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159 Cards in this Set
- Front
- Back
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Emmetropia |
Eye focus light precisely on the retina |
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Myopia |
(nearsighted) light rays focus in front of the retina |
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Hyperopia |
(farsighted) when light reaches retina the object is not in focus |
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Astigmatism |
Light rays focus on multiple points on the retina |
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Presbyopia |
When the crystalline lens is no longer able to change shape and focus on objects At different distances |
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Compound myopic astigmatism |
Both sphere and cylinder are myopic or minus power(compounds) ex: -2.00 -.75 x180 |
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Compound hyperopic astigmatism |
Adding the sphere and cylinder together results in a hyperopic value, the added value and the original sphere value are both hyperopic. Ex: +2.00 -.75x180 |
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Mixed astigmatism |
When adding the sphere and cylinder together the original sphere power and the added value have different signs. Resulting in one being myopic and the other hyperopic. Ex: +1.00-1.25x180 |
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One meter=___in |
39.37 |
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One cm= ____ in |
.39 in |
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2.5 cm =____in |
1in |
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One mm=____ in |
.4in |
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25 mm=____in |
1in |
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UVC rays |
Absorbed by atmosphere 200nm-290nm |
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UVB |
Source of sunburns 290nm-315nm |
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UVA |
Associated with skin aging. 315nm-389nm |
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Light reflection Grass and soil Sand Water Snow |
10% 15% 25% 80% |
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Index of refraction |
Relationship between the speed of light in air and the speed of light in a medium. |
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Speed of light |
186,000 miles per second |
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Angle of incidence |
Angle of incoming ready of light |
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Angle of reflection |
Angle at which the ray leaves the surface |
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Angle of refraction |
Angle that light rays take as they travel through a medium |
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Where is light directed in a prism |
Base |
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Average blink rate |
7to12 times per minute |
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Medial rectus |
Tword the nose |
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Lateral rectus |
Away from the nose |
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Superior rectus |
Upward |
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Inferior rectus |
Downward |
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Superior oblique |
Top of the eye tword the nose |
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Inferior oblique |
Top of the eye away from the nose |
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Cornea |
Clear, outer portion of the eye |
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Total eye refractive power |
60D |
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Cornea refractive power |
2/3 |
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Crystalline lens refractive power |
1/3 15-16D |
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Iris |
Colored part of eye. Controls light inside eye. Devides the front and back of eye |
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Pupil |
Center of iris. Light ray pass through to get to retina |
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Crystalline lens |
Transparent located behind the iris. |
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Ciliary muscles |
(Zonular fibers) shape the lens to focus light on the retina. |
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How zonular fibers work |
Zonules relax, ciliary body contract, causes crystalline lens to thicken. (Ability to see up close) Zonules contract,ciliary body relax, causes crystalline lens to thin.(ability to see far away) |
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Accommodation |
Ability of crystalline lens to change to allow eye to focus |
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Aphakic |
Without crystalline lens |
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Pseudophakic |
With an intraocular implant |
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OD |
Oculus dexter |
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OS |
Oculus sinister |
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OU |
oculus uterque |
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Visible light |
380nm and 750nm |
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Optical center |
Single point on lens where light may pass without being refracted Plus lens-where bases meet Minus lens-where apex meet |
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Plus lens |
Magnify Against the motion Weaker when closer to the eye Pincushion distortion Converge light Thicker in center Correct hyperopia |
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Minus lens |
Minify Becomes stronger when closer to eye Barrel distortion Diverge light Thinner in center Correct myopia |
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Vertex distance |
Distance glasses are from eye |
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Three types of aberrations |
Spherical Marginal Distortion |
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Spherical aberration |
Parallel light rays enter, peripheral rays focus sooner than center rays |
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Marginal aberrations |
Small bundle of light strikes lens from an angle. Astigmatism is created. |
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Distortion aberration |
As rays approach lens edge, magnification,or minification increases and distorts the image |
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How to measure base curve |
Lens clock |
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Major reference point |
Point where the prism equals the amount prescribed |
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Cancelling prism |
Base in &base out Base up &base up Base down &base down |
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Compounding prism |
Base in &base in Base out & base out Base up & base down |
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Specific gravity |
Density of material |
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ABBE value |
Chromatic aberrations in material. Occur because color components have different wavelengths Higher value=lower amount aberrations |
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Reflectance |
%of light reflected from highly polished surface |
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Transmittance |
Amount of light that passes through a material. In our case measures how much uva |
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Characteristics Cr39 |
Good Optics, half weight of glass, more impact-resistant than glass, can have scratch resistant, easy to tint and UV coat. Good for Rx less than+/-2.00 |
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Characteristics Polycarbonate |
Highly impact-resistant, thinner and lighter than CR 39, can block UV rays, can be scratch resistant, tinting difficult |
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Characteristics Trivex |
Strong, light, impact-resistant, built-in UV protection, can be made without scratch coating, easily tinted and AR coated |
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Characteristics Hi-index |
Index of refraction higher than 1.58 thinner and lighter than plastic, good Optics, built-in UV protection, these curves can be ground thinner reducing lens thickness, easy to tint, requires AR coating |
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Characteristics Glass |
Scratch resistant, heavier and shatter more easily |
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Index of refraction |
Indicates how much the material will bend or refract light |
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ASTM |
American Society for testing materials |
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FTC |
Federal Trade Commission promotes consumer protection and elimination and prevention of anticompetitive business prices |
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Lensometer Rectle (target) |
Prism scale with series of circles used to Center lens |
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Lensometer Prism dial |
Used to measure prism |
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Lensometer Marking device |
Ink blotting mechanism used to Mark Optical centers |
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Lensometer Lens holder |
Spring-loaded arm used to hold lens in place |
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Lensometer Lens table |
Adjustable straight metal shelf Warframe rest to make sure axis reading is correct |
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Lensometer Power Wheel (power drum) |
Large wheel used to find power of Lens marked with powers ranging from -20 to +20 diopters. Black numbers r+ powers and red numbers are negative powers |
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Lensometer elevation level |
Changes angle of lensometer |
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Lensometer Axis wheel |
Large Wheel Marked from 0 degrees to 180 degrees used to find access location |
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What do sphere lines look like on a lensometer |
3 thin close lines |
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What do cylinder lines look like on a lensometer |
Three widely spaced lines |
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How do you determine if the lens is spherical on a lensometer |
If both sets of lines are in sharp focus at the same time |
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How can you tell if a lens is a spherocylindrical lens on the lensometer |
It's both sets of lines are not in focus at the same time |
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How Can you tell if a prismatic lens is centered on the lensometer |
When lines are located on indicator rings at point that matches prescribed prism |
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Anti reflective coating |
Improves light transmission to almost 100%. improve night driving |
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Grey tint |
Do not distort colors. Reduce overall brightness.Do not distort colors.Comfortable to wear for an extended period Of time. Comfortable to wear for an extended period Of time. |
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Brown tint |
Reduce glare.Absorb higher frequency colors.Increase contrast.Good for emerging cataracts,Hazy Days, tasks that require contrast |
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Green tint |
Filter some blue light and glare.Great contrast and good color balance.Good for tennis, golf, driving.Best absorption of infrared wavelengths. |
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Yellow, gold, orange tint |
Reduce blue light.Good for skiing, cycling, shooting. Provide maximum contrast.Good for overcast days and low light driving |
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Red tint |
Increase contrast.Good for fishing in early morning, late evening hours.Good for low lighting conditions |
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Purple and Rose tint |
Good contrast against a green or blue background.Good for hunting water skiing, snow, snowmobilers.Pink good for computer users |
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Melanin tint |
Melanin is additive.Selectively block Violet and high-energy blue light. And to provide high contrast without altering colors.Golfers and low-vision patients |
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Blue tint |
Can be used in most lighting conditions.Good for tennis, golfers, snowmobiling, shooting green targets.Can add more glare |
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Mirror tint |
Reflex mirror reduce light transmission by 20 to 30%.Designed for bright sunlight conditions such as water activities and cycling |
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Round face frame selection |
Use rectangular frame shapes that are whiter than longer.Do not use round frame shapes |
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Oval shape frame selection |
Use frames as wide or a little wider than the broadest part of the face |
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Oblong face frame selection |
Use wider frames, overal, decorative or contrasting temples |
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Triangular face frame selection |
Detailing on the top half of the eyeglasses use frames that are wide at the bottom or rimless styles |
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Diamond shape frame selection |
Use frames with detailing or distinctive browline Use oval or cat eye shapes |
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Square shape frame selection |
Use Narrow, oval shaped frame styles with more width then depth |
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Saddle bridge |
Plastic Bridge, distributes weight evenly across the nose, no room for adjustment |
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Modified saddle bridge |
Plastic Bridge, fixed nose pads, more room for adjustment |
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Keyhole bridge |
Plastic Bridge, looks like a keyhole, weight is supported by side pads |
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Pad bridge |
Used with Metal Frames, nose pads attached by metal arm, frame does not touch the face |
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Metal saddle bridge |
Used with Metal Frames, frame rests directly on the nose |
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Eye wire or rim |
Frame that goes around the lens |
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Boxing system |
An imaginary box containing the lens is used to determine the length and depth of the lens |
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"A" measurement |
Horizontal measurement across the lens part of the boxing system |
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"B" measurement |
Vertical measurement. add 1 millimeter for Groove. part of the boxing system |
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Effective diameter |
Geometric Center geometric Center to longest outermost Edge Times by 2 |
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Darrin or 180 degree line |
Halfway between the top and bottom of the Len |
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Geometric center, box center |
Where A and B measurements meet |
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Frame difference, Len difference |
Difference between the A&B measurements |
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DBC |
Measure from far left side of one lens opening too far left side of other opening |
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End pieces |
Attach temples to the frame front |
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Hinges |
Hold temples to frame front |
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Butt portion |
Closest to the front |
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Bend |
Where the temple goes over the ear |
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Shaft |
Between the butt portion and bend |
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Skull temple |
Most common style |
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Library temples |
Straight with no Bend, great for constant off and on wear |
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Cable style temples |
Wrap around the ear, great for kids and active people to prevent eye glasses from slipping |
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Plastic frame |
Zyl Cost-effective, lightweight colorful easy to adjust, easier to break and can burn it overheated |
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Optyl frame |
Vacuum injected epoxy resin, available in Many Colors, memory capable, cost-effective, hypoallergenic, lightweight |
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Metal frame |
Fitting flexibility, lighter softer appearance |
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MONEL |
Mixture of metals, most widely used, flexible, corrosion resistant |
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Titanium |
Lightweight, durable and strong, corrosion resistant, comes in many colors, not all are hundred percent titanium |
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Beryllium |
Lower-cost, good for high skin acidity or salt water exposure, available in colors, lightweight and strong, easy to adjust |
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Stainless steel |
Lightweight, low toxicity, great strength, hypoallergenic, Iowa of Steel and chromium, most are 10 to 30% chromium, resist corrosion |
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Aluminum |
Lightweight, highly corrosion-resistant, commercial aluminum with silicon and iron is hard and strong |
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Nose pad frontal angle |
Closer together at the top than at the bottom, mirrors the shape of the nose, each pad should be at same height and same distance from eyewire |
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Splay or spread angle |
Front edges are closer than back edges. And her mirror slope of the nose.Flat Bridges have wide splays |
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Vertical angle Nose pads |
Bottom edges should be closer to the other than top |
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Hexagon wrench |
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Angling pliers |
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Corneal abrasion |
A break in the corneal epithelium.Can heal very quickly.Symptoms: pain, light sensitivity, excessive tearing |
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Keraticonus |
Progressive, non inflammatory condition.Cornea thins and bulges forward |
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Corneal ulcer |
Loss of epithelium enter may be caused by bacterial, single, viral infection or injury |
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Corneal infiltrate |
Collection of white blood cells that form as a result of an inflammatory condition |
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Neovasvularization |
Cause because cornea lacks oxygen.Cornea swells |
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Conjunctivitis |
Inflammation of the conjunctiva Causes can be bacterial, viral, fungal or allergic |
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Pinguecula |
Yellowish,triangular,thickening of bulbar conjunctiva Do not affect Vision, but can affect fit of contact lenses |
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Pterigium |
Triangular fold of growing membrane Can continue to advance over visual access and distort vision |
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Subconjunctival hemorrhage |
Blood between the conjunctiva and sclera Goes away on its own |
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Ectropion |
Lower lid pulls away from the globe Most common in older adults |
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Entripion |
Upper or lower lid turns in tword eye Not very common |
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Ptosis |
Droopinh of the upper lid |
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Chalazion |
Inflammation of the meibomian or Zeiss gland on eye lid Similar to a stye
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Stye (hordeolum) |
Nodules that form on the eyelids as a result of blocked Zeis or meibomian gland |
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Giant papillary conjunctivitis (gpc) |
Most often associated with soft contact lenses. Caused by the mechanical rubbing of palpebral conjunctiva |
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Cataracts |
Condition that occurs when the crystalline lens becomes cloudy |
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Antimetropia |
Patient who is myopic in one eye and hyperopic in other |
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Aniseikonia |
Image seen by one eye is larger than the image seen by the other eye |
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Anisometropia |
When eyes have unequal refractive powers |
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Strabismus |
Occurs when one or both eyes turn in,out,up or down Caused by poor eye muscle control |
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Retinal detachment |
Occular emergency Retina can die and unless there is immediate medical intervention Vision can be lost forever |
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Glaucoma |
Condition in which increased internal pressure of the eye damages the optic nerve |
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Macular degeneration |
Degenerative condition of the macula caused by hardening of the arteries that feed the macula |
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Retinitis pigmentosa |
Progressive, inherited retinal dystrophy affecting the rods, cones or retinal pigment epithelium |
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Aniseikonia |
Image seen in one eye is larger that seen in other |
