Week 2 - Sports vision Flashcards
Why do we study sports vision:-
• Sports vision is becoming increasingly important to the vision practitioner
• Visual demands for a variety of different sports
• Appliances used in sports
• Visual task analysis for rifle shooting
Give sports with a high, medium and low demand for Static visual acuity:-
• Sports with a high demand for SVA: Target sports (archery, shooting, darts)
•Sports requiring medium demand for SVA:
basketball
• Sports with a low demand for SVA: American football
Give sports that have a high, medium and low demand for Dynamic Visual Acuity (DVA):-
• High demand: baseball or cricket batsmen
• Medium demand: Football
• Low demand : Golf
Give sports that require high, medium and low demands for Binocular vision:
• High demand: boxing
• Medium demand: gymnastics
• Low demand: long distance running
Give sports that require high, medium and low demand for Depth perception/stereopsis:-
• High demand: hockey (blocking a shot)
• Medium demand: platform diving
• Low demand: weightlifting
Give three sports that require high, medium and low demands for Accommodation:-
• High demand: tennis
• Medium demand hurdling: (running over obstacles)
• Low demand: swimming
Sports in relation to test important facts:-
• Sportsman may need higher visual standards than normal; request corrections which usually isn’t required
• May therefore perform tests that are not standard: Dynamic VA
• May perform tests in non-standard ways :- BV test while in sports position
Is visual performance of athletes superior to non-athletes? (4 points)
Yes:-
- athletes have a large visual field, and better peripheral acuity
- athletes have a greater field of motion perception, better dynamic visual acuity, better depth perception
-athletes have a greater consistency of simultaneous binocular vision, and a closer near point of convergence
- athletes have better ocular motility, both for pursuit and saccades
What does athlete better vision tell us?
• The fact that these abilities are better in athletes does not tell us their origin.
- Are they better because only because people with these particular enhanced abilities went on to become good athletes?
- Are they better because the nature of the sport naturally enhances these abilities in all its participants?
Can the visual performance of athletes be improved by vision training?
• Yes, for some visual abilities.
• consists of a variety of manipulations attempting to improve the quantity measured.
• Often the training will simply be a variation of the measuring technique.
Does improved visual performance from training improve sports performance?
• There is no good evidence to either support or refute the hypothesis that improving visual abilities using vision training can improve an athlete’s performance.
• It is very difficult in such situations to avoid a placebo effect.
Optical appliance for use in sports:- ( 5 total)
• Snooker glasses:- glasses with large lens
- puts optical centres higher than in primary gaze to aid with player taking shot
• Squash glasses
- Safety glasses made out of strong polycarbonate to PUT OVER existing glasses
•Shooting glasses
• Swimming goggles
- can be made to prescription
•Diving masks
Glasses for Visual Display Units:-
•VDU specs are provided in various forms, with tints and multi-focal segments.
• One should use your common sense and beware of gimmicky type glasses that the manufacturers will produce with no scientific evidence of their usefulness.
Night driving glasses:-
• Night driving glasses have a yellow tint to help to reduce glare from oncoming cars.
• In general, at night when the illumination is low, it is a bad idea to start removing what little light there is using a filter.
• Driving glasses also tend to have fine metal frames, and high jointed sides in order to provide as large a field of view as possible.
Fishing glasses:-
• Polaroid lenses with axis of transmission vertical help anglers to see fish beneath water’s surface.
• When viewing surface of water, reflected light has a large amount of horizontally polarised light
• vertical axis of polarisation of the glasses helps to reduce reflected light, enabling the angler to see beneath water’s surface.
Skiing Goggles:-
• Skiing goggles are used as protection against shards of ice crystals and against the radiation hazard that is particularly high when skiing,
• Yellow filter absorbs harmful ultra-violet light and the safety lens help in any impact.
• The goggles must be made to fit over existing glasses if needed, and should be ventilated to prevent misting.
Adaptation effects:- Rifle shooting
• Shooting as a sport is always done under good lighting conditions, indoors or out.
• Adaptation effects only come into play in the form of light adaptation.
• High levels of illumination outside would make shooting a very difficult hobby for an albino.
Time taken to respond :- Rifle shooting
• Shooting is normally performed from a static position, so the effects of a space scotoma are not important.
Flicker:- Rifle Shooting
• Flicker is not a problem for the rifle shooter.
Position in visual field:- Rifle Shooting
• Targets are always centred on the fovea in order to attain the maximum possible acuity.
• Because of the fixed nature of the target, good scanning is not required.
Viewing distance - Accommodation:- Rifle Shooting
- Viewing distance
a) accommodation
• Viewing distance is always at infinity to the target.
• The gun sight may be 50 cm away.
• Presbyopic marksmen normally prefer to have a full distance correction, and suffer from a small amount of blur at the distance of the gun sight.
• Some marksmen use pinholes, or variable apertures on a corrective lens in order to increase the depth of field, bringing both the gun sight and the target into clear simultaneous focus.
Viewing distance : convergence - rifle shooting-
•Because the task is monocular, convergence is not a problem
•Physiological diplopia occurring when sighting a target may occur
•Many marksmen use an occluder over their non-sighting eye in order to suppress this.
- The occluder is normally light coloured.
- Visual subtense of task detail (size / acuity) - rifle shooting
• The visual subtense of the target can be very small, sometimes beyond the marksman’s ability to see.
• Vernier acuity, in the form of sighting to the centre of the larger circles in the target, is often used to improve the resolution.
• Telescopic aids for scoring, or telescopic sights on the gun are often used.
- Motion of task- rifle shooting
• The task is static whilst practising - so dynamic effects need not be considered.
• But, this is not always the case - hunting as a sport has moving targets.
- Contrast of task detail- rifle shooting
• The contrast of the task detail is usually as high as possible because of the small angular subtense of the target.
- Colour of task - rifle shooting
The colour of the task is unimportant in rifle shooting
- Clarity of task detail- rifle shooting
• Hazy conditions in atmosphere can cause some loss of clarity.
• Some marksmen use yellow filters as a contrast enhancing device.
• The scientific effectiveness of such a device has yet to be proved, and its usefulness varies from person to person.
- patient should be to try various filters to see if they help.
- Stereopsis requirements- rifle shooting
• The task is normally viewed monocularly, so stereopsis is not required.
- Visual field requirements - rifle shooting
• The visual field requirement is small for the shooting, but should be larger for safety purposes.
- The marksman must be able to confirm that the area he is shooting into is free of any people wandering about.
- Hazards- rifle shooting
• The main hazards from shooting are from hot gases and particles from the explosive used to propel the bullet, and from gun recoil.
• Marksmen should always wear safety lenses whilst shooting to reduce the risk from this mechanical injury.
• They should also always wear ear covering.
- Training requirements- rifle shooting
• The nature of the visual task in this sport is very demanding.
• Practice and training for use of the visual equipment, gun sights and for shooting will rapidly enhance visual performance.
