24 - Best Practices of Handling Glasses Flashcards
What advice should you give pxs when taking glasses off?
Take off with two hands
Review steps for taking glasses off with right and left hands only
Glasses should be placed lenses down. T/F
False
Where should glasses always be kept when not being worn?
Case
Should you leave glasses in car?
Do not leave them in car where they are exposed to cold/hot
What should you do when cleaning glasses? 2
-Rinse lenses before wiping them with a micro-fibre cloth
-Frames need cleaning to
What can acetone do/help with lenses? 2
-Do not use acetone on polycarbonate frames
-Difficult - to - remove lens spots were taken care of using acetone
How do we clean a lens with an AR coating? 4 steps
1) Rinse the lenses with lukewarm water
2) Clean using mild dishwashing liquid or hand soap (no hand cream) Rub soap on both sides for 5 seconds
3) Rinse the soap off with tap water
4)Dry with a soft, clean cloth, such as a cotton towel
5 Characteristics of Crown Glass Lenses
- Resists scratching
-not easily affected by environmental factors
-refractive index - 1.523
-low chromatic aberration
-abbe value - 58
What is disadvantage of crown glass? 2
heavy
not impact resistant
4 Characteristics of High-Index Glass
-Index 1.6 - spherical/aspheric designs/segmented bifocals/progressive
-1.90 index - not used often, doesn’t pass FDA standards
-Abbe value similar to polycarb - 30/31
-high index = lighter than crown glass for more than -7D
Does a corning clear 1.6 surfaced with 1.5mm centre thickness, and after hardening, is impact resistant enough to pass FDA standards. T/F
True
What should we consider when looking at a high-index lens? 6
- index of refraction
-weight
-impact resistance
-finished lens thickness
-abbe value - ease of production
3 Characteristics of Polycarbonate
-soft material
-anti-scratch coating
-high-impact resistance
When is safety of an eye of high concern? 5
-children
-monocular individuals
-good VAs in 1 eye only
-safety eyewear
-sports eyewear
4 Characteristics of CR-39
-come with anti-scratch coating
-half the weight of crown glass lenses
-do not fog up as easily as glass lenses
-index of refraction = 1.498
5 Characteristics of trivex?
-very impact-resistant
-originally used for military
-very lightweight, density 1.11
-Abbe value = 43 to 45
-good resistance to damage from chemicals
5 Characteristics of NXT?
- Developed early 1990s - bullet proof material
- light weight
- extremely strong
- compatible with polarization and photochromatic
- highly flexible
What is the index of refraction, abbe value and density of a NXT lens?
index of refraction = 1.53
abbe value = 45
density = 1.11
3 Characteristics of Laminated Lenses?
-made from 2 or more layers of material
-polarization is stretched between two layers of regular lens material
-used to increase impact resistance
What are 5 coatings for lenses?
-Scratch resistant coatings (SRS)
-Color coating
-antireflection coatings
-antifog coatings
-mirror coating
What do lens coatings/scratch resistants do to impact resistant lenses?
decreases the impact resistance
What size/material is the ball used in the drop test?
1 inch steel ball
5 Things to remember for basic/ non-impact requirements
-can be glass depending on environment (dust due to scratching)
-thickness minimum 3mm
-+3.00D can be thinned to 2.5mm
-Tested with ball drop test
-marked with manufacturers logo or identifying
Things to remember for high impact requirements
-pass 3 safety test
-minimum 2mm at the thinnest point
-if they pass all 3 tests must have + with the manufacturer’s logo
What 3 safety tests must be conducted if we are testing for high impact resistance?
-high mass impact test
-High velocity impact test
-Penetration test
