Occupational Eye Disorders By: H.R.Sarreshtehdar, MD

Introduction The reported incidence of occupational injuries that lead to visual disability approaches 70,000 workers in the united states each year. Many of these injuries are preventable. Knowledge about the work environment and potential work related risks, is important. Assessment of visual function is an important part of pre-employment medical screening and monitoring of the workforce.

History Caution : For chemical burns, emergency treatment should be started immediately. Mechanical injury : Tetanus inoculations and about the nature of the forces. Foreign body : Type of material Chemical burn : Alkali or acid Irritants : Assessment of exposures Previous underlying eye & visual disorders

Eye examination Even if an injury is thought to have affected only one eye, both eyes should be examined. Observation : swelling, redness, symmetry visual acuity Color vision Visual field testing Ocular motility and pupils Other tests

This should always be tested and the result recorded before treatment. That tested first binocularly and then for each eye separately. Values can be reported in one of two ways : 1- As the last line read correctly 2- The last line read correctly plus number of letters read correctly on the following line. A reserve capacity 2 to 3 times greater than the threshold is needed to work comfortably. Eye examination ( visual acuity )

Color vision appears to be particularly sensitive to toxic exposures, include solvents ( styrene, toluene, Perc & CS 2 ) and mercury. Screen tests : - Ishihara plates detect only red-green defect. - Waggoner H-R-R plates detect blue-yellow defect also. Quantitative tests Eye examination ( color vision )

Color blindness Congenital (more common) bilateral 99% red-green (Ishihara) Acquired Non-occupational Choroid, retina or optic nerve diseases Occupational Exposure to organic solvents (styrene, toluene)

Those test peripheral and central field. Those should be tested in who with suspected head injury or decrease in visual acuity. Confrontation field : most frequently use - Each eye is tested separately and binocular. - Test for four quadrants of peripheral vision. - The examiner brings his fingers slowly into view from the periphery. Amsler grid : Evaluate central visual field Eye examination ( visual field )

Eye movement must be test in all directions to make sure that they are the same in both eyes (symmetry). Neurotoxins effect on the eye movement. Limitation of upward or downward gaze occurs frequently in orbital floor fractures. Pupillary reactions to light must be examined. Eye examination ( Motivation )

Ophthalmoscopic examination Slit lamp examination Fluorescent staining of the cornea Contrast sensitivity Measurement of intraocular pressure Tear tests X-Ray, MRI and Sonography Neurotesting Eye examination ( others )

Acid burns : battery acids and clean metal - That tend to be fixed by protein in tissues Alkali burns: cleaning agents (NaOH & KOH), ammonia - Alkalis are not quickly neutralized by tissue, their destructive action can continue for hours. Clinical findings : skin and eyelid show edema and erythema. VA acuity is decreased. Complications : bluring of cornea, glaucoma, obliteration of the blood vessels Chemical burns

Emergency treatment with use immediately to wash the eyes with copious amounts of water until the patient can be taken to an emergency facility. The lids must held open. Topical anesthetic PH test Remove damaged epithelium Antibiotic and corticosteroid Chemical burns ( treatment )

Reflex lid closure usually protects eye surface Direct contact with molten metal or glass can cause severe injury to lids. Irrigation may be necessary to remove particulate matter. Extensive loss of lid skin can lead to exposure and drying of the cornea. Healing of lid skin is frequently fallowed by scarring. Thermal burns

Welder’s flash : exposure to UV radiation - After a latent period (6-8 h), this cause and acute onset of severe pain,Photophobia,blepharospasm and tearing - Treatment include an antibiotic ointment and patching the eye to prevent lid movement or blinking for usually hours. caution: The patient should not be given topical anesthetic to use at home. Mechanical injury (abrasions cornea)

Superficial foreign bodies : those are most commonly occuring work related eye injuries. - Fluorescein stains helps to locate the foreign body treatment by applying a topical antibiotic and covering the affected eye with a path dressing for hours. - scarring usually dose not occur caution: The patient should not be given topical anesthetic to use at home. Mechanical injury (abrasions cornea)

Intraocular foreign bodies History of irritating sensation Minimal discomfort at the moment of impact No superficial foreign body Vision may be normal Occupational history very important X-ray for opaque and sonography for non- opaque objects Mechanical injury

Intraocular foreign bodies : Type of material is important: Soluble metallic salts (iron and copper) it can cause irreversible toxic damage to the retina. They must be removed. Inert material (aluminum, plastic & glass) it may be unnecessary to remove. Organic material (wood and plant) it may cause infection. Remove is recommended. Mechanical injury

Optic neuropathy  Methanol( industrial solvent) Fixed & dilated pupils with optic disc edema,hyperemia & Central vision loss  CS2( rubber&viscose rayon production) Retinopathia (microaneurysms),Optic disc pallor & Central vision loss  Ethylene glycol & Thallium

Exposure to aerosol, dust, smoke and vapor. Acute: burning, tearing, belepharospasm. treatment is like to abrasions of cornea. Chronic: fatigue, dryness, burning and redness. irrigation with saline solution, adequate ventilation and avoidance of irritants are best preventive measures. Eye irritant

o Ionizing radiation o UV radiation o Visible radiation o Infrared radiation Radiation eye injuries

X-rays, beta rays, and other radiation sources in adequate doses can cause ocular injury. Eye lid vulnerable to x-ray damage (loss of lashes and scarring). Damage to conjunctiva lead to dryness of eyes. X-ray radiation in a dose of rad directed toward the lens surface can cause cataract. lonizing radiation eye injuries

Wavelengths < 300 nm can damage the corneal epithelium (arc welding, high altitudes and reflection of snow, water or sand). Wavelengths of nm are transmitted through the cornea, and approximately 80% are absorbed by the lens, where they may cause cataractous changes.  Any opacity in the lens is called a cataract. Types include age-related (most common), congenital, traumatic, diseases and toxic. UV radiation eye injuries

Visible light has a spectrum of nm. They can penetrate to the retina and cause tree type injuries : - Thermal : Increase C in the retina lead to photocoagulation of retinal tissue. - Mechanical : Sonic shock waves (lasers) - Photic : Prolonged exposure to light (Sun gazing and arc welding). The older humans are more sensitive to injuries. Visible radiation eye injuries

Infrared has a spectrum > 750 nm. Wavelengths spectrum of nm are biologically active for damage tissue. This can produce lens changes (cataract). Occupational exposure include processes in which thermal energy is used such as heating and dehydrating processes. glassblowers and furnace workers particularly are at risk. IR radiation eye injuries

Points to eye safety Have a safe work environment Identify of material(MSDS) Risk assessment Wear the proper eye and face protection Good selection Good use Prepare for eye injuries and first aid needs

Occupations include computer operator, librarians and students. Symptoms include sore eyes, fatigue and headache. Environmental and ergonomic factor are important contributors. There is no evidence that working with VDT can cause refractive eye disorders. Eye strains

Prolonged VDT use causes asthenopia esp. in astigmatism persons  For prevention & treatment Correct awkward postures Correct lighting of environment Correct refractive errors Eye strains

Primary visual targets should be located: In front of the operator Slightly below eye level (up to 30°) About cm away Light source is to the side of or above the user VDT ergonomics

Reduce illumination in the room to 500 lux. Maximum ratio of 1:3 between the brightness of computer screen and its surroundings. Use of glare reduction filters. Look up from the screen from time to time (20 seconds every 20 minutes).

About 60% of workers who suffer eye injuries did not wear eye protection at the time of the injury. Appropriate eye protection is the most important single intervention. assessment risk of operations and exposures. Visual checking in routine health exams. Planning for eye emergencies. Engineering modification. Prevention

There are many etiologies for occupational eye disorders including injuries, exposures and ergonomic factors. Most importantly, essentially of these disorders are more easily prevented than treated. The ophthalmologic effects of potentially neurotoxic chemical are a more difficult problem. Summery