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Ophthalmic Optics > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

Computer Vision

A

The complex of eye and vision problems related to near work which are experienced during or related to computer use

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2
Q

Prevalence of CVS

A

Eye and vision problems are the most frequently reported health-related problems for computer workers. Poor vision caused or aggravated by computer use

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3
Q

Why is working at a computer more visually demanding?

A

Traditional BV problems with near work, frequent saccadic eye movements, continuous eye focusing, alignment demands.
Problems specific to the computer: Poorer contrast, increased glare (direct light, not reflected), different working distance (further than reading), Different viewing angles

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4
Q

When do problems with CVS occur?

A

When the visual demands of the task exceed the visual abilities of the individual to comfortably perform the task

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5
Q

Is CVS a diagnosis?

A

No, not in ICD-9/10. Patients with CVS have one or more of the symptoms listed later, symptoms will determine diagnosis.

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6
Q

Symptoms of CVS

A

Eyestrain/eye fatigue, dry eyes, burning eyes, light sensitivity, blurred vision, HAs, pain of shoulders, neck, back.

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7
Q

Factors to Consider in resolving CVS

A
  1. Take a thorough history
  2. Ergonomics
  3. Refractive Error
  4. Illumination
  5. Dry eye symptoms
  6. Plus at near
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8
Q

Taking a thorough history (for CVS)

A

Consider using a pre-exam questionnaire: How many hours a day do you spend on the computer, how far away is the screen, is it at/above/below the eye level. What type of room lighting do you have, do you get up and down from the desk frequently.

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9
Q

Ergonomics

A

Adjustment of the workstation to the individual needs of the operator is important for overall performance and comfort. Inadequate viewing distances and angles can impose the necessity of awkward postures, contributing to musculoskeletal problems.

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10
Q

Proper viewing distance at the computer

A

20-26 inches away

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11
Q

Proper viewing angle down at the computer

A

10-20 degrees

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12
Q

20/20/20 rule

A

Every 20 mins look at least 20 feet away for 20 secs

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13
Q

Correcting refractive error for CVS

A

The presence of even a minor vision problem can often significantly affect worker comfort and productivity. If they have small amounts of astigmatism or hyperopia that you wouldn’t normally correct and they are complaining of CVS, this could be the issue.

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14
Q

Illumination and Glare with CVS

A

Many problems related to lighting may be caused by the introduction of computers into offices where the lighting was originally designed for traditional desktop work. Shouldn’t be in complete darkness, but need to reduce the room light. Bright lights in the peripheral field of view may cause discomfort glare.

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15
Q

Fixing glare for CVS

A

Faint tint on glasses? Pink/red/yellow- not really proven significantly. Or AR coating, visors on the computer. Anti-glare screens: Antireflective screens, privacy filters.

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16
Q

Dry eye syndrome with CVS

A

Many office environments contribute to eye irritation for workers because of the dry atmosphere. Use of computers is associated with a decreased frequency of blinking and increased tear evaporation. Tell patients to blink more! Give them tear products.

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17
Q

Plus at near for CVS

A

Accommodative disorders are the prevalent among symptomatic computer users. Test accommodation: NRA/PRA, accommodative facility, FCC, PRIO testing

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18
Q

PRIO computer testing

A

Duplicates the accommodative demand of a computer screen, and the light characteristics. Device is placed on the nearpoint rod at the computer working distance. Use dynamic retinoscopy to determine add

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19
Q

Comparing PRIO vs. MEM

A

Accommodative response is the same.

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20
Q

Study involving most accurate nearpoint test.

A

Presbyopes: Similar results between methods. No matter what test used, the results were predictable
Prepresbyopes: highly variable with NRA/PRA, and Snellen VA, lowest variability with dynamic ret and FCC.

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21
Q

Computer glasses

A

Common computer lenses: single vision for intermediate, occupational/computer progressives, Bifocals (inter/near), Trifocals with a large intermediate.

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22
Q

Intermediate add

A

About half the add power added to the distant power (for single vision glasses). Air on side of weaker rather than stronger. For intermediate/near bifocals, the other half of the add will be in the segment. For trifocals, part of the segment will have half the add, the other part will have the full add.

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23
Q

Computer progressives

A

Have a much larger intermediate area, less distance.

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24
Q

3D vision syndrome

A

The intentional mismatch between vergence and accommodative distance. Similarities between this and CVS (this difference is this is at near)

25
Q

Ways to see 3D

A

Anaglyph, passive polarized, active shutter, glasses free

26
Q

Why is seeing 3D important?

A

It helps develop efficient reading skills, it increases participation as more schools adopt 3D as a teaching tool, increasingly utilized in a growing lift of professions

27
Q

Causes of 3D viewing challenges

A

Refractive problems: nearsightedness, farsightedness, astigmatism.
Lack of BV: two eyes not properly aligned, strabismus is present, inputs from the two eyes not successfully combined in the brain and 3D stereoscopic perception will not occur.
Amblyopia, Eye coordination problems, accommodation problems, dizziness and nausea from rapid motion effects (disagrees with balance system)

28
Q

3D benefits as a public health tool

A

AOA says there is no evidence that viewing or attempting to view 3D will harm a child’s eyes. Difficulties with 3D can unmask undiagnosed deficiencies and lead to treatment

29
Q

Treatment Options for 3D vision

A

Glasses/contact lenses for simple refractive error, glasses to improve eye-focusing or eye coordination, treatment for amblyopia or strabismus, optometric vision therapy to teach eye coordination

30
Q

UVA, UVB, UVC

A

UVA: 320-400nm
UVB: 290-320nm
UVC: 100-290nm

The longer the wavelength the more into the skin. UVB (absorbed by cornea/lens)is most dangerous as UVA (may be absorbed by lens) doesn’t go into skin, and UVC is mostly absorbed by the ozone

31
Q

Benefits of UV

A

Minimum exposure required to maintain vitamin D adequacy. Prevents ricketts, osteomalacia, and osteoporosis

32
Q

Sun protection factor

A

Higher SPF blocks more UVB rays. Just applies to UVB. The SPF number is the theoretical amount of time you can stay in the sun compared to without it.

33
Q

UV radiation increases:

A

Closer to the equator, higher the altitude, between 10am and 2pm in the Summer

34
Q

Factor involved in determining the UV index

A

Elevation of the sun in the sky, amount of ozone n the stratosphere, cloud conditions.

35
Q

UV Index range

A

0 (nighttime) to 15/16 (tropics at high elevations and clear skies). 1-2 (low), 3-5 (moderate), 6-7 (high), 8-10 (very high, UV levels dangerous), 11+ (extreme, light skin can burn in minutes)

36
Q

UV index

A

The next day’s forecast of the amount of damaging UV radiation expected to reach the time when the sun is highest in the sky (solar noon)

37
Q

UV and the eye

A

The entire eye is subject to damage, UV has direct DNA damage and or phosensitixing reactions causing production of free radicals and eventual oxidative damage. IR has higher potential for tissue damage. Tissue must absorb energy to cause damage. UV may cause pterygium/pinguecula

38
Q

Studies about UV exposure and eye

A

Most studies state that many eye diseases are caused by sunlight. Especially Photokeratitis–> caused by UV

39
Q

Outcomes associated withe UVR with strong evidence of causality

A 
Immune effects (activation of latent virus infection)
Effects on skin (types of skin cnacer and sunburn)
Effects on eye (photokeratitis and conjunctivitis, solar retinopathy, pterygium, cancer of cornea and conjunctiva, cortical cataract)
40
Q

Cornea and UV light

A

Corneal epithelium plays a significant role in protecting eye from UV. Anterior layers of cornea are believed to be twice as effective at absorbing UVB as the posterior layers

41
Q

Photokeratitis

A

CAUSED BY UV
Really akin to a sunburn of the cornea and conjunctiva, presents with tearing, pain, photophobia. Not apparent until at least several hours after exposure.

42
Q

Peripheral Light focusing

A

Obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. Can create areas of concentrated light in the nasal corneal limbus and the lens cortex. May be implicated in pterygium and age-related cortical cataracts. Only wraparound sunglasses or UV blocking contact lenses may provide protection against PLF.

43
Q

Lens and UV light

A

Age-related cataracts. Clear association between UVB and CORTICAL cataracts, NOT nuclear cataracts

44
Q

Choroid and Retina and UV light

A

Uveal melanoma, solar retinopathy, maybe AMD

45
Q

Light blocking capabilities of lens materials

A

Crown glass about 39%, polycarb, trivex, CR-39 100% of UVB, CR-39 lets in about 10% of UVA

46
Q

UV coatings

A

For plastic lens, submerge into a hot UV dye, just like you would tint a lens.Glass lenses have certain lenses

47
Q

AR coatings and UV reflection

A

Near complete protection against all frontal UV exposure. AR coatings may reflect UV radiation off the back side of the lens into the eye.

48
Q

Preferred sunglas frame recommendations

A

Ensure sufficient pantoscopic tilt and faceform wrap. Fit very closely to wearer’s head and face

49
Q

ANSI standard for nonprescription sunglasses

A

Impact-resistant standards, flammability standards, Cosmetic (lens free of pits, scratches, grayness, water marks, bubbles), Refractive (zero power in any meridian: plano with tolerance of +.12 to -.25, cylinder less than .12, prism less than 1/4) Transmittance depends on color and other factors

50
Q

Transmittance standard for nonprescription for sunglasses

A

Light: 40%, Med 8%-40%, Dk 3-8%, have to let in 6-8% light from traffic signal. 1% max UV

51
Q

Contact Lenses and UV

A 
UV-blocking contact lenses (class 2) must absorb 70% UVA and 95% UVB. Class 1 blockers must block 90% of UVA and 99% UVB.
Should be able to reduce PLF
52
Q

Does UV transmission increase through contact lens wear?

A

Wearing contact lenses does not significantly affect the transmission of UV through the lens

53
Q

Advantages of Contact lenses as UV protection

A

Protects limbal stem cells, reduces PFL, no back side UV reflections, worn all day

54
Q

Disadvantages of CL as UV protection

A

No protection to eyelids or most of the conjunctiva

55
Q

High energy violet/blue light

A

Has been implicated as having a role in ARMD. Has non visual functions in mammals, regulates the circadian cycle. Present outdoors from sun, all year long. Present indoors from LED light in most modern lighting and display systems

56
Q

Ciracadian Rhythms

A

Physical and mental behavior and mental behavior changes following a 24 hour cycle. Nerve cells in the hypothalamus above the optic chiasm in the suprachiasmatic nucleus. less light= more melotonin, more blue light=less melatonin= more wakefullness

57
Q

IOLs and UV

A

IOLs need to be UV blocking, there has been support that they need to be blue filter too especially if the person has ARMD

58
Q

Corneal Ectasia

A

Thinning of cornea. Genetic disorder (keratoconus) Refractive surgery, Trauma, Keratitis.

59
Q

Corneal Collagen Cross-linking

A

Indicated for Corneal ectasia. Safer than corneal transplant. Increases rigidity of cornea to prevent further deformation. Use riboflavin to absorb UVA and induce photochemical reaction. This interaction produces oxygen reactive free-radical species. Results in covalent bonds between collagen fibers

Ophthalmic Optics (3 decks)

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