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The authors examined 41 eyes of 22 compensated type I diabetics 1 - 2 years after laser photocoagulation, using an automatic static perimeter Peritest. One fifth of the investigated patients had marked changes - DR20. The patients are not aware of the diminution of the visual field. Even the most extensive diminution of the visual field in this group did not restrict the ability to drive motor vehicles.
We report two cases in which heteronymous, altitudinal visual field defects resulted in loss of fusion and transient overlap of preserved hemifields. This phenomenon resulted in complaints of diplopia similar to that described as "hemifield" slide previously described by temporal hemianopsias. These cases illustrate that generalized loss of fusion, and not the particular type of hemianopic field defect, is responsible for the symptoms known as hemifield slide.
We report on a patient with an asymmetrical bilateral developmental anomaly of the occipital lobes which led to a loss of almost the entire visual field. MRI and 18FDG scans confirmed the presence of a larger lesion of the visual cortex of the right hemisphere. The patient recovered parts of her visual field with time as measured by computerized perimetry, progressing from near blindness of the right eye to a remarkable recovery of vision. Because the patient had neonatal damage to both occipital lobes, we hypothesized a cortical plasticity process similar to that described in subhuman species.
Discrimination of curvature in nearly straight stimuli was measured for twelve stimulus orientations, corresponding to the hours of the clock, at eleven positions in the visual field of human observers. Displacements below the diameter of a photoreceptor can be detected foveally. In the periphery of the visual field, stimuli oriented towards the fovea yield best results. This anisotropy of orientation discrimination seems not to have an optical cause. It has a close correlation both to the structure and functional properties of cat ganglion cells, to the organization of receptive fields in area 17 and to the geometry of ocular dominance stripes.
We report the comparison of field extent measured using two kinetic perimeters: 1) a double-arc perimeter developed by van Hof-van Duin for use in infants and young children, and 2) the standard Goldmann apparatus. Targets used were the V-4-e target on the Goldmann and both 2- and 6-degree targets on the double-arc perimeter. Visual fields were measured by assessing looking responses toward targets presented in a pseudorandom order at 45 degrees, 135 degrees, 225 degrees, and 315 degrees. Fifty-six children (mean age: 6.8 years, range: 4 to 10 years) were tested, with retests undertaken in 20%. The extent of total field size was highly correlated among the three tests (P less than .001) and test-retest reliability was high for all three targets (P less than .001). Our previous observation of continued growth with age in visual field extent using the 6-degree target in 4- to 10-year-old children was confirmed and also seen with the 2-degree target in arc perimetry and with the V-4-e in the Goldmann apparatus. Kinetic perimetry using a double-arc perimeter with 2- and 6-degree target sizes appears reliable and comparable, in the four meridia tested, to conventional kinetic perimetry techniques in 4- to 10-year-old children.
Clinical detection and follow-up of homonymous visual field defects require appropriate perimetric procedures: since postgeniculate lesions are usually characterised by absolute scotomata, time consuming threshold methods can be replaced by supraliminal strategies with comparatively high stimulus densities. Compared with equidistant rectangular grids, a centripetal stimulus condensation represents the physiological conditions more adequately and thus is more effective. It allows one to differentiate central changes of the visual field, like macular sparing or splitting, which also interfere with reading performance. This procedure requires test points to be located to either side of the vertical meridian, rather than directly on it. Multimodal assessment of visual subfunctions (using static, kinetic or colour test points, random dot patterns or optokinetic stimulation) specifies the effect of the lesion in different channels or regions of the visual pathways. Automation of perimetric procedures and continuous monitoring of fixation are important tools, enhancing the quality of examination and follow-up. The above mentioned psychophysical techniques for detection of functional defects and documentation of eventual recovery, as well as matching neuroimaging findings, are demonstrated by illustrative cases.
We assessed the variability of results in normal subjects of computerized static threshold perimetry of the central 30 degrees field. Variability of measured threshold values was highly dependent on eccentricity. This included variability among individuals, test-to-test variability within individuals, and intratest variability. All values were significantly larger in the midperiphery than centrally. We found that the mean sensitivity decrement with age was eccentricity dependent, so that the age-corrected normal visual field became not only depressed but also steeper with age. Distributions of individual pointwise deviations from the age-corrected normal mean thresholds were significantly nongaussian. The dependency of variability on test point location, the nongaussian distributions of deviations from age-corrected means, and the variability of age-induced sensitivity reduction should all be considered in the interpretation of computerized visual fields, and particularly in the design of statistical programs for field analysis. Programs not considering these factors are likely to result in misleading analyses.
Twenty-four eyes of 20 patients with chronic open angle glaucoma who had a trabeculectomy were studied retrospectively. Trabeculectomy resulted in a significant lowering of mean intraocular pressures and improvement of pressure control for the group. Progression of visual field defects occurred in all 24 eyes preoperatively, while postoperatively, the fields of 14 eyes showed no change, but the other ten showed further progression. A comparison of the pressures of the eyes showing continued progression after surgery with the eyes showing no further progression revealed no significant difference in the mean preoperative or postoperative pressure or the mean pressure reduction after surgery. Measurements of the quality of the control, however, showed that the quality of pressure control was significantly better in the eyes that did not show progression of field loss postoperatively. Careful postoperative follow-up observation of the visual field remains necessary even after successful surgical pressure reduction.
To examine whether concurrently presenting surrounding scripts affect single Alphabet recognition, subjects compared letters which appeared in the left or the right visual field to a previously presented sample letter. Four different comparison stimuli were prepared, target letter embedded in same-type print letters, in different-type letters, in different kinds of characters, and in blank space (control). The results indicated that both RTs for letter matches and visual field differences were different depending upon the kind of letters that surrounded the target Alphabet. This finding strongly suggests that letter recognition is affected by the presence of neighbouring letters, and further that the nature of the surroundings can differentially affect cerebral hemispheric functioning.
Previously described misperceptions of target size in the peripheral visual field have been conflicting. We found that whether an illuminated peripheral target appears larger or smaller than a foveal target of the same physical size depends upon luminance: in general, dim peripheral targets are underestimated and bright peripheral targets are overestimated in size. We attribute misestimations of peripheral target size primarily to the optical degradation of peripheral retinal images and propose a qualitative model for how image extent may be determined by the visual system.
Objective. To observe the influences of 21 d head down tilt (HDT) bed rest on the intra-ocular pressure, visual field and near vision in human and to study the countermeasure of Chinese herb against weightlessness. Method. Ten subjects were randomly divided into control group and Chinese herb group. -6 degrees HDT was used to simulate weightlessness. Intra-ocular pressure, near vision and vision field were measured before, during and after bed rest in both groups. Result. Intra-ocular pressure and near vision showed a wave-like decrease change during bed rest, and there exists a certain coherence between them. Visual field showed no obvious changes. Taking Chinese herb was able to antagonize the decreasing of intra-ocular pressure and near vision during various phases of bed rest. Conclusion. 1) Bed rest could lead to the decreasing of intra-ocular pressure and near vision; 2) Taking Chinese herb was able to antagonize the negative influences of bed rest on visual function.
Seventy psychotherapy patients were given two pairs of goggles each taped over to allow vision from only the left or the right lateral visual field (LVF and RVF). Sixty percent reported at least a one-point difference between visual fields on a five-point anxiety scale; 23% reported at least a two-point difference. Among 21 patients with major depression, 11 reported greater anxiety through the LVF, four reported greater anxiety through the RVF, and six reported no difference. Among 18 with posttraumatic stress disorder (PTSD), 10 reported greater anxiety from the RVF and four from the LVF, and four reported no difference. The absolute difference in anxiety ratings was significantly greater (P < .001) between the two pairs of experimental goggles than between two pairs of control goggles allowing monocular vision among 40 patients in whom the four pairs were tested. During a subsequent psychiatric interview, 40 of 49 patients who were responsive while using the experimental goggles manifested an intensification of their usual symptoms on one side and an alleviation on the other. The possible physiological, psychological, and therapeutic implications of these findings are discussed.
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PURPOSE: To study the relationship of reaction time to the psychometric function in normal subjects, normal sensitivity test locations in patients with glaucoma, and test locations with 10 to 20 dB loss in patients with glaucoma. METHODS: The authors tested 10 patients with glaucoma and 10 age-matched normal volunteers with the Humphrey perimeter, first with program 24-2 and then with the method of constant stimuli to generate frequency of seeing curves. At two widely separated visual field locations on the program 24-2 grid, they presented stimuli in 2-dB intervals, 10 dB either side of the program 24-2 threshold, at 0 dB and 60 dB (15 repetitions per intensity). For the patients with glaucoma, they chose a visual field location with normal sensitivity and a location in an area of 10 to 20 dB loss. RESULTS: Analysis of variance with post hoc t-tests showed that reaction time (RT) at the 0-dB intensity was prolonged by approximately 90 msec in the abnormal sensitivity test location of patients with glaucoma compared to the control and the glaucoma normal sensitivity groups (P<0.0001). However, this difference was accounted for by only 4 of the 10 patients with glaucoma, reaching 100% of stimuli seen with the brightest stimulus at the moderately damaged test location. Reaction time at the frequency of seeing 50% estimated threshold showed no significant differences among the groups. Prolongation of RT from the 0-dB value was analyzed as a function of increasing attenuation of stimulus intensity. The results fit the equation RT = a + b(Intensity3) for all groups. CONCLUSIONS: There is no significant difference in RT between normal subjects and patients with glaucoma either at threshold or to suprathreshold stimuli. Reaction time increases after a power function with increasing attenuation of stimulus intensity up to the threshold.
PURPOSE: To report a case of visual field defect caused by damage of the nerve fiber layer associated with an internal limiting lamina defect after uneventful epiretinal membrane peeling. DESIGN: Interventional case report. METHODS: In the right eye, a 43-year-old male patient developed a nasal step and mild inferior arcuate scotoma after uneventful epiretinal membrane surgery without any associated glaucoma. Transmission electron microscopy was performed on the epiretinal membrane specimens. RESULTS: An epiretinal membrane specimen showed adhesion between epiretinal membrane and axons of nerve fiber layer in the area of the internal limiting lamina defect. CONCLUSION: Adhesion between epiretinal membrane and retinal tissue in the area of the internal limiting lamina defect may cause damage of the nerve fiber layer and visual field defect after epiretinal membrane peeling.
The existence and distribution of atrophic radial peripapillary capillaries in 33 autopsy eyes of patients with chronic glaucoma or different optic nerve atrophies are compared with their visual field defects and stage of atrophy or excavation of the disc. No correlation of defective RPC and visual field defects was found. The selective atrophy of RPC is therefore supposed to be secondary to different atrophies of the disc.
Symptomatic suprageniculate lesions in multiple sclerosis expressed as a visual field defect are infrequent. The present case developed a bilateral homonymous defect as the initial and unique symptom of the disease. It was confirmed by nuclear magnetic resonance imaging, which disclosed extensive demyelinating areas in both optic nerve radiations. The mode of onset, perimetric findings, and unusual presentation of this condition are briefly discussed.
The multi-fixation glaucoma screening chart, which uses the oculokinetic perimetry (OKP) technique, is a hand-held tangent screen with a central black test stimulus on a white background and a series of 26 numbered fixation targets arranged around the stimulus at various locations. When the numbers on the chart are read by the patient from 40 cm distance, the test stimulus passes through the relevant parts of the central visual field which are most vulnerable to glaucomatous damage. The test is positive (that is, abnormal) if at least one fixation number is associated with consistent disappearance of the stimulus. The OKP test was performed in 222 eyes of 126 glaucoma patients (aged 16-91 years) and 186 right eyes of 186 normal individuals (aged 19-86 years) using a 1.5 mm diameter stimulus. A further 144 eyes of 88 glaucoma patients (aged 60-85 years) and 31 right eyes of 31 normal individuals (aged 60-85 years) were tested with a 3 mm diameter stimulus. All eyes were also tested with conventional perimetry and the results of the conventional perimetry were categorised according to the Aulhorn-Karmeyer classification by four ophthalmologists without any knowledge of the OKP results. When the 1.5 mm stimulus was used, a true positive OKP result was obtained in 45% of eyes with relative scotomas, 81% of eyes with small absolute scotomas separate from the blind spot and 100% of eyes with more severe visual field defects.(ABSTRACT TRUNCATED AT 250 WORDS)