Journal article
Role of the completion phenomenon in the evaluation of Amsler grid results.
- Achard OA Neuro-Ophthalmology Unit, Hôpital Cantonal Universitaire, Geneva Switzerland.
- Safran AB
- Duret FC
- Ragama E
- 1995-09-01
Published in:
- American journal of ophthalmology. - 1995
Aged
Aged, 80 and over
Female
Humans
Macular Degeneration
Male
Middle Aged
Reproducibility of Results
Scotoma
Sensitivity and Specificity
Vision Tests
Visual Acuity
Visual Fields
English
PURPOSE
To evaluate the limitations, particularly those related to the perceptual completion phenomenon, of Amsler grid tests in patients with central scotomas caused by macular disorders.
METHODS
We tested 15 affected eyes of 15 patients with macular lesions. In each subject, the central visual field was assessed by using four different types of Amsler grid testing and a tangent screen. Tests were conducted in a random order, and the sequence of tests was repeated once. The distance between the fixation point and the closet border of the plotted scotoma was assessed. For each patient, reproducibility in repeated examinations was evaluated by assessing changes in location of the computed center of the defects and by measuring changes in the position of the center of the scotoma.
RESULTS
The tangent screen was more sensitive than Amsler grids in delineating the borders of the scotoma, and the results were more reproducible. Furthermore, by using a tangent screen, the fixation point was found adjacent to the scotoma.
CONCLUSION
Poor sensitivity and intraindividual variations found with Amsler grid testing are at least partly a result of the perceptual completion phenomenon. This phenomenon proved to be a dynamic and fluctuating process, as the results of two successive Amsler grid tests were not comparable, even when the technique was identical and the time between tests was no more than two to 15 minutes.
To evaluate the limitations, particularly those related to the perceptual completion phenomenon, of Amsler grid tests in patients with central scotomas caused by macular disorders.
METHODS
We tested 15 affected eyes of 15 patients with macular lesions. In each subject, the central visual field was assessed by using four different types of Amsler grid testing and a tangent screen. Tests were conducted in a random order, and the sequence of tests was repeated once. The distance between the fixation point and the closet border of the plotted scotoma was assessed. For each patient, reproducibility in repeated examinations was evaluated by assessing changes in location of the computed center of the defects and by measuring changes in the position of the center of the scotoma.
RESULTS
The tangent screen was more sensitive than Amsler grids in delineating the borders of the scotoma, and the results were more reproducible. Furthermore, by using a tangent screen, the fixation point was found adjacent to the scotoma.
CONCLUSION
Poor sensitivity and intraindividual variations found with Amsler grid testing are at least partly a result of the perceptual completion phenomenon. This phenomenon proved to be a dynamic and fluctuating process, as the results of two successive Amsler grid tests were not comparable, even when the technique was identical and the time between tests was no more than two to 15 minutes.
- Language
-
- English
- Open access status
- closed
- Identifiers
-
- DOI 10.1016/s0002-9394(14)72162-2
- PMID 7661204
- Persistent URL
- https://folia.unifr.ch/global/documents/95436
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