Quick, accurate and affordable assessment of visual field defects (scotomas) provides crucial information for the purposes of diagnosing eye diseases, selecting appropriate medical interventions, monitoring the effectiveness of therapeutic procedures, and predicting rehabilitation needs. Automated perimetry is time-consuming and unsuitable for frequent monitoring of rapid development of diseases such as age-related macular degeneration (AMD). It becomes unreliable when steady central fixation cannot be maintained. The Amsler grid test has been shown to be insensitive and unreliable. The goal of the proposed research is to evaluate the efficacy of a new visual field test for assessing the central visual field. In this Regular Dot-Array Test (RDAT) a rectilinear dot-array is flashed briefly, and a scotoma manifests itself as an interruption of the regular dot pattern, typically, some missing dots. The patient describes the immediate percept of the interruption by reporting the number of abnormal dots. The following characteristics distinguish the RDAT from existing visual field tests: 1) It uses spatially extended regular dot-arrays to examine a large area of the visual field simultaneously. 2) The regularity of a dot-array allows subjects to make quantitative reports about the sizes of perceived field defects instantly, and thus the test result doesn't depend critically on the subject's ability to maintain steady fixation. 3) The dot-array density can be adjusted to reduce perceptual filling-in (PFI) so that small and long-standing scotomas can be detected. 4) It is possible to account for the effect of dot-array PFI, so that the sizes of scotomas can be more accurately determined. 5) The test can be conducted on personal computers, and thus is widely accessible. The combination of these characteristics makes the RDAT an important addition to existing field tests. It can be useful in situations where existing field tests have been shown to be ineffective or unreliable (central scotomas associated with AMD, for example), or where a quick and low-cost assessment of visual field is desired (screening, primary care settings, or self-administered monitoring).
Five specific aims will be accomplished. 1) Determine the optimal testing parameters and procedure for the RDAT. 2) Assess the sensitivity and specificity of the RDAT for detecting macular scotomas. 3) Assess the ability of the RDAT to quantify the sizes and locations of scotomas. 4) Assess the test/retest reliability, the dependence on fixation stability and the efficiency of the RDAT, in relation to existing visual field tests. 5) Establish the relationship between the findings of the RDAT and existing field tests. The long-term goal is to develop a low-cost, easy-to-use, and widely accessible clinical tool for evaluating the macula.
| Liu, Lei; White, Janis (2010) Early age-related macular degeneration impairs tolerance to stimulus degradation. Optom Vis Sci 87:532-42 |
