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At least 1,603 records · Page 89Linked to original sources
PubMed1995

Optic nerve axon count and axon diameter in patients with ocular hypertension and normal visual fields.

BACKGROUND: At postmortem examination, the authors obtained eight eyes of five individuals with elevated intraocular pressure and normal visual fields to study the axon count and mean axon diameter. METHODS: Automated image analysis was used to calculate the total axon count and mean axon diameter per nerve and per nerve segment for each eye. The authors applied the method of identification analysis to compare each study eye with a corresponding normal eye of patients of the same age. RESULTS: There was no statistically significant difference compared with control subjects for total axon count or segmental axon count for any of the eyes. Two eyes showed a statistically significant difference for mean axon diameter for the whole nerve but not for individual segments of the nerve. CONCLUSIONS: Some eyes subjected to varying duration and magnitude of intraocular pressure elevation with normal visual fields may maintain normal axon counts and mean axon diameters.

Aged↗
PubMed1988

Correlation of afferent pupillary defect with visual field loss on automated perimetry.

The study was designed to ascertain the relationship between visual loss in the central 30 degrees of vision and the density of the relative afferent pupillary defect (APD). The APD of 26 patients was quantified using a neutral log density filter. The mean threshold light sensitivity on Humphrey automated perimetry (Program 30-1) of one eye was substracted from the fellow eye total to yield the interocular visual field difference (VFD). A direct correlation was noted such that the log density of the APD increased linearly with an increase in VFD (r = 0.69, P = 0.0001). In the absence of ptosis or ocular media opacification, a VFD greater than 8.7 that is not associated with an APD is suggestive of functional visual loss. Four patients had an APD despite normal static automated perimetry, indicating that an APD may be one of the earliest signs of retinal ganglion cell or axonal dysfunction.

Adolescent↗
PubMed1993

Short-wavelength color visual fields in glaucoma suspects at risk.

Glaucoma suspect eyes were seen during a five-year study on color visual fields that used a 440-nm test on a bright-yellow background (96 normal eyes, 55 suspect eyes, and 110 eyes that developed glaucoma). The predictive ability of the test was assessed in 25 eyes followed up for more than one year, five of which developed glaucoma. These five eyes and those at high risk showed higher mean defect (P < .0001) and number of defective points (P < .0001) than the other suspect groups, which were not significantly different from normal eyes. The mean defects (+/- standard deviations) and average number of defective points were 1.4 +/- 2.3 dB with 8.9 points (low-risk eyes), 1.1 +/- 1.2 dB with 8.0 points (medium-risk eyes), 6.7 +/- 2.8 dB with 27.7 points (high-risk eyes), and 9.3 +/- 1.8 dB with 39.4 points (eyes that developed glaucoma). Normal eyes had an average of 3.4 defective points. These results were similar when all 55 suspect eyes were analyzed. Color visual fields identify early functional loss in eyes at greatest risk for primary open-angle glaucoma.

Color Perception↗
PubMedDate not supplied

Hyperbaric oxygen therapy reduces visual field defect after macular hole surgery.

BACKGROUND AND OBJECTIVE: One of the serious complications that may arise after macular hole (MH) surgery is a temporal visual fields (TVF) defect. We hypothesized that hyperbaric oxygen (HBO) therapy improves the visual field (VF) in these patients. MATERIALS AND METHODS: Vitrectomy for MH was performed on 73 eyes from 1994 to 1997. TVF defect was detected in 19 eyes and, of that 19, 12 patients were followed. Seven patients were treated with HBO therapy and 5 were controls. HBO was performed for approximately 110 minutes a day with 100% oxygen inhalation and a maximum of 2.8 atmospheric pressure. This continued for 20 days. The preoperative VF determined by kinetic perimetry was considered to be 100%, and the VF following HBO therapy was compared with that standard. RESULTS: We detected VF defect (postoperative VF area average 71.9+/-12.8% of the preoperative VF). In all 5 patients who had no HBO therapy, TVF defects remained, while the TVF recovered remarkably in all patients treated with HBO therapy. The VF recovered to 81.7+/-16.7% of the preoperative VF after 3 days of HBO, and to 91.6+/-15.8% months after HBO therapy. CONCLUSION: We speculated that the cause of TVF defect is likely to be chorioretinal circulation disturbance during surgery, and that HBO activates the retinal cells and improves VF. We conclude that HBO is useful in the treatment of TVF defect after macular hole surgery.

Female↗
PubMed2002

Central versus peripheral visual field stimulation results in timing differences in dorsal stream sources as measured with MEG.

Small, achromatic circular sinusoids were presented in the central and peripheral visual fields to investigate dorsal visual stream activation. It was hypothesized that peripheral stimulation would lead to faster onset latencies, as well as preferentially activate dorsal stream visual areas relative to central field stimulation. Although both central and peripheral stimulation activated similar areas, the onset latencies of neuromagnetic sources in two dorsal stream areas were found to be significantly shorter for peripheral versus central field stimulation. The results suggest that information from central versus peripheral fields arrives in the higher-order visual areas via different routes.

Adult↗
PubMed2006

[Visual field and road traffic. How does peripheral vision function?].

Peripheral vision is very important for visual perception in all fields of traffic. The central visual field is most important because the major part of information input occurs here. The peripheral parts of the visual field have excellent motion detection and the capability to perceive flicker stimuli. In addition to the central visual field the horizontal parts to the left and right are important, especially for road traffic. Information input occurs in a continuous sequence of saccadic eye movements which transport critical objects into the fovea. After fixation, the observer analyses the object and decides whether or not a reaction is necessary. Triggering of a saccadic eye movement only can occur if the critical object is suprathreshold in size, contrast, colour, motion and temporal modulation. This is the reason why perception of peripheral objects needs more time than the perception of objects in the fovea. Without an intact central and peripheral visual field participation in traffic is not possible.

Automobile Driving↗
PubMed1998

Visual fields after removal of subretinal hemorrhages and neovascular membranes in age-related macular degeneration.

BACKGROUND: Surgical removal of subretinal hemorrhaging and membranes in eyes with age-related macular degeneration is feasible from a technical point of view, but no advantage over the spontaneous course of the disease has been proven. Visual acuity usually does not improve much. A realistic aim of surgical intervention may be diminution of the central scotoma size, which has not been studied. METHOD: In a prospective study visual fields were measured preoperatively and 6 weeks and 6 months postoperatively in eyes operated on for subretinal hemorrhages and membranes in exudative age-related macular degeneration. The OCTOPUS 1-2-3 program glx, which tests the visual field of 60 degrees diameter at 59 points, was used. Changes in the total size of areas with sensitivity loss of 10-20 dB (= relative scotoma) and > 20 dB (= absolute scotoma) were interpreted as surgical effect. Patients with postoperative retinal detachment or neovascular recurrence were excluded. 30 eyes of 29 patients were enrolled (mean age 75.3 years, 11 male, 18 female) and divided into 3 groups: 14 eyes with massive subretinal hemorrhage of diameters > 30 degrees; 12 eyes with hemorrhages of 10 degrees-30 degrees; 4 eyes with mere neovascular membranes < 10 degrees. RESULTS: (1) The visible area of damage is diminished by surgery (P < 0.01). The reduction for lesions > 30 degrees is 80%; for lesions between 10 degrees and 30 degrees the improvement is 43%. For lesions < 10 degrees there is no significant change. (2) The absolute scotoma size diminishes in all three groups (P = 0.05). The reductions are 63%, 57% and 21%, respectively. (3) Areas of absolute scotoma do not regain full function but are converted to relative scotoma depth, at best. Therefore, in the > 30 degrees group an overall increase (P < 0.01) of the relative scotoma size is observed. (4) The mean sensitivity in the 60 degrees field enhances by 1.6 dB (average over 30 eyes, P = 0.04). (5) Mean preoperative visual acuities were 0.03, 0.12 and 0.17, respectively, with no significant change after surgery. The power of testing is sufficient (0.93) to reject an increase of acuity from 0.12 to 0.2 in group 2. CONCLUSIONS: For hemorrhagic subretinal lesions of diameter > 10 degrees a relevant reduction of central scotoma size is achieved by surgery. The final benefit for the patients depends on the frequency of surgical complications and neovascular recurrence.

Aged↗
PubMed1999

Stronger occipital cortical activation to lower than upper visual field stimuli. Neuromagnetic recordings.

We recorded whole-scalp magnetoencephalographic (MEG) responses to black-and-white checkerboards to study whether the human cortical responses are quantitatively similar to stimulation of the lower and upper visual field at small, 0-6 degrees, eccentricities. All stimuli evoked strong occipital responses peaking at 50-100 ms (mean 75 ms). The activation was modeled with a single equivalent current dipole in the contralateral occipital cortex, close to the calcarine fissure, agreeing with an activation of the V1/V2 cortex. The dipole was, on average, twice as strong to lower than to upper field stimuli. Responses to hemifield stimuli that extended to both lower and upper fields resembled the responses to lower field stimuli in source current direction and strength. These results agree with psychophysical data, which indicate lower visual field advantage in complex visual processing. Parieto-occipital responses in the putative V6 complex were similar to lower and upper field stimuli.

Adult↗
PubMed1995

Influence of myopic refraction on visual field defects in normal tension and primary open angle glaucoma.

It is known that the prevalence of normal tension glaucoma (NTG) or primary open angle glaucoma (POAG) is higher in the myopic population and that the prevalence of myopia and NTG is higher in Japan than in western countries. To evaluate the influence of myopic refractive error in the central 10 degrees of the visual field in NTG eyes, the data obtained from NTG eyes with the Humphrey Visual Field Analyzer were analyzed in comparison with data from POAG eyes. One hundred and twenty eyes of 86 NTG patients and 197 eyes of 138 POAG patients whose ages were 65 years or younger were included in this study. All of them had clear ocular media, refractive power less than +1.0 diopter and no myopic degeneration in the fundus. Multiple linear regression analysis was performed with the dependent variable of the deviation of the measured threshold value from the normal reference value (TD; STATPAC 2), and independent variables of myopic refractive power and the mean deviation (MD; STATPAC 2) as an index of the disease stage at each test point of the Humphrey 10-2 program and at the most central 12 test points of the 30-2 program. Myopic power was found to have a significant positive correlation with the depression in the lower cecocentral area in both NTG and POAG eyes, while only in NTG eyes it had a significant negative correlation with the depression in the upper arcuate area extending just nasal to the fixation point.

Aged↗
PubMed2006

Visual field defects and retinal ganglion cell losses in patients with glaucoma.

OBJECTIVE: To determine whether the structure-function relationships for glaucoma in humans and experimental glaucoma in monkeys are similar. METHODS: The study was based on retinal ganglion cell density and visual thresholds in patients with documented glaucoma. Data were analyzed with a model that predicted ganglion cell density from standard clinical perimetry, which was then compared with histologic cell counts. RESULTS: The model, without free parameters, produced accurate and relatively precise quantification of ganglion cell density associated with visual field defects. For 437 sets of data, the unity correlation for predicted vs measured cell density had a coefficient of determination of 0.39. The mean absolute deviation of the predicted vs measured values was 2.59 decibels (dB), and the mean +/- SD of the distribution of residual errors of prediction was -0.26 +/- 3.22 dB. CONCLUSIONS: Visual field defects based on standard clinical perimetry are proportional to neural losses caused by glaucoma. CLINICAL RELEVANCE: The evidence for quantitative structure-function relationships provides a scientific basis for interpreting glaucomatous neuropathy from visual thresholds and supports the application of standard perimetry to establish the stage of the disease.

Aged↗
PubMed2006

Correlation of asymmetric glaucomatous visual field damage and water-drinking test response.

PURPOSE: To determine whether there is a correlation between asymmetric glaucomatous visual field (VF) damage and water-drinking test (WDT) response. METHODS: A retrospective analysis was conducted of VF and WDT data from 101 patients with glaucoma in clinical therapy, who were receiving treatment with the same topical medication in both eyes, and asymmetric VF defect. Eyes were classified according to mean deviation (MD) into "better" and contralateral "worse" eyes. Maximum mean difference in basal IOP was 2 mm Hg between both eyes. The peak IOP and fluctuation obtained with the WDT were compared between both groups. For the statistical analysis, the Tukey post hoc multiple comparison test and paired t-test were used. RESULTS: Better and contralateral worse eyes presented mean MDs of -4.6 +/- 5.3 and -9.0 +/- 7.4 dB, respectively (P < 0.001). Mean basal IOPs were 13.9 +/- 3.3 and 13.9 +/- 3.1 mm Hg, respectively (P = 0.67). Mean maximum IOPs after water ingestion were 16.5 +/- 3.8 mm Hg in the group with less severe VF defect and 17.2 +/- 4.1 mm Hg in the contralateral group with worse visual fields (P < 0.001). Mean fluctuation (maximum IOP - minimum IOP after water ingestion) was 3.6 +/- 1.8 and 4.4 +/- 2.2 mm Hg (P < 0.001), respectively. CONCLUSION: Eyes with worse MDs presented higher IOP peaks and fluctuation after water ingestion. This study demonstrates a lower capacity of eyes with worse glaucomatous lesion to respond to a stimulus that leads to a transitory elevation of IOP.

Circadian Rhythm↗
PubMed1983

A new technique of visual field evaluation for unilateral ptosis.

A technique of uniocular visual field testing under binocular viewing conditions for evaluation of unilateral ptosis is described. The eye with the nonptotic lid is covered with a red filter, and both eyes fixate the white fixation light while a green test light is used. The resultant field reveals the true functional field loss due to the ptosis and avoids changes due to the patient elevating his brow.

Aged↗
PubMed1986

Recognition of emotion in hemifaces presented to the left and right visual fields.

Thirty-two right-handed subjects (16 males and 16 females) participated in a choice reaction time experiment replicating two previous studies which demonstrated the superiority of the left hemisphere in rapidly identifying facial emotion as either positive or negative. Slides of hemifaces split along the vertical axis, showing either positive (happiness, surprise) or negative (anger, disgust, or sadness) affect were presented tachistoscopically to either the left or right visual field. A 2 X 2 X 2 mixed ANOVA revealed main effects for visual field and type of affect. In contrast to earlier studies which presented full face stimuli, presentation of hemifaces produced a strong left visual field advantage and, as expected, positive faces produced faster reaction times than negative faces.

Adolescent↗
PubMed1995

Decision strategies and visual-field asymmetries in same-different judgments of word meaning.

The accuracy with which observers judged whether two words belonged to the same semantic category was determined from a detection-theoretic analysis of same-different judgments. In Experiment 1, one word was presented centrally and the other word in either the left visual field (LVF) or the right visual field (RVF); in Experiment 2, both words were presented to either the LVF or the RVF. In order to obtain receiver-operating characteristics (ROCs) of performance, observers were asked to rate their confidence that the two words belonged to the same semantic category. Two models of the decision strategy were fitted to the obtained characteristics: a differencing model, in which the decision variable was the difference between the two observations; and an optimal model, in which each observation was judged in relation to a criterion. In both experiments, the optimal model provided a better fit than the differencing model to the obtained characteristics. Maximum-likelihood estimates of both the criterion-free parameter, d', and the area under the operating characteristic, p(A), were greater for words presented in the RVF than for those presented in the LVF.

Adult↗
PubMed1993

Swivel arm perimeter for visual field testing in different body positions.

To investigate the influence of body position on visual field results, a 'swivel arm perimeter' was built, based on a modified Octopus 1-2-3. Here, the measuring unit was detected from the control unit and mounted on a swivel arm, allowing its movement in all directions. The first results obtained with this device have indicated that its development was worthwhile.

Humans↗
PubMed1993

Visual field prognosis in early glaucoma. A long-term clinical follow-up.

Fifty-four eyes of 45 patients with ocular hypertension developed early glaucomatous optic disc or visual field changes after a mean follow-up of 5.1 years without therapy. These changes initiated antiglaucomatous treatment, and the eyes have been followed further on therapy for 2-14 years (mean 8.0 years) in a retrospective study. The mean intraocular pressure (IOP) was lowered from 28.9 to 19.3 mmHg. Half of the eyes were still without field defects at the end of the study, whereas 7 eyes developed extensive field damage noticeable to the patients. The eyes with deteriorating visual fields could not be differentiated from the stable ones by means of the pre-therapy IOP, nor the mean or peak IOP on treatment. There was an accumulation of topical and general risk factors in the progressive eyes. The results support the importance of taking other risk factors than the IOP into consideration in the management of our glaucoma patients.

Acetazolamide↗
PubMed2006

The effect of visual training for patients with visual field defects due to brain damage: a systematic review.

The objective of this review was to evaluate whether systematic visual training leads to (1) a restitution of the visual field (restoration), (2) an increase in the visual search field size or an improvement in scanning strategies (compensation) and (3) a transfer of training-related improvements in activities of daily living such as reading. To retrieve relevant publications, computer-aided searches of databases (Medline, Embase, Cinahl, Cochrane Central Registers of Controlled Trials) and extensive reference tracing and hand searching were performed. Subsequently, all retrieved and blinded studies were scored on methodological quality. 14 studies were included, 2 randomised controlled trials (RCTs) and 12 within-subject repeated-measures designs (RMD). One of the two RCT studies had good quality. The internal validity of the RMD studies varied from poor to good. Five studies reported a significant effect of the vision restoration therapy (VRT), whereas two studies reported no effect using scanning laser ophthalmoscopy or Goldmann perimetry as outcome measure. All authors of the studies on scanning compensatory therapy (SCT) found a significant effect of up to 30 degrees visual search field, a significant increase in reading speed or decrease in reading errors. It is unclear to what extent patients benefit from restoration therapy in relation to a more efficient scanning strategy which enables them to read faster or to avoid obstacles in a better way. No study has given a satisfactory answer. SCT seems to provide a more successful rehabilitation with more simple and user-friendly training techniques. Validated questionnaires provide the most reliable subjective data to assess the transfer of the relevance of training procedures to activities of daily living of the patient. Hence, SCT is recommended until the effect of the VRT is defined.

Brain Diseases↗
PubMedDate not supplied

Correlation between visual field and color Doppler parameters in chronic open angle glaucoma.

The authors evaluated, by means of colour Doppler imaging, the blood flow in ophthalmic artery and posterior ciliary arteries in subjects with chronic open angle glaucoma. On the basis of the visual field indices (MD, SF, CPSD) the patients' eyes were divided in two groups: group A with better indices and group B with great damage. At the posterior ciliary arteries they found these values: PSV 10.264 +/- 2.363 cm/s (group A) vs. 7.882 +/- 1.251 cm/s (group B) (p < 0.008); RI 0.615 +/- 0.065 (group A) vs. 0.695 +/- 0.064 (group B) (p < 0.009). These data highlight a correlation between the visual field damage and the reduced supply of optic nerve head.

Aged↗