We obtained data over 3 years on temporal-modulation perimetry (TMP), standard automated [white-on-white (W/W)] perimetry, and short-wavelength-sensitive [blue-on-yellow (B/Y)] perimetry in ocular hypertensive (OH) patients and patients with early glaucomatous visual-field loss (EG). Evidence of visual-field defects was obtained with the use of both B/Y perimetry and TMP in the majority of OH and EG eyes that demonstrated progression on W/W perimetry as well as in all stable EG eyes. Using the nerve-fiber-bundle pattern to compare testing procedures, we determined that these defects were generally as extensive or more extensive than the concurrent W/W abnormalities. In terms of location over the 3 years of testing, TMP and B/Y defects were reasonably consistent in the EG eyes, somewhat less consistent in the OH eyes demonstrating progression, and both inconsistent and infrequent in the stable OH eyes. The greatest degree of overlap occurred between the location of defects obtained by use of the higher TMP frequencies (8 and 16 Hz) and that of defects obtained by use of B/Y perimetry. Since these two methods are thought to isolate different visual mechanisms subserved by different visual pathways, these results suggest that early glaucomatous visual-field damage as revealed by TMP and B/Y perimetry may not be specific to a single visual pathway.

Mathematical analyses of motion perception have established minimum combinations of points and distinct views that are sufficient to recover three-dimensional (3D) structure from two-dimensional (2D) images, using such regularities as rigid motion, fixed axis of rotation, and constant angular velocity. To determine whether human subjects could recover 3D information at these theoretical levels, vie presented subjects with pairs of displays and asked them to determine whether they represented the same or different 3D structures. Number of points was varied between two and five; number of views was varied between two and six; and the motion was fixed axis with constant angular velocity, fixed axis with variable velocity, or variable axis with variable velocity. Accuracy increased with views, decreased with points, and was greater with fixed-axis motion. Subjects performed above chance levels even when motion was eliminated, indicating that they exploited regularities in addition to those in the theoretical analyses.Theoretical investigations of visual motion have provided a number of specific analyses of the minimum number of points and views required to recover three-dimensional (3D) structure from two-dimensional (2D) images. Recovery of 3D structure, in this context, is denned as determining the x, y, and z coordinates of each point, up to a scale factor. These analyses differ in the constraints that are imposed. UUman (1979) showed that under a rigidity constraint, three views of four noncoplanar points are sufficient to recover structure in an orthographic projection, up to a reflection about the frontal plane. The required numbers of points and views are reduced by adding further constraints, such as planarity (Hoffman & Flinchbaugh, 1982), fixed axis of rotation (Hoffman & Bennett, 1986;Webb & Aggarwal, 1981), and constant angular velocity (Hoffman & Bennett, 1985). These proofs are summarized in Table 1.A number of empirical studies have addressed issues related to theoretical analyses of the recovery of structure from motion. Several studies (e.g., Braunstein & Andersen, 1986;Schwartz & Sperling, 1983;Todd, 1985) have questioned the generality of the rigidity constraint. Other studies have considered the recovery of structure with small numbers of views or with small numbers of points. Lappin, Doner, and Kotlas (1980) found that subjects could make accurate judgments based on 3D structure This research was supported by a contract to D. Hoffman from the Office of Naval Research, Cognitive and Neural Sciences Division, Perceptual Sciences Group. We thank Joseph Lappin and James Todd for helpful comments on an earlier version of this article and Johnna Eastbum and James Tittle for assistance in various aspects of this research.

Manual kinetic perimetry is a common technique for detection and evaluation of visual field loss in glaucoma and other ophthalmic diseases. Previous investigations have examined the accuracy and reproducibility of kinetic perimetry, but have disagreed as to the source of variability in the test results.(1,2) In these studies, patient response characteristics could not be specified. The present study examined the effects of controlled patient factors on performance of manual kinetic perimetry. Three technicians each conducted thirty-six kinetic perimetry examinations on normal and abnormal visual fields with varying degrees of response errors and sensitivity fluctuations, using the KRAKEN computer simulation program.(3) Performance measures included elapsed time, number of plotted isopter and scotoma boundaries, time per boundary, mean error over the entire field, and mean local error within sectors. In addition, perimetrists judged the cooperation and reliability of the simulated patient on a five-point scale. Measures of accuracy yielded significant differences in location within the visual field: central vs peripheral and superior vs inferior. Measures of efficiency yielded significant effects of patient cooperation, normal vs abnormal visual fields, and technician's level of experience. Patient cooperation, as judged, agreed with simulated reliability. This approach appears to have promise as a training procedure for manual kinetic perimetry.

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