The Effect of Acute Hypovolemia on the Eye.

INTRODUCTION: To investigate the effects of acute hypovolemia induced by blood donation on the eye. Methods or Study Design: This prospective, observational study included a single eye from each of 48 healthy men between 20 and 40 years of age who had donated 500 ml of blood and 28 eyes of 28 healthy, age- and gender-matched control subjects. The ocular parameters including ocular perfusion pressure (OPP), intraocular pressure (IOP), axial length (AL), central corneal thickness (CCT), choroidal and retinal thicknesses, and retinal nerve fiber layer (RNFL) were measured before blood donation and at 10 min and 1, 2, 3, and 4 h after blood donation.

RESULTS: The mean OPP was significantly reduced following blood donation (baseline, 43.4 ± 4.9 vs. 40.8 ± 4.6 mmHg; p = 0.003). The mean subfoveal choroidal thickness (SFCT) was measured as 322.96 ± 76.23, 291.63 ± 77.85, 309.77 ± 75.72, 312.31 ± 75.98, 315.73 ± 75.43, and 317.75 ± 75.73 µm before blood donation, at baseline, 10 min, and 1, 2, 3, and 4 h following donation, respectively [F(2.462, 115.731) = 22.618, p < 0.001]. In the control group, the SFCT was measured as 302.04 ± 32.04, 301.43 ± 35.16, 298.07 ± 37.33, 298.96 ± 39.17, 302.54 ± 39.24, and 301.61 ± 40.41 µm at baseline, 10 min, and 1, 2, 3, and 4 h following donation, respectively [F(2.124, 57.340) = 0.592, p = 0.566]. There was no difference in AL, CCT, RNFL, retinal thicknesses, and IOP measurements performed before and after blood donation (p > 0.05).

CONCLUSIONS: Acute hypovolemia caused a significant reduction in SFCT which persisted for 3 h. This study may pave way for better understanding of choroidal thickness changes in disease states.