One of the current controversies in eye blood flow research is the issue of choroidal autoregulation. Early studies generally found passive choroidal blood flow responses to changes in perfusion pressure which led to the conclusion that the choroid is devoid of autoregulatory ability. Moreover, the choroid's high flow rate and low oxygen extraction suggested little need for choroidal autoregulation. However, more recent studies find that choroidal blood flow does not always respond passively to changes in perfusion pressure, and that choroidal blood flow can be remarkably well maintained over a wide range of perfusion pressure, particularly when arterial pressure is the manipulated variable. Interestingly, when choroidal blood flow is maintained, the IOP is also largely unresponsive to changes in arterial pressure, but when the choroid is passive, the IOP becomes arterial pressuredependent. This finding suggests IOP homeostasis and perhaps preservation of choroidal thickness and thus retinal position and optical pathlength as a basis for choroidal autoregulation. Thus, there are experimental data and functional arguments to refute or support choroidal autoregulation. Resolving this controversy requires reconciling the discrepancies in the choroidal blood flow studies (i.e., can the results be explained by the blood flow measuring methodologies used or the experimental conditions), and addressing the broader issues of the choroid's functions and the integration of its intrinsic and extrinsic control mechanisms.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience