Contents - oshc.org.hk · The eyes are undoubtedly one of the most important human organs. We perceive the world and receive most of the mundane messages through the "windows of the

1

Contents

1. Introduction 2

2. Eye Structure 3

3. Situations that May Cause Harm to the Eyes 3

4. Common Eye Diseases and Problems 5

5. Eye Protection at Work 8

6. Ways to Alleviate Eye Fatigue 14

7. How to Manage Eye Injuries 15

8. Eye Protection Tips 15

Eye Protectionfor Better Visual Health

Tips on Eye Protection

2



1 Introduction

The eyes are undoubtedly one of the most important human organs. We perceive the

world and receive most of the mundane messages through the "windows of the soul"

— our eyes. We use them every day to handle a series of work tasks, such as reading

documents or operating computers. After work, we keep them busy by watching TV

programmes, reading books or spending hours on playing video games. All these

activities strain our eyes and make them dry and tired, which in turn affect our health.

This brochure describes some daily situations that may do harm to our eyes, and shows

us how to prevent such harm. It will also introduce some practical tips on ocular care and

protection.

3

2 Eye Structure

When we look at an object, light rays are refracted by the cornea and lens to focus an

image on the retina. We can see the lens and the retina as the lens and the film in a

camera respectively.

The thickness of the lens is controlled by

the ciliary muscle. The muscle contracts

and thickens the lens for a nearby object,

and it relaxes the lens to return to its

normal shape for a distant object.

Our vision may become blurred after we have been continuously looking at a nearby

object (such as reading a book or staring at a computer screen at work for a long period

of time). That is because the ciliary muscle has become too tired to relax completely. This

type of eye fatigue is temporary; our vision will be back to normal after we have rested

our eyes. If we leave our eyes fatigued for a prolonged period of time and constantly

overuse them, the fatigue may turn to a chronic eyestrain, leading to reduced vision and

chronic fatigue syndrome of our entire bodies.

3 Situations that May Cause Harm to the Eyes

In our everyday lives, we always harm our eyes unconsciously. For example:

• Wear glasses that are unsuitable for our eyes

Wearing glasses with insufficient degrees will strain our eyes. This may lead to ocular

pain, headaches, sore shoulders, dizziness and other forms of physical discomfort. You

should therefore do ocular check regularly, and replace your glasses with new ones

whenever necessary.

• Lean toward the computer screen unconsciously while working

Remain a comfortable distance of approximately 350-600 mm

away from the computer screen while you are working.

• Use a computer for a long period of time

Take regular short breaks to rest your eyes.

Retina

LensImage focused clearly on the retina

Cornea

Ciliary muscle

4



• Read in a crowded vehicle

If we read a newspaper or book in a crowded

vehicle, we tend to bring it closer to our eyes. Our

eyes will be further strained if we read during a

bumpy ride because it is more difficult for our eyes

to focus on the book under such situation.

• Sleep without taking off contact lens

We should always take off our contact lenses

before going to bed, even if they are designed for

continuous use. As we secrete fewer tears during

our sleep, wearing contact lens to bed will greatly

burden our corneas.

• Read when lying down

Doing our reading in an improper posture and

poor lighting will tire our eyes. Only read in a

proper posture and a suitable environment.

• Be addicted to video games

You should refrain from playing video games for

prolonged periods.

• Keep the light on while sleeping

Our eyeballs react to light, even when our eyelids

are closed. Our eyes cannot be fully rested if we

leave our lights on while we are sleeping.

5

• Watch television with mono-focal presbyopic glasses Mono-focal presbyopic glasses should only be

used for nearby objects. If you watch TV or look at anything farther away than its optimal focal length, your eyes will be strained and blurred.

• Send an SMS while walking Concentrating on small fonts will easily tire our

eyes, and focusing on a particular point while moving will strain our eyes further.

4 Common Eye Diseases and Problems

Xerophthalmia (Dry Eyes)The increasing popularity of computers has made xerophthalmia more common. Dryness

of eyeballs is a primary cause of eyestrain. As there are insufficient tears to moisturize our

eyes, our eyeballs become dry and unhealthy – this leads to xerophthalmia.

Generally, we blink our eyes 20 times per minute to brush our eyeballs with tears and

supply them with water and nutrients. However, statistics show that the frequency of

blinking drops substantially – to just one fifth of its normal frequency – when we are gazing

at a computer screen, television or video game. This is because our eyes tend to remain

open more frequently when we are staring at a particular point. This in turn reduces the

tears on the surface of our eyeballs and makes our eyes drier. If you want to rest your eyes,

it is important to blink intentionally to maintain sufficient moisture on your eyeballs.

PresbyopiaThe lenses in our eyes tend to lose their elasticity as we grow older, and

we may find it more difficult to focus on nearby objects. This eye defect

is called presbyopia. People who suffer from this may experience blurred

vision when they are looking at nearby points; for example, reading a book.

The symptoms of presbyopia usually occur at around the age of 40.

If we avoid wearing reading glasses or bifocals, our eyes may get

tired easily. Besides, those who suffer from presbyopia may also

experience headaches, tiredness and nausea if they do not wear

suitable presbyopic glasses.

Presbyopia usually stops progressing at the age of 60 to 65. However, it is a fallacy that

presbyopia will stop progressing if you avoid wearing corrective glasses. If you experience

presbyopic symptoms at any age, you should have regular optical checks to ensure you are

using the suitable corrective glasses.

6



Cataract Cataract is an eye disease caused by clumping of proteins which makes the lens opaque.

Other than heredity, factors like aging, diabetes, eyeball injuries, and ultraviolet ray

damage to eyes can also cause cataract.

Symptoms of cataract:

•Difficultyinfocusingonnearbyobjects,evenwiththeaidofpresbyopicglasses

•Cloudyorblurryvision

•Glareordazzle(particularlyinbrightlight)

•Doublevisioninoneeye

Senile cataract may develop slowly without causing any pain or irritation, so it is difficult

to recognize at the onset of it. People who suffer from this disease experience blurry

vision. As the cloudy part of the lens gradually expands from its rim to its centre, more

light rays are blocked and the opacity may increase to a point that the vision of the

patient is seriously impaired. Oral medicines and eye drops may slow down the progression

of cataract at an early stage, but surgery will be required if it worsens.

GlaucomaGlaucoma is an eye disease in which ocular hypertension (increase of intraocular pressure)

occurs, leading to impaired vision as a result of optic nerve damage. Intraocular pressure is

mainly maintained by the circulation of liquid aqueous humor. If the flow of the aqueous

humor is stopped, the intraocular pressure will build up and add pressure to our optic

nerves. Glaucoma is therefore resulted.

Cataract

Diabetes Ultraviolet Ray

Eyeball Injuries

7

There are two types of glaucoma: chronic and acute, but both may lead to blindness

if they are left untreated. Chronic glaucoma develops slowly, and there are rarely any

symptoms in the early stage of it. Once

the sufferer becomes aware of his or

her partial loss of vision, the disease has

already progressed significantly. Regular

eye tests are therefore important.

Acute glaucoma – the symptoms of which

include severe headaches, eye pain and

vomiting – occurs when the intraocular

pressure suddenly increases. Sufferers of

acute glaucoma are mostly middle-aged

females. Acute glaucoma must be treated

within 24 hours, or it may cause blindness.

Diabetic RetinopathyDiabetic retinopathy is an eye disease caused by complications of diabetes, which may

eventually lead to blindness. There are a lot of small blood vessels on the retina –they

are especially vulnerable to poor blood sugar control. As the viscosity of the blood of

diabetics increases, it blocks the tiny blood vessels in the retina - causing lack of oxygen

and nutrients of the retina. This leads to retinal bleeding, and causes diabetic retinopathy

eventually.

Not all diabetics will get diabetic retinopathy, but a high percentage of them will. It is

therefore very important to identify one’s diabetes. Diabetic retinopathy may not occur if

a diabetic keeps his or her blood glucose level under control.

The early symptoms of diabetes are:

•excessivethirst •frequenturination •sweetodourofurine •fatigue

The early symptoms of diabetic retinopathy are almost unnoticeable. Diabetics are advised

to have their eyes examined regularly.

Glaucoma

headaches eye pain

vomiting

8



5 Eye Protection at Work

I. Working in Factories and Construction SitesHuman eyes are susceptible to injuries by external hazards. These may result in visual

impairment or even blindness. The Factories and Industrial Undertakings (Protection of

Eyes) Regulation stipulates that the proprietor of any industrial undertaking shall provide

suitable eye protection to employees undertaking certain processes and to other persons

who may be at risk due to such specific processes. In fact, most eye injuries are avoidable if

employers and employees work closely together in taking effective precautions. Therefore:

1. Employers should provide employees with a safe working environment and protective equipment.

2. Employers should educate employees about eye protection.

3. Employees should use eye protectors properly, and report any damage or defect found

on the protectors to the employer immediately.

The specified processes under the Factories and Industrial Undertakings (Protection of Eyes) Regulation are:

1. Dry grinding of metals or articles of metal applied by hand to a revolving wheel, band or disc driven by mechanical power.

2. Turning (external or internal) of non-ferrous metals, or of cast iron, or of articles of such metals or such iron, where the work is done dry, other than precision turning where the use of eye protectors or a screen would seriously interfere with the work, or turning by means of hand tools.

3. Welding or cutting of metals by means of an electrical, oxy-acetylene or similar process.

4. Truing or dressing of an abrasive wheel.

5. Any work carried out with a hand-held cartridge-operated tool, including the operation of loading and unloading live cartridges into such a tool, and the handling of such a tool for the purpose of maintenance, repair or examination when the tool is loaded with a live cartridge.

6. The handling in open vessels or manipulation of acids, alkalis, dangerous corrosive materials, whether liquid or solid, and other substances which are similarly injurious to the eyes.

7. The use of compressed air for removing swarf, dust, dirt or other particles.

8. Any process involving the use of an instrument which produces light amplification by the stimulated emission of radiation.

9. The production of metal castings at pressure die-casting machines.

10. Working at a spout of, or attending to, a cupola or furnace where there is a reasonably foreseeable risk of injury to the eyes from molten metal.

11. Pouring or skimming molten metal.

12. Work in the manufacture of glass and in the processing of glass and the handling of cullet where in any of the foregoing cases there is a reasonably foreseeable risk of injury to the eyes of any person engaged in the work from particles or fragments thrown off.

13. Inspection of glass bottles which contain aerated liquids.

14. The following processes when carried on by means of hand tools or other portable tools: (a) Fettling of metal castings involving the removal of metal. (b) Cutting out or cutting off (not including drilling or punching back) of cold rivets or

bolts from boilers or other plant or from ships. (c) Chipping or scaling or scurfing of boilers or ships' plates. (d) Breaking, cutting, dressing, carving or drilling of concrete, plaster, slag or stone

(whether natural or artificial).

9

Use of Eye Protectors

Eye protectors are essential for performing tasks that involve exposure to hazardous rays,

or splatter of chemicals and flying particles.

Various types of eye-protection equipment:

(A) Protective Goggles

They are suitable for cutting off dust, particles, flying chips, chemical splattering and

smoke.

(Goggles with direct vents are unsuitable for protecting (Fitted with indirect vents) our eyes from chemical splattering or smoke)

(B) Safety Glasses

They are suitable for cutting off particles, flying chips and impact of fragments.

(Frontal protection) (Fitted with side protection)

(C) Goggles for Protection from Glare, and for Use in Gas Welding and Smeltering Furnaces

They are suitable for smeltering furnace work (together with a face shield), glare,

molten metal, strong light and gas welding, etc.

(D) Electric Arc-Welding Helmets and Face Shields

Suitable for electric arc welding, and for protection

from electric sparks, strong ultraviolet radiation (can

be used with safety goggles) etc.

10



Key Points on the Proper Use of Personal Protective Equipment (PPE)(1) Right Selection You must understand the nature and seriousness of the

potential hazards before you select the appropriate PPE that meets the relevant standards. Note that some PPE must fit the physique of the user to function properly.

(2) Correct Use You should fully understand and follow the correct

procedures of using the PPE. (3) Good Maintenance The PPE should be cleaned and dried after use. They should also be properly stored

and regularly inspected. (4) Visual Inspection If you discover any damage on the PPE, you should report this to your supervisor

immediately. So, the damaged PPE can be replaced.(5) Suitability The PPE must meet the needs of the working environment, and it should be as user-

friendly as possible.

II. Working in Offices Prolonged use of computers and display screen equipment may easily lead to pain in upper

limbs and backs of users, as well as fatigue of eyes and muscles. It may also reduce work

efficiency. The design of display screens, chairs, lighting and ventilation systems in the

workplace, as well as the working postures, can also adversely affect the health of users.

Key points to maintain good visual health in the workplace

A Display Screens

• Aclear,sharpandsteadyimageshouldbeprovidedbythescreen. • Thefontsizeofthecharactersshouldbesuitable,andthere

should be sufficient spacing between individual characters and between lines.

• Thebrightnessandcontrastof the imageon the screenshould be adjustable.

• Thescreenshouldbeabletotilttosuittheindividualneeds. • Thescreenshouldbekeptatacomfortableviewingdistance

of 350 - 600 mm from the user’s eyes, and the first line of words on the screen should be approximately at/or just below the eye level of the user.

• While staringat the screen,onewill tend toblink less.Therefore, the user should blink intentionally to keep his or her eyeballs moisturized.

11

B Keyboards

• Thekeyboardshouldbethinand its tiltedangleshouldbe

adjustable. It should also be detachable from the display screen

to allow the user to change his or her posture frequently.

• Itshouldbeneutralincolourandnon-reflective.

• Thelettersandsymbolsonthekeysshouldbeclearandeasytorecognize.

• Thereshouldbeenoughspaceinfrontofthekeyboardtosupporttheuser’shands.

• Round-edgedeskispreferable.

• Useawristrestforkeyboardtoalleviatewristdiscomfortforprolongeduseofkeyboard.

• Whileusingakeyboard,yourforearmsshouldbekeptatarightangletoyourupperarms.

C Work Surfaces

• Theworksurfaceshouldbelargeenough

to accommodate the screen, keyboard,

mouse, and other peripheral.

• The height of thework surface for

the screen and keyboard should be

adjustable to suit the user’s needs.

• There should be enough leg room

underneath the work surface.

D Chairs

• Chairsshouldbeadjustableinheight.

• Thebackrestofthechairshouldbeadjustableinbothitsheightandits

tilted angle to provide adequate support to the lower back of the user.

• Thearmrestsofthechairshouldnotobstructthekeyboardoperations.

• Thechair shouldhavea stable five-prongedbase,and it shouldbe

equipped with castors for easy movement.

• Theseatcushionshouldnotbetoohardor toosoft. Its frontedge

should be scrolled.

E Footrests

•Astablefootrestshouldbeusedifthechair istoo

high for the user to rest his or her feet comfortably

on the floor.

12



F Document Holders

• If the operator needs to read documents for data entry task,

he or she should use a document holder to avoid awkward

neck postures and movements.

The Working EnvironmentGood Illumination

• Officesshouldbeequippedwithsufficient lighting

and auxiliary lighting facilities. Illumination for

general office work should be kept at 300 to 500 Lux.

Reflections and Glare

• Toavoidglareandreflections,thescreenshould

not be placed directly under a light source or

close to a window.

• Thescreensshouldbeperpendiculartothelight

sources and windows. All windows should be

fitted with blinds to prevent excessive sunlight.

Noise

• Noisesproduced in theworkplacebyequipments suchas

printers and photocopiers should be controlled to avoid

creating a nuisance to employees. Noisy equipments should be

kept away from the workstations, or separated by a barrier.

Temperature and Humidity

• Thetemperatureandhumidity in theworkplaceshouldbekeptat

suitable levels. The optimal temperature for office work is 20 - 25°C in

summer, and 23 - 26°C in winter; and the relative humidity should be

between 40 and 70%.

Win

do

w

13

Adequate Fresh Air

• Theworkplaceshouldhaveagoodventilationsystem

to ensure a sufficient supply of fresh air.

• To avoid dry eyes, the air supply from the air

conditioner should not blow directly onto the faces

or bodies of workers.

Rest and Breaks

• Employeesshouldtakeshortbreaksfromtimetotimeto

alleviate the fatigue caused by prolonged computer use.

• Workallocationsshouldbeplannedinawaytoincorporate

different tasks (like photocopying and other paperwork)

with computer operations. This will not only minimize the

time workers spend on a static position or making repetitive

movements, but also give them opportunities to rest their

different muscle groups.

• Ifanoperatorneedstofocus

on a display screen for a long

period of time, he or she

should take breaks to look

at distant objects to relieve

eyestrain. Exercises for visual

comfort are a l so h ighly

recommended.

• Prolongeduseof computers can induce

muscular fatigue in the upper limbs

and lower backs of the users. Stretching

exercises are recommended during breaks

as they can effectively relieve mental stress

and muscle strain.

14



1 2

Gently press 3 times along theupper and lower areas around the zygomatic

Slightly exert pressure on the several points around your eyes as shown in the picture

6 Ways to Alleviate Eye Fatigue

Appropriate treatment and adequate rest are essential to alleviate eye fatigue. Yet,

inappropriate treatment may do harm to our eyes. The following are some suitable ways

to relieve eye fatigue:

I. Eye Massage

Gently massage the eye socket area to improve blood circulation. Never press the

eyeball over the eyelid as it may hurt the cornea.

Correct eye-massage methods

II. Apply a warm or cold towel to the eyes

The application of a warm towel can reduce eye fatigue by improving blood circulation

and relieving stressed muscles around the eyes. It also helps the secretion of tears that

moisturizes dry eyes. A cold towel helps improving blood circulation and soothing

swollen and irritated eyes.

III. Artificial tears for dry eyes

Other than the single-use vials prescription, a lot of artificial tears contain preservative

ingredients. It may do harm to the cornea if used frequently. Therefore, follow the

instructions and dosage information given when you use artificial tears.

15

7 How to Manage Eye Injuries

If your eye is accidentally injured by a foreign object or chemical, stay calm and treat the

wound as soon as possible.

1. Don’t rub your eye or you may damage your cornea.

Instead, flush the eye immediately with copious

amounts of clean water for about 15 minutes to remove

the foreign object or dilute the chemical.

2. Cover the eye loosely with a clean and soft dressing,

and do not move your eye to avoid further damage.

3. After the first-aid treatment, you should go to a

hospital for further treatment as soon as possible.

If your eye is hit by a hard object, apply a cold towel on it gently to alleviate pain and

swelling. Then, go to a hospital immediately for further treatment.

Note for Contact Lens WearersIf you wear contact lenses, do NOT attempt to remove them before you flush your eyes

with clean water as this may hurt your eyes further. Normally your contact lenses will be

flushed away by the running water. If they stay in your sockets, let the medical personnel

deal with them.

8 Eye Protection Tips

Our eyes are the windows of our soul. As we grow older, our eyes may start to show a lot

of defects due to overuse and unhealthy living style. Learning how to protect your eyes

will not only help you keep them healthy, but also enable you to lead a physically and

mentally healthy life.

1. Personal Hygiene • Wipethedirtinyoursocketsawaywhenyouwashyourfaceto

avoid eye inflammation, hordeolum, and other ocular diseases.

• Neversharetowelswithothersorrubyoureyeswithyourhands.

• Neveruseotherpeople’seyedropsortheirglasses.

16



2. Daily Life • Keepabalanceddiettoattaindifferentnutrientsthathelpoureyesstayhealthy:

Vitamin A (from animal liver, carrots and dark green vegetables), Vitamin B Complex

(lean meat and beans),Vitamin C (kiwi fruits and oranges), Vitamin E (cashew nuts

and peanuts), Anthocyanin (blueberries and black grapes), Xanthophylls (pumpkins

and papayas), and Essential Fatty Acids like Omega-3 (salmon, sardine and tuna).

• Donotsmokeordrinkalcohol.

• Getenoughsleeptorestyoureyesandsootheyourfatigue.

• Maintainasuitableviewingdistancefromthescreenwhile

watching TV. To prevent eyestrain, do not set the contrast too

sharp or watch TV without sufficient lighting in the room.

• Onlyusecomputersinwell-litplaces.Ifyouneedtostareatthe screen for long periods of time, look at distant objects regularly to alleviate your eye fatigue.

• Weargoggleswhenyouarecleaningtheworkingandlivingspaces (such as dusting the ceilings). Be careful with the nozzle to avoid spraying the cleaning detergent at your eyes.

• Adjustyourairconditionertomaintainaproperhumiditylevel in the room to prevent your eyes from becoming dry.

• WearsunglasseswithUVblockingfunctionwhenyouworkor engage in outdoor activities.

• Whenyouread,makesurethat: 1. The light (artificial or natural) is sufficient, balanced,

steady and soft. 2. Your chair is adjusted to a suitable height, so that you

can keep an appropriate distance from the book. 3. Keepyourbackstraight. 4. The paper should not be reflective. 5. The font size should be large enough. 6. Whenever you feel tired, look at distant objects or simply close your eyes. 7. Do not read in a car or in bed.

• Takegoodcareofyoureyes.Donot

hesitate to consult an ophthalmologist

if you feel any discomfort or you notice

any problem with your vision.

Documents

Contents - oshc.org.hk · The eyes are undoubtedly one of the most important human organs. We perceive the world and receive most of the mundane messages through the "windows of the