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Comparison of Fourier-Domain and Time-Domain Optical Coherence Tomography in the Measurement of Thinnest Corneal Thickness in Keratoconus.

Wang C, Xia X, Tian B, Zhou S - J Ophthalmol (2015)

Bottom Line: Results.Conclusions.The existence of systematic differences suggested that the two instruments cannot be used interchangeably.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, China.

ABSTRACT
Objective. To compare fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT (TD-OCT) in the determination of thinnest corneal thickness (TCT). Methods. This study included 55 keratoconus patients and 50 healthy volunteers. The RTVue-OCT (FD-OCT) and Visante-OCT (TD-OCT) were used for the measurement of the TCT. Three consecutive scans were performed. The comparison and agreement between the two modalities were analyzed by paired t-test, the Pearson correlation, intraclass correlation coefficient (ICC), and Bland-Altman plots. intraobserver repeatability was analyzed by the intraobserver within-subject standard deviation (S (w)), coefficient of variation (CV(w)), and ICC. Results. The TCT value of normal corneas was higher by RTVue-OCT (530.4 ± 19.7 μm) than Visante-OCT (521.5 ± 18.3 μm) (p < 0.001). For keratoconus eyes, the TCT was 425.0 ± 58.2 μm and 424.4 ± 55.7 μm (difference being 0.6 ± 10.2 μm, p = 0.604). Strong correlation (r = 0.938∼0.985) (ICC = 0.915-0.984) was observed between the two OCTs, and each OCT exhibited excellent repeatability in determining the TCT in all subjects (ICC = 0.984-0.994). Conclusions. The values of TCT obtained from RTVue-OCT and Visante-OCT were highly correlated; however, the two values were different. Both OCT instruments exhibited good intraobserver reliability. The existence of systematic differences suggested that the two instruments cannot be used interchangeably.

No MeSH data available.


Related in: MedlinePlus

Bland-Altman plots showing the agreement between the RTVue-OCT and Visante-OCT measurements of the TCT. (a) Normal eyes. (b) Keratoconic eyes.
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fig3: Bland-Altman plots showing the agreement between the RTVue-OCT and Visante-OCT measurements of the TCT. (a) Normal eyes. (b) Keratoconic eyes.

Mentions: The two OCT systems exhibited strong correlation in the measurement of TCT for both normal and keratoconic eyes (Figure 2; correlation coefficient (r) = 0.938–0.985) (ICC = 0.915–0.984) (Table 1). Bland-Altman plot was used to demonstrate the effect of average TCT on the difference between the two methods (Figure 3). A constant bias (mean difference = 8.20 μm) was observed for normal eyes, as consistently higher TCT values were obtained by RTVue-OCT as compared to Visante-OCT (95% LoA width = 13.97 μm; range 1.03–15.0 μm) (Figure 3(a)). For keratoconic eyes, a proportional bias was observed between the RTVue-OCT and Visante-OCT (R = 0.25, p = 0.023; 95% LoA width = 34.42 μm; range −16.97–17.45 μm) (Figure 3(b)), with a mean difference of 0.59 ± 10.19 μm.


Comparison of Fourier-Domain and Time-Domain Optical Coherence Tomography in the Measurement of Thinnest Corneal Thickness in Keratoconus.

Wang C, Xia X, Tian B, Zhou S - J Ophthalmol (2015)

Bland-Altman plots showing the agreement between the RTVue-OCT and Visante-OCT measurements of the TCT. (a) Normal eyes. (b) Keratoconic eyes.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4496494&req=5

fig3: Bland-Altman plots showing the agreement between the RTVue-OCT and Visante-OCT measurements of the TCT. (a) Normal eyes. (b) Keratoconic eyes.
Mentions: The two OCT systems exhibited strong correlation in the measurement of TCT for both normal and keratoconic eyes (Figure 2; correlation coefficient (r) = 0.938–0.985) (ICC = 0.915–0.984) (Table 1). Bland-Altman plot was used to demonstrate the effect of average TCT on the difference between the two methods (Figure 3). A constant bias (mean difference = 8.20 μm) was observed for normal eyes, as consistently higher TCT values were obtained by RTVue-OCT as compared to Visante-OCT (95% LoA width = 13.97 μm; range 1.03–15.0 μm) (Figure 3(a)). For keratoconic eyes, a proportional bias was observed between the RTVue-OCT and Visante-OCT (R = 0.25, p = 0.023; 95% LoA width = 34.42 μm; range −16.97–17.45 μm) (Figure 3(b)), with a mean difference of 0.59 ± 10.19 μm.

Bottom Line: Results.Conclusions.The existence of systematic differences suggested that the two instruments cannot be used interchangeably.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, China.

ABSTRACT
Objective. To compare fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT (TD-OCT) in the determination of thinnest corneal thickness (TCT). Methods. This study included 55 keratoconus patients and 50 healthy volunteers. The RTVue-OCT (FD-OCT) and Visante-OCT (TD-OCT) were used for the measurement of the TCT. Three consecutive scans were performed. The comparison and agreement between the two modalities were analyzed by paired t-test, the Pearson correlation, intraclass correlation coefficient (ICC), and Bland-Altman plots. intraobserver repeatability was analyzed by the intraobserver within-subject standard deviation (S (w)), coefficient of variation (CV(w)), and ICC. Results. The TCT value of normal corneas was higher by RTVue-OCT (530.4 ± 19.7 μm) than Visante-OCT (521.5 ± 18.3 μm) (p < 0.001). For keratoconus eyes, the TCT was 425.0 ± 58.2 μm and 424.4 ± 55.7 μm (difference being 0.6 ± 10.2 μm, p = 0.604). Strong correlation (r = 0.938∼0.985) (ICC = 0.915-0.984) was observed between the two OCTs, and each OCT exhibited excellent repeatability in determining the TCT in all subjects (ICC = 0.984-0.994). Conclusions. The values of TCT obtained from RTVue-OCT and Visante-OCT were highly correlated; however, the two values were different. Both OCT instruments exhibited good intraobserver reliability. The existence of systematic differences suggested that the two instruments cannot be used interchangeably.

No MeSH data available.


Related in: MedlinePlus