TOPIC 6: VISUAL ERGONOMICS

Question 1

Study the paper on digital eye strain – A Comprehensive Review.
What are the symptoms of DES?

Answer 1

ocular surface related:
eye discomfort
watering
redness
itching
dryness
eye strain
reduced concentration
glare
excessive sensitivity to light
inability to keep the eyes open

accommodation or vergence related:
blurry vision after computer use
difficulty refocusing from one distance to another
diplopia

musculoskeletal symptoms:
headaches and occasionally sore neck or back

Question 2

What causes these symptoms of DES?

Answer 2

1. Extraocular mechanism
   postural problems secondary to improper placement of computer screens, unsuitable table or chair height, or incorrect distance between the eye and screen resulting in unnecessary stretching or forward bending often resulting in a muscular sprain
2. accommodative mechanism
   Changes in accommodation lag have been noted secondary to digital device usage over prolonged periods. However, the effects on accommodation, convergence, and pupillary size are mainly due to the demanding near work and not per se due to the screen
3. ocular surface mechanism
   Largely caused by reduced blink rate,

Eyeblink helps maintain a normal ocular surface through a whole cycle of secretion of tears, wetting of ocular surface, evaporation, and finally, drainage of tears

increased surface of cornea exposure caused by horizontal gaze at the computer screen and reduction of tear production due to the aging process and contact lens usage

Question 3

How to resolve DES? (Management strategies)

Answer 3

1. Average daily screen time should be reduced to a reasonable limit. Track screen time and control screen time (≤ 4 h daily).
2. Digital device practices: proper ambient lighting, digital device positioning, adjusting image parameters (resolution, text size, contrast, luminance), and taking frequent breaks (20/20/20 strategy).
3. It is recommended to sit upright at a desk or table with screens approximately 20 inches from the eyes.
4. The height of the screen should be positioned lower than the height of the eyes, such that the viewing distance is 15–20° below the eye level.
5. Frequent blinking of eyes minimizes the chances of developing dry eyes.
6. Environments with an illumination of over 1000 lx are known to decline user performance . A contrast setting around 60–70% is considered comfortable by most people. The brightness should be adjusted such that the light coming from monitors matches the light in the surrounding workspace. Anti-glare screens can also help in reducing the amount of light reflected from the screens. A clearly legible font of at least size 12 preferably in a dark color over light background should be chosen.
7. Refractive error correction and use of glasses with antireflective coating
8. Parents should be counseled to monitor their child’s screen usage and incorporate family time.
9. Encourage children towards outdoor recreational activities.