesis is strictly influenced by surgery, anesthesia, and patients’ comorbidities. We report of a 55-year-old caucasian man who presented with complaints of sudden painless loss of vision and unilateral campimetric deficit. We recorded a preserved visual acuity but at fundus examination a bilateral ischemic optic neuropathy (ION) was suspected. Our hypothesis was supported by uncommon and peculiar visual field defects and a history of cardiovascular surgery shortly before was a striking data. When we examined his medical records we found strong accordance with what is reported in literature to be risk factors for postoperative ION development. He presented intraoperative hypotension, anemia, and hypothermia, he was older than 50 years, and surgery lasted for more than five hours. We are currently monitoring his visual acuity and visual fields which remain unchanged. As there is no proved therapy for such severe adverse events, we recommend intraoperative check of blood pressure, blood loss, and body temperature, associated with repeated eye checks and patients’ interview.

Normal visual fields as assessed by computerized static threshold perimetry in patients with untreated primary hypothyroidism

1989 ◽  
Vol 121 (4) ◽  
pp. 495-500 ◽  
Author(s):  
Bengt Hallengren ◽  
Per Manhem ◽  
Margareta Bramnert ◽  
Inga Redlund-Johnell ◽  
Anders Heijl
Keyword(s):  
Visual Field ◽  
Prospective Study ◽  
Visual Fields ◽  
Primary Hypothyroidism ◽  
Common Finding ◽  
Visual Field Defects ◽  
Computer Assisted ◽  
Computerized Perimetry ◽  
Assisted Analysis ◽  
Field Defects

Abstract. In this prospective study, 25 consecutive patients with untreated primary hypothyroidism were tested with a highly sensitive perimetric technique, since a high prevalence of visual field defects has been described in this condition. All patients had clinical hypothyroidism, a serum TSH value > 20 mU/l (reference range 0.4–4.0) and decreased/low normal serum total T4 concentration. Visual fields were tested with fully automated threshold-measuring computerized perimetry of the central 30 degrees field. Interpretation of fields included computer-assisted analysis provided by a perimetric statistical programme package. In 23 patients, conventional inspection and computer-assisted analysis showed no visual field defects. Two patients were excluded from the latter analysis: one patient who did not respond adequately at computerized perimetry and in whom manual field tests were entirely normal; one patient who had low sensitivity values in the uppermost parts of both visual fields owing to markedly swollen upper eye lids. In conclusion, although pituitary hyperplasia has been well documented in primary hypothyroidism, the present prospective study clearly indicates that visual field defects are not a common finding in patients with this disease.

Retrogeniculate Visual Field Defects

Visual Fields ◽  
2010 ◽  
Author(s):  
Thomas R. Hedges III
Keyword(s):  
Visual Field ◽  
Vision Loss ◽  
Visual Fields ◽  
Field Testing ◽  
Visual Field Defects ◽  
Automated Perimetry ◽  
Loss Of Vision ◽  
Data Points ◽  
Field Defects ◽  
Macular Sparing

Automated perimetry has changed visual field testing considerably in recent years. What was considered an art has become an exercise in interpreting a set of data points obtained mechanically. Automated perimetry saves ophthalmologists time, which ideally should allow for more visual fields to be obtained on patients with unexplained vision loss. However, one must still keep in mind that automated perimetry still depends on the subjective responses from the patient. More important, automated perimetry has made interpretation of visual field defects, especially those due to occipital lesions, more difficult. For example, macular sparing may not be reflected, especially with programs limited to the central 24° or 30°. A 10° field may be required to show macular sparing. Also, sparing or involvement of the temporal crescent will not be shown with 24° or 30° visual fields. The limitation of most programs may lead to the appearance of incongruity when in fact the field is indeed congruous. Sometimes, a small homonymous hemianopic scotoma will be detected when one eye is tested but will be completely missed when the other eye is tested, giving the false impression that the visual loss is monocular. This is especially problematic if the patient also falsely interprets his or her homonymous loss of vision as monocular. Such individuals may complain of loss of vision in one eye when in fact it is one half of their visual field that is defective. The strategy of automated testing on either side the vertical and horizontal meridians may lead to the false impression that field defects respect the vertical or horizontal meridian when they do not. Automated perimetry should make it possible to test more patients with unexplained vision loss, but all automated visual fields must be interpreted with caution and, when necessary, substantiated with some other method, such as the tangent screen, which remains the most powerful method of detecting the size, shape, and density of visual field defects. Because most ophthalmologists no longer use tangent screen testing, at least an Amlser grid should be used to qualify the nature of a paracentral visual field defect.

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