Environmental smoking and ocular hemodynamics
M. Feucht, K. A. Mollenhauer, K. A. Breidenbach
Purpose: Environmental smoking has to be regarded as a major risk factor for cardiovascular diseases. Passively inhaling cigarette smoke might especially affect the vascular tone in vascular beds which are not autoregulated like the choroidal vasculature.
Methods: 21 healthy (smokers and non-smokers) subjects ( 9m, 12f; mean age: 35y) were passively exposed for 20 minutes to heavy cigarette smoke in a small occluded chamber. At baseline IOP, blood pressure, heart rate, ocular pulse amplitudes, optic nerve head capillary blood flow and capillary retinal blood flow were examined. Retinal capillary blood flow was measured by means of scanning laser doppler flowmetry (Heidelberg - Retina-Flowmeter) and ocular pulse amplitudes, representing primarily choroidal hemodynamics, were recorded by using the OBF-system (Uk)Ltd. Optic nerve head blood flow was determined by means of continuous laser doppler flowmetry according to Riva. All measurements were repeated immediately after cigarette smoking. For statistical analysis the Wilcoxon-test was applied.
Results: The analysis of all measured parameters did not show any significant difference before and after smoke exposure. Dividing the subjects in two groups, however, i.e. into smokers and non-smokers lead to significant differences. In the non- smoker group all parameters did not change significantly. In the smoker group (n = 8) pulsatile ocular blood flow did not change (delta x = - 28µl/min) significantly, but optic nerve head capillary blood flow decreased significantly on the temporal neuroretinal rim from x = 10.3AU to 9.5AU and nasally from x = 8.4AU to x = 8.2.AU. The decrease at the nasal neuroretinal rim was not significant. Retinal capillary blood flow showed no statistically significant change.
Conclusions: Acute environmental smoking for 20 minutes does not change ocular hemodynamics in non-smokers. These results suggest that a healthy vascular regulatory system might compensate for an induced vasoconstriction. In smokers, however, even environmental smoking leads to a further decrease of optic nerve head blood flow.
Department of Ophthalmology,University of Hamburg, Martinistr. 52, D-20246 Hamburg, Germany