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PubMedDate not supplied

Stato-kinetic dissociation in subjects with normal and abnormal visual fields.

PURPOSE: The aim of the study was to assess the presence and the importance of stato-kinetic dissociation (SKD) in subjects with normal and pathological visual fields (VF). METHODS: A "customized" perimetric test designed for the assessment of SKD was carried out in seven homogeneous samples of subjects (normal, glaucomatous, ocular hypertensive, retinopathic, cataract, anterior visual pathways neuropathic and posterior visual pathways neuropathic). The results were statistically compared (Anova). RESULTS AND CONCLUSIONS: SKD is a physiological phenomenon, more evident in the central, paracentral and superior VF, influenced by age and partially by sex. SKD increases in the VF periphery when a posterior visual pathway disorder or retinopathy is present, and decreases in the centro-paracentral VF of glaucomatous and ocular hypertensive eyes. This SKD behaviour should be useful for early diagnosis of glaucoma.

Adolescent↗

PubMedDate not supplied

Automatic perimetry and visual P300: differences between upper and lower visual fields stimulation in healthy subjects.

Human visual-evoked potentials (VEPs) from upper and lower hemifield stimulation are thought to reflect the anatomical and functional differences between the hemiretinas and corresponding visual pathways. Conflicting results have, however, been reported in topographic studies on the putative cortical generators. We have estimated by automatic perimetry (Octopus 2000R, Program 32) and compared the sensitivity thresholds of lower and upper hemifields of the retina in 12 healthy subjects with no history or evidence of visual or neurological diseases. A visual P3 that is linked to cognitive function was recorded in an odd-ball paradigm with presentation of high-contrast checkerboards at two different spatial frequencies at 20 degrees eccentricity in each hemifield. VEP and P3 were recorded at O1 and O2 and at Cz according to the 10/20 international system. Lower sensitivity thresholds were found, and higher VEP and event-related potential (ERP) amplitude values were obtained when stimulating the lower, compared with the upper, visual hemifield. The results are consistent with previous findings and anatomical and physiological evidence in animals and man. Interactions between perceptive process in the visual system and higher cognitive functions are a possible explanation for this finding.

Adult↗