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Compact Laser Doppler Flowmeter (LDF) Fundus Camera for the Assessment of Retinal Blood Perfusion in Small Animals.

Mentek M, Truffer F, Chiquet C, Godin-Ribuot D, Amoos S, Loeuillet C, Bernabei M, Geiser M - PLoS ONE (2015)

Bottom Line: Here we present the results obtained with a new rodent-adapted compact fundus camera based on laser Doppler flowmetry (LDF).Inter-day reproducibility was good (0.79 and 0.7, respectively).Upon ocular blood flow cessation, the retinal artery velocity signal substantially decreased, whereas the ONH signal did not significantly vary, suggesting that it could mostly be attributed to tissue light scattering.

View Article: PubMed Central - PubMed

Affiliation: HP2 laboratory, Grenoble Alpes University, 38000, Grenoble, France; INSERM U1042 laboratory, 38000, Grenoble, France.

ABSTRACT

Purpose: Noninvasive techniques for ocular blood perfusion assessment are of crucial importance for exploring microvascular alterations related to systemic and ocular diseases. However, few techniques adapted to rodents are available and most are invasive or not specifically focused on the optic nerve head (ONH), choroid or retinal circulation. Here we present the results obtained with a new rodent-adapted compact fundus camera based on laser Doppler flowmetry (LDF).

Methods: A confocal miniature flowmeter was fixed to a specially designed 3D rotating mechanical arm and adjusted on a rodent stereotaxic table in order to accurately point the laser beam at the retinal region of interest. The linearity of the LDF measurements was assessed using a rotating Teflon wheel and a flow of microspheres in a glass capillary. In vivo reproducibility was assessed in Wistar rats with repeated measurements (inter-session and inter-day) of retinal arteries and ONH blood velocity in six and ten rats, respectively. These parameters were also recorded during an acute intraocular pressure increase to 150 mmHg and after heart arrest (n = 5 rats).

Results: The perfusion measurements showed perfect linearity between LDF velocity and Teflon wheel or microsphere speed. Intraclass correlation coefficients for retinal arteries and ONH velocity (0.82 and 0.86, respectively) indicated strong inter-session repeatability and stability. Inter-day reproducibility was good (0.79 and 0.7, respectively). Upon ocular blood flow cessation, the retinal artery velocity signal substantially decreased, whereas the ONH signal did not significantly vary, suggesting that it could mostly be attributed to tissue light scattering.

Conclusion: We have demonstrated that, while not adapted for ONH blood perfusion assessment, this device allows pertinent, stable and repeatable measurements of retinal blood perfusion in rats.

No MeSH data available.


Related in: MedlinePlus

LDF optical unit scheme.(A) Optical system with the different optical units. In are conjugated images and Pn are conjugated pupils. F: illumination fiber; GL1: first relay with focusing; BS1: cold mirror; L3: relay lens; BS2: beam splitter cube with pupil images on surfaces; I1 laser source and I2 detection fiber; GL2: relay lens group to CCD camera at I3. (B) 3D view of the front part of the instrument with the glass rods and LEDs to illuminate the fundus. Central hole of 2 mm acts as entrance pupil (P0). (C) Fundus image obtained with the imaging unit. Dots represent typical LDF recording locations on the ONH and retinal artery.
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pone.0134378.g001: LDF optical unit scheme.(A) Optical system with the different optical units. In are conjugated images and Pn are conjugated pupils. F: illumination fiber; GL1: first relay with focusing; BS1: cold mirror; L3: relay lens; BS2: beam splitter cube with pupil images on surfaces; I1 laser source and I2 detection fiber; GL2: relay lens group to CCD camera at I3. (B) 3D view of the front part of the instrument with the glass rods and LEDs to illuminate the fundus. Central hole of 2 mm acts as entrance pupil (P0). (C) Fundus image obtained with the imaging unit. Dots represent typical LDF recording locations on the ONH and retinal artery.

Mentions: The optical system, designed for Campbell and Hughes’s general rat eye model [22] consists of an external illumination source, a common unit, an imaging unit and a confocal LDF unit [23] (Fig 1).


Compact Laser Doppler Flowmeter (LDF) Fundus Camera for the Assessment of Retinal Blood Perfusion in Small Animals.

Mentek M, Truffer F, Chiquet C, Godin-Ribuot D, Amoos S, Loeuillet C, Bernabei M, Geiser M - PLoS ONE (2015)

LDF optical unit scheme.(A) Optical system with the different optical units. In are conjugated images and Pn are conjugated pupils. F: illumination fiber; GL1: first relay with focusing; BS1: cold mirror; L3: relay lens; BS2: beam splitter cube with pupil images on surfaces; I1 laser source and I2 detection fiber; GL2: relay lens group to CCD camera at I3. (B) 3D view of the front part of the instrument with the glass rods and LEDs to illuminate the fundus. Central hole of 2 mm acts as entrance pupil (P0). (C) Fundus image obtained with the imaging unit. Dots represent typical LDF recording locations on the ONH and retinal artery.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520556&req=5

pone.0134378.g001: LDF optical unit scheme.(A) Optical system with the different optical units. In are conjugated images and Pn are conjugated pupils. F: illumination fiber; GL1: first relay with focusing; BS1: cold mirror; L3: relay lens; BS2: beam splitter cube with pupil images on surfaces; I1 laser source and I2 detection fiber; GL2: relay lens group to CCD camera at I3. (B) 3D view of the front part of the instrument with the glass rods and LEDs to illuminate the fundus. Central hole of 2 mm acts as entrance pupil (P0). (C) Fundus image obtained with the imaging unit. Dots represent typical LDF recording locations on the ONH and retinal artery.
Mentions: The optical system, designed for Campbell and Hughes’s general rat eye model [22] consists of an external illumination source, a common unit, an imaging unit and a confocal LDF unit [23] (Fig 1).

Bottom Line: Here we present the results obtained with a new rodent-adapted compact fundus camera based on laser Doppler flowmetry (LDF).Inter-day reproducibility was good (0.79 and 0.7, respectively).Upon ocular blood flow cessation, the retinal artery velocity signal substantially decreased, whereas the ONH signal did not significantly vary, suggesting that it could mostly be attributed to tissue light scattering.

View Article: PubMed Central - PubMed

Affiliation: HP2 laboratory, Grenoble Alpes University, 38000, Grenoble, France; INSERM U1042 laboratory, 38000, Grenoble, France.

ABSTRACT

Purpose: Noninvasive techniques for ocular blood perfusion assessment are of crucial importance for exploring microvascular alterations related to systemic and ocular diseases. However, few techniques adapted to rodents are available and most are invasive or not specifically focused on the optic nerve head (ONH), choroid or retinal circulation. Here we present the results obtained with a new rodent-adapted compact fundus camera based on laser Doppler flowmetry (LDF).

Methods: A confocal miniature flowmeter was fixed to a specially designed 3D rotating mechanical arm and adjusted on a rodent stereotaxic table in order to accurately point the laser beam at the retinal region of interest. The linearity of the LDF measurements was assessed using a rotating Teflon wheel and a flow of microspheres in a glass capillary. In vivo reproducibility was assessed in Wistar rats with repeated measurements (inter-session and inter-day) of retinal arteries and ONH blood velocity in six and ten rats, respectively. These parameters were also recorded during an acute intraocular pressure increase to 150 mmHg and after heart arrest (n = 5 rats).

Results: The perfusion measurements showed perfect linearity between LDF velocity and Teflon wheel or microsphere speed. Intraclass correlation coefficients for retinal arteries and ONH velocity (0.82 and 0.86, respectively) indicated strong inter-session repeatability and stability. Inter-day reproducibility was good (0.79 and 0.7, respectively). Upon ocular blood flow cessation, the retinal artery velocity signal substantially decreased, whereas the ONH signal did not significantly vary, suggesting that it could mostly be attributed to tissue light scattering.

Conclusion: We have demonstrated that, while not adapted for ONH blood perfusion assessment, this device allows pertinent, stable and repeatable measurements of retinal blood perfusion in rats.

No MeSH data available.


Related in: MedlinePlus