بسم الله الرحمن بسم الله الرحمن الرحیمالرحیم

By :Sotoudeh Manesh MDMD

Occupational eye disorders Occupational eye disorders

ImportantImportant

Ergophthalmology Ergophthalmology

USA:1.4 million injuryUSA:1.4 million injury &illness&illness in2002 in2002

- 47% of all head injury- 47% of all head injury

- ocular foreign body:38%- ocular foreign body:38%

- contusion/abrasion:27%- contusion/abrasion:27%

- burn:12%- burn:12%

- conjectivitis:11%- conjectivitis:11%

Non-construction>welder>cutter>truck driverNon-construction>welder>cutter>truck driver

- 4%workers compensation claim &1%total paymnt - 4%workers compensation claim &1%total paymnt

Two General Types of Vision andTwo General Types of Vision andEye Assessments Can Be DifferentiatedEye Assessments Can Be Differentiated

• ScreeningScreening

— — Identifies those at high riskIdentifies those at high risk

or in need of a professionalor in need of a professional

examinationexamination

— — May detect disorders inMay detect disorders in

early, treatable stageearly, treatable stage

— — Provides public withProvides public with

valuable information andvaluable information and

education about eye careeducation about eye care

— — Results in referral to an eyeResults in referral to an eye

care professional or primarycare professional or primary

care providercare provider

• ExaminationExamination

— — Examines subjects for Examines subjects for

eyeeye

disorders and diseasesdisorders and diseases

— — Diagnoses eye disordersDiagnoses eye disorders

and diseasesand diseases

— — Prescribes treatmentPrescribes treatment

Source: Prevent Blindness AmericaSource: Prevent Blindness America

Components Of Vision ScreeningComponents Of Vision Screening

History and symptomsHistory and symptoms

Visual acuity at any distanceVisual acuity at any distance

Visual fieldVisual field

Colour visionColour vision

Depth perceptionDepth perception

Contrast sensitivityContrast sensitivity

Visual acuityVisual acuity

Snellen chart Snellen chart

Acuity at Acuity at

Near&Distance Near&Distance

Near visual acuityNear visual acuity

• DefinitionDefinitionThe ability to see clearly at a normal reading The ability to see clearly at a normal reading

distancedistance

• Method of measuringMethod of measuringJaeger card-reduced snellen chartJaeger card-reduced snellen chart

• Causes of decreased near V.A in the Causes of decreased near V.A in the presence of normal distance V.Apresence of normal distance V.A

Presbyopia,uncorrected hyperopia,centerallyPresbyopia,uncorrected hyperopia,centerally located cataracts and drug side effectslocated cataracts and drug side effects

Visual fieldVisual field

Confrontation testConfrontation test

primetryprimetry

Visual fieldVisual field

• Normal extensionNormal extension 70 degrees Inferiorly, 60 degrees superiorly,95 degrees 70 degrees Inferiorly, 60 degrees superiorly,95 degrees

temporally and 60 degrees nasally.temporally and 60 degrees nasally.

Total horizontal visual field extent to 190 degreesTotal horizontal visual field extent to 190 degrees

• Factors that influenceFactors that influence the visual field the visual field Size, distance, background illumination, colour,Size, distance, background illumination, colour,

Kind of job, Bi or monocular vision, age, use ofKind of job, Bi or monocular vision, age, use of

Personal protective device ( safety spectacle)Personal protective device ( safety spectacle)

Color blindnessColor blindness

Normally, there are three kinds of Normally, there are three kinds of cones (each one sensitive to a cones (each one sensitive to a specific range of wavelengths):specific range of wavelengths):

""redred" cones (64%)" cones (64%)""greengreen" cones (32%)" cones (32%)""blueblue" cones (2%) " cones (2%)

The normal human retina contains two kinds of light sensitive cells: the rod cells (active only in low light) and the cone cells (active in normal daylight and responsible for color perception).

The different kinds of inherited color blindness result from partial or complete loss of function of one or more of the different cone systems.

Different Types of Color BlindnessDifferent Types of Color Blindness

• Monochromacy:Monochromacy: occurs when two or all three of the cone occurs when two or all three of the cone

pigments are missing and color and lightness vision is reduced to pigments are missing and color and lightness vision is reduced to

one dimension. one dimension.

Total color blindnessTotal color blindness

• Dichromacy:Dichromacy: occurs when only one of the cone pigments is occurs when only one of the cone pigments is

missing and color is reduced to two dimensions.missing and color is reduced to two dimensions.

Partial color blindnessPartial color blindness

red-greenred-green

blue-yellowblue-yellow

DichromacyDichromacy

Photoreceptor AnatomyPhotoreceptor Anatomy

• Example: if you Example: if you

stimulate all 3 types of stimulate all 3 types of

cones about equally the cones about equally the

result is white or no result is white or no

color. color.

Colour vision testColour vision test

Ishihara

plates

Colour vision deficiency in wokplaceColour vision deficiency in wokplace

• StyreneStyrene

• TolueneToluene

• PerchloroethylenePerchloroethylene

• Carbon disulfideCarbon disulfide

• Metallic mercurryMetallic mercurry

• Mercury vapporMercury vappor

• n-hexann-hexan

Depth perception Depth perception ((Stereopsis)Stereopsis) The ability to precieve depth or relative distanceThe ability to precieve depth or relative distance

Some jobs that need stereoscopic visionSome jobs that need stereoscopic vision Furk-lift truck operator , crane driver, pilot ,Furk-lift truck operator , crane driver, pilot ,……

Factors that influence depth perceptionFactors that influence depth perception Uncorrected refractive errores, amblyopia , squintUncorrected refractive errores, amblyopia , squint

low level of illumination , anisometropia , age ,low level of illumination , anisometropia , age ,

Advantages of binocular vision over monocularAdvantages of binocular vision over monocular The presence of stereopsis , improved visual acuity , an enlarged The presence of stereopsis , improved visual acuity , an enlarged

Field of peripheral vision , slightly brighter of objectField of peripheral vision , slightly brighter of object

Clinical tests for stereopsisClinical tests for stereopsis Contour stereotestContour stereotest Titmus stereotestTitmus stereotest

Random dot stereotestRandom dot stereotest Frisby testFrisby test

Random Dot-E testRandom Dot-E test

Clinical Contrast Sensitivity TestsClinical Contrast Sensitivity Tests

• Pelli-Robson chartPelli-Robson chart

• Regan low-contrastRegan low-contrast

• Vistech chartVistech chart

• Melbourne edge testMelbourne edge test

Occupational EYE Occupational EYE Illness Illness

EYE injuriesEYE injuries

EYE DiseasesEYE Diseases

EYE Chemical BurnsEYE Chemical Burns

1.1. Alkali burnsAlkali burns

2.2. Acid burnsAcid burns

3.3. IrritantsIrritants

Eye Acid BurnsEye Acid Burns

Sulfuric acidSulfuric acidNitric acidNitric acidChlorohydric acidChlorohydric acidHipochloric acidHipochloric acidPerchloric acidPerchloric acidFlurohydric acidFlurohydric acidCholorCholorSo2 So3 So2 So3 No2 N2o4 ?No2 N2o4 ?

Alkali BurnsAlkali Burns

Sodium hydroxideSodium hydroxide

Potassium hydroxidePotassium hydroxide

AmoniaAmonia

CementCement

LyeLye

DetergentsDetergents

Emergency Emergency

• Treatment should be immediate, even Treatment should be immediate, even

before making vision tests!before making vision tests!

• Premedicate with proparacaine or Premedicate with proparacaine or

tetracaine.tetracaine.

• Copious irrigation: LR or NS X 30 min.Copious irrigation: LR or NS X 30 min.

• Wait 5 minutes and check pH. If not Wait 5 minutes and check pH. If not

normal, repeat.normal, repeat.

Mild-to-Moderate Chemical BurnsMild-to-Moderate Chemical Burns

• Critical signsCritical signsCorneal epithelial Corneal epithelial

defects range from defects range from

scattered superficial scattered superficial

punctate keratitis punctate keratitis

(SPK) to focal (SPK) to focal

epithelial loss to epithelial loss to

sloughing of the entire sloughing of the entire

epitheliumepithelium

• Other Signs:Other Signs:Focal area of conjunctival Focal area of conjunctival

chemosis.chemosis.

Hyperemia.Hyperemia.

Mild eyelid edema.Mild eyelid edema.

Mild-anterior chamber Mild-anterior chamber

reaction.reaction.

11stst or 2 or 2ndnd degree burns to degree burns to

periocular skin.periocular skin.

Mild-to-Moderate Chemical BurnsMild-to-Moderate Chemical Burns

• Critical signs:Critical signs:Pronounced Pronounced

chemosis and chemosis and

perilimbal blanchingperilimbal blanching

Corneal edema and Corneal edema and

opacificationopacification

Moderate-to-Severe Chemical BurnsModerate-to-Severe Chemical Burns

• Other signs:Other signs:Increased IOCIncreased IOC

22ndnd & 3 & 3rdrd degree burns of degree burns of

the surrounding tissuethe surrounding tissue

Local necrotic retinopathyLocal necrotic retinopathy

Moderate-to-Severe Chemical BurnsModerate-to-Severe Chemical Burns

Treatment :Treatment :

IrrigationIrrigation

AntibioticsAntibiotics

Artificial tearArtificial tear

SteroidsSteroids

Ascorbic acidAscorbic acid

Calcium gluconateCalcium gluconate

dilating eye dropdilating eye drop

Complications :Complications :

ScaresScares

GlaucomaGlaucoma

BlindnessBlindness

Physical traumaPhysical trauma

• Corneal abrasionCorneal abrasion

Illinois EMSC31

Corneal lacerationCorneal laceration

Foreign BodyForeign Body

• Symptoms:Symptoms: Foreign-body sensationForeign-body sensation

TearingTearing

Blurred visionBlurred vision

PhotophobiaPhotophobia

Commonly, a history of a Commonly, a history of a

foreign bodyforeign body

Corneal Foreign BodyCorneal Foreign Body

Penetrating ocular injuryPenetrating ocular injury

• Incidence : 1.4%-4%Incidence : 1.4%-4%

• Industries at Greatest risk: construction; manufacturingIndustries at Greatest risk: construction; manufacturing

• Object: metal fragment ;glass; nail Object: metal fragment ;glass; nail

• Sign:Sign:

• Flat eyeFlat eye

• Low visionLow vision

• Low intraocular pressureLow intraocular pressure

• hyphemahyphema

Foreign BodyForeign Body

متالیک : • متالیک : نمکهای نمکهای

برگشت : • غیرقابل توکسیک آسیب سبب مس و آهن برگشت : نظیر غیرقابل توکسیک آسیب سبب مس و آهن نظیر

شبکیه شبکیه در در

• : محلول کمتر : مواد محلول کمتر مواد

دارند • بهتری پروگنوز ،شیشه پالستیک دارند آلومینیم، بهتری پروگنوز ،شیشه پالستیک آلومینیم،

• : ارگانیک خارجی : اجسام ارگانیک خارجی اجسام

مشکل • بسیار درمان با چشمی داخل عفونت سبب مشکل چوب بسیار درمان با چشمی داخل عفونت سبب چوب

بد پروگنوز بد و پروگنوز و

RadiationRadiation ::

UV < 400 nmUV < 400 nm

IR > 700 nmIR > 700 nm

Visible 400 Visible 400 –– 700 nm 700 nm

Ionising <0.0001 nmIonising <0.0001 nm

ELF 1000 - 10000 Km ELF 1000 - 10000 Km

Electromagnetic SpectrumElectromagnetic Spectrum

Radio Micro I.R. Visible U.V. X-ray -ray

104 106 1010 1013 1023Hz

UV Sources :UV Sources :

SunSun

WeldingWelding

LampsLamps

FoundryFoundry

Blacksmitch Blacksmitch

• UV-CUV-C:100-290nm:does not normally :100-290nm:does not normally

penetrate the earth atomospherpenetrate the earth atomospher

• UV-BUV-B:290-320 nm: cortical cataract; :290-320 nm: cortical cataract;

petrygium;petrygium; photokeratit; intraocular photokeratit; intraocular

melanoma??melanoma??

• UV-AUV-A:320-400nm: petrygium:320-400nm: petrygium

Infra Infra Red Red

IR - A : 780 IR - A : 780 –– 1400 nm 1400 nm

IR IR –– B : 1400 B : 1400 –– 3000 nm 3000 nm

IR IR –– C : 3000 - 10000 nm C : 3000 - 10000 nm

•All form of cataractAll form of cataract

•Pathagnomonic: exfoliative or splitting Pathagnomonic: exfoliative or splitting

of anterior lens capsuleof anterior lens capsule

IRIR sources : sources :SunSunHeatersHeatersSteel IndustrySteel IndustryGlass IndustryGlass IndustryLasers YAG - Neodymium - CO2Lasers YAG - Neodymium - CO2LampsLampsWeldingWelding

IRIR absorption in Eye : absorption in Eye :Cornea : IR-C IR-B

Lens : IR-A

Retina : IR-A

As shorter wave length more heat

production

Causes of occupational cataracts Causes of occupational cataracts ::microwaves,microwaves,

TNTTNT

, ionizing radiation, ionizing radiation

, infrared radiation, , infrared radiation,

naphthalene, dinitrophenol, naphthalene, dinitrophenol,

dinitrol-o-cresol,dinitrol-o-cresol,

ethylene oxide. ethylene oxide.

• Intense exposure to UV light Intense exposure to UV light

in the 295-320 nm range can in the 295-320 nm range can

cause cataracts that usually cause cataracts that usually

appear within 24 happear within 24 h

• "X-ray radiation in a dose of "X-ray radiation in a dose of

500-800 R directed toward the 500-800 R directed toward the

lens surface can cause lens surface can cause

cataracts, cataracts,

Laser eye damageLaser eye damage

a short introduction

http://www.adm.uwaterloo.ca/infohs/lasermanual/documents/section11.html

The majority of injuries involve the eye and, to a lesser extent, the skin

Summary of reported laser accidents in the United States and their causes from 1964 to 1992

Exposure Limits – Laser ClassificationExposure Limits – Laser Classification

Class 1 Lasers

Class 1 lasers do not emit harmful levels of radiation .

Class 2 Lasers

Capable of creating eye damage through chronic exposure. In general, the human eye will blink within 0.25 second when exposed to Class 2 laser light, providing adequate protection. It is possible to stare into a Class 2 laser long enough to cause damage to the eye.

At LCVU we use almost exclusively Class 3 and Class 4 lasers!

Class 3a Lasers (1-5 mW)

Not hazardous when viewed momentarily with the naked eye, but they pose severe eye hazards when viewed through optical instruments (e.g., microscopes and binoculars).

Class 3b Lasers (5-500 mW )

Injury upon direct viewing of the beam and specular reflections. Specific control measures must be implemented.

Class 4 Lasers (> 500 mW )They pose eye hazards, skin hazards, and fire hazards. Viewing of the beam and of specular reflections or exposure to diffuse reflections can cause eye and skin injuries. All control measures to be outlined must be implemented.

Exposure Limits – Laser ClassificationExposure Limits – Laser Classification

The effects of the laser depends strongly on the The effects of the laser depends strongly on the wavelengthwavelength

http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/8-50/INTRO.htm

The biological damage caused by lasers is produced through thermal, acoustical and photochemical processes.

Thermal effects are caused by a rise in temperature following absorption of laser energy. The severity of the damage is dependent upon several factors, including exposure duration, wavelength of the beam, energy of the beam, and the area and type of tissue exposed to the beam.

The most likely effect of intercepting a laser beam with the eye is a thermal burn which destroys the retinal tissue. Since retinal tissue does not regenerate, the damage is permanent.

Potential eye damagePotential eye damage

Acoustical effects result when laser pulses with a duration less than 10 microseconds induce a shock wave in the retinal tissue which causes a rupture of the tissue. This damage is permanent, as with a retinal burn.Acoustic damage is actually more destructive than a thermal burn. Acoustic damage usually affects a greater area of the retina, and the threshold energy for this effect is substantially lower.

Potential eye damagePotential eye damage

Beam exposure may also cause Photochemical effects when photons interact with tissue cells. A change in cell chemistry may result in damage or change to tissue. Photochemical effects depend strongly on wavelength.

the severity of the eye damage depends strongly on whether it occurs by intrabeam exposure or scattered laser light

Potential eye damagePotential eye damage

http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/8-50/INTRO.htm

Example of eye damageExample of eye damage

Experience has demonstrated that most laser injuries go unreported for 24–48 hours by the injured person. This is a critical time for treatment of the injury.