Changes in the anterior chamber of the eye during acute hypoglycaemia in humans.
1. The changes in the volume and depth of the anterior chamber of the eye during acute insulin-induced hypoglycaemia were examined in nine healthy non-diabetic subjects (aged 23-31 years). The dimensions of the anterior chamber of the eye were measured by a photogrammetric technique, with Polaroid photographs taken of the lower half of the mid-sagittal plane of the eye at an angle of 55 degrees at a magnification of x16. Photographs were taken before and at regular intervals after the induction of acute hypoglycaemia using an infusion of unmodified (soluble) insulin at 2.5 m-units min-1 kg-1. Plasma adrenaline was measured regularly throughout the study. 2. Plasma glucose fell from 4.5 +/- 0.2 mmol/l (mean +/- SEM) to a nadir of 1.0 +/- 0.1 mmol/l (P < 0.01), which coincided with the onset of the acute autonomic reaction. Plasma adrenaline rose from 0.3 +/- 0.1 nmol/l to a peak of 3.2 +/- 0.6 nmol/l (P < 0.01) at 15 min after the autonomic reaction. 3. The volume of the anterior chamber decreased by 8.2% from 284.7 +/- 21.5 microliters at baseline to 264.5 +/- 17.0 microliters (P < 0.01) at the onset of the autonomic reaction. No significant alteration in axial anterior chamber depth was evident, but peripheral anterior depth decreased from 2.25 +/- 0.20 mm at baseline to 2.07 +/- 0.14 mm (P < 0.05) at the onset of the autonomic response.(ABSTRACT TRUNCATED AT 250 WORDS)