Age dependence of perimacular white blood cell flux during isometric exercise

Purpose. To investigate the age dependence of perimacular white blood cell flux (WBCF) during isometric exercise. Methods. Fourteen healthy young (age range: 21-29 years; 24 ± 3 years, mean ± SD, 12 male and 2 female) and 15 healthy middle-aged (age range: 45-57 years; 53 ± 4 years, mean ± SD; 5 male and 10 female) volunteers were studied. Subjects performed isometric handgrip for 10 minutes and squatting for 6 minutes. WBCF was assessed with the blue field entoptic technique, mean arterial pressure (MAP) was measured with an automated oscillometric device, intraocular pressure (IOP) was measured by Goldmann applanation tonometry and ocular perfusion pressure (OPP) was calculated as 2/3 MAP - IOP. Results. Baseline WBCF was significantly higher in young subjects than in middle-aged subjects (191 ± 28 vs 142 ± 23; p = 0.001). Isometric handgrip induced a significant increase in WBCF in the middle-aged subjects (23 ± 24%; p = 0.005), but not in the young subjects. Squatting significantly increased WBCF in both groups (young: 42 ± 23%; p = 0.004 and middle aged: 51 ± 27%; p < 0.001). A significant deviation from baseline WBCF was observed when OPP increased by 42 ± 4% (p = 0.003) and 35 ± 4% (p < 0.001) for the young and middle-aged subjects, respectively. The OPP-WBCF relationship was not different between the two study groups. Conclusion. Altered retinal autoregulation as observed in vascular ocular disease appears to be unrelated to the normal physiological aging process.