- Although scratch resistance and antireflection coatings are harder than CR39, they _____ lens impact resistance.
- What type of lens can be tested before it is edged (uncut-finished stage)?
- Chemical tempering: the smaller Na or Li ions are replaced by larger K ions, creating ________.
- What is the advantage of heat tempering as compared to chemical?
- True or False. Chemical treated glass can be drilled and grooved and pass the drop ball test. However, it is not recommended because edges can chip/crack leading to decreased impact strength.
- Dispenser must keep records for ___ years after purchase of lenses to include name and address of purchaser.
- _____ is used for photochromatic lenses.
- Dress lens must be capable of withstanding the impact of a 5/8 inch steel ball weighting _____ oz dropped from a distance of ______ inches.
- True or False? Plastic lenses must be safety tested after ARC is applied.
- What type of lens is best to avoid? A) crown glassB) trivexC) polycarbonate D) CR-39
- In chemical tempering, the lens is immersed in _______.
- Heat treatment of glass lenses: can be confirmed by viewing the lens when placed between __________.
- ______ is used for clear and tinted crown glass.
- In class we mentioned how polycarbonate lenses should be offered to all patients and recommended for all of the following except: A) patients with at-risk eye(s)B) patients purchasing safety eyewear C) patients purchasing sports wearD) childrenE) monocular patientsF) all the above are candidates
- Polycarbonate lenses can safely be made thin as _____ to ____ mm. It is _____ density. It also has a high. Index, so thickness can be _______.
- Plastic lenses are permissible to conduct _____ testing. Ex: ultex A
- Which method of glass treatment causes the lens to NOT be as impact resistant. A) heat-treatmentB) chemically tempered
- When testing ______ lenses, the lens manufacturer is responsible for batch testing. They can be edged without further testing.
- A heat-treated glass lens shows a ______ cross pattern. Pattern does not need to be perfect.
- Which glass treatment process is preferred? A) heat-treatmentB) chemical tempering