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Original Research

Visual evoked potential repeatability using the Diopsys NOVA LX fixed protocol in normal older adults

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Pages 1713-1729 | Published online: 07 Sep 2018

Figures & data

Table 1 Subject demographics comparing those who had a single examination and those who returned for a second examination

Figure 1 Histogram of age for the entire cohort of subjects at the time of their first examination.

Figure 1 Histogram of age for the entire cohort of subjects at the time of their first examination.

Figure 2 Representative VEP report generated by the Diopsys NOVA device.

Note: Permission received from Diopsys Inc. Diopsys NOVA vision testing system (software version 2.18; Diopsys Inc., Pine Brook, NJ, USA) Available from: http://diopsys.com/visual-electrophysiology-products/visual-evoked-potential-vep/).Citation34
Abbreviations: VEP, visual evoked potential; uv, microvolt; ms, millisecond; OD, right eye; OS, left eye; VA, visual acuity; Lc, low contrast; Hc, high contrast.
Figure 2 Representative VEP report generated by the Diopsys NOVA device.

Table 2 Mean P100 parameters at first examination

Table 3 Intrasession repeatability outcomes

Figure 3 Mean P100 parameters for each of the three trials at the first examination session.

Notes: (A) Amplitude using the low contrast stimulus; (B) amplitude using the high contrast stimulus; (C) latency using the low contrast stimulus; and (D) latency using the high contrast stimulus. Error bars represent the SD. An asterisk above a bar indicates the trial that was significantly different from the other trials for that eye. An asterisk joining two bars indicate paired trials that were significantly different between right and left eyes.
Abbreviations: RLCA, low contrast amplitude, right eye; LLCA, low contrast amplitude, left eye; RHCA, high contrast amplitude, right eye; LHCA, high contrast amplitude, left eye; RLCL, low contrast latency, right eye; LLCL, low contrast latency, left eye; RHCL, high contrast latency, right eye; LHCL, high contrast latency, left eye.
Figure 3 Mean P100 parameters for each of the three trials at the first examination session.

Figure 4 (A) Serial P100 amplitude recordings and (B) serial P100 latency recordings for each of the 46 subjects at the first examination.

Notes: Each subject underwent three trials per eye under low and high contrast stimulus conditions (Trial 1: Circle; Trial 2: Square; Trial 3: Triangle). (A1) P100 amplitude for right eyes with low (15%) stimulus contrast, (A2) P100 amplitude for left eyes under low stimulus contrast, (A3) P100 amplitude for right eyes under high (85%) stimulus contrast, (A4) P100 amplitude for left eyes under high stimulus contrast. (B1) P100 latency for right eyes with low (15%) stimulus contrast, (B2) P100 latency for left eyes under low stimulus contrast, (B3) P100 latency for right eyes under high (85%) stimulus contrast, (B4) P100 latency for left eyes under high stimulus contrast. For each test condition, the ICC and it’s 95% CI are presented.
Abbreviation: ICC, intraclass correlation coefficient.
Figure 4 (A) Serial P100 amplitude recordings and (B) serial P100 latency recordings for each of the 46 subjects at the first examination.

Figure 5 Bland–Altman plots of P100 parameter limits of agreement between fellow eyes at visit 1.

Notes: Each data point represents the difference between the corresponding trials (first, second, or third) for a given subject. (A) P100 amplitude with low (15%) stimulus contrast, (B) P100 amplitude under high (85%) stimulus contrast, (C) P100 latency under low stimulus contrast, and (D) P100 latency under high stimulus contrast. Regression analysis revealed a relationship between parameter difference and parameter magnitude only for high contrast amplitude (dashed line). Colored dots in (B) are the data points that were excluded during regression analysis.
Figure 5 Bland–Altman plots of P100 parameter limits of agreement between fellow eyes at visit 1.

Table 4 P100 amplitude and latency by age, sex, and ethnicity

Table 5 Coefficient of variation for P100 parameters by age, sex, and ethnicity

Table 6 P100 parameters of the returning subjects

Figure 6 Bland–Altman plots of intersession P100 parameter limits of agreement.

Notes: Each data point represents the difference between corresponding trials (first, second, or third) for a given subject. The green circles represent right eyes, and blue squares represent left eyes. (A) P100 amplitude with low (15%) stimulus contrast, (B) P100 amplitude under high (85%) stimulus contrast, (C) P100 latency under low stimulus contrast, and (D) P100 latency under high stimulus contrast.
Figure 6 Bland–Altman plots of intersession P100 parameter limits of agreement.

Table 7 Intersession repeatability values

Figure 7 (A) P100 amplitude recordings and (B) P100 latency recordings for each of the 27 recordings performed on nine returning subjects at the first (circle) and second (square) examination sessions.

Notes: (A1) P100 amplitude for right eyes with low (15%) stimulus contrast, (A2) P100 amplitude for left eyes under low stimulus contrast, (A3) P100 amplitude for right eyes under high (85%) stimulus contrast, and (A4) P100 amplitude for left eyes under high stimulus contrast. (B1) P100 latency for right eyes with low (15%) stimulus contrast, (B2) P100 latency for left eyes under low stimulus contrast, (B3) P100 latency for right eyes under high (85%) stimulus contrast, and (B4) P100 latency for left eyes under high stimulus contrast. For each test condition, the ICC and its 95% CI are presented.
Abbreviation: ICC, intraclass correlation coefficient.
Figure 7 (A) P100 amplitude recordings and (B) P100 latency recordings for each of the 27 recordings performed on nine returning subjects at the first (circle) and second (square) examination sessions.