9-filters/lighting, telescopes, legal Flashcards
What SINGLE feature (besides the healthcare itself) will make the BIGGEST difference in the success of a LV pt in a healthcare setting?
LIGHTING - may be increased/enhanced by a chosen filter - more light = more glare, so you must chose the correct filter
what’s the best filter color for CONTRAST enhancement?
yellow
glare becomes photophobic when the light is __X brighter than its background
3x - or any time it interferes w/ visual fxning
What type of glare: causes the patient to be symptomatic and fatigue - i.e. shiny reflection on the page while reading
-what two spectrums of wavelengths should you try to eliminate to rid this glare?
discomfort (not disability) glare
-rid the UV (blues) and the IR (reds) –>NoIR filters
T/F: NoIR filters absorb ALL UV types (up to ___nm), and additional visible light.
-so do these filters absorb long or short wavelengths?
true - up to 400nm
-SHORT wavelengths filtered - only allow longer wavelengths (that don’t scatter w/i eye like the short wavelengths do) into the eye
A 20% NoIR filters allows what percentage of light THROUGH.
-in other words, it blocks how much light percentage?
TRANSMITS WHAT IT SAYS - 20%
BLOCKS 80%
-this is opp to typical filters
What’s the difference between UVshields and NoIR filters?
UVshields: block UV and visible spectrums
NoIR: block UV, visible, AND IR - cooling relief from heat energy of sun
Selecting a NoIR filter: start from (lightest/darkest), allowing the (least/most) transmission, and work your way toward what if the pt still complains of glare?
start: LIGHTEST, MOST transmission – go darker as they complain of glare
- caution: there’s a delicate balance here.
filters work based on the principal of the elimination of light _____.
scatter - that’s what hampers the REMAINING VA the most - if you can reduce the scatter, you can maximize their remaining VA.
Which color filter is the ONLY one that won’t tint stuff different colors?
What’s the disadvantage?
gray
-does NOTHING for CONTRAST
AMD - three problems w/ vision
-recommended filter color based off problems?
1) decreased contrast
2) blurred VA
3) discomfort glare
–> YELLOW.
GLAUCOMA - four problems w/ vision
-recommended filter(s)?
1) decreased contrast
2) night blindness
3) loss of peripheral vision
4) increased illum. requirement
-yellow for glare control, then dark gray for outdoors, light gray for indoors
RP - name some key problems
- extreme difficulty in BRIGHT AND DIM light
- discomfort/dazzling glare, decreased contrast, night blindness, bad response to mag, loss of peripheral VA, increased illum req.
-NoIR 40% light amber - good for hazy, overcast days in people sensitive to indoor lighting.
Name that term:
- MINIMUM light levels that should be used.
- suggested illumination for the specific visual task
- DIRECTED LIGHT BRIGHTNESS which must be maintained at task levels by using coller bulbs and bringing lamps closer/in proper position
- minimum light –> ambient
- suggested illum –> task light
- directed light brightness –> lux
Which telescope’s exit pupil is OUTSIDE the telescope and is able to be aligned w/ the pt’s entrance pupil? Does it have MORE OR LESS mag than the other type?
keplerian - exit pupil OUTSIDE - but it’s longer, heavier, more expensive
-MORE MAG than Galilean - up to 10x; Galilean can only go up to 4x
name the three positions of a spectacle-mounted telescope in a carrier lens, its placement on the lens, and its use (BFT)
- Bioptic position - ABOVE LOS, must tip head down- mobility
- Full diameter - directly in front, not mobile - full-time use (maxtv)
- Telemicroscope- DOWNWARD position - near/intermed use
What LVDs might you use for:
1) distance spotting?
2) distance continuous?
3) intermed viewing?
1) monocular, binocular, bioptic position spectacle mount
2) sportglasses, MaxTV, full diameter spect. mount, manual/AF Ocutech
3) telemicroscope spect mount, focusable telescope
How to determine required MAG for certain telescope?
Denominator of BVA/denominator of GOAL acuity:
i. e. BVA 20/100, goal 20/50 (watching TV) - 100/50 = 2X
- note: most target acuities are ~20/40-20/50. Don’t need 20/20.
T/F: caution when putting Rx into a spectacle-mounted telescope, as it may change the overall mag of the telescope.
FALSE - the mag does NOT change w/ addnl Rx put into scope.
Dr. Jamara’s suggestion:
-the pt should have >__.__D of sph power to incorporate their Rx into a fixed focus telescope
-the pt should have >__.__D of astigmatism to incorporate their Rx into ANY type of telescope
- 50 Sph
1. 50 astig
The LONGER the telescope prescribed, the (more/less) plus power you’re giving) - more useful for (near/dist) tasks?
MORE power = longer; useful for bigger add
-want infinity? shorten telescope
For UNRESTRICTED license in MA: minimum ___ dist VA, AND at least ___ deg VF
For DAYTIME ONLY license in MA: between ___-___ dist VA, AND at least ___ deg VF
For BIOPTIC (Daytime only): -bioptic VA must be \_\_\_ and at least \_\_\_ in EACH eye, AND not less than \_\_\_ deg VF
20/40; 120 deg HORIZ VF (better eye)
20/50-20/70, 120 deg HORIZ VF (better eye)
20/40, minimum 20/100 EACH eye, 120 deg HORIZ VF
T/F: 20/40 acuity is based on actual acuity demands while driving
FALSE - it’s an arbitrary number put out by the AOA (Ophthalmology) - street signs vary greatly
What is the requirement for a RESTRICTED driver’s license for a person w/ visual impairment in MA?
CORRECTED acuity to 20/40-20/120 in the BETTER eye.
-varies state to state - some may say daylight only, limited distance, limited purpose/no freeway driving
What’s the max telescope mag allowed in MA?
fixed focus 3x
T/F: VF has a weak correlation w/ driving safety.
T/F: Color vision has no correlation w/ driving safety
False - VF has STRONG corr.
True - no correlation w/ color
T/F: contrast is tested in some states before a driver’s license is issued
FALSE - CS is NOT tested in ANY state
What is the magnification of a telescope whose objective lens diameter is 15mm and whose exit pupil diameter is 2mm? What type of telescope is it?
What if the telescope’s objective lens dia was 10, and the exit pupil diameter was 4mm, and you were TOLD that the image filled the exit pupil and moved WITH motion?
OBJ/exit pupil = 15mm/2mm = 7.5X - must be Keplerian
OBJ/exit pupil = 10/4 = 2.5X - Keplerian or Galilean, but knowing WITH motion implies Galilean
Define:
- radiance:
- illuminance:
- lux:
- radiance: how much light released from a SOURCE (property of the source itself)
- illuminance: the degree to which something is illuminated
- lux: measurement of actual light available at a given distance (=lumens per square meter)
