Repeatability Using Automatic Tracing with Canon OCT- HS100 and Zeiss Cirrus HD-OCT 5000

Agreement and precision of wide and cube scan measurements between swept-source and spectral-domain OCT in normal and glaucoma eyes

This study aimed to evaluate agreement of Wide scan measurements from swept-source optical coherence tomography (SS-OCT) Triton and spectral-domain OCT (SD-OCT) Maestro in normal/glaucoma eyes, and to assess the precision of measurements from Wide and Cube scans of both devices. Three Triton and three Maestro operator/device configurations were created by pairing three operators, with study eye and testing order randomized. Three scans were captured for Wide (12 mm × 9 mm), Macular Cube (7 mm × 7 mm-Triton; 6 mm × 6 mm-Maestro), and Optic Disc Cube (6 mm × 6 mm) scans for 25 normal eyes and 25 glaucoma eyes. Parameter measurements included circumpapillary retinal nerve fiber layer(cpRNFL), ganglion cell layer + inner plexiform layer (GCL+), and ganglion cell complex (GCL++). A two-way random effect analysis of variance model was used to estimate the repeatability and reproducibility; agreement was evaluated by Bland-Altman analysis and Deming regression. The precision estimates were low, indicating high precision, for all thickness measurements with the majority of the limits < 5 µm for the macula and < 10 µm for the optic disc. Precision of the Wide and Cube scans were comparable. Excellent agreement between the two devices was found for Wide scans, with the mean difference < 3 µm across all measurements (cpRNFL < 3 µm, GCL+  < 2 µm, GCL ++  < 1 µm), indicating interoperability. A single Wide scan covering the peripapillary and macular regions may be useful for glaucoma diagnosis and management.

Agreement and Precision of Wide and Cube Scan Measurements between Swept-source and Spectral-domain OCT in Normal and Glaucoma Eyes

This study aimed to evaluate agreement of Wide scan measurements from swept-source optical coherence tomography(SS-OCT) Triton and spectral-domain OCT(SD-OCT) Maestro in normal/glaucoma eyes, and to assess the precision of measurements from Wide and Cube scans of both devices. Three Triton and three Maestro operator/device configurations were created by pairing three operators, with study eye and testing order randomized. Three scans were captured for Wide (12mm×9mm), Macular Cube (7mmx7mm-Triton; 6mmx6mm-Maestro), and Optic Disc Cube (6mmx6mm) scans for 25 normal eyes and 25 glaucoma eyes. Thickness of circumpapillary retinal nerve fiber layer(cpRNFL), ganglion cell layer+inner plexiform layer(GCL+), and ganglion cell complex(GCL++) was obtained from each scan. A two-way random effect analysis of variance model was used to estimate the repeatability and reproducibility; agreement was evaluated by Bland-Altman analysis and Deming regression. Precision limit estimates were low: <5µm for macular and <10µm for optic disc parameters. Precision for Wide and Cube scans of both devices were comparablein both groups. Excellent agreement between the two devices was found for Wide scans, with the mean difference<3µm across all measurements (cpRNFL<3µm, GCL+<2µm, GCL++<1µm), indicating interoperability. A single Wide scan covering the peripapillary and macular regions may be useful for glaucoma management.

Precision and Agreement of Individual and Simultaneous Macular and Optic Disc Volumetric Measurements With Spectral Domain Optical Coherence Tomography

Purpose: To evaluate the precision of individual and combined macula and optic disc volumetric analysis, and the agreement between these two scan modes with spectral domain optical coherence tomography (OCT). Methods: Macular and optic disc volumetric measurements were performed with individual and combined scan protocols in one eye of 75 healthy subjects. Three repeated measurements were performed with each protocol. From the macular area, retinal thickness in nine different sectors and ganglion cell complex thickness in eight different sectors were analyzed from both scan modes. From the optic disc area, the peripapillary retinal nerve fiber layer (pRNFL) thickness in 12 clock sectors and the optic disc parameters were evaluated. For all the parameters, repeatability limit and agreement analysis were performed. Results: For the retinal thickness measurements in macula, the combined scan had two to three times larger repeatability limit than the individual scan for all the sectors except the central sector, where the repeatability limit was five times larger. The limits of agreement intervals were lower than 20 μm for all sectors, except the central. The ganglion cell complex measurements also had larger repeatability limits for the combined scans, and the limits of agreement intervals were <10 μm for all sectors. For the pRNFL thickness, the repeatability values were distributed like a vertically elongated ellipse for both scans, but still the repeatability was better for individual scan compared to the combined scan. The shortest and widest interval are obtained for sectors 9 (9 μm) and 12 (40 μm), respectively. The repeatability limit was <0.15 units for all disc parameters with both scan modes. Conclusion: The individual macula and optic disc scans had better repeatability than the combined scan mode, and the two scan modes cannot be used interchangeability due to the wide limits of agreement.

Comparison of the Thickness of the Fiber Layer of the Retinal Nerves in Spectral Domain Optical Coherence Tomography in Normal Eyes Older Than 40 Years

PURPOSE

To compare measurements of the thickness of the retinal nerve fibre layer (RNFL) and assess the agreement between three different devices for spectral domain optical coherence tomography.

MATERIAL AND METHODS

The RNFL thickness of both eyes of 23 normal subjects older than 40 years was measured using Canon HS100, Topcon Maestro, and NIDEK RS-3000 devices. Both eyes of each subject were scanned in random order. All scans were completed on the same day in the morning. The average and four quadrants (superior, inferior, nasal, and temporal) of RNFL thickness were measured. To determine the differences in RNFL thickness, analysis of variance for repeated measurements was performed. A Bland-Altman plot was plotted, and coefficients of determination were calculated.

RESULTS

A total of 46 eyes of 23 subjects were enrolled in this study. The average RNFL thickness as determined by the three OCT devices was correlated (p < 0.001), but differed significantly between the three devices, as most were quadrant measurements. The mean average RNFL thickness was 98.5 ± 6.6 µm as measured by Canon HS100, 108.5 ± 8.8 µm as measured by Topcon Maestro, and 104.9 ± 9.0 µm as measured by NIDEK RS-3000. Topcon Maestro showed the highest average RNFL thickness value. Bland-Altman plots revealed considerable agreement among the three devices, except for the inferior quadrants between Topcon Maestro and NIDEK RS-3000 measurements. All three devices reveal considerable coefficients of determination values for mean RNFL thickness (0.917 - 0.127).

CONCLUSION

Although the peripapillary RNFL thickness measurements taken with Canon HS100, Topcon Maestro, and NIDEK RS-3000 were in good agreement, they were not interchangeable in clinical practice, as the values differed significantly.

Review on Retrospective Procedures to Correct Retinal Motion Artefacts in OCT Imaging

Motion artefacts from involuntary changes in eye fixation remain a major imaging issue in optical coherence tomography (OCT). This paper reviews the state-of-the-art of retrospective procedures to correct retinal motion and axial eye motion artefacts in OCT imaging. Following an overview of motion induced artefacts and correction strategies, a chronological survey of retrospective approaches since the introduction of OCT until the current days is presented. Pre-processing, registration, and validation techniques are described. The review finishes by discussing the limitations of the current techniques and the challenges to be tackled in future developments.

Repeatability, reproducibility and agreement of foveal avascular zone measurements using three different optical coherence tomography angiography devices

Purpose

To evaluate the repeatability, the reproducibility and the agreement of foveal avascular zone (FAZ) measurements using three different optical coherence tomography angiography (OCT-A) devices.

Procedures

This prospective study included 24 eyes of 24 healthy volunteers. OCT-A imaging was performed using RTVue XR Avanti, Canon OCT-HS100 and Spectralis OCT-A. Repeated measurements were performed under the same conditions on two separate days, and the area of the FAZ was determined and analyzed using the above devices.

Results

All three devices showed a high ICC and there was no significant difference between the ICCs (pairwise comparison) of the three devices (Optovue–Canon (p = 0.66); Canon–Heidelberg (p = 0.21); Heidelberg–Optovue (p = 0.37). Agreement analysis of the three devices revealed a significant elevation of FAZ area values with the Heidelberg device and a slight underestimation of the FAZ area with the Canon device. Nevertheless, overall we found a high level of agreement between all of the three devices (ICC ≥ 0.958 (0.905–0.982)).

Conclusions

Good reproducibility and repeatability were observed for all three devices. However, the agreement analysis revealed slight, but significant differences, which might limit alternating use of these devices for clinical research and follow-up examinations.

Evaluation of optic disc, retinal nerve fiber and macular ganglion cell layers in pediatric diabetes

PURPOSE

Our aim was to compare optic disc parameters, retinal nerve fiber (RNFL) and macular ganglion cell layers between children and adolescents with diabetes mellitus (type 1) and healthy controls.

METHODS

Sixty-three eyes of 63 pediatric diabetic patients without diabetic retinopathy and 44 eyes of 44 healthy controls were included in this cross-sectional and comparative study. Diabetic and control groups were similar in the aspect of age, gender and refractive error. Measurements of optic disc parameters (i.e., rim area, disc area, cup-to-disc ratio, cup volume), thickness of RNFL and macular ganglion cell-inner plexiform layers (GCL + IPL) were taken with the spectral domain optical coherence tomography.

RESULTS

There were not statistically significant differences between the diabetic patients and healthy controls in terms of intraocular pressure (p = 0.14), retinal nerve fiber layer thickness (p = 0.61), rim area (p = 0.92), disc area (p = 0.10), vertical cup-to-disc ratio (p = 0.16), cup volume (p = 0.13), and average macular GCL + IPL thickness (p = 0.43). On the other hand, binocular RNFL thickness symmetry percentage was statistically significantly different in the diabetic and control groups (p = 0.01).

CONCLUSION

Diabetic children and adolescents without diabetic retinopathy have more binocular RNFL thickness asymmetry compared to healthy controls.

Assessment of optic disc and ganglion cell layer in diabetes mellitus type 2

The purpose of this study was to compare the optic disc parameters, retinal nerve fiber (RNFL), and macular ganglion cell layers between patients with diabetes mellitus (DM) type 2 and healthy controls.In this cross-sectional study, 69 eyes of 69 diabetic patients without diabetic retinopathy and 47 eyes of 47 healthy controls were included. Optic disc parameters (i.e., rim area, disc area, cup to disc ratio, cup volume), RNFL, and macular ganglion cell-inner plexiform layers (GCL + IPL) thickness were measured by means of spectral domain optical coherence tomography.There were not statistically significant differences between the diabetic patients and healthy controls in terms of RNFL thickness (P = .32), rim area (P = .20), disc area (P = .16), cup volume (P = .12), and average macular GCL + IPL thickness (P = .11). Nevertheless, binocular RNFL thickness symmetry percentage (P =.03), average cup to disc ratio (P = .02), and superior-nasal macular GCL + IPL thickness (P = .04) were statistically significantly different in the diabetic and control groups.Diabetic patients without retinopathy have more binocular RNFL thickness asymmetry, higher cup to disc ratio, and thinner sectoral macular GCL + IPL when compared to healthy controls. Our results may support the statement that DM causes inner retinal neurodegenerative changes.