Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
42 Cards in this Set
- Front
- Back
|
what is the role of the OD in Occupational Vision
|
1. certify that prospective employees meet visual standards for occupations
2. help an employer establish visual standards 3. determine aspects of patients work that may be responsible for visual discomfort of inability to perform their job |
|
|
lighting in the workplace
what are the characteristics in respects to QUALITY OF LIGHTING |
1. concerned with distribution of light in the field of view
2. non uniformities in light distribution contribute to poor performance and discomfort 3. glare sources and uneven illumination increase blink rate |
|
|
lighting in the workplace
in respect to workplace design |
1. provide proper illumination levels per IES recommendations
2. provide even illumination 3. avoid glares and reflections 4. keep light sources away from line of sight |
|
|
what are the symptoms for computer vision syndrome
|
1. headaches
2. blurred near vision 3. accommodative facility problems 4. diplopia 5. eyestrain 6. glare sensitivity 7. eye irritation 8. neck, back and shoulder pain |
|
|
computer vision syndrome
what are some case Hx that you would ask? |
1. type of computer work and nature of visual demand
2. duration on computer work 3. position and work distance from computer 4. lighting sources and their locations in workspace 5. nature, severity, and freq of symptoms associated with computer work |
|
|
computer vision syndrome
what are the main criteria that you have to correct |
1. correct even marginal refractive errors
2. give presbyopes special Rx 3. watch for dry eye 4. watch for glare 5. look for OMD 6. improve patients work environment |
|
|
computer vision syndrome
when correcting refractive error, what should you take into consideration |
1. correct even low amounts or hyperopia and astigmatism
2. correct patients with accommodative insufficiency with plus lenses 3. correct pseudomyopia with plus lenses |
|
|
computer vision syndrome
presbyopic considerations |
1. patient may require special Rx for computer use
2. segmented bifocals need to be fit higher than typical lower limbus 3. PALs with wider intermediate zones 4. computer glasses -SV intermediate Rx -Bifocal with top portion for intermediate -PAL with wide intermediate zone |
|
|
computer vision syndrome
watch for dry eye |
1. common in contact lens wearers
2. blink rate typically reduced in computer use 3. recommend artificial tears combined with frequent breaks 4. consider lowering screen height slightly |
|
|
computer vision syndrome
glare |
1. especially a problem with older patients
2. use glare filter 3. even new monitors can produce glare 4. improper lighting may create problems 5. AR coating DO NOT eliminate reflections from monitors |
|
|
what are the two main causes of broken lenses
|
1. ROCKS (25%)
2. SPORTS (18%) -mainly basketball and baseball (swimming) |
|
|
what material should you use in industrial safety eyewear
|
POLYCARBONATE is the only lens material that can adequately resist the high energy impact of both large and small objects
90% of injuries caused by small objects moving really fast |
|
|
what is the employers role in eye protection
OD ROLE |
1. employer responsible for OSHA compliance
2. employer may have policies that are stricter than OSHA 3. its the OD's job to CONSULT with the employer |
|
|
what are the eyewear requirements for sports
|
1. 3mm thick polycarb
2. nosepads 3. temple pads 4. headstraps |
|
|
what are the difference between non industrial eye injuries and industrial
|
non industrial
1. typically large objects 2. slow velocity industrial 1. typically object size less than 6mm 2. high velocity |
|
|
field of view in relation to high plus lenses
what happens to FOV in aphakia?? |
1. decrease in peripheral and macular field of view in aphakia
2. decrease in MACULAR is GREATER 3. creates RING SCOTOMA |
|
|
what is the difference between peripheral and macular FOV in aphakia?
|
peripheral FOV
-FOV of steadily fixating eye subtended at the entrance pupil macular FOV: -FOV for the moving eye subtended by the center of rotation |
|
|
what is a ring scotoma
|
1. The prismatic effect of the high plus lens creates an angular gap in object space completely around the lens
2. The angular size of the gap is equal to the prismatic effect at the edge of the lens |
|
|
how do you calculate ring scotoma
|
+12D lens with a horizontal dimension of 44cm, centered in the front of the pupil. what is the size of the ring scotoma?
2.2(12)= 26.4PD (approx 15 degrees) |
|
|
what happens to the ring scotoma as the eye rotates
|
1. scotoma moves in opposite direction of the eye movement
2. "jack in the box" phenomenon, stationary objects pop in and out of the scotoma as the eye moves |
|
|
at what distance is the ring scotoma most difficult
|
INTERMEDIATE
|
|
|
what ocular rotation in the aphakic eye
|
1. increase in ocular rotations is caused by prismatic effects of the lens
2. The amount of prismatic deviation depends on the lens power and angular separation of the two alternately fixated points |
|
|
Aphakia Lenses
lens aberrations? |
1. lenses greater than +8.00D, either oblique astigmatism or curvature of image can be eliminated by using aspheric surfaces
2. both cannot be eliminated using one set of curves 3. aspheric experience PINCUSHION effect |
|
|
lenticular design
adv/disadv |
1. make the optical portion smaller that has the high Rx
2. decrease weight 3. decrease thickness 4. decrease FOV |
|
|
what are the cosmetic problems with high minus lens
|
1. thick edges
2. minification of eyes by observers 3. multiple ring effects |
|
|
what are the issues with high plus lenses
|
1. increased ocular rotations
2. increased lens aberrations 3. distortion 4. magnified eyes 5. motion of objects in FOV 6. increases the demand for convergence |
|
|
what are the FOUR type of magnifications
|
1. relative distance magnifcation
2. relative size magnification 3. angular magnification 4. projection magnification |
|
|
what is relative distance magnifications?
examples and devices? |
mag that results from decreasing the distance of the object from the eye
bringing something closer MICROSCOPES and PLUS LENS |
|
|
what is relative size magnifications?
examples and devices? |
magnification created by increasing the size of the object, but keeping the distance at its original spot
large print books, magazines and newpapers does not increase demand for accommodation |
|
|
what is projection magnifications?
examples and devices? |
magnification resulting from optical or electronic enlargement of image on screen, used in combination with RDM
CCTV, really big print on TVs |
|
|
what is angular magnifications?
examples and devices? |
magnification produced by an optical system
compares the apparent increase in the size of an object seen through the optical system with the size of the object seen WITHOUT the optical system afocal telescopes |
|
|
what are the advantage and disadvantage of GALILEAN telescope
|
1. Shorter than Kepler
2. Lighter than Kepler 3. Erect Image |
|
|
what are the advantage and disadvantage of KEPLERIAN telescope
|
1. Better image quality than Galiean
2. Greater FOV than Galilean 3. Higher Magnification than Galiliean 4. Need Image Erecting Prism for use in low vision |
|
|
what are the optics of the Galilean vs the Keplerian
|
Galilean:
1. Objective: PLUS 2. Eyepiece: MINUS 3. ERECT IMAGE Keplerian: 1. Objective: PLUS 2. Eyepiece: PLUS 3. IMAGE INVERSE |
|
|
how are telescopes used by UNCORRECTED AMETROPES
|
Magnification for an afocal telescope assumes patient is emmetropic or corrected to emmetropia
myopes: decrease mag in galilean increase mag in kepler hyperopes: increase mag in galilean decrease mag in kepler |
|
|
what is the definition of an afocal telescope
|
an optical system that provides angular magnification without a change in vergence
|
|
|
telescope length in respect to refractive error and magnification
|
1. separation is INCREASED for uncorrected HYPEROPE
2. separation is DECREASED for uncorrected MYOPE 3. for a given mag, galilean is SMALLER than keplerian |
|
|
what are the difference between microscope lenses vs telemicroscope
|
1. microscopic lenses offer larger FOV
2. telemicroscopes offer longer, more comfortable reading distance |
|
|
what is a reading cap?
what determines the power of the reading cap? |
1. reading cap is a Plus Lens placed in front of an afocal telescope so that PARALLEL light enters the afocal telescope
2. power of the reading cap depends on the working distance +2.50D = 40cm +5.00D = 20cm |
|
|
hand magnifiers
how do you increase field of view |
FOV increases as the magnifier is brought closer to the eye
|
|
|
hand magnifiers
when the object is at the primary focal plane of the magnifier...what happens if you change the eye to lens distance |
changing eye to lens distance does not affect the magnification
AFFECTS THE FIELD OF VIEW |
|
|
hand magnifiers
what happens to accommodation when the object is AT THE PRIMARY FOCAL PLANE of the magnifier inside the focal plane?? |
NO ACCOMMODATION
when object lies inside the focal length of the magnifier, either ACCOMMODATION or an ADD is required |
