• Choroidal blood flow helps maintain a stable temperature environment for the outer retinal layers, especially in the macular area. Recent studies in monkeys have demonstrated a centrally mediated reflexive mechanism that increases choroidal blood flow in response to light or light-generated heat. This increase in choroidal blood flow can be detected as an elevation in ocular surface temperature. With the use of ocular surface temperature as a semiquantitative index of alterations in choroidal blood flow, the existence of a similar reflex was demonstrated in normal human volunteers.
Parver LM, Auker CR, Carpenter DO. Choroidal Blood FlowIII. Reflexive Control in Human Eyes. Arch Ophthalmol. 1983;101(10):1604-1606. doi:10.1001/archopht.1983.01040020606021