Photodetector sensitivity level and Heidelberg retina flowmeter measurements in humans

L. Kagemann, Alon Harris, H. S. Chung, C. P. Jonescu-Cuypers, D. Zarfati, B. Martin

Research output: Contribution to journalArticle

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Abstract

Purpose. In vitro models suggest that Heidelberg retina flowmeter (HRF) measurements are affected by changes in photodetector sensitivity. We measured blood flow in a single volume of human retinal tissue in vivo at various sensitivity (DC) levels. Methods. The peripapillary retinal regions of 12 normal subjects were examined by HRF under five different sensitivity settings: (1) average DC range below 100; (2) average DC range below 125; (3) average DC range near 150 (normal sensitivity); (4) average DC range above 175; and (5) average DC range above 200 or extremely overexposed. The distributions of flow values were examined by point-wise analysis. All pixels from a common tissue location were analyzed, and the effect of their brightness on the flow measurement was evaluated by ANOVA with Fisher's protected least significant difference model. Results. ANOVA analysis of image DC level showed that significantly different DC levels were achieved for each of the five sensitivity settings (P < 0.0001). Flow values decreased with increasing DC for each of the 25th percentile, 50th percentile (P < 0.0001 for each), 75th percentile (P = 0.0026), 90th percentile (P = 0.0216), and mean (P = 0.0004) flow values. The percentage of pixels with values of zero (avascular tissue) increased with increasing photodetector sensitivity (P < 0.0001). Conclusions. Improper sensitivity settings alter the detected percentage of avascular tissue and the blood flow measurements in tissue containing capillaries. Consistent assessment of retinal blood flow requires consistent photodetector sensitivity settings between longitudinal imaes.

Original languageEnglish
Pages (from-to)354-357
Number of pages4
JournalInvestigative Ophthalmology and Visual Science
Volume42
Issue number2
StatePublished - 2001

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Flowmeters
Retina
Analysis of Variance

ASJC Scopus subject areas

  • Ophthalmology

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Kagemann, L., Harris, A., Chung, H. S., Jonescu-Cuypers, C. P., Zarfati, D., & Martin, B. (2001). Photodetector sensitivity level and Heidelberg retina flowmeter measurements in humans. Investigative Ophthalmology and Visual Science, 42(2), 354-357.

Photodetector sensitivity level and Heidelberg retina flowmeter measurements in humans. / Kagemann, L.; Harris, Alon; Chung, H. S.; Jonescu-Cuypers, C. P.; Zarfati, D.; Martin, B.

In: Investigative Ophthalmology and Visual Science, Vol. 42, No. 2, 2001, p. 354-357.

Research output: Contribution to journalArticle

Kagemann, L, Harris, A, Chung, HS, Jonescu-Cuypers, CP, Zarfati, D & Martin, B 2001, 'Photodetector sensitivity level and Heidelberg retina flowmeter measurements in humans', Investigative Ophthalmology and Visual Science, vol. 42, no. 2, pp. 354-357.
Kagemann, L. ; Harris, Alon ; Chung, H. S. ; Jonescu-Cuypers, C. P. ; Zarfati, D. ; Martin, B. / Photodetector sensitivity level and Heidelberg retina flowmeter measurements in humans. In: Investigative Ophthalmology and Visual Science. 2001 ; Vol. 42, No. 2. pp. 354-357.
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