Acute effects of cigarette smoking on tissue circulation in human optic nerve head and choroid-retina.

OBJECTIVE

To study the acute effects of cigarette smoking on tissue circulation in the human optic nerve head (ONH) and choroid-retina.

DESIGN

Nonrandomized, comparative trial (sequential self-controlled).

PARTICIPANTS

Nine healthy habitual smokers (age, 28 +/- 4 years; number of cigarettes smoked per day, 27 +/- 10; length of smoking history, 10 +/- 4 years; mean +/- standard deviation).

INTERVENTION

Using the laser speckle method, normalized blur (NB) value, a quantitative index of tissue blood velocity, was measured every 0.125 second and averaged over three pulses across an area located in the temporal site of the ONH free of visible surface vessels (NB(ONH)) and across an area located halfway between the macula and the ONH with no discrete vessels visible (NB(ch-ret)). NB(ONH), NB(ch-ret), and intraocular pressure (IOP) in one randomly chosen eye, and blood pressure (BP) and pulse rate (PR) were measured before and 1, 5, 10, 15, 20, 25, 30, 45, 60, and 90 minutes after sham smoking using a short drinking straw as a cigarette substitute (control). One week later, NB(ONH), NB(ch-ret), and IOP in the same eye, and BP and PR were measured after cigarette smoking according to the same time schedule as in the control experiment.

MAIN OUTCOME MEASURES

NB(ONH) and NB(ch-ret).

RESULTS

In the control experiment, all parameters examined showed no significant change during the experimental period. Differences in NB(ONH) and NB(ch-ret) before and after actual smoking were significantly greater than those in the control experiment (analysis of variance, P = 0.0000, 0.0000). BP and PR were significantly increased between 1 and 30 minutes after actual smoking as compared with control data, while IOP showed no significant change at any time of measurement.

CONCLUSIONS

These results indicated that cigarette smoking increased tissue blood velocity in the ONH and possibly in the choroid in habitual smokers.