The purpose of this study is to establish baseline reference values for tests of static and dynamic visual acuity and gaze stabilization in collegiate athletes and non-athletes, and to determine if there are differences in vision scores between collegiate athletes and non-athletes with and without a history of concussion.
An IRB-approved human subjects study (IRB-FY 20-339) was designed to investigate dynamic vision pre-and post-concussion in collegiate athletes. In addition to examining if there are changes in objective tests of dynamic vision after concussion, it is important to determine if there are baseline differences in dynamic vision objective tests when comparing collegiate athletes and similar-aged controls. Dynamic vision will be assessed through the administration of the Dynamic Visual Acuity (DVA) test and the Gaze Stabilization Test (GST). Baseline testing of GST and DVA is performed using the Bertec Vision Advantage TM system. Athletes are eligible to participate if they are currently enrolled students, actively participating on specified teams, provide consent to participate, and are able to complete the testing protocol. Non-athlete control subjects are students enrolled in a Doctor of Physical Therapy (DPT) program and serve as a sample of convenience.
Study Type
OBSERVATIONAL
Enrollment
145
Dynamic Vision Acuity is tested with the Dynamic Vision Acuity (DVA) and Gaze Stabilization Test (GST) using the Bertec Vision Advantage System.
California State University, Northridge, Jacaranda Hall 1578, 1576, 1574
Northridge, California, United States
Dynamic Visual Acuity (DVA)
Subjects move their head at approximately 85 degrees per second per the standard test protocol. A metronome automatically generated by the computer assists in maintaining the correct head speed. When the sensor identifies 85 deg/sec, an optotype appears on the screen and the subject verbally identifies the optotype's orientation. This continues with progressively smaller sized letter until the athlete is no longer able to correctly identify the orientation. The computerized system uses a convergence algorithm to determine the accuracy of the response requiring 3 correct answers at the smallest letter size to assign a result. The computer then compares each subject's DVA score to their SVA, which is expressed a Log of minimal angle resolvable units (LogMAR). Simply, the computer considers the number of lines on an eye chart that are lost with head moving (DVA) compared to the head steady condition, known as static visual acuity (SVA)
Time frame: August 31, 2021 - May 15, 2024
Gaze Stabilization Test (GST)
The subjects are asked to move their head in the horizontal plane and identify an optotype's orientation at increasing speeds. The optotype remains the same size while the head speed increases. A metronome is utilized to ensure correct head speeds which change throughout the test. When the subject reaches or exceeds the minimum threshold for velocity as measured by a wearable gyroscope attached to the forehead, the optotype appears on the screen for 75 ms, and the subject verbally identifies the direction of the optotype. The subject answers 3 of 5 trials correctly to confirm visual acuity for that velocity. The velocity of head movement begins very slowly (10 deg / second) and the rotational speed increases incrementally as long as the subject is asymptomatic and can see clearly. The test continues until the subject "fails", meaning the subject is unable to answer 3 of 5 trials correctly at a given velocity. The maximum head velocity is measured in degrees/second
Time frame: August 31, 2021 - May 15, 2024
Static Visual Acuity (SVA) test
The SVA tests the subject's ability to see clearly with their head held still, similar to reading a Snellen eye chart. An optotype is briefly flashed on the screen and the subject is asked to correctly identify its orientation (which directing the capital "E" is facing) as it gets progressively smaller. Once the subject gives an inaccurate answer, the computer ends the test and provides their SVA baseline value based on the smallest optotype they could identify.
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Time frame: August 31, 2021 - May 15, 2024