Dispensing in Sport Lecture 7 Flashcards
What are the aims of sports eyewear?
Improve vision:
-e.g. By enhancing contrast and reducing glare
Provide Protection:
- e.g. Impact resistance via a strong frame material and UV prtection via the lens coat
What are soem examples of sports glasses?
- Racquet sports glasses
- Snooker glasses
- Shooting glasses
- Ski goggles
- Swimming goggles
- Diving mask
- Cycling/running
Why is a squashball to the eye so dangerous?
The squash ball is the perfect size to fit into the orbital cavity and not be defected by facial structure - e.g. if a football was launched at the face, the person’s nose and cheek bones would deflect the ball because of its size whereas with a squash ball this doesn’t happen.
Squash balls often travel at high velocities.
What can blunt trauma to the eye cause?
Blow out fracture
Ruptured globe
Hyphema - A collection of blood in the space between cornea and the iris.
Retinal haemorrage
Retinal detachment
Commotio retinae -raumatic retinopathy secondary to direct or indirect trauma to the globe
What are the regulations concerning racquet sports glasses?
Can racquet lenses have a prescription?
How is an Rx added to racquet glasses and what must be beared in mind when doing so?
Can racquet lenses be worn ontop of other glasses?
- They Must conform to EN167 and EN166 (Personal eye protection).
- Must conform to Squash- BS7930:1
- It is mandatory for all doubles squash players and juniors to wear protective eyewear.
Racquet glasses Can be glazed with Rx
The Rx is Glazed ‘loose’ to allow impact to be absorbed by glasses (i.e. the material bends to absorb impact)
They cannot be worn over specs.
Why is a wrap around style (as seen in the picture) popular in racquet glasses?
It provides a wide field of view so a ball can be seen coming from all angles.
How are frames in racquet sports glasses specially adapted for their purpose?
The frames contain thick silicone molded cushion pads to absorb shock and thuc protect the nose on impact.
Elasticated headbands intead of standard sides mean that a tight fit can be ensured and as a result there is no risk of the glasses falling off during play.
They can be ventilated to prevent steaming up during play.
The frame material is often nylon for it’s properties of being strong, flexible, lightweight (and hypoallergenic).
How may a lens be adapted to fit into a racquet frame ?
You may change the base curve of the lens to allow them to fit in the wrap around style frame.
What is the typical lens material for racquet sports glasses?
Polycarbonate for the sake of it having high impact resistance.
What coating may be added to sports racquet glasses lenses?
They may be coated for anti-fog
What is really important to consider when dispencing snooker glasses?
The head position at which the player plays and how that effects vision.
Why do snooker glasses tend to have joint angles?
To allow for the patient to tilt their glasses back and forth ( retroscopically and pantoscopically) for best vision
What lens considerations must be taken when prescribing snooker glasses?
Lenses must be of a large blank size because depth within frame will be greater than usual.
The glasses should be dispensed with an MAR (anti-reflection coating) as snooker is an indoor activity.
The visual axes must still be approximately the lens
What should you consider when prescribing shooting glasses?
What type of shooting the px does.
Patient preference when shooting - i.e. do they occlude one eye?
For what type of shooting would a bronze tint be recommended?
Clay pigeon shooting
For what type of shooting may a yellow tint be reccommended?
Where the target is black on white - yellow tints offer a good contrast.
For what type of shooting may red or pink tints be reccommended?
Any shooting when the patient is aiming for black or green targets.
(Thus think about sports like golfing for which they may be useful too)
What is a mounted occluder and which sport glasses may feature them?
A mounted occluder is essentially a flap attached over the lens so px can occlude the eye when they like.
This may be featured in shooting glasses where px prefer to shoot with only one eye open.
What sport lenses may have a pinhole in them and why?
Shooting glasses may feature a pinhole - this would be for extra focus.
And for what reasons?
Px that are shooting require accuracy
You may choose the lighter tint as the darker tint lets less light through thus biologically the pupil would dilate. From a focussing point of view this is bad as we want the pupil to be as small as possible ( i.e. naturally mimic a pinhole). Thus we would want the lighter tint.
True or false - clip in lenses can be provided for swimming goggles?
True
Why do we normally use planoconcave/planoconvex lenses for swimming goggles?
The curvature being placed all at the back vertex means the power of the lens is not influenced by the surrounding medium ( i.e. remember the refractive index of water is greater than that of air - this makes makes a difference to rx).
Doing this, therefore, also makes the lens easier to glaze with an rx
True or false - clip in lenses for swimming gogles only come in standard spherical sizes thus when prescribing all we do is match the spherical lens as close as possible to the px’s rx.
True - relaistically swimming google rx is only needed to be good enough for the px to walk to the chnaging rooms and swim without bumping into anyone or anything.
[Px with high cycls may find this problematic]
What are considerations of prescribing a diving mask?
Lens must be able to adapt to Pressure changes
Rx!
Watertight fit must be ensured
Frame must fit around the breathing apparatus thus can be full or half mask
Why may a px choose to go for a clear seal on their diving mask (i.e. the edges of the mask to be clear)?
To provide some (additional) peripheral vision
Why may a px opt to go for a dark seal around their diving mask?
The dark seal ( i.e. the mask being dark) reduces total internal reflections
True or false - for diving masks, lenses are often clip in (i.e. they can be removed).
True
Why is silicone used as a frame material for diving masks?
As it allows for a watertight fit/seal
What material are the lenses for a diving mask usually made out of and why?
Diving mask lenses are usually made out of tempered glass - this is so that they can withstand the pressure chnages of the water associated with diving.
What are the points to consider when prescribing cycling/running glasses?
Impact resistance e.g. to things like small rocks and stones
Smaller debris (dust, insects)
UV protection
Glare protection - depending on the time of day and conditions in which they run/cycle
FOV
Contrast enhancement - to do with running/cycling conditions
What filters may a patient perhaps want on runnning/cycling lenses?
Polarising filters
Contrast enhancing tints ( yellow is popular)
What style of glasses are most popular for running/cycling and why?
How is the lens altered to fit this?
Wrap around glasses are most popular as they allow for a bigger FOV.
In order to fit in the wrap around glasses. lenses are prescribed with a higher base curve.
What are frame considerations for cycling/running glasses?
Lightweight material
High impact material
Detachable sides
Silicone side grips + nose pads for excellent fit (i.e. to keep the glasses on).
[Fit of the glasses is key here]
True or False - Cycling glasses often come with interchangeable lenses?
True - so px can fit lens with the right filters for the conditions in which they choose to go running or cycling in
When prescribing professional sports glasses what is it always good to make sure?
That you are aware of any regulations of that sport for eyewear
