Reproducibility of measurements and variability of the classification algorithm of Stratus OCT in normal, hypertensive, and glaucomatous patients

Figures & data

Table 1 Coefficient of variation by diagnosis (%)

	RNFL thickness average (AvgT)	Superior average RNFL thickness (Savg)	Inferior RNFL thickness (Iavg)
Normal (n = 13)	2.78 (1.17–3.82)	3.89 (2.13–6.98)	3.97 (2.82–4.69)
OHT (n = 17)	2.68 (1.64–3.18)	3.55 (1.52–8.80)	3.30 (2.57–4.74)
Glaucoma (n = 19)	4.44 (2.48–7.63)*	7.22 (3.24–12.14)	6.36 (3.95–10.41)*
Wilcoxon Test (p)	0.036*	ns	0.045*

Notes: 50th percentile coefficient of variations with quartile 1 and quartile 3 in parenthesis;

* Indicate values that are significantly different of this group compared to the other two groups.

Abbreviations: OHT, ocular hypertension; RNFL, retinal nerve fiber layer.

Table 2 Intraclass correlation coefficient by diagnosis

	RNFL thickness average (AvgT)	Superior average RNFL thickness (Savg)	Inferior average RNFL thickness (Iavg)
Normal (n = 13)	0.927 (0.818–0.975)	0.874 (0.722–0.956)	0.642 (0.344–0.857)
OHT (n = 17)	0.937 (0.863–0.975)	0.823 (0.647–0.928)	0.900 (0.790–0.960)
Glaucoma (n = 19)	0.943 (0.883–0.976)	0.856 (0.718–0.938)	0.876 (0.758–0.946)

Notes: ICCs, with lower 95% CI and higher 95% CI in parenthesis.

Abbreviations: CI, confidence interval; ICC, intraclass correlation; OHT, ocular hypertension; RNFL, retinal nerve fiber layer.

Table 3a Color-code distribution for the three different measurements and parameters in the normal group

Savg	Number of patients
Color-code	1st meas	2nd meas	3rd meas
White (ONL)	0	0	1
Green	15	16	14
Yellow	2	1	1
Red	0	0	1
Iavg
White (ONL)	0	1	1
Green	15	16	14
Yellow	2	0	2
Red	0	0	0
AvgT
White (ONL)	0	0	1
Green	16	17	15
Yellow	1	0	0
Red	0	0	1

Abbreviations: AvgT, average thickness; Iavg, inferior average; meas, measurements; Savg, superior average; ONL, over normal limits.

Table 3b Color-code distribution for the three different measurements and parameters in the OHT group

Savg	Number of patients
Color-code	1st meas	2nd meas	3rd meas
White (ONL)	1	1	0
Green	10	11	13
Yellow	1	0	0
Red	1	1	0
Iavg
White (ONL)	0	0	0
Green	13	13	13
Yellow	0	0	0
Red	0	0	0
AvgT
White (ONL)	0	0	0
Green	12	12	12
Yellow	1	1	1
Red	0	0	0

Abbreviations: AvgT, average thickness; Iavg, inferior average; meas, measurements; Savg, superior average; ONL, over normal limits.

Table 3c Color-code distribution for the three different measurements and parameters in the glaucoma group

Savg	Number of patients
Color-code	1st meas	2nd meas	3rd meas
White (ONL)	0	0	0
Green	9	6	8
Yellow	2	6	2
Red	8	7	8
Iavg
White (ONL)	0	0	0
Green	8	7	7
Yellow	2	3	2
Red	9	9	10
AvgT
White (ONL)	0	0	0
Green	6	6	6
Yellow	2	3	2
Red	11	10	11

Abbreviations: AvgT, average thickness; Iavg, inferior average; meas, measurements; Savg, superior average; ONL, over normal limits.

Table 4a Variability of color-coded classification for average thickness parameter: category changes (number of patients in parenthesis)

	No changes	1 category	2 categories
Normal (n = 13)	100% (13)	0% (0)	0% (0)
OHT (n = 17)	82.4% (14)	11.8% (2)	5.9% (1)
Glaucoma (n = 19)	89.5% (17)	10.6% (2)	0% (0)
All eyes (n = 49)	89.8% (44)	8% (4)	2% (1)

Abbreviation: OHT, ocular hypertension.

Table 4b Variability of color-coded classification for superior thickness parameter: category changes (number of patients in parenthesis)

	No changes	1 category	2 categories
Normal (n = 13)	84.6% (11)	7.7% (1)	7.7% (1)
OHT (n = 17)	70.6% (12)	23.6% (4)	5.9% (1)
Glaucoma (n = 19)	52.7% (10)	31.6% (6)	15.8% (3)
All eyes (n = 49)	67.3% (33)	22.2% (11)	10.1% (5)

Abbreviation: OHT, ocular hypertension.

Table 4c Variability of color-coded classification for inferior thickness parameter: category changes (number of patients in parenthesis)

	No changes	1 category	2 categories
Normal (n = 13)	92.3% (12)	7.7% (1)	0% (0)
OHT (n = 17)	76.5% (13)	23.6% (4)	0% (0)
Glaucoma (n = 19)	79% (15)	15.8% (3)	5.3% (1)
All eyes (n = 49)	81.5% (40)	16.2% (8)	2% (1)

Abbreviation: OHT, ocular hypertension.