Changes in central retinal artery blood flow after ocular warming and cooling in healthy subjects.
Indian J Ophthalmol
;
2010 May; 58(3): 189-194
Article
in English
| IMSEAR
| ID: sea-136052
ABSTRACT
Context Retinal perfusion variability impacts ocular disease and physiology. Aim:
To evaluate the response of central retinal artery (CRA) blood flow to temperature alterations in 20 healthy volunteers. Setting andDesign:
Non-interventional experimental human study. Materials andMethods:
Baseline data recorded Ocular surface temperature (OST) in °C (thermo-anemometer), CRA peak systolic velocity (PSV) and end diastolic velocity (EDV) in cm/s using Color Doppler. Ocular laterality and temperature alteration (warming by electric lamp/cooling by ice-gel pack) were randomly assigned. Primary outcomes recorded were OST and intraocular pressure (IOP) immediately after warming or cooling and ten minutes later; CRA-PSV and EDV at three, six and nine minutes warming or cooling. StatisticalAnalysis:
Repeated measures ANOVA.Results:
(n = 20; μ ± SD) Pre-warming values were; OST 34.5 ± 1.02°C, CRA-PSV 9.3 ± 2.33 cm/s, CRA-EDV 4.6 ± 1.27 cm/s. OST significantly increased by 1.96°C (95% CI 1.54 to 2.37) after warming, but returned to baseline ten minutes later. Only at three minutes, the PSV significantly rose by 1.21 cm/s (95% CI 0.51to1.91). Pre-cooling values were OST 34.5 ± 0.96°C, CRA-PSV 9.7 ± 2.45 cm/s, CRA-EDV 4.7 ± 1.12 cm/s. OST significantly decreased by 2.81°C (95% CI −2.30 to −3.37) after cooling, and returned to baseline at ten minutes. There was a significant drop in CRA-PSV by 1.10cm/s (95% CI −2.05 to −0.15) and CRA-EDV by 0.81 (95% CI −1.47 to −0.14) at three minutes. At six minutes both PSV (95% CI −1.38 to −0.03) and EDV (95% CI −1.26 to −0.02) were significantly lower. All values at ten minutes were comparable to baseline. The IOP showed insignificant alteration on warming (95% CI of difference −0.17 to 1.57mmHg), but was significantly lower after cooling (95% CI −2.95 to −4.30mmHg). After ten minutes, IOP had returned to baseline.Conclusion:
This study confirms that CRA flow significantly increases on warming and decreases on cooling, the latter despite a significant lowering of IOP.
Full text:
Available
Index:
IMSEAR (South-East Asia)
Main subject:
Reference Values
/
Retinal Artery
/
Temperature
/
Blood Flow Velocity
/
Female
/
Humans
/
Male
/
Young Adult
Language:
English
Journal:
Indian J Ophthalmol
Year:
2010
Type:
Article
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