An experimental study of lateral displacement of ganglion cells (GCs) from foveal cones in six human retinas is reported. At 406-675 microm in length, as measured in radially oriented cross-sections, Henle fibers are substantially longer than previously reported. However, a new theoretical model indicates that the discrepancies in these reports are mainly due to meridional differences. The model takes into account the effects of optical degradation and peripheral ON/OFF asymmetry and predicts a central GC:cone ratio of 2.24:1. It provides estimates of cumulative counts and GC receptive field density at 0 degrees -30 degrees along the principal meridians of the visual field.

Background-A longstanding but controversial hypothesis is that individuals who exhibit frequent, large increases in blood pressure (BP) during psychological stress are at risk for developing essential hypertension. We tested whether BP changes during psychological stress predict incident hypertension in young adults. Methods and Results-We used survival analysis to predict hypertensive status during 13 years of follow-up in a sample of Ͼ4100 normotensive black and white men and women (age at entry, 18 to 30 years) enrolled in the CARDIA study. BP responses to 3 psychological challenges-cold pressor, star tracing, and video game tasks-were measured.Hypertensive status was defined as use of antihypertensive medication or measured BP Ն140/90 mm Hg. After adjustment for race, gender, covariates (education, body mass index, age, and resting pressure), and their significant interactions, the larger the BP responses were to each of the 3 tasks, the earlier hypertension occurred (PϽ0.0001 to Ͻ0.01). The systolic BP effect for the cold pressor task was apparent for women and for whites in race-and gender-specific models, whereas the diastolic BP effect for the video game was apparent for men. Conclusions-Young adults who show a large BP response to psychological stress may be at risk for hypertension as they approach midlife.