Purpose
The magnocellular (M cell) visual pathway is sensitive to moving stimuli and can be measured using Frequency Doubling Time (FDT) perimetry. The purpose of this study was to investigate differences in M cell function between athletes and non-athletes.
Methods
The protocol attained IRB approval and was in compliance with Declaration of Helsinki. Fourteen collegiate baseball players were compared to 17 student controls. FDT perimetry was used with 0.3 and 0.6 log unit neutral density filters with higher FDT score indicating decreased M cell activity. The following demographic data was collected for all subjects: starting age of organized sports play, starting age of unorganized sports play, hours per week of organized (league based) sports play, hours per week of unorganized sports play, number of visually active (e.g. ball contact) sports currently played, and total number of sports played. Multiple regression analysis was performed comparing these demographic characteristics of the combined cohort (n=31) to FDT scores. Batting average (n=6) and total number of assists (n=5) were compared to FDT score for those who participated in recent competition.
Results
FDT scores were higher in athletes than non-athletes, a difference which reached statistical significance with 0.6 log unit filters but not 0.3 log unit filters (22.36 ± 24.83 vs 7.24 ± 10.27, P=0.045 and 8.07 ± 11.12 vs 3.71 ± 6.56, P=0.21, respectively). Hours per week of organized sports play was positively correlated with FDT 0.3 log unit filter scores (t-stat=3.26, P=0.004) and 0.6 log unit filter scores (t-stat=2.97, P=0.0007) on multiple regression analysis. The number of visually active sports played was found to have a statistically significant negative correlation with FDT 0.3 log unit filter scores (t-stat=-2.03, P=0.05). Higher batting averages were significantly associated with higher FDT scores with the 0.6 log unit filter (P=0.03) and approached significance with 0.3 log unit filter (P=0.07). The number of assists and FDT scores were inversely related; however, this was not a strong association and did not reach statistical significance.
Conclusions
M cell activity was depressed in athletes and among those with higher batting averages. Current sports participation, and not life long duration of participation, correlated to FDT score and may indicate a degree of visual cortical plasticity although a cause and effect relationship cannot be proven.
Keywords: 642 perimetry •
564 innervation: neural regulation •
691 retina: proximal (bipolar, amacrine, and ganglion cells)