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OPTM2190 – DISPENSING DISPENSING WHAT IS IT AND WHY AM I DOING IT What is Optical Dispensing  Fitting of lenses to frames, “glazing”  Selecting and providing appropriate spectacles from a given prescription  Optometry – Providing a prescription for correction refractive errors, the diagnosis of ocular disease and disorders, vision therapy, treatment of some conditions  Ophthalmology – Diagnosis and treatment of ocular disease, and prescribing for correction of refractive error Importance  Able to trouble-shoot when there’s a complain (Prescription/dispensing issues) and ensure patient satisfaction  Training staff, shortage of qualified dispensers  Selecting and providing appropriate spectacles from a given prescription  Warranty issues are easier to sort out  Benefits of income derived from sale of spectacles  Must know the frames well, and which are suited to which purpose for frame purpose decisions  Advising how to best combine fashion with function (Spectacles) Optometry

SPECTACLE FRAME MEASUREMENTS FRAME CATEGORIES There are two different catergories of spectacle frames

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Plastic  Easier to adjust Metal  Not as easily adjustable

Bridge – Between left and right lenss Temple tip – part at the end of temple Why do we need frame measurements?

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Accurate frame measurements are essential for the correct  Ordering correct lens size  Edging and fitting of lens to the frame  Positioning of the optical centre of lens along with lens height (For progressives and bifocals) Methods for taking frame measurements (Will give different results) 1. Datum system  Older system  Involves measurements being taken in relation to the ‘datum’ line  Measuring bridge – Subtract half a mm to counteract for the lens

2. Boxing system  More recent  Involves considering each eye in the frame as a box, with dimensions of those of the peak bevels both vertically and horizontally  Geometric centre – Located in geometric centre of the box for each eye  Frame size – Equal to the sum of the eye size + DBL (Bridge size)  Effective diameter (ED) – Equal to double the distance between the geometric centre of the lens shape and the furthest edge on the lens shape. Helps determine the smallest lens blank size from which lens can be cut  Measurement for the box – Taken from inside bevel of the frame from highest, lowest, most nasal and most temporal parts of the frame.  Assumption of bevel – 0.5mm

Comparing Boxing and Datum System  Datum system – Have a number to represent eyesize, dash, or any number to represent the datum system

Temple Length

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Taken from point where the screw intersects with horizontal axis of the temple to tip of temple, measured along the temple axis

FRAME MARKINGS FRAME MARKINGS  Most frames are marked with significant amounts of information regarding the shape and supplier of the frame  Size – Frames are marked with eyesize and DBL  Temple length (mm) , Tecjnically in the vicinity of 115-180. Usually marked on  Edging and fitting of lens to the frame  Manufacturer dtails 0 Shoul be marked/with the country it was made in, manufacturer armies and manufactuere name, frame name/style number, number for thr PosiMost frames are marked with significant amounts of information regarding shape and supplier of frame

(Useful for identification and ordering

PUPILLARY DISTANCES VISUAL AND PUPILLARY AXIS Optical Centre (OC)

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OC of a lens is the point at which light is not refracted  Prismatic effect 1 prism – Light will be bent so it is displaced by 1cm for every m travelled

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Important for the eye to be looking through OC of lens in order to prevent unwanted refraction of light If eye is not looking through OC of lens in the habitual situation, then it may over time lead to:  Visual discomfort  Decrease in ability of the two eyes to function together as a team

Axes of the eye

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Any optic system with more than one surface can have a unique optical axis  Not as easily adjustable

Foveola – Centre of the pupil to centre of cornea – pupillary axis Convention for PD is mm MEASURING THE PD NEAR PD  When we look at a near object, the eyes tun inwards around the centre  Not as easily adjustable

LENS TYPES SPHERICAL LENSES  Brings parallel light to a single point focus  Surface is perfectly symmetrical  Easier to adjust 

Metal  Not as easily adjustable

Parts of a long bone  Diaphysis – Shaft of the bone grows from the primary ossification centre  Epiphysis – End of the bone grows from a secondary ossification centre  Metaphysis – Connection between the epiphysis and diaphysis (Where most growth occurs in the bones) Skeletal Divisions  Bones are divided into two groups according to their location/region within the body  Axial Skeleton - Axis of the body (Bones of the head, neck and trunk) - Posture, support, protection and attachment for major muscles of limb movement  Appendicular Skeleton - Bony girdles attaching limbs to axis - Bones of the upper and lower limbs (Appendages) The cranium The Ribs Called the false ribs because the coastal cartilages does not connect to the sternum...