Limits...
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

Corneal pachymetry of a patient with keratoconus generated by the (a) RTVue-OCT and (b) Visante-OCT. (a) Minimum of corneal thickness can be acquired from the table of “keratoconus analysis” on the upper right and the thinnest point is also marked on the pachymetric map on the lower right. A real-time monitoring on the upper left is used for pupil centering. (b) Minimum of corneal thickness in different regions is demonstrated on the table on the lower right and the thinnest point is also marked on the pachymetric map on the left.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4496494&req=5

fig1: Corneal pachymetry of a patient with keratoconus generated by the (a) RTVue-OCT and (b) Visante-OCT. (a) Minimum of corneal thickness can be acquired from the table of “keratoconus analysis” on the upper right and the thinnest point is also marked on the pachymetric map on the lower right. A real-time monitoring on the upper left is used for pupil centering. (b) Minimum of corneal thickness in different regions is demonstrated on the table on the lower right and the thinnest point is also marked on the pachymetric map on the left.

Mentions: The RTVue-OCT (Model RT100, Optovue Inc, Fremont, CA, USA) system was used for measuring TCT. The scan beam wavelength, scan speed, axial resolution, and transverse resolution were 840 nm, 26,000 A-scans per second, 5 μm, and 8 μm, respectively. The RTVue-OCT was originally designed for retinal imaging. An additional lens adapter, known as low-magnification cornea anterior module (CAM-L), was used for anterior segment imaging. Using the corneal pachymetry protocol, the “thinnest” values were automatically generated in the “keratoconus analysis” table (Figure 1(a)). For RTVue-OCT examination, the subject was kept in sitting position with an external fixation, without the application of topical anesthesia, and three consecutive scans were carried out at an interval of 4-5 seconds.


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)

Corneal pachymetry of a patient with keratoconus generated by the (a) RTVue-OCT and (b) Visante-OCT. (a) Minimum of corneal thickness can be acquired from the table of “keratoconus analysis” on the upper right and the thinnest point is also marked on the pachymetric map on the lower right. A real-time monitoring on the upper left is used for pupil centering. (b) Minimum of corneal thickness in different regions is demonstrated on the table on the lower right and the thinnest point is also marked on the pachymetric map on the left.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Corneal pachymetry of a patient with keratoconus generated by the (a) RTVue-OCT and (b) Visante-OCT. (a) Minimum of corneal thickness can be acquired from the table of “keratoconus analysis” on the upper right and the thinnest point is also marked on the pachymetric map on the lower right. A real-time monitoring on the upper left is used for pupil centering. (b) Minimum of corneal thickness in different regions is demonstrated on the table on the lower right and the thinnest point is also marked on the pachymetric map on the left.
Mentions: The RTVue-OCT (Model RT100, Optovue Inc, Fremont, CA, USA) system was used for measuring TCT. The scan beam wavelength, scan speed, axial resolution, and transverse resolution were 840 nm, 26,000 A-scans per second, 5 μm, and 8 μm, respectively. The RTVue-OCT was originally designed for retinal imaging. An additional lens adapter, known as low-magnification cornea anterior module (CAM-L), was used for anterior segment imaging. Using the corneal pachymetry protocol, the “thinnest” values were automatically generated in the “keratoconus analysis” table (Figure 1(a)). For RTVue-OCT examination, the subject was kept in sitting position with an external fixation, without the application of topical anesthesia, and three consecutive scans were carried out at an interval of 4-5 seconds.

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