1) What are lugs?
2) What is a bevel?
1) Top corner of front frame w/ the screw
2) Groove on frame that allows lens to fit in
Describe supra frames
Partial eyewires, bridge and lugs. Eyewire doesn’t encircle lens. Bottom is held in place with nylon string or held by bolts. Sticks to groove on lens itself.
Describe rimless frames
No frame front, bridge and lugs attached directly to lens itself via bolts or press studs. Requires 2 – 4 holes drilled into each lens. Requires strong lens.
What’s Cellulose Acetate?
- Features?
- How’s it made?
- Adjustment?
- Other notes?
- Most common frame material
- Reasonably inert (but dissolves in solvents e.g. acetone and whitens when contacting skin”
- Uses multicoloured pellets melted into a block before being cut off in sheets.
- Can be heat adjusted at 50-60 degrees. Melts at 140.
- Frame design/pattern embedded into material itself.
What’s Bioacetate?
Cellulose acetate often made from non-renewable resources whilst bio-acetate uses good stuff like plant material.
Note: Often added plasticisers to increase short life span.
Describe Cellulose Proprionate?
- Features?
- How it’s made?
- Adjustment?
- Other notes?
Similar to cellulose acetate except
- A bit stronger and lighter
- Solid colour through frame
- Made by moulding
- Adjust at 60-100
- Melts at 190
- Heat will shrink material.
Describe Cellulose Nitrate
- Features?
- How it’s made?
- Adjustment?
- Other notes?
Appearance similar to cellulose acetate except catches fire at 60 degrees. Smells like moth balls when rubbed. Becomes dark yellow with age if frames used to be clear. DO NOT ADJUST OR YOU WILL BLOW UP.
Describe Epoxy
- Features?
- How it’s made?
- Adjustment?
- Other notes?
a.k.a. Optyl.
- Can return to original form when heated and cooled w/o holding.
- Polymerisation within a mould. Surface dyed.
- Temples have no wire reinforcement.
- Head adjust at 80+. Requires holding to prevent memory.
Describe Polyamides
- Features?
- How it’s made?
- Adjustment?
- Other notes?
Nylon-type plastices, seen as SPX or PA commonly.
- Often in sunglasses, sport frames, and saftey frames
- Strong + Soft
- Flexible
- Solvent resistant
- Polymerisation within a mould
- Cold adjusted (heat adjust will snap).
- Shrinks at 80, melts at 180-300.
Describe Polycarbonate as a frame material
- Features?
- How it’s made?
- Adjustment?
- Other notes?
- Used in some sports and saftey specds
- Used for side shields of saftey specs
Describe Silicone Rubber
- Features?
- How it’s made?
- Adjustment?
- Other notes?
- For nose-pad, temple tips, etc.
- Soft, flexible, comfy
- Temp stable
Describe Carbon Fibre composite
- Features?
- How it’s made?
- Adjustment?
- Other notes?
- Carbon fibre set in plastic
- Tensile strong but brittle
- Opaque
- Cold glazing required
- Rim fractures easily
Describe metal frames in general
- Features?
- Repairing?
- Other notes?
- Usually alloy
- Whilst it’s easier to break metal frames, it’s also easier to mend them.
- Repairs via soldiering which requires intense heat often not found in general clinics.
Describe Nickel Alloys
- Features?
- Easy/hard to work with?
- Other notes?
- Easy to work w/ and soldered
- Corrosion resistance but contact dermatitis
- Turn green when contact sweat unless plated/lacquer coated to prevent corrosion and allergenic effects.
Describe Stainless Steel frames
- Features?
- Easy/hard to work with?
- Other notes?
Thin “springy” frames often.
- Iron + chromium alloy
- “Hypoallergenic”
- Hard to work w/ (cannot solder repair)
Describe Aluminium frames
- Features?
- Easy/hard to work with?
- Other notes?
- Uncommon
- Light+ soft (thick in some sections for strength)
- “Hypoallergenic”
Describe Titanium frames
- Features?
- Easy/hard to work with?
- Other notes?
Ideal frame material
- Light, strong, inert
- Pure titanium is hypoallergenic
- Expensive
Often it’s an alloy.
Describe memory metals as frames
Flexible, springy metals (alloys). Return to original shape after bending. Used in briges and temples.
What to consider when choosing a frame?
- Prescription
- Previous wear
- Ease of adjustment
- Frame size
- Temple length
- Face shape
- Fashion/colour
How to choose a frame that fits the patient’s face?
What to consider?
- Match top of frame to eyebrow shape
- Avoid frames that overlap eyebrow
- Avoid too large frames that rest on cheeks
If want to hide frame, try:
- Sem-rimless/rimless
- Supraframes
- Thin metal frames
- Frame colour to match skin tone
How to do standard alignment?
Start with front alignment.
- Use a face-form shape which curves the frames to wrap around the face
. Cosmetically more appealling although worse optically.
Select temple angle.
- This should be a little over 90 degrees e.g. 95 degrees (splayed to fit around head)
Check pantascopic tilt.
- Around 6 degrees for SVL, 12 for progressives (since higher tilt gives larger FoV when looking down)
- Limited by if it sits on cheeks with too much tilt.
Check temple bend.
- Do temple tips touch both surfaces simultaneously?
- Ensure each bend is smooth and equal.
- Temple tips should bend inwards slightly to wrap around ears/head.
How to adjust nose pads?
Distribute weight evenly w/o excessive pressure ideally.
- Adjust pad angle so sit flat against the nose and distribute weight evenly
- Adjust width, frontal angle, and splay
- Increasing width of pads will lower frame and vice versa.
How to adjust pantoscopic tilt to make it even?
Increasing tilt will raise frame on one side.
1) Adjust temple angle so that…
2) Temple curves do what? purpose?
3) Temple bend and tip?
1) It’s not too tight on their heads.
2) Curve around side of head to avoid pressure on the head.
3) Temple bend should be even curve. Tip should wrap around to avoid pressure points on ear.
