Lec.1 Ultraviolet Radiation & Nonprescription Flashcards
Based on the AOA 2013 American Eye-Q Survey:
___% of americans wear sunglasses to safeguard vision from sun damage.
___% used sunglasses for comfort and reduction of glare.
___% said UC protection is the most important factor when purchasing sunglasses.
40, 32, 28
Electromagnetic spectrum for ultraviolet is _____nm.
100-400
Electromagnetic spectrum for visible spectrum is _____nm.
400-700
Electromagnetic spectrum for infrared spectrum is ____.
760nm-1mm
- UV-A is ____nm.
- UV-B is ____nm.
- UV-C is ____nm.
a. 100 - 290
b. 290 - 320
c. 320 - 400
- c
- b
- a
Peripheral Light-focusing (PFL) can create areas of concentrated light in the ______ and _______.
nasal corneal limbus, lens cortex
T/F PLF may be implicated in pterygium and age-related cortical cataracts.
True
Intensity of light reaching the nasal limbus reaches levels __X higher than the intensity of temporally incident light.
20
Peak effect for UV-A and UV-B is about ___degrees behind the frontal plane.
120
According to the World health Organization, __% of the lifetime UV radiation exposure occurs by 18 years of age.
dd
Where do you see an increase of UV radiation?
- closer to the equator
- higher altitude (1000ft up increases UV by 4%)
- 10am-2pm (60% of the UV falling on Earth)
- During summer and autumn
Peak solar ultraviolet radiation intensities are typically experienced in which season?
summer
What reduces the UV radiation?
greater the path traveled (increase air mass)
the lower the sun is from its zenith (increase Zenith angle)
Turbidity (attenuation by atmospheric aerosols)
Exposure to UV-B can be reduced by __% by wearing a hat with a brim.
Exposure to UV-B can be reduced by __% by wearing a hate with a brim with glasses with ordinary plastic lenses.
50, 95
Transitions Optical National Survey (2002)
__% respondents knew UV can cause skin cancer
__% respondents knew that UV can harm the eyes
__% of the respondents wear sunglasses
79, 6, 18
Crown glass covers ___nm and below.
340
CR-39 covers ___nm and below.
400
Polycarbonate covers ___nm and below.
420
Is there an affect on the amount of UV being transmitted going from Tint #1 to #2 to #3?
No affect
Crizal Sun places an AR coating on the front or back side of the lens to eliminate glare and reflections?
back-side
ANSI Z80.3 requirements for ________, ________, ________, and ________ properties.
flammability, cosmetic, refractive, transmittance
What is Eye-Sun Protection Factor (E-SPF)?
helps consumers determine how much total UV radiation is entering the eye. (UV through the lens and UV reflected from the back surface of the lens into the eye)
What degrees has the maximum reflection of UV radiation into the eye with Eye-Sun Protection Factor?
140-155
To have an E-SPE of 50, about __% of the incident UV would be entering the eye.
2
Crizal sunshield UV has an E-SPF of __.
50+
the EPF rating is based on what 4 protection criteria?
- frame coverage
- ultra-violet (UV) protection
- blue light protection
- infrared protection
Which protections carry more weight?
UV protection > blue light protection > infrared light protection
T/F Cocoons OVERx are sunglasses that can be worn over prescription eyewear or contact lenses.
True
According to ANSI, how much UV-A and UV-B UV-blocking contact lenses must minimally absorb?
70% UV-A
95% UV-B
What are the two classes of UC blocking contact lenses, according to FDA and ANSI?
FDA Class 1 blocking (block 90% UVA, 95% UVB) - for high exposures
FDA Class 2 blocking (block 70% UVA, 95% UVB) - for general purposes
Between which months have the high UV index in LA?
march to october
T/F The amount of UV radiation absorbed by photochromic lenses is relative to their darkness?
False. it’s relative to the material of the lense
T/F The higher the index, the less UV transmission.
True
Does putting a coating on the lenses block some of the UV?
Yes. CR-39 with LIte-Guard UV coating can move the UV block from 370nm to 420nm
T/F AR coating in the back can reduce visible glare but it reflects UV radiation off the back-side of the lens into the eyes.
True
Which ANSI standard is street eyewear?
a. ANSI Z87.1
b. ANSI Z90.1
c. ANSI Z80.1
c. ANSI Z80.1
Which is the ANSI standard for nonprescription sunglasses?
ANSI Z80.3
What is the tolerance of nonprescription sunglasses?
Sphere: +0.12D to -0.25D sphere; Cylinder 0.12D
Prism: less than 1/4 prism diopter
According to ANSI, UV-blocking contact lenses must absorb a minimum of __% of UV-A and __% of UV-B.
70, 95
Percentage of UV being blocked or transmitted is a function of the lens ________.
thickness
With peripheral light focusing (PLF), at what degree does the most UV-A + UV-B going into the eyes?
120
T/F UV-blocking CL can block out most of the UV-B radiations whereas sunglasses, clear CL and none won’t have any effects.
True
Is there a significant differences in UV transmission with worn and unworn contact lenses?
NO
People who have worn UV-blocking contact lenses will have a macular pigment density levels greater or less?
Greater. This will lessen the chance of developing macular degeneration.
What is the yellow lens cocoons OVERx?
it blocks the high energy blue and letting most of the visible spectrum in.
According to the Global Solar UV Index, the higher the value, the _______ the potential for damage.
greater
What is the UV index range according to the Global Solar UV Index?
0-11+
