Frame and Facial measurements 2024 PDF

OPT505: Clinical Skills and Refractive Management Frame materials and Frame measurements Claire Wright Core Competencies 4.1.1 ABILITY TO ADVISE ON, ORDER AND TO DISPENSE THE MOST SUITABLE FORM OF OPTICAL CORRECTION TAKING INTO ACCOUNT DURABILITY, COMFORT, COSMETIC APPEARANCE, AGE AND LIFESTY...

OPT505: Clinical Skills and Refractive Management Frame materials and Frame measurements Claire Wright Core Competencies 4.1.1 ABILITY TO ADVISE ON, ORDER AND TO DISPENSE THE MOST SUITABLE FORM OF OPTICAL CORRECTION TAKING INTO ACCOUNT DURABILITY, COMFORT, COSMETIC APPEARANCE, AGE AND LIFESTYLE (MULTIFOCAL DISPENSE) 4.1.2 ABILITY TO ADJUST A SPECTACLE FRAME OR MOUNT TO OPTIMISE PHYSICAL AND OPTICAL PERFORMANCE One Time Code: ST-FL-WI Aims of today Understand different types of frame materials Have an understanding of their manufacturing process Be able to discuss properties of different frame materials Be able to select most appropriate material/frame for different patient prescriptions and lifestyles Describe standard frame measurements One Time Code: ST-FL-WI Ideal Properties of a frame Think about… The material The weight Who it should be suitable for How it can be adjusted if needed Anything else you can think of! One Time Code: ST-FL-WI How should it fit? Think about… Where on the face it is going to sit What aspects of the frame we might be able to adjust What facial aspects are important in frame choice What problems might occur if badly fitting Anything else you can think of! What measurements would we need? Imagine we are making a custom frame for our patient… What parts of the frame can we measure? Which parts of the face can we measure? Why are these measurements important? Anything else you can think of! Why is frame choice important? Knowledge of frame materials means we can make the best recommendation for:  Allergies  Lifestyle  Prescription  Cost We can offer advice about the care and fit of the frames Why is frame choice important? As a practitioner the ideal frame for us is: - low cost - easy to glaze and process - widely available - hypoallergenic - high thermal and chemical resistance - stable material - low specific gravity (weight) - strong - easy to adjust Plastic Materials A material that can be shaped or moulded Made up of a mixture of long chain polymers and plasticisers The amount of plasticisers used can alter the frame properties - e.g. brittleness or hardness Plastic groups (set by if it can be adjusted with heat): - thermosetting - thermoplastic *A plasticiser is a substance which when added to a - thermoelastic material, usually a plastic, makes it flexible, resilient and easier to handle* Groups of Plastics Thermosetting – once formed these plastics cannot be returned to a plastic state by heat therefore are ‘set’ – carbon fibre and polyester Thermoplastic – these plastics can be moulded into different shapes when heat is applied. When cooled they will set,but may be made plastic again by re-heating. Most frame materials are thermoplastic to enable frame adjustments and adaptions Thermoelastic – the material has ‘memory of the original shape it was moulded to. If it is heated beyond the recommended adjustment temperature it will return to it’s original shape - Optyl Cellulose Acetate Most common plastic frame material Easy to manufacture and cheap to produce Easy to adjust initially but – dries out with age, increasing adjustment temperature required – Also prone to warping (e.g. on a dashboard). Dissolves in acetone! Key identifying point: – Common/ cheap – Sides are always reinforced Cellulose Acetate Reinforced Side Cellulose Acetate: Properties Properties Manufacture 1. Cotton linters, acetic acid & plasticiser 2. Produced in sheets by acetate transfer, extrusion moulding, and injection moulding 3. Polished by barrel polishing Colouring Lamination or dye moulding Joints Pinned or heat inserted Sides Fully reinforced Adjustment 57oC temperature Flammable No Stability Strong but can warp or blister in high heat Chemical resistance Resistant to most household chemicals (except acetone)  Cellulose Proprionate Very common plastic frame material Difficult to distinguish from acetate (as so similar) Easy to manufacture and cheap to produce Easy to adjust initially but – More resistant to aging that cellulose acetate Key identifying point: – Common/ cheap – Sides are always reinforced – Injection moulded joints – Very shiny hard finish to colouring Cellulose Proprionate: Properties Properties Manufacture 1. Cellulose flakes, propionic acid, acetic acid, plasticiser & stabiliser 2. Produced by injection moulding 3. Polished by barrel polishing Colouring Dyeing over a pale base, transfer printing & then lacquered (hard, high gloss finish) Joints Injection moulded Sides Fully reinforced Adjustment 67oC temperature Flammable No Stability Strong but can warp or blister at high temperatures Chemical resistance Resistant to most household chemicals  Nylon (Polyamides) Frequently used in children's frames, safety eyewear and sunglasses Can be pure nylon or mixed with other material to increase flexibility and other properties Difficult to adjust (frame heater not recommended) – Often has metal sides/ reinforcement to allow adjustment Key identifying point: – Distinctive feel compared to other plastics – Often reinforced or mixed with metal sides – Blended nylon frames are often used for babies/ toddlers Nylon (Polyamides): Properties Properties Manufacture 1. Nylon 2. Production is by injection moulding Colouring Surface dyed Pure nylon limited to black/brown or grey Joints Screwed Sides Often metal reinforced Adjustment temperature Not recommended – cold glaze Flammable No Stability High resistance to breakage Chemical resistance Resistant to most household chemicals SPX Unique to Silhouette, though other manufactures are now using similar materials. Hypoallergenic Lightweight and elastic – for easy adjustment Frames are cold glazed Key identifying point: – Almost always Silhouette noted on almost all frames – Often clear with colour on top layer – Unusual shapes – precision glazing used. SPX: Properties Properties Manufacture 1. Super-polyamide (SP) and secret ingredient X! Nylon derivative 2. Injection moulded Colouring Laminated Joints Injection moulded Sides Reinforced Adjustment temperature 95oC (overheating causes shrinkage) Flammable No Stability Strong/high impact resistance Chemical resistance Resistant to most common chemicals Grilamid e.g.TR90 and GTR55 Grilamid is a transparent co-polyamide. Two types used in frames are Grilamid TR55 and Grilamid TR90 – Cannot be distinguished with the naked eye. Material found in coffee machines, petrol pumps, water bottles etc. – Cheap and easy to produce Key identifying point: – Transparent plastic – Partial reinforcement (usually at the bend) – Cold Glaze – Resistant to most chemicals –apart from Alcohol cleaner! Grilamid: Properties Properties Manufacture 1. Co-polyamide (transparent) 2. Produced injection moulding Colouring Dyed (always transparent) Joints Heat inserted Sides Short reinforcement Adjustment Depends upon reinforcement metal temperature Flammable No Stability Strong and resistant to cracking Chemical resistance Resistant to most common chemicals Epoxy Resin (Optyl) Memory plastic – thermoelastic material – Adjusted easily to any shape if maintained when cooled (try cold water) – Will revert to original shape when reheated – Cool in water to set adjustment Hypoallergenic Key identifying points: – Optyl noted on all frames – Short side reinforcement Epoxy Resin (Optyl): Properties Properties Manufacture 1. Epoxy resin (no plasticiser) 2. Production is by compression moulding Colouring Dyeing and then lacquering Very high gloss finish Joints Heat sunk Sides 15mm reinforcement Adjustment 80-120oC (brittle when not heated to correct temperature) temperature Flammable No, resistant to burning Stability Strong Chemical resistance Resistant to most common chemicals Carbon Fibre Frame fronts only Cannot be adjusted (cold glazed) Lightweight and very strong Key identifying point: – Normally opaque – Front material only with metal sides – Limited colour range Carbon Fibre: Properties Properties Manufacture 1. nylon 80% and carbon fibre 20% 2. Production by injection moulding Colouring Naturally grey Coloured by coating and lacquering Joints Screwed Sides Normally metal sides added Adjustment temperature No adjustment possible – heat only softens surface Flammable No Stability Very strong but can split if dropped Chemical resistance Resistant to most household chemicals Polycarbonate Most commonly used for safety specs and sports goggles Very very strong material Key identifying point: – Often protection eyewear e.g. sports or occupational – Sides not reinforced – Strong with some flexibility Polycarbonate: Properties Properties Manufacture 1. Polymer of carbonate groups 2. Production is by injection moulding (?) Colouring Naturally transparent Dyed (?) Joints Screwed/moulded Sides Not reinforced Adjustment temperature 100oC Flammable No Stability Virtually unbreakable Chemical resistance Can become opaque with some chemicals Cellulose Nitrate No longer used as a frame material Banned in the U.K. as highly flammable – It is illegal to re-glaze a cellulose nitrate frame Made from cotton linters and nitric acid with a camphor elasticise. Key identifying point: – Camphor smell when filed – Turns bright yellow with age – Only old UK frames (almost none in circulation now) * Though banned in the U.K. it is still used in the Developing World so it is important to know about cellulose nitrate and its hazards. Cellulose Nitrate: Properties Properties Manufacture 1. Cotton linters, nitric acid with a camphor elasticise 2. Production is by routing (cannot be moulded) Colouring The colours are normally produced by lamination and shaving veneers Produces a good sheen finish Joints Pinned Sides Full reinforced Adjustment 65oC temperature Flammable Yes – flashpoint is at 70oC Stability Strong (as long is it is not heated) Chemical resistance Resistant to most household chemicals Polymethyl Methacrylate (Perspex) Much less common now – Was popular around the 1960’s – Lightweight but quite rigid and brittle – Difficult to adjust as easily broken if not heated to correct temperature Key identifying point: – Normally used for supra (half-frame) designs – Sides are not reinforced – Very shiny finish – lightweight but not flexible Polymethyl Methacrylate (Perspex): Properties Properties Manufacture 1. Acetone, sodium cyanide, methanol & sulphuric acid 2. Produced by routing Colouring Laminating onto pale base shades (high lasting polish) Joints Mushroom pinned Sides No reinforcement Adjustment temperature 68oC (brittle in low heat & blisters with excessive heat) Flammable No Stability Rigid but brittle Chemical resistance Resistant to most household chemicals Metal Frames Metal is used extensively in the manufacture of frame parts or complete frames with a wide variety of pure metals, plated and alloy metals being used. Metal frames usually consist of: Base metals (the structural metal of the frame) Plating (usually several layers) Lacquer coating Plastic side tips and nose pads (usually cellulose acetate or silicon) Nickel Silver/Monel Most common group of metal frames Cheap and easy to manufacture, glaze and adjust Various combinations of copper, nickel, zinc, magnesium, iron and manganese NOT hypoallergenic – nickel and other allergies common Key identifying point: – Difficult to distinguish one from the other – Cheaper frames – Heavier than some other metals – Not used for rimless mounts or half frames Nickel Silver/Monel: Properties Properties Manufacture 1. NS – copper, nickel, zinc, magnesium 2. M – copper, nickel, iron, manganese Colouring Electrolyte colour transfer Joints Screwed Sides Same metal usually Adjustment temperature Heat needed – not specified Flammable No Stability Reasonable strength – can be broken with over adjustment Chemical resistance Good but can corrode with age Stainless Steel It is assembled by welding (it cannot be soldered in the normal way) Often used for brow bars of rimless mounts and combination frames. May be coated with silver, gold or even coloured plastics, making identification difficult. Key identifying point: – Lightweight – Strong – Not flexible – Often used in half frames or rimless mounts Stainless Steel: Properties Properties Manufacture 1. Iron together with chromium (18%) and nickel (8%) 2. Heat and welding (can’t be soldered) Colouring Electrolyte colour transfer Can be coated in gold, silver or plastic Joints Screwed Sides Same metal Adjustment temperature Heat required Flammable No Stability Very strong/corrosion resistant Chemical resistance Resistant to most common chemicals Titanium Titanium is the World’s fourth most abundant metal element. Expensive to produce – Cannot be soldered in the normal fashion – required lasers (unable to repair) Flexible and lightweight – 20% more elastic than nickel silver – Half the weight of nickel silver. Titanium very corrosion and abrasion resistant with a surface hardness 3x that of gold filled. Hypoallergenic material Key identifying point: – Very lightweight and flexible – Very thin frames can be produced – Often used in rimless mounts and half frames Titanium: Properties Properties Manufacture 1. Titanium metal 2. Cutting, pressing and laser soldering in oxygen free environment (e.g. argon) Colouring Galvanised or ion plated Joints Screwed (in full frames) Sides Alloyed to allow adjustment Adjustment temperature Pure titanium is very difficult – but if sides are alloyed, normal adjustment possible Flammable No Stability Very strong and corrosion resistant Chemical resistance Resistant to most common chemicals Gold “Solid” gold is too expensive for the vast majority Too soft to be a satisfactory frame manufacture. Types of Gold used (Hallmarked in UK): – Pure gold is 24 carat – 18 carat gold (18 parts pure gold and 6 parts alloy). – 12 carat gold (12 parts pure gold and 12 parts alloy). Key identifying point: – Hallmark – High quality gold Gold: Properties Properties Manufacture 1. Gold and alloy 2. Heated and soldered Colouring None Joints Screwed Sides Gold or other Adjustment temperature Easy to adjust, even without heating Flammable No Stability Poor – it is quite a soft metal Chemical resistance Yes – stable material Rolled (Filled) Gold A gold ‘skin’ is bonded to a base metal – Base normally nickel silver or bronze Quality of material is stamped on frame as a fraction (parts per 1000) – E.g. 1/10 12 ct Not hypoallergenic due to mix of metals It is easily repaired by soldering (can discolour) Key identifying point: – Stamp on frame – French pin joint – Gold in colour Rolled (Filled) Gold: Properties Properties Manufacture 1. Gold hammered out to form thin ‘skin’ 2. Skin of gold bonded to base metal (alloy) 3. Cold hammered and rolled to produce shape Colouring None Joints French pin Sides Gold or other Adjustment temperature Easy to adjust, even without heating Flammable No Stability Poor – it is quite a soft metal Chemical resistance Yes – stable material Gold Plated Cheap (inferior version of rolled gold) – Less gold used Easy/ cheap to produce These frames are very often finished with an anti-corrosion layer. Key identifying point: – Looks like costume jewellery (yellow colour) – Ages poorly – Cheaper frame Gold Plated: Properties Properties Manufacture 1. Thin layer of gold (sometimes multiple layers) added to base metals with electroplating Colouring None Joints Screwed Sides Standard Adjustment temperature Low – easy to adjust Flammable No Stability Varies with base metal Chemical resistance Okay, anti-corrosion layer added separately to improve general resistance Aluminium Aluminum is lightweight, strong, very rigid. Difficult to manufacture – more expensive than Nickel silver It is also extremely difficult to adjust. Key identifying point: – Lightweight but very rigid – Cold to the touch – Normally thicker than stainless steel or titanium – Matt finish to colour Aluminium: Properties Properties Manufacture 1. Aluminium 2. Riveted (cannot be soldered or brazed) Colouring Anodised (large range of colours) Joints Screwed Sides Same metal normally Adjustment temperature Very difficult as so rigid, heat required Flammable No Stability Very strong and corrosion/tarnish & stain resistant Chemical resistance Resistant to most common chemicals Other Gold Wash – A base metal is covered with a very thin deposit of gold either by electro or chemical deposition. – Used in cheap sunglasses – Tarnishes easily Shape Metal Alloys – Copper (50-80%), aluminium, zinc and titanium. – The material is fatigue resistant and has a super-elastic effect 8 x more flexible than stainless steel – It is usually used on bridge and side components To create a super flexible frame Natural Materials: Wood/Cork Sustainable Eyewear Made with 42% natural materials mainly wood cork or plant-based cellulose May have recycled plastic sides for ease of adjustment Can be obtained from managed sources. https://www.botaniqeyewear.com/ Natural Materials: Horn Extremely rare, almost non existent. Usually Buffalo or Yak horn. Very difficult to adjust. Can be obtained from managed sources. https://www.tdtomdavies.com/collections/precious Natural Materials:Turtleshell Mostly Hawksbill Turtle (endangered - protected species) Made in sheets by layering plates together under steam Colour and finish depends on which part of the shell was used (back or underbelly) – Green, red or amber Metal added to create joints – But could be adjusted at 75 C Real shell is obtainable under license from managed sources. Frame Types Supra Full Frame Rimless Mount The Bridge Regular W Saddle Keyhole Pad on Arm Comfort Joints Sides Ends So which frame is best? There is no right or wrong answer… We need to take into consideration the patients needs and their lens requirements Most Common Plastics Material Properties Sides Most Common Sides reinforced Easy & cheap to make Cellulose Acetate Easy to adjust (57oC) Will dry out with age Dissolves in acetone! Cellulose Proprionate Very Common Sides reinforced More difficult to adjust than Acetate (67oC) Sides reinforced Very shiny hard finish More resistant to age than Acetate Nylon Common in Children's frames Sides either metal or Difficult to adjust (no heat) reinforced Nylon Sides either metal or reinforced Nylon All plastics can be classed as Hypoallergenic as very rare to cause a reaction Most Common Plastics Material Properties Sides Exclusive to Sillhouette Sides reinforced Light weight SPX Cold glaze Clear with overlayed colour Memory plastic (Thermosetting) Short reinforcement Can adjust to any shape and will stay there-if cooled in place. Optyl Must heat at lot (80-100oC), otherwise will snap! Hypoallergenic Transparent Partial reinforcement Easy & Cheap to make only near bend/tip Grilamid (TR90 & GTR55) Lightweight Popular in Children's frames All plastics can be classed as Hypoallergenic as very rare to cause a reaction Most Common Metals Material Properties Hypoallergenic/Allergy Most Common Metal used Allergy causing! Cheap and easy to make Nickel Silver/Monel Easy to adjust Acetate tips Lightweight/thin Hypoallergenic Strong Stainless Steel Not flexible More expensive to produce Acetate tips Lightweight Hypoallergenic Strong Quite flexible Titanium More expensive as pure metal Acetate tips Cannot be repaired (soldering) Most Common Metals Material Properties Hypoallergenic/Allergy Real gold coated around a nickel silver frame Not Hypoallergenic due to the Has Hallmark like jewellery CT rating base metal. The gold is. Rolled Gold Easily adjusted Acetate tips More common than rolled ot real gold Not Hypoallergenic due to the Electroplated with some gold not enough to give base metal. Gold Plated a Hallmark Easy & cheap to produce Acetate tips Good or bad? Frame fitting scenarios Describe how the frame is misaligned and some suggested processes for correcting the fit Section 4.1 Vision has gone funny Section 4.1 Vision has gone funny Problem: One lens is higher than the other Eye’s not looking through optical centres (wrong Rx/ prismatic effect) Solution: Lower the left side Raise the right side (change the pantoscopic angle) Side view of adjustment 110 150 ear Section 4.2 Eyelashes catching frame  Section 4.2 Eyelashes catching frame Problem: The lenses are too close to the eyes Solution: Increase the length of side Adjust the nose pads (bring in) Increase pantoscopic tilt – as this will bring the frame away from the top row of lashes Section 4.3 Seeing double  Section 4.3 Seeing double Problem: Frame too high (prismatic effect or wrong rx) Solution: Widen nose pads Raise both sides (Increase 110 150 the pantoscopic angle) ear Section 4.4 One lens closer to face than the other  Section 4.4 One lens closer to face than the other Problem: Length of side to short on left side One side closer to temple Solution: Increase length of side for left side. Ensure sides are parallel Section 4.5 Fitting picture: What’s going on here?  Section 4.5 Fitting picture: What’s going on here? Problem: Sides too tight Pushing frame forwards Solution: Widen head width. Bring sides out Frame measurements Frame measurements involve measuring the dimensions of a spectacle frame. These measurements can be related to facial measurements to ensure a correctly fitting spectacle frame is dispensed for your patient. Please watch the following video: on DLE The slides which follow demonstrate the measurements through images. Facial Measurements Please watch the following video: https://www.youtube.com/watch?v=GxvjDIfWWzU Please see the Xerte videos on Frame & Facial measurements https://xerte.plymouth.ac.uk/xerte/play.php?template_id=7100#page1 Please revise the guides provided on Moodle Make sure you own a city rule & bring it along with you to help in the practical sessions How to measure a PD! AOP student guide to measuring a PD Box lens size This is the size of the rectangle containing the lens shape formed by the horizontal and vertical tangents to the lens shape Record both the vertical and the horizontal box lens size Distance between lenses (DBL) Distance between the nearest point on the apices of the two lenses Box centre distance* The distance between the box centres. This can be determined by measuring the distance between the most nasal point on the one lens to the most temporal on the other lens Bridge width* Minimum distance between the pad surfaces of the frame measured along the bridge width line. Bridge height The vertical distance from the bridge width line to the intersection point of the vertical symmetry axis with the lower edge of the bridge (crest height plus 5 mm). Splay angle of pad The Angle between the pad plane and a normal to the back plane of the front Frontal angle of pad The angle between the vertical and the line of intersection the pad plane with the back plane of the front Distance between pad centres The horizontal distance between the two pad centres Angle of side* Vertical angle between a normal to the back plane of the front and the line of the side when opened Length to bend* The distance between the dowel point and the ear point Length of drop The distance from the ear point to the extreme end of the side Downward angle of drop Downward inclination of the drop from the line of the side, measured near the ear point and in the vertical plane containing the line of the side Length to tangent The distance from the dowel point to the tangent to the inner surface of the curl Total length of side For a curl side, the overall length from the dowel point to the extreme end Angle of let back The horizontal angle between the inner surface of the fully opened side, adjacent to the joint, and a normal to the back plane of the front Head width Distance between the sides at the ear points Temple width Distance between the sides 25 mm behind the back plane of the front Facial Measurements Facial measurements allow us to ensure the correct frame fit and lens position. Front to Bend & Angle of Side* Splay Angle of Pad Angle that determines the position of the pads Be careful when measuring! Bridge Projection Determines the horizontal position of the frame front, in relation to the eyelashes Can be either + or – Place the frame rule on the crest of the nose at the predicted spectacle lens position Move slide gauge towards patients eye getting them to blink repeatedly Take a reading from the ruler at the point where the slide first makes contact with the patients eyelashes Head Width Measured from ear point to ear point with head width calipers This is the uncompensated width, for tighter fitting frames e.g. sportswear, specs for near vision, hearing aids, reduce this measurement by 10mm Can be measured using facial gauge and a dispensing rule if calipers not available Frontal Angle of Pad Determines the pad bridge or adjustable pads on arms fitting Measure right and left sides Distance between Rims at 10mm Determines the fitting on the nose at 10mm below the crest of the bridge Ensure curser is in correct position Use the 10mm side of the ruler Place the facial rule on the crest of the bridge Gently squeeze the cursor until it touches the bridge Record the DBR at 10mm below crest Distance between Rims at 15mm Determines the fitting on the nose at 15mm below the crest of the bridge Ensure curser is in correct position Use the 15mm side of the ruler Place the facial rule on the crest of the bridge Gently squeeze the cursor until it touches the bridge Record the DBR at 15mm below crest Apical Radius This is the radius around the crest of the nose, it determines the contact fitting on the bridge. If the apical radius is too large, the frame will ‘rock’ on the bridge If the apical radius is too small there will be a gap at the top of the bridge. If in doubt go for the larger radius Crest Height The distance between the crest of the nose and the lower limbus (or lower eyelid) The bridge height is 5 mm greater than the crest height Many frame measurements use the horizontal centre line (HCL) as a reference line. For Facial measurements we assume that the lower limbus coincides with the HCL. Recommended Reading Brooks, CW. And Borish, IM. (2007) System for Ophthalmic Dispensing. 3rd edn. St Louis: Butterworth Heinemann Elsevier Griffths, AI. (2000) Practical Dispensing. 3rd edn. London: Association of Dispensing Opticians Bates, S. (2014) ‘Dispensing handmade frames’ Optometry Today 11(4) pp.44-48 doi: http://www.optometry.co.uk/uploads/articles/cet-2014/ apr_11_cet1_c-36100__dispensing_handmade_frames.pdf