Ophthalmic Frames Flashcards
What are the most common frame materials today?
- Cellulose Acetate (Zyl)
- Metal
- Optyl
- Nylon
- Propionate
What is Cellulose Acetate (Zyl)?
Most common plastic made by mixing cotton seed fibers with plasticizers and stabilizers
What are the 2 forms of Cellulose Acetate (Zyl)
- Block acetate
- Acetate Granules
Describe Block Acetate?
a form of Cellulose Acetate (zyl) that is a sheet of extruded material from which the frame fronts are milled or cut.
What is the process of making Block Acetate called?
Pantographing
Describe Acetate Granules?
a form of Cellulose Acetate (zyl) that are small pellets of material which are liquified and injection molded.
What are the advantages/disadvantages of Block Acetate?
Lots of waste plastic but result is good strength and stability.
What are the advantages disadvantages of Acetate Granules?
More cost effective way of manufacturing. But some shifting and deformities can occur with temp changes. Metal is usually added into the frame to hold shape.
What are the advantages of Cellulose Acetate (Zyl)?
- Variety of color/texture
- Temple adjustments are easy
- Material is workable
- Frame has some give to it to adjust for lens sizing
What are the disadvantages of Cellulose Acetate (Zyl)?
- Gets brittle over time and may turn whitish
- Colors lost
- Slight shifting so you cannot produce them thin
- overheating can result in pitting
- Heavier than other plastics
- Overheating loosens hinges and hardware
What is Propionate?
new generation of material with properties of strength and shape retention lending itself to injection mold fabrication.
What are the advantages of Propionate?
- Greater stability and shape retention
- lighter weight then acetate
- Overcoats are applied making them more scratch resistant
- Sturdy ultra thin design
What are the disadvantages of Propionate?
- Difficult to dye so colors may fade
- Needs more plasticizers and so gets more brittle with age
- Solvents ruin finish of the frame(including Alcohol)
- Low tolerance to heat, bubbling can occur
What is Nylon material?
A thermoplastic used in eyeglass fabrication that is durable and highly resistant to breakage.
What are the advantages of Nylon?
- Hypoallergenic
- Comfort from light weight
- Chemically resistant
- impervious to heat
- Good for kids and sports
- very durable and resistant to breakage
What are the disadvantages of Nylon?
- Very stiff and difficult to adjust
- Color selection is usually dark solid colors, crystalline colors are not possible.
- Dries out and gets brittle over time
- unforgiving to lenses not sized exactly
What is Carbon Fiber?
a new breed of injection molded plastic frames, lightweight and strong. Black in color, requiring other colors to be baked on.
What are the main visible attributes of Carbon fiber frames?
- delivers the look of an ultrathin plastic frame while holding many characteristics of a metal frame.
- typically carbon front and metal temples
- Black in color, requiring other colors to be baked on.
What are the advantages of Carbon Fiber?
- Comfort
- Baked on enamel finish maintains shine and durability
- Carbon is relatively impervious to Heat
- Adjustable, but hard to damage
- One piece designs deliver a metal look without screws going loose.
What are the disadvantages of Carbon Fiber?
- Front of frame is difficult to adjust
- Color selection is limited to dark
- Sensitive to a variety of solvents
- Lens cut outs can be an issue as there are not screws on a lot of them.
What is Polycarbonate Frame material?
plastic material originally created as a safety material. Extremely durable, filters UV, and accepts dyes. It is most commonly used for sports and industrial safety frames
What are the advantages of Polycarbonate Frames?
- Virtually unbreakable
- light weight
- can accept limited range of dyes, generally used in clear state
- absorbs UV
What is Polyamide?
A blend of different nylon materials. Each manufacturer has their own special blend.
What are the advantages of Polyamide?
- Durable and adjustable.
- Stronger then acetate and propionate
- Hypoallergenic
- comfortable and light weight
- resistant to solvents, oils, cosmetics and chemicals
- Resistant to climate conditions
- available in all color ranges, from solid to opaque
- Flexible, no plasticizers that dull the finish
What is the difference between Polyamide and other materials?
most frame materials stretch when heated, Polyamide shrinks
What are the disadvantages of Polyamide?
- Limited stretch (cannot use oversized lenses)
- Sensitive to overheating and shrinking
What is Optyl material?
An epoxy resin made by vacuum casting
What is Optyl material’s Shape Memory?
if out of original shape, to reset, heat frame to 80 degrees celsius and it will go back to original shape and will not shrink.
What are the advantages of Optyl?
- Hypoallergenic
- 30% lighter than acetate
- shape and adjustment retention
- extremely heat resistant
- protectant coating on outer surface to prevent scratching
- good chemical resistance
- Full color range. Dye is mixed into resin or applied after casting
What are the disadvantages of Optyl?
- adjustments can be difficult due to the frames rest to their original shape when heated
- under heating the frame can cause breakage with adjustments
What is kevlar?
a safety product that by nature has an amber tone
What are the advantages of Kevlar frames?
- safety product
- temperature doesn’t effect it
What are the disadvantages of Kevlar Frames?
- adjustments can be difficult to achieve and are prone to relaxing
- limited color(must be dark colors)
- limited style range
- alterations to the bridge and shape configuration are extremely difficult
Describe Aluminum Frames
A lightweight metal that was one of the first metals used outside of gold and silver.
What are the advantages of Aluminum frames?
- Lightweight
- Good resistance to corrosion
- Naturally silver in color allowing high luster
What are the disadvantages of Aluminum?
- Durability of colored finishes is poor.
- Cant be soldered, so it’s pieces are attached by rivets. (this is not the most durable way to attach pieces)
- Fitting is limited
- Stiff and hard to adjust
Describe Beryllium
a hard, light and flexible element. Generally mixed with other metals to get better endurance to fatigue. A frequent example being copper to create a light weight and flexible alloy (copper beryllium)W
What are the advantages of Beryllium?
- can make a stable but flexible bridge
- when mixed with copper it is strong and springy, allowing for thinner temples w/good holding power
- Great strength in a thinner profile
What are the disadvantages of Beryllium?
- expensive, so it is usually mixed with other metals
- medium corrosion resistance
- adjustments are prone not to stay
Describe Cobalt
element used as a stabilizing metal in high quality frames
What are the advantages of Cobalt?
- can add strength in a thinner profile
- Corrosion resistant
What are the disadvantages of Cobalt?
High cost, so usually will not be used alone
How is Copper used in frames?
not as a stand alone material, but instead mixed in with other material to add stability at a lower cost as it is a stable metal itself.
What is Monel?
the most common frame material for metal frames. an alloy made from copper, zinc, iron, and manganese.
What are the advantages of Monel?
- Cost Efficient material
- good resistance to stress, good tensile strength
- adjustments hold well
- accommodates eye wires and adapts to lens curves.
- Particularly good for nosepieces, bridges and end pieces due to it’s ability to withstand stress
What are the disadvantages of Monel?
- Can be difficult to shape and reshape
- Medium corrosion resistance
How is Nickel used in frames?
used in combination with other metals to make a complete frame
What are the advantages of Nickel?
- malleable and works well as nose pad arms
- Resists corrosion and tarnish
What are the disadvantages of Nickel?
high cost keeps usage low
Describe Titanium
Lightweight and strong metal alloy
What are the advantages of Titanium?
- strong and flexible
- 40% lighter then gold frames
- readily shaped and holds adjustments
- a rare earth metal, resists corrosion and tarnish
- hypo allergenic
What are the disadvantages of Titanium?
High cost
Describe Trillium
an alloy of Nickel, copper, and tin
What are the advantages of Trillium?
- Strong
- Flexible
- light weight
- stable construction
What are the disadvantages of Trillium?
Adjustments can be difficult and may not hold
All frames should be pre-adjusted in what method before dispensing?
4 Point Touch
What is a Skewed Bridge Misalignment?
horizontally misaligned one side is higher that the other
What is a X-ing misalignment?
when the bridge of the frame is twisted
What is a Coplaner misalignment?
when one lens is closer to the patients eye than the other
What are the 3 steps to Standard Frame Alignment?
- Check that Pantoscopic angle is 8-12 degrees
- Make sure the Temples Spread is evenly sitting at 90 degrees when open
- check the the Temple’s Fold evenly when frame is closed
What is the proper standard Pantoscopic angle?
8-12 degrees
