Filling-in along horizontal and vertical meridians. 2006

Frank Antony Proudlock, and Aman Khanna, and Irene Gottlob
Department of Ophthalmology, University of Leicester, Leicester, United Kingdom. fap1@le.ac.uk

OBJECTIVE Filling-in is not homogeneous across the visual field; rather, fading time (FT) varies with eccentricity and polar angle. The reasons for this are unclear. The authors investigated FT along horizontal and vertical meridians in central and peripheral visual fields for luminance-defined targets, comparing Weber contrast sensitivity (CSw). They also compared cone-mediated and rod-mediated filling-in with previously described photoreceptor densities. This represents the first investigation into rod-mediated filling-in. METHODS Fading times were recorded in nine volunteers using luminance-defined stimuli at eccentricities of 0 degrees , 2.5 degrees , 5 degrees , 10 degrees , and 20 degrees for high-contrast stimuli and 0 degrees , 1.25 degrees , 2.5 degrees , 3.75 degrees , and 5 degrees for low-contrast stimuli and were compared with CSw at each location. Fading times were also recorded at 0 degrees , 2.5 degrees , 5 degrees , 10 degrees , and 20 degrees using red-green stimuli and at 5 degrees , 10 degrees , and 20 degrees under dark-adapted conditions and compared with cone and rod densities in the nasal, temporal, superior, and inferior hemimeridians. RESULTS Consistent anisotropy was evident in central and peripheral fields for luminance-defined targets and for chromatic targets, with horizontal meridians taking longer to fill in. The same pattern was observed in CSw and the previously described cone density. Log FT and CSw were correlated irrespective of visual field location. The ratio of rod-mediated FT to rod density decreased with eccentricity. CONCLUSIONS Anisotropy between horizontal and vertical meridians for FT is consistent in central and peripheral fields, reflecting patterns in CSw and cone density. This is discussed in the context of cortical processes underlying filling-in. For rod-mediated filling-in, more peripheral eccentricities are characterized by reduced FTs in relation to rod density.

UI MeSH Term Description Entries
D008297 Male Males
D010466 Perceptual Closure The tendency to perceive an incomplete pattern or object as complete or whole. This includes the Gestalt Law of Closure. Gestalt Law of Closure,Perceptual Completion Phenomena,Closure, Perceptual,Closures, Perceptual,Completion Phenomena, Perceptual,Perceptual Closures,Phenomena, Perceptual Completion
D003623 Dark Adaptation Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation. Scotopic Adaptation,Adaptation, Dark,Adaptation, Scotopic
D005133 Eye Movements Voluntary or reflex-controlled movements of the eye. Eye Movement,Movement, Eye,Movements, Eye
D005260 Female Females
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D014794 Visual Fields The total area or space visible in a person's peripheral vision with the eye looking straightforward. Field, Visual,Fields, Visual,Visual Field
D015350 Contrast Sensitivity The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate VISUAL ACUITY and to detect eye disease. Visual Contrast Sensitivity,Sensitivity, Contrast,Sensitivity, Visual Contrast
D058609 Visual Field Tests Method of measuring and mapping the scope of vision, from central to peripheral of each eye. Automated Perimetry Exam,Campimetry,Perimetry,Tangent Screen Exam,Visual Field Exam,Automated Perimetry Exams,Campimetries,Exam, Automated Perimetry,Exam, Tangent Screen,Exam, Visual Field,Exams, Automated Perimetry,Exams, Tangent Screen,Exams, Visual Field,Field Exam, Visual,Field Exams, Visual,Field Test, Visual,Field Tests, Visual,Perimetries,Perimetry Exam, Automated,Perimetry Exams, Automated,Screen Exam, Tangent,Screen Exams, Tangent,Tangent Screen Exams,Test, Visual Field,Tests, Visual Field,Visual Field Exams,Visual Field Test

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