RR: Computer Vision Syndrome Flashcards
What are the ocular findings related to computer vision syndrome?
- Eyestrain/Eye Fatigue
- Burning Sensations/Irritation
- Redness/Dry eyes
What % of US workers using a computer over 3hrs/day experience CVS (computer vision syndrome)?
90%
What are the non-ocular (ergonomic) symptoms associated with CVS?
- Headache
- Pain in shoulders/wrist
- Pain in Neck
- Pain in back
What are the 3 pathophysical causes of CVS?
- Ocular surface mechanisms
- Accommodative mechanisms
- Extraocular mechanisms
Prolonged computer (VDT) use causes what 3 accommodative/covergence findings?
- Less power of accommodation
- Removal of NPC
- Deviation of phoria for near vision
Patients below the age of 40 who use VDTs lost _____ (more/less) accommodation amps than those who did not.
Lost more accommodation
Gur and Ron found a high prevalence of what 3 things a the end of the day, 4 days later?
- exophoria
- Convergence insuffiency
- Low fusional convergence
What type of shift do VDTs cause? How much?
myopia, 0.12D
Blink rate is decreased further in a dark setting. What % is it reduced?
60%
- more in post-menopausal women
What’s the normal blink rate?
10-15x a minute
T/F: Upper and lower case documents are easier to read than all uppercase.
True
What was used to help schoolchildren with myopia that report visual changes after 30 mins of computer usage.
Screen filters
Extemely low refresh rates (flicker) can cause what?
epileptic seizures
Lower refresh rates means _____ is weaker and blink rates were _____.
- accommodation was weaker
- blink rates were lower
What type of lamp is best used to decrease visual asthenopia?
Sodium lamps
Where should a computer be placed to reduce symptoms?
35-40 inches
How much tilt should a computer screen have?
10-20degrees
Studies show a person should take regular work breaks every __ hours.
4 hours
One of the most simple and therapeutic modes of therapy are _____.
Lubricating eye drops
What are the accommodative symptoms of CVS?
- AI (Near blur)
- Accom. Infacility (slow focus from dist/near vice versa)
- Acc. Spasm (blur at distance after near)
- Fatigue/Eyestrain (can’t sustain near work)
What is the basis of CVS?
- Extended near point demand
- Poor resolution/contrast
- dark background of computer screen
What happens to accomodation in upgaze?
Decreases
How much does accommodation decrease in upgaze at 20’, 30’ and 60’
20’ = reduced by 1.25D
40’ (straight ahead) = reduced by 2D
60’ (cpu sits 20’ up) = reduced by 3D
What are the causes of dry eyes at the computer?
- Decreased blink rate (1/3 of usual)
- Increased exposure
- dry office environment
What’s the normal, reading and computer blink rate?
Normal = 22/min Reading = 10/min Computer = 7/min
What does a technica american optic offer as a progressive lens design? What does this lens specify?
- enhanced midrange and near lens design(small distance area)
- specifies distance Rx and add power
How should the head be positioned when looking at a computer?
Head back, chin tucked, ears shoulder and hips aligned
How should the elbows be positioned when looking at a computer?
At sides - slightly more than 90 degree bend
How should the eyes be positioned when looking at a computer?
Level with top 1/3 of screen; 18-24in away
When working on the computer, how many times should one take a break?
Every 30 mins
What are some suggestions to decrease effects of CVS?
- 20-20-20 rule
- Size up
- Sharpen up
- Reduce glare (good lighting)
- Look down (easier to focus)
- Think blink more
The asthenopic symptoms of eyestrain and tired eyes from CVS are diagnosed as wht?
Binocular Vision and Accommodative issues
It is important to specify what Rx while prescribing the Readables Varilux lens?
Specify computer Rx
It is important to specify what Rx while prescribing the Access Sola lens?
Specify near Rx
The Shamir Office Occupational lens is best used in what environment? How many powers are there to choose from?
- best in small office environments
- 4 different powers to choose from
