Investigative Ophthalmology and Visual Science (supp), vol 36, No. 4, p. 520

Từ Thư viện Khoa học VLOS
Bước tới: chuyển hướng, tìm kiếm
 Tạp chí Investigative Ophthalmology and Visual Science 1995 ; 4 (36):520
 Tác giả   Jianguo Sun và Vo Van Toi
 Nơi thực hiện   Department of Biomedical Engineering, Bioengineering Center,Tufts University, 4 Colby Street, Medford, MA 02155
 Từ khóa   paradigms,
  DOI   URL  [ PDF]


Purpose: A previous study suggested novel paradigms for measuring the speeds and numbers of leucocytes perceived in the perifoveal retinal capillaries by the blue field entoptic phenomenon (Ref. 1). In this study we investigate the "superimposing" paradigm (SP) and compare it with the "alternating" paradigm (AP).

Methods: A newly developed blue field entopscope was used; it was monitored by a PC-compatible laptop. The stimulated light had 430 nm wavelength, 12o field size and 15 cd/m2 intensity. Twenty subjects (12 males, 8 females) with normal vision and good health participated in this study. Their ages ranged from 18 to 63 years (36±12). When using the AP the subjects switched back and forth between the field where they perceived the blue-field-evoked leucocytes and the field where they saw the computer-simulated particles. When using the SP, by contrast, the subject perceived simultaneously both the leucocytes and particles on the same field. In both paradigms, the subjects were asked to adjust the velocity and number of particles in order to match them with those of the leucocytes. All measurements were repeated 5 times in random order. Sessions prior to the measurements allowed evaluating subject performance. All simulations, experiments, data processing and statistical analysis were interactively conducted with the laptop.

Results: (a) For the velocity evaluation, the average results of all subjects obtained with both paradigms are comparable (0.67±0.19 mm/s for SP and 0.68±0.22 mm/s for AP) and are in agreement with previously reported data; however, the average standard deviation evaluated separately on each subject showed that the AP data are more dispersed than SP data (11.7% and 8.41%, respectively). (b) For the number evaluation, the SP yielded results twice as much as the AP (70±31.5 and 46±35, respectively) and the difference was strongly confirmed (p=0.00025); further, the average standard deviation on each individual was again better with the SP than with the AP (17.7% and 19.1%, respectively). (c) Subjects spent 34% less time to perform the tests with SP than with AP. (d) The SP was preferred by 95% of the subjects for velocity measurement and by 65% for number measurement.

Conclusions: SP is a promising new measurement technique. The discrepancy between the two paradigms in the number measurement suggested that the AP may be influenced by the memory and light adaptation mechanisms induced by switching alternately between the two fields.

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