Download Potential eye damage

‫بسم هللا الرحمن الرحیم‬
Occupational eye disorders
By :Sotoudeh Manesh MD
Important
Ergophthalmology
USA:1.4 million injury &illness in2002
- 47% of all head injury
- ocular foreign body:38%
- contusion/abrasion:27%
- burn:12%
- conjectivitis:11%
Non-construction>welder>cutter>truck
driver
- 4%workers compensation claim &1%total paymnt
•
Two General Types of Vision and
Eye Assessments Can Be Differentiated
Screening
•
Examination
— Identifies those at high risk
— Examines subjects for
or in need of a professional
eye
examination
disorders and diseases
— May detect disorders in
— Diagnoses eye disorders
early, treatable stage
and diseases
— Provides public with
— Prescribes treatment
valuable information and
education about eye care
— Results in referral to an eye
care professional or primary
care provider
Source: Prevent Blindness America
Components Of Vision Screening
History and symptoms
Visual acuity at any distance
Visual field
Colour vision
Depth perception
Contrast sensitivity
Visual acuity
Snellen chart
Acuity at
Near&Distance
Near visual acuity
• Definition
The ability to see clearly at a normal reading
distance
• Method of measuring
Jaeger card-reduced snellen chart
• Causes of decreased near V.A in the
presence of normal distance V.A
Presbyopia,uncorrected hyperopia,centerally
located cataracts and drug side effects
Visual field
Confrontation test
primetry
Visual field
• Normal extension
 70 degrees Inferiorly, 60 degrees superiorly,95 degrees
temporally and 60 degrees nasally.
Total horizontal visual field extent to 190 degrees
• Factors that influence the visual field
 Size, distance, background illumination, colour,
Kind of job, Bi or monocular vision, age, use of
Personal protective device ( safety spectacle)
Color blindness
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).
Normally, there are three kinds of
cones (each one sensitive to a
specific range of wavelengths):
"red" cones (64%)
"green" cones (32%)
"blue" cones (2%)
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 Blindness
• Monochromacy: occurs when two or all three of the cone
pigments are missing and color and lightness vision is reduced to
one dimension.
 Total color blindness
• Dichromacy: occurs when only one of the cone pigments is
missing and color is reduced to two dimensions.
 Partial color blindness
red-green
blue-yellow
Dichromacy
Photoreceptor Anatomy
•
Example: if you
stimulate all 3 types of
cones about equally the
result is white or no
color.
Colour vision test
Ishihara
plates
Colour vision deficiency in wokplace
• Styrene
• Toluene
• Perchloroethylene
• Carbon disulfide
• Metallic mercurry
• Mercury vappor
• n-hexan
Depth perception (Stereopsis)
 The ability to precieve depth or relative distance
Some jobs that need stereoscopic vision
 Furk-lift truck operator , crane driver, pilot ,…
Factors that influence depth perception
 Uncorrected refractive errores, amblyopia , squint
low level of illumination , anisometropia , age ,
Advantages of binocular vision over monocular
 The presence of stereopsis , improved visual acuity , an enlarged
Field of peripheral vision , slightly brighter of object
Clinical tests for stereopsis
Contour stereotest
 Titmus stereotest
Random dot stereotest
 Frisby test
 Random Dot-E test
Clinical Contrast Sensitivity Tests
•
Pelli-Robson chart
•
Regan low-contrast
•
Vistech chart
•
Melbourne edge test
Occupational EYE
Illness
EYE injuries
EYE Diseases
EYE Chemical Burns
1. Alkali burns
2. Acid burns
3. Irritants
Eye Acid Burns
Sulfuric acid
Nitric acid
Chlorohydric acid
Hipochloric acid
Perchloric acid
Flurohydric acid
Cholor
So2 So3
No2 N2o4 ?
Alkali Burns
Sodium hydroxide
Potassium hydroxide
Amonia
Cement
Lye
Detergents
Emergency
•
Treatment should be immediate, even
before making vision tests!
•
Premedicate with proparacaine or
tetracaine.
•
Copious irrigation: LR or NS X 30 min.
•
Wait 5 minutes and check pH. If not
normal, repeat.
Mild-to-Moderate Chemical Burns
• Critical signs
Corneal epithelial
defects range from
scattered superficial
punctate keratitis
(SPK) to focal
epithelial loss to
sloughing of the entire
epithelium
Mild-to-Moderate Chemical Burns
• Other Signs:
Focal area of
conjunctival chemosis.
Hyperemia.
Mild eyelid edema.
Mild-anterior chamber
reaction.
1st or 2nd degree burns to
periocular skin.
Moderate-to-Severe Chemical Burns
• Critical signs:
Pronounced
chemosis and
perilimbal
blanching
Corneal edema and
opacification
Moderate-to-Severe Chemical Burns
• Other signs:
Increased IOC
2nd & 3rd degree burns of
the surrounding tissue
Local necrotic retinopathy
Treatment :
Irrigation
Antibiotics
Artificial tear
Steroids
Ascorbic acid
Calcium gluconate
dilating eye drop
Complications :
Scares
Glaucoma
Blindness
Physical trauma
• Corneal abrasion
Corneal laceration
Foreign Body
31
Illinois EMSC
Corneal Foreign Body
•
Symptoms:
 Foreign-body sensation
 Tearing
 Blurred vision
 Photophobia
 Commonly, a history of a
foreign body
Penetrating ocular injury
• Incidence : 1.4%-4%
• Industries at Greatest risk: construction; manufacturing
• Object: metal fragment ;glass; nail
• Sign:
• Flat eye
• Low vision
• Low intraocular pressure
• hyphema
‫‪Foreign Body‬‬
‫•‬
‫نمکهای متالیک ‪:‬‬
‫•‬
‫نظیر آهن و مس ‪:‬سبب آسیب توکسیک غیرقابل برگشت در شبکیه‬
‫•‬
‫مواد کمتر محلول‪:‬‬
‫•‬
‫آلومینیم‪ ،‬پالستیک ‪،‬شیشه پروگنوز بهتری دارند‬
‫•‬
‫اجسام خارجی ارگانیک‪:‬‬
‫•‬
‫چوب سبب عفونت داخل چشمی با درمان بسیار مشکل و پروگنوز بد‬
Radiation
:
UV < 400 nm
IR
> 700 nm
Visible 400 – 700 nm
Ionising <0.0001 nm
ELF
1000 - 10000 Km
Electromagnetic Spectrum
Radio
Micro
I.R.
104 106 1010 1013
Visible
U.V.
X-ray
-ray
1023 Hz
UV Sources :
Sun
• UV-C:100-290nm:does not normally
Welding
Lamps
penetrate the earth atomospher
•
UV-B:290-320 nm: cortical cataract;
Foundry
petrygium; photokeratit; intraocular
Blacksmitch
melanoma??
• UV-A:320-400nm: petrygium
Infra Red
IR - A : 780 – 1400 nm
IR – B : 1400 – 3000 nm
IR – C : 3000 - 10000 nm
• All form of cataract
• Pathagnomonic: exfoliative or
splitting of anterior lens capsule
IR sources :
Sun
Heaters
Steel Industry
Glass Industry
Lasers YAG - Neodymium - CO2
Lamps
Welding
IR 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 :
microwaves,
TNT
, ionizing radiation
, infrared radiation,
naphthalene, dinitrophenol,
dinitrol-o-cresol,
ethylene oxide.
• Intense exposure to UV light
in the 295-320 nm range can
cause cataracts that usually
appear within 24 h
• "X-ray radiation in a dose of
500-800 R directed toward the
lens surface can cause
cataracts,
Laser eye damage
a short introduction
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
http://www.adm.uwaterloo.ca/infohs/lasermanual/documents/section11.html
Exposure 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!
Exposure Limits – Laser Classification
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.
The effects of the laser depends strongly on the
wavelength
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/8-50/INTRO.htm
Potential eye damage
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 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 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
Example 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.
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/8-50/INTRO.htm