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
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.
