EFFECT OF DIFFERENT PHOTOTHERAPY LIGHTS ON RETINAL AND CHOROIDAL BLOOD-FLOW

The response of retinal (RBF) and choroidal (ChBF) blood flow to illum ination with light with different spectra was investigated in spontane ously breathing newborn piglets. After 1 h in complete darkness, the a nimals were exposed to blue, white or green light in such a manner tha t equal energy was delivered to the eye. RBF and ChBF showed different flow responses. After 60 min exposure to blue light, RBF increased fr om 0.22 +/- 0.01 ml/min/g at baseline to 0.32 +/- 0.03 ml/min/g (+/- S EM) (p < 0.03). Apart from this increase, RBF did not change significa ntly during any of the experimental settings. ChBF, on the other hand, was significantly affected by illumination. Thus, at 120 min of light exposure all three types of light decreased ChBF significantly from b aseline (darkness) levels. Blue light decreased ChBF (mean +/- SEM) fr om 13.78 +/- 0.84 to 7.61 +/- 0.67 ml/min/g (p < 0.01), white light fr om 17.43 +/- 1.86 to 9.86 +/- 1.07 ml/min/g (p < 0.01), and green ligh t from 14.13 +/- 1.64 to 8.31 +/- 1.30 ml/min/g (p < 0.02). The result s indicate that light is an important modulator of ChBF and to a certa in extent also RBF. Further, the results suggest that ChBF and RBF are regulated differently.