Week 2 - Sports vision

Question 1

Why do we study sports vision:-

Answer 1

• 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

Question 2

Give sports with a high, medium and low demand for Static visual acuity:-

Answer 2

• 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

Question 3

Give sports that have a high, medium and low demand for Dynamic Visual Acuity (DVA):-

Answer 3

• High demand: baseball or cricket batsmen
• Medium demand: Football
• Low demand : Golf

Question 4

Give sports that require high, medium and low demands for Binocular vision:

Answer 4

• High demand: boxing
• Medium demand: gymnastics
• Low demand: long distance running

Question 5

Give sports that require high, medium and low demand for Depth perception/stereopsis:-

Answer 5

• High demand: hockey (blocking a shot)
• Medium demand: platform diving
• Low demand: weightlifting

Question 6

Give three sports that require high, medium and low demands for Accommodation:-

Answer 6

• High demand: tennis
• Medium demand hurdling: (running over obstacles)
• Low demand: swimming

Question 7

Sports in relation to test important facts:-

Answer 7

• 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

Question 8

Is visual performance of athletes superior to non-athletes? (4 points)

Answer 8

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

Question 9

What does athlete better vision tell us?

Answer 9

• 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?

Question 10

Can the visual performance of athletes be improved by vision training?

Answer 10

• 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.

Question 11

Does improved visual performance from training improve sports performance?

Answer 11

• 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.

Question 12

Optical appliance for use in sports:- ( 5 total)

Answer 12

• 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

Question 13

Glasses for Visual Display Units:-

Answer 13

•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.

Question 14

Night driving glasses:-

Answer 14

• 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.

Question 15

Fishing glasses:-

Answer 15

• 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.

Question 16

Skiing Goggles:-

Answer 16

• 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.

Question 17

Adaptation effects:- Rifle shooting

Answer 17

• 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.

Question 18

Time taken to respond :- Rifle shooting

Answer 18

• Shooting is normally performed from a static position, so the effects of a space scotoma are not important.

Question 19

Flicker:- Rifle Shooting

Answer 19

• Flicker is not a problem for the rifle shooter.

Question 20

Position in visual field:- Rifle Shooting

Answer 20

• 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.

Question 21

Viewing distance - Accommodation:- Rifle Shooting

Answer 21

5. 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.

Question 22

Viewing distance : convergence - rifle shooting-

Answer 22

•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.

Question 23

6. Visual subtense of task detail (size / acuity) - rifle shooting

Answer 23

• 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.

Question 24

7. Motion of task- rifle shooting

Answer 24

• 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.

Question 25

8. Contrast of task detail- rifle shooting

Answer 25

• The contrast of the task detail is usually as high as possible because of the small angular subtense of the target.

Question 26

9. Colour of task - rifle shooting

Answer 26

The colour of the task is unimportant in rifle shooting

Question 27

10. Clarity of task detail- rifle shooting

Answer 27

• 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.

Question 28

11. Stereopsis requirements- rifle shooting

Answer 28

• The task is normally viewed monocularly, so stereopsis is not required.

Question 29

12. Visual field requirements - rifle shooting

Answer 29

• 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.

Question 30

13. Hazards- rifle shooting

Answer 30

• 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.

Question 31

14. Training requirements- rifle shooting

Answer 31

• 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.