May the best-sighted win? The relationship between visual function and performance in Para judo

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ABSTRACT

This study aimed to establish the optimal cut-off point(s) between classes in a new, evidence-based classification system for VI judo. We collected results from international VI judo competitions held between 2012 and 2018. Data on visual acuity (VA) and visual field (VF) measured during classification were obtained. Performance was determined by calculating a win ratio for each athlete. VA was significantly associated with judo performance (r = −.33, p <.001), VF was not (r =.30, p =.15). Decision tree analysis suggested to split the data into two groups with a VA cut-off of 2.5 logMAR units. Stability assessment using bootstrap sampling suggested a split into two groups, but showed considerable variability in the cut-off point between 2.0 and 3.5 logMAR. We conclude that to minimise the impact of impairment on the outcome of competition, VI judo should be split into two sport classes to separate partially sighted from functionally blind athletes. To establish an exact cut-off point and to decide if other measures of visual function need to be included, we argue for continued research efforts together with careful evaluation of research results from a multidisciplinary perspective.

KEYWORDS:

• Paralympic sports
• judo
• vision impairment
• evidence-based classification
• decision tree analysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

¹ As classification procedures for VI sports underwent significant changes in the lead up to the Paralympic Games of London 2012, only data obtained from 2012 onwards was included.

² http://www.ibsasport.org/sports/judo/results/

³ logMAR stands for the logarithm of the minimum angle of resolution, i.e. the minimum visual angle at which a person can resolve details, measured in minutes of arc (1 minute of arc is 1/60^th degree). A logMAR score of 4.0 corresponds to a visual field of 10800 minutes of arc or 180 degrees. Any value above 4.0 logMAR would refer to a minimal angle of resolution larger than a full visual field.

⁴ On some of the classification sheets we accessed during data collection for this study, we even found VA values reported as “>2.6” rather than specific values. These classifications were excluded from the research data as we could not extract an exact VA value, but it suggests that indeed classifiers might be more concerned with determining the correct sport class of an athlete than the exact level of VA.

Additional information

Funding

This research is supported by classification research grants from the International Blind Sports Federation (IBSA) and the International Paralympic Committee (IPC).