Final Flashcards
Heat Hazards
Heat is an issue, blast injuries can have intraocular foreign bodies. The Halifax disaster
Chemical Hazards
True ocular emergency. From generally either strongly basic or acidic compounds. Severity is determined by the type, volume, concentration, duration of exposure and degree of the penetration. Protein coagulation of the cornea usually prevents acids from penetrating into the cornea. Alkaline substances penetrate the cornea and enter anterior chamber. Responsible for 7% of work-related eye injuries. Following chemical insult to the eye, the degree of blanching of the limbal vessel is the most significant indicator for future corneal healing
Common sources or alkali
Cleaning products, fertilizers, drain cleaners, cement, plaster, mortar, airbag rupture, firewords, potash
Common sources of acids
Battery acid, bleach, glass polish, vinegar, chromic acid, nitric acid, hydrochloric acid
Treatment for chemical injuries
immediate copious irrigation. A delay as little as 20 seconds is sufficient to cause significantly greater harm and increase the pH of the anterior chamber. Remove the source of the insult, control inflammation with topical steroids, prevent infection, control IOP, control pain. Safety goggles!
Physical Hazards
Smoke and Dust hazard, radiation hazards (UV from welding), high intensity irradiations may have latency periods of only 30 mins before onset of symptoms, low intensity exposures may have latencies as much as 24 hours before onset of symptoms. Infrared radiation injuries (high temp furnaces, certain lasers) thermal effect of IR is more permanent than UV damage, produces cataracts. IR has latency of 15 to 20 years.
Radiation Eye protection
UV welding helmets, considered secondary protectors, must wear Z87.1 safety eyewear under helmet. Photosensing lens, darken in response to the light comfort of the viewer. UV solar protection, LASER protection: goggles are best but spectacles are acceptable, lenses marked with wavelength and optical density. ANSI Z136.1-2014 is the acceptable standard.
Eye injuries in children
Best way to prevent eye injuries in children is to resist children’s request for toy weapons
Tracking Injuries in Sports
US consumer product safety commission operates an injury surveillance system, National Electronic Injury Surveillance System provides data on both product-related and non-product related injuries. NEISS does injuries in the ER, but could be bad cause not everyone goes to the ER.
Eye injuries in sports
Patients with certain eye conditions are more at risk for sports-related eye injuries, certain sports have a higher risk for eye injury,
Patients who may be more at risk for serious sports-related eye injuries
High myope, monocular patient, amblyope, peripheral retinal disease, history of eye surgery (cataract, keratoplasty, radial keratotomy)
Sport that has the most sports related injuries
Basketball
Negligence in sports safety
failure to recommend the appropriate type of eyewear, failure to recommend the appropriate lens material, failure to inform patient of increased risk for eye injury in certain sports (boxing)
Purpose of eye protective devices
Prevent damaging forces from reaching the eyes, dissipate potentially harmful forces over time and area, frontal bone best for distributing forces when protecting the eyes, eye protective devices are only effective when worn by the player
What sports eyewear do you recommend?
Helmet with face protection, helmet with separate eyewear, face supported protection, eye protector
Eye Safe sports
Gymnastics, track and field, swimming, diving, skiing, wrestling, bicycling
Moderate Risk sports
Tennis, badminton, soccer, volleyball, water polo, football, fishing, golf
High Risk (use small fast projectiles)
Air rifle, BB gun, paintball
High risk (use of hard projectiles, sticks, close contact)
Basketball, baseball/softball, cricket, lacrosse, hockey, squash, racquetball, fencing
High risk (use intentional injury)
Boxing, full-contact martial arts.
Sports Eyewear
ASTM F803-14 eye protectors for selected sports ) racket sports, basketball, baseball fielders, women’s lacrosse, field hockey, soccer
ASTM F910-04 face guard for youth baseball
ASTM F1776-14 eye protectors for use by players of paintball sports
Eye protector classification
Type 1: Lens and frame frontpiece molded as one unit
Type 2: Lens, plano or Rx, mounted in a frame manufactured as a separate unit
Type 3: Frame without a lens
Type 4: Full or partial face shield
Baseball/Softball (youth batter and base runner)
ASTM F910
Baseball/Softball (fielder)
ASTM F803 for baseball
Basketball
ASTM F803 for basketball
Field Hockey
ASTM F803 for Women’s lacrosee
Paintball
ASTM F1776
Racquet sports
ASTM F803 for selected sports
Soccer
ASTM F803 for selected sports
Ocular Injuries associated with airsoft guns
Mean age of those inured was 18 years, final VA’s ranged from 20/20 to 20/70, hyphema was a commonly observed finding, no open globe injuries or retinal detachments occurred (more common with BB guns)
Ocular Injuries associated with paintball
Severe ocular injuries: hemorrhage, hyphema, cataract, retinal detachment, optic nerve avulsion, chorioretinitis sclopetaria
Fireworks related injuries
Parts of the body most injured were hands, head/face, eyes. Types of eye injuries: burns, contusions/lacerations, other diagnoses. Sparklers are not safer for kids, Bottle rockets are not safer for kids.
Material for sports eyewear
Polycarbonate or trivex
Environmental Lighting
Significant effect on occupational vision, environmental vision and eye safety, can optimize visual performance. As lighting levels increased higher speed of production, lower error rate. When contrasts are low or the task is small, increasing illuminance will have a large effect on performance, when contrasts are high or the task is large, increasing illuminance will have little effect on performance.
Luminous Power
Total light power produced by a source in all direction. Lumens.
Luminous intensity
Light power produced by a source in a given direction. Candelas. (lumens/steradian)
Illuminance
The light incident on a surface. Foot candles (lumens/Ft2). Lux (lumens/m2)
Luminance
The light coming off a surface in a specific direction. Foot-lamberts (lumens/steradian/m2)
Luminaire
A complete lighting unit consisting of a light source, housing, supports, shields, etc.
Surface reflectance
Ceiling: 80-90 Walls: 40-90 Furniture tops: 25-45 Machines and Equip: 25-45 Floors: 20
Sources of Light
Incandescent: produces light though heat
Luminescent: produces light through excitation of individual atoms
Incandescent Sources of Light
Conventional light bulbs, halogen lamps. Adv: low initial cost, small lamps, easy to install, excellent color rendering, readily available. Disadv: short life, least efficient.
Luminescent Sources of lighting
Fluorescent, high intensity discharge lamps (mercury lamps, metal halide lamps, high pressure sodium lamps) Low pressure sodium lamps, LED, Adv: more efficient, less heat, longer life, decent color rendering. Disadv: glare, reflections, flicker, large size, contains mercury, higher cost, more complicated
High Intensity Discharge Lamps Adv and DIsadv
Very efficient, lots of light over wide area, long life
May have poor color rendering, ballast delay when starting contain mercury
Low pressure sodium lamps Adv and Disadv
Very efficient, lots of light over wide area, long life
Non-existent color discrimination
LED Adv and Disadv
Very efficient, incredibly long-lasting
Dimmer, cost, some color degradation
Standard Illuminants
Illuminant A: average incadescent
Illuminant B: direct sunlight
Illuminant C: average daylight, recommended for color vision tests
Environmental Lighting
Two major components, quantity (amount of light), quality (color, brightness, glare, uniform illumination)
Direct Lighting
Most efficient lighting system, prone to producing harsh shadows and marked reflections from the work surface
Indirect Lighting
Provides diffuse lighting with minimal shadowing and reflections, less efficient due to absorption from the reflecting surfaces
Supplemental Lighting
Incandescent-goose neck lamo
Fluorescent with parabolic louver
Determining Illumination Levels
Based on system adopted by the IESNA: determine the task characteristics, determine the criticality of the task, determine the age of the users
Object color
The perceived or spectral color of an object based on its reflecting characteristics of the illuminating source
Color
Important for jobs which require color matching, different light sources produce different colors
Color Rendering
How natural and normal will a light source make thins appear compared to natural sunlight. Color rendering index: scale of 1-100, , incandescent is 100. Indoor lighting 80-85. Lss pressure sodium is basically 0.
Correlated Color Temperature
A relatively simple metric through which source appearance can be quantified. Useful vecuase light sources emit light that is viewed as having a particular whiteness that may be/is different from another source. Equates the appearance of a source to a blackbody radiator operating at the same temperature.
Lighting conditions for color testing
Daylight, Macbeth Lamp (approximates natural sunlight)
Glare
Relatively bright light which interferes with optimal vision, or produces discomfort
Distracting Glare
Caused by lens reflections
Discomfort Glare
Sensation of irritation or pain from sources of light in the field of view. Prevented by avoiding large bright areas within a space, limiting luminance ratios to less than 10:1, indirect lighting systems
Disability Glare
Causes objects to have lower contrast than they would have if there were no glare, similar to turning on the room lights while watching a slide show, increases the brightness of the background and lowers the brightness of the object, washes out what you are looking at
Reflected Glare
Glare caused by reflected light sources, example is the glare off a shiny page in a book when held at the wrong angle when reading, if all surfaces were diffusely reflecting and all lighting indirect, reflected glare would not be a problem. Elimination of reflected glare: change position of task or light, use a dull or matte finish on a surface, change light source, change lighting type
Uniformity of Illumination
IESNA considers illumination to be uniform if the maximum and minimum levels are not more than 1/6 above or below the average level. Closer spaced lights improve uniformity
Brightness Ratio
A 3:1 or 1:3 ratio is good for most near work and tasks, higher ratios are more comfortable for more distant tasks, up to 40:1 is seldom used storage or outdoor activities. Brightness ratios are important in playing ball, changing the oil in your car, threading a needle, and reading
Luminaire Source Efficiency and Color rendition Index table
Incandescent has poor efficiency (17-23), but great CRI (100). Low pressure sodium is 10x more efficient (170) than incandescent, but CRI is nonexistent (0). Fluorescent (70-80) CRI:(50-90)
Laser
Light Amplification Stimulated Emission Radiation
Laser Radiation
Travels through space as an EM wave, highly directional, monochromatic, exhibits coherence
Coherence
Collimated light that is in the same phase, same wavelength, and traveling in the same direction
Laser output can be described by:
Pulse duration, Irradiance, wavelength
Pulse Duration
Pulsed lasers produce exposure that range from femtoseconds to milliseconds, continuous wave lasers produce longer exposures; pulse durations of 0.25 second or longer are considered to be continuous wave`
Irradiance
Incident laser power per unit area delivered to a target surface. Irradiance= power/area (watts/cm2). Depends on the laser spot size and power (lower spots size will increase irradiance for a particular power)
Wavelength
Determines how effectively light is captured by the tissue target (absorption) and how well light penetrates overlying media to reach a tissue target. Ophthalmic Laser wavelengths: UV (100-380), visible(380-760), IR (760-1)
Safety Requirements for Lasers
ANSI Z136.1-2014 (safe use of lasers)
ANSI Z136.3-2011 (safe use of lasers in health care facilities)
Laser viewing conditions
Direct intrabeam viewing
Specular Reflection
Diffuse
Direct Intrabeam Viewing
Laser beam from source to eye: unimpeded, unobstructed
Specular Reflection
A mirror like reflection, remember, the angle of incidence is between the normal and the light ray, not between the surface and the light ray. The angle of incidence= the angle of reflection in specular reflection. This is a more troublesome issue with lasers: unwanted reflection
Diffuse
The change of the spatial direction of a beam of radiation when it is reflected in many directions by a surface or a medium. Just because the beam is disrupted doesn’t mean that it is safe, a class 4 can cause a fire secondary to a diffused laser beam issue.
Old Laser Classification Class 1
Class 1: no eye hazard, eye safe, exempt from control measures, no warning label required, outputs up to 0.4 microwatts.
Old Laser Classification Class 2
Class 2: low power/low risk, natural avoidance (blink reflex, pupillary constriction), no warning label required, outputs up to 1 mW of visible radiation, sometimes additional 2a categorization
Old Laser Classification Class 3a
Class 3a: eye safe when viewed directly, retinal damage if viewed with an optical instrument (ex. binoculars) , required caution or danger label, outputs up to 5mW of visible radiation
Old Laser classification Class 3b
Moderate power/moderate risk, retinal damage
Old Laser classification Class 4
High power/high risk, retinal damage, can cause combustion, danger label required, outputs greater than 500mW
Old Control Measures on Laser Protection
Engineering: interlocks, shutters, watch-dog timers, first line of defense, more reliable than administrative controls and are given higher priority. Administrative: control measures include training, safety approvals, laser safety officer designation, standard operating procedures, 2nd line of defense. Personal Protective Equipment: Control measures incorporating personal safety protective devices, laser eye protection, protective clothing, gloves, last line of defense-used when engineering and administrative controls can’t ensure safety
Newer/Revised Safety Standards
ANSI Z136.1/IEC 60825
Required warning label on laser equipment, additional triangular warning label required for Class 2 or higher. Warning label should include: class, emitted wavelength, pulse duration, maximum ouput power, precautionary statement for users
New Class 1
Safe under normal use conditions, exempt from control measures, laser eye protection not required
New Class 1M
Safe under normal use conditions except when using magnifying optics, Exempt from control measures except under unusual viewing conditions
New Class 2
Safe assuming intact blink reflex, exempt from control measures except under unusual viewing conditions, emits radiation in the visible spectrum only
New Class 2M
Safe assuming intact blick reflex and not viewed through optical instrument, exempt from control measures except under unusual viewing conditions, Laser eye protection not required
New class 3R
Safe with careful handling and restricted viewing, exempt from most control measures except under unusual viewing conditions, laser eye protection not usually required, laser controlled area warning sign often recommended, caution used on warning sign
New Class 3B
May be hazardous with direct or specular exposure, protective eyewear required with any possibility of direct viewing, appropriate control measures required, laser eye protection required, warning used on warning sign
New Class 4
Most dangerous, eye damage from direct, specular, or diffuse viewing, protective eyewear required, appropriate control measures required, laser eye protection required, laser controled area warning sign required, Danger or warning used on warning sign
Laser Ocular Effects and Damage
Extensive damage to Retina, usually macula
Laser Eye protection
Attenuation Effect, refers the decrease in radiation power as a laser beam passes through an absorbing or scattering medium, works by blocking or hugely reducing the power/intensity of particular wavelengths that enter the eye. Wavelength specific, protective eyewear must be selected for wavelength of light employed by the laser. Laser glasses are laser specific, not just for any laser! Optical density must be appropriate to laser output (power)
Standard Alignment of Nosepads
There is a specific standard alignment for nosepads that should be used during the preliminary adjustment of the frame
Frontal Angle of Nosepads
Like a chickens wings, when viewed from the front, refers to vertical positions of pads, tops of pads closer together than bottoms, angles in approx 20 degrees from a true vertical
Splay angle of nosepads
Like the miss America wave, view from above, you will want the face of the pads rest fully on the nose; nose is wider at the base than the bridge, therefore, back edges of pads should be further apart than the front edges, about 25-30 degrees
Vertical angle of nose pads
Like signaling to park an airplane, view from the side, probably the most neglected angle, pad bottoms are slightly closert to the frame front than the top, approximately 15 degrees
Ideal pad face distance from frame
Pads should have same amount of rock, same amount of play, both pads also should be at same height, faces of nosepads approx 1mm closer to the nose than the actual eyewire
Frame Adjustment
- Temple Spread
- Equality of lens vertex distance
- Pantoscopic tilt of frame front
- Frame Straightness
- Nose pad adjustments
- Temple position and bend, lateral pressure, earpiece curl
Final nosepad adjusment frame goal
Achieve the correct frame height, proper vertex distance
Final nosepad adjustment pad specifics
Pads halfway between nose crest an nasal canthus, long pad diameter perpendicular to floor with head erect, full surface of pad resting uniformly on the nose
Widening the distance between pads
Tilt the top of the pliers temporally making the pivot point the pad attachment point on the arm. Tilt the bottom of the pliers temporally making the pivot point the top of the pads arm’s inverted U. Why? The frame is too high on the face, the bifocal or trifocal segments are too high, the progressive addition fitting cross the heights are too high, the bridge is too small for the nose, the lenses are too far from the eyes
Narrowing the distance between the pads
Tilt the top of the pliers nasally making the pivot point the pad attachment point on the pad arm, tilt the bottom of the pliers nasally making the pivot point the top of the pad arm’s inverted U. Why? The frame sits too low on the face, the bifocal or trifocal segments are too low, the progressive addition fitting cross heights are too low, the bridge is too large for the nose, the lashes rub the back surface of the lenses
Moving Frame Right or Left
Need to move the frame right, move pads to the right (same for left)
Final Nosepad adjustment Check
Is the distance between the pads correct, are the pads on the correct part of the nose, do the splay angles of the pads match the splay angles of the nose, do the frontal angles of the pads match the frontal angles of the nose, do the vertical angles of the pads equal the pantoscopic angle of the frame front, do the pads fit flat on the surface of the nose
To move frame away from face
Narrow adjustable nose pads, increase effective length of pad arms, shrink bridge, decrease face form
To move frame close to face
Widen adjustable nose pads, decrease effective length of pad arms, stretch bridge, increase face form
To move frame higher on face
Narrow distance between nosepads, lower vertical position of nosepads, shrink bridge
To move frame lower on face
Widen distance between nosepads, raise vertical position of nose pads stretch the bridge
To move frame off the cheeks
Decrease pantoscopic tilt, raise the frame, increase vertex distance
To move frame off the brow
Increase pantoscopic tilt, lower the frame, increase vertex distance
Possible benefits of CLs in the work environment
Increased VA Enhanced visual field Decreased reflections Better performance in the rain, mist Less problem with perspiration Less likely to smear or smudge No fogging Better seal with mask or goggles
Potential Chemical Hazards on CL
Hard: the chance of a chemical becoming trapped behind the lens is unlikey; substance would be eliminated rapidly by tear flow
Soft: Water soluble gases and fumes and substances capable of being absorbed into a hydrogel material might prolong exposure with a more severe response. No extended contact wear, frequent replacement
Potential Mechanical Hazards on CL
Hard: the chance of a foreign body becoming trapped behind the lens is possible, lens could shatter with enough striking energy
Soft: may provide slightly more protection from foreign bodies striking the eye
Potential physical hazards on CL (temp extremes, IR and UV radiation, microwaves)
depending on absorption characteristics of the CL material, contact lens will not have a deleterious effect and may have a small positive effect. No greater risk but NOT a substitute for eye protection
