Interobserver repeatability of Heidelberg retinal flowmetry using pixel-by-pixel analysis

Itay Ben Zion, Alon Harris, Danny Moore, Adam Werne, Matthew Ralstin, Brent Siesky, Lynne McCranor, Carlos Rospigliosi, William Steinmann, L. Jay Katz, Hanna J. Garzozi

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

PURPOSE: To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. PATIENTS AND METHODS: Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560×640 μm area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95% confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. RESULTS: ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. CONCLUSIONS: This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.

Original languageEnglish
Pages (from-to)280-283
Number of pages4
JournalJournal of Glaucoma
Volume18
Issue number4
DOIs
StatePublished - Apr 2009

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Flowmeters
Rheology
Physicians
Ocular Hypertension
Observer Variation
Optic Disk
Glaucoma
Perfusion
Confidence Intervals

Keywords

  • Blood flow
  • Eye
  • Glaucoma
  • Heidelberg retinal flowmeter

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Interobserver repeatability of Heidelberg retinal flowmetry using pixel-by-pixel analysis. / Zion, Itay Ben; Harris, Alon; Moore, Danny; Werne, Adam; Ralstin, Matthew; Siesky, Brent; McCranor, Lynne; Rospigliosi, Carlos; Steinmann, William; Katz, L. Jay; Garzozi, Hanna J.

In: Journal of Glaucoma, Vol. 18, No. 4, 04.2009, p. 280-283.

Research output: Contribution to journalArticle

Zion, IB, Harris, A, Moore, D, Werne, A, Ralstin, M, Siesky, B, McCranor, L, Rospigliosi, C, Steinmann, W, Katz, LJ & Garzozi, HJ 2009, 'Interobserver repeatability of Heidelberg retinal flowmetry using pixel-by-pixel analysis', Journal of Glaucoma, vol. 18, no. 4, pp. 280-283. https://doi.org/10.1097/IJG.0b013e318181544a
Zion, Itay Ben ; Harris, Alon ; Moore, Danny ; Werne, Adam ; Ralstin, Matthew ; Siesky, Brent ; McCranor, Lynne ; Rospigliosi, Carlos ; Steinmann, William ; Katz, L. Jay ; Garzozi, Hanna J. / Interobserver repeatability of Heidelberg retinal flowmetry using pixel-by-pixel analysis. In: Journal of Glaucoma. 2009 ; Vol. 18, No. 4. pp. 280-283.
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abstract = "PURPOSE: To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. PATIENTS AND METHODS: Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560×640 μm area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95{\%} confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. RESULTS: ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. CONCLUSIONS: This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.",
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AU - Zion, Itay Ben

AU - Harris, Alon

AU - Moore, Danny

AU - Werne, Adam

AU - Ralstin, Matthew

AU - Siesky, Brent

AU - McCranor, Lynne

AU - Rospigliosi, Carlos

AU - Steinmann, William

AU - Katz, L. Jay

AU - Garzozi, Hanna J.

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N2 - PURPOSE: To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. PATIENTS AND METHODS: Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560×640 μm area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95% confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. RESULTS: ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. CONCLUSIONS: This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.

AB - PURPOSE: To determine the interobserver reproducibility of Heidelberg retinal flowmeter (HRF) blood flow measurements using independently selected study areas for pixel-by-pixel analysis. PATIENTS AND METHODS: Blood flow measurements were performed on 257 scans from 15 patients, 14 of whom had glaucoma or ocular hypertension. HRF was used to record capillary perfusion in a 2560×640 μm area of the supratemporal peripapillary region and pixel-by-pixel analysis was performed from an area adjacent to the optic disc with a minimum of 1600 pixels. Each observer independently selected the area for analysis. The percentage of pixels with <1 arbitrary unit of flow (no flow) and 10, 25, 50, 75, and 90th percentiles of flow values was calculated. Interobserver variability was assessed by estimating the intraclass correlation coefficient (ICC) and its 95% confidence interval. Bland-Altman plots of the difference between the 2 physicians versus the average of the 2 physicians for each outcome were created. RESULTS: ICC was 0.79 (range: 0.74 to 0.83) for mean flow values. For 0, 10, 25, 50, 75, and 90th percentiles of flow, the ICC was 0.67 (0.60 to 0.73), 0.74 (0.68 to 0.79), 0.82 (0.78 to 0.86), 0.85 (0.82 to 0.88), 0.85 (0.81 to 0.88), and 0.77 (0.72 to 0.82), respectively. Zero flow pixels had a nonsignificant mean difference between observers (P=0.542), whereas the remainder of the flow values demonstrated significant mean differences. CONCLUSIONS: This study demonstrates that independent observers can review high-quality HRF scans and may produce different absolute values while retaining strong consistency of agreement when independently selecting areas for analysis using the pixel-by-pixel method.

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KW - Eye

KW - Glaucoma

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