2007, Piran, Slovenia

Employment Standards
VISUAL ACUITY STANDARDS FOR BEACH LIFEGUARDS
Michael Tipton, Emily Scarpello 1 , Tara Reilly, James McGill 2
Department of Sport & Exercise, Institute of Biomedical & Biomolecular Sciences, University
of Portsmouth, Portsmouth
1
School of Life and Health Sciences, Aston University, Birmingham, UK
2
Department of Ophthalmology, Southampton General Hospital, Southampton, UK
Contact person: michael.tipton@port.ac.uk
INTRODUCTION
The ability of beach lifeguards to rescue people at sea is predicated on their ability to see
those in trouble within their patrolled area which extends 300 m out to sea. Over the last
decade a small number of authorities have introduced specific eyesight standards for
lifeguards. For example, the California Department of Parks and Recreation recommend that
entry level lifeguards exhibit a corrected visual acuity of 20/20 or better and an uncorrected
visual acuity of 20/40 or better in each eye. However, such standards are the exception rather
than the rule, and most organisations employ more general requirements such as the need for
"good" eyesight. Even the specific standards (e.g. 20/20) do not appear to have been based on
any operationally-relevant research.
It can be calculated that the required visual acuity, as determined by the angle subtended by a
25 cm diameter human head at 300 m, would be 6/17; but we hypothesised that it would have
to be better than this due in the operational scenario due to factors associated with
location/detection, colour, contrast, lighting and movement. To discriminate the features of a
face at this distance requires 6/3, beyond the capability of most individuals. However, it is
important to consider the use of binoculars; a BLG must be able to locate/detect something in
the water with the naked eye as a cue to instigate further investigation with binoculars (BLG
do not routinely scan the patrolled area using binoculars).
We have undertaken the first study to determine, in an operational scenario, the visual acuity
required by beach lifeguards (BLG) in order to identify a human head at the outer edge of a
patrolled area of 300 m out to sea.
METHODS
The experiment received ethical approval and twenty-one BLG (16 male, 15 female, all under
35 y) gave their consent to participate. Eye tests were undertaken to ensure normal vision
(mean [range]) visual acuity, direct ophthalmoscopy to determine the presence of any
significant media opacities or retinal abnormalities. The subjects also undertook tests to detect
any evidence of binocular vision anomaly and colour vision deficiency (distance cover test
and near Mallet Unit detection of stable and correctly aligned Nonius markers, and the correct
and equal detection of the '26' and '42' Ishihara protan/deutan classification plates).
Measurements of stereopsis (TNO test; seconds of arc) and contrast sensitivity (Pelli-Robson;
contrast threshold %, score