By Tom Sutton, DPT Student
One important aspect of baseball, let alone sports is undoubtedly vision. The input an athlete takes in while competing in a game or practice environment is paramount for peak performance. Having good hand-eye coordination and tracking skills to locate the ball as a batter or to accurately place the ball across the plate as a pitcher are just a few reasons why a baseball player needs good vision.
A recent study by Dimitrios Palidis and colleagues was conducted to evaluate the dynamic visual acuity (DVA) of 23 males on a high school baseball team in Vancouver, Canada. DVA is evaluated by two tests which are static-object (head rotation, with vision locked on a still object) and dynamic-object (head still with vision locked on moving target) fixation. This study was published in the Public Library of Science (PLOS) in February 2017.
Distinct Eye Movement Patterns Enhance Dynamic Visual Acuity
Dimitrios J. Palidis1, Pearson A. Wyder-Hodge1, Jolande Fooken1,2, Miriam Spering
Background
In a study by Palidis et al, the investigators tested whether or not there is a relationship between a high school baseball player’s eye movement kinematics and DVA performance. With both static and dynamic methods of testing DVA, static-object is used in a variety of practice settings and requires the athlete to utilize the vestibulo-ocular reflex (VOR) to maintain fixation on the object.(2)
Methods
The study consisted of 23 males on the same high school baseball team with an average of 19.5 years. The study was performed at the University of British Columbia (UBC) in Vancouver, Canada. The researchers reported that the baseball players had either normal or corrected-to-normal visual acuity and those who did not have normal acuity wore contact lenses or glasses during the study. The study tested dynamic visual acuity by using black Landolt-C rings (see figure 1) and had the athletes track the “gap” in the letter “C” as it was spinning and moving horizontally on the screen from left to right. The athlete then had to decide with 4 arrow keys whether the “gap” in the letter “C” was located in the top right, top left, bottom right or bottom left corner. The “C” on the screen moved at a constant speed of either 50 or 70 degrees per second with random speeds and movements every trial.(1) Every time the athlete was correct in guessing which the corner the “gap” of the “C” was located, the width of the gap would decrease. The static acuity test (see figure 2) was performed with a visual acuity chart with numbers that the athletes were instructed to read from top to bottom while rotating their head.
Figure 1: The Landolt-C Ring test evaluating dynamic object acuity.(1)
Figure 2: The static acuity test,(1) utilizing VOR.(2) The top numbers signified a visual acuity of 20/800 vision and the bottom numbers were indicative of 20/20 vision. (1)
Results
The study showed that when athletes used smooth pursuit to track the object during the test as opposed to using anticipatory saccadic movements, their perceptual performance improved and translated to better DVA. As reported by Paladis et al, players who utilized anticipatory saccadic movements showed less accuracy and acuity during the dynamic object test.
Applicability and Conclusion
Have you ever noticed when watching a baseball game, the pitcher may squint as he is trying to see the signals given by the catcher? Sunlight is one thing, but when this happens during a night game, this may cause some viewers to wonder. In this case, the catcher may have highlighted marks on their hands and fingers to make it easier for the pitcher to see the calls made before he makes his pitch. If the pitcher is having trouble seeing the signs by the catcher, this may warrant a visit to the optometrist.
There are a few different ways to apply visual evaluation and training to a clinical setting before seeing an optometrist. A clinician or trainer can test an athlete’s vision with the static-object test using an acuity chart. Additionally, to further evaluate or enhance an athlete’s ability on the field, it may be prudent to find out what their dominant eye is. Although it is an older study from 2006, Shneor et al found that the dominant eye of given individual processes visual information better and faster and additionally takes over primary visual processing as seen in tests such as bionocular rivalry and hole-in-the-card.(3) Additional ways to test to see what the athlete’s dominant eye is, more can been seen here.
Utilizing computer-based tests to help facilitate better tracking skills and VOR training can be useful ways to assess an athlete’s visual ability and acuity to enhance their skill set and take their game to the next level. As suggested by Deveau et al, eye movement exercises can be a great intervention in an athlete’s training program. (4)
Blog Post written by Tom Sutton, DPT Student at the University of St. Augustine. Tom is currently in his final Clinical Rotation with me at Catz Physical Therapy Institute.
References
Dimitrios J. Palidis DJ, Wyder-Hodge PA, Fooken J, Spering M. Distinct eye movement patterns enhance dynamic visual acuity. PLOS ONE. 2017;12(2):e0172061. doi:10.1371/journal.pone.0172061.
Demer JL, Crane BT, Tian JR, Wiest G. New tests of vestibular function. Ann N Y Acad Sci. 2001; 942: 428–445. PMID: 11710482
Shneor E, Hochstein S. Eye dominance effects in feature search. Vision Research. 2017;46(25):4258–4269. doi:10.1016/j.visres.2006.08.006
Deveau J, Ozer DJ, Seitz AR. Improved vision and on-field performance in baseball through perceptual learning. Curr Biol 2014; 24:R146–R147. doi: 10.1016/j.cub.2014.01.004
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Blog Post written by Tom Sutton, DPT Student at the University of St. Augustine. Tom is currently in his final Clinical Rotation with me at Catz Physical Therapy Institute.
Chris Butler Sports PT 