LAB QUIZ 1 Flashcards
Hypoallergenic, lightweight frame materials
(lighter than cellulose acetate/zyl) Optyl, Cellulose propionate
Frame material w/ memory
(returns to orig molded shape when heated) Optyl
Frame material resistant to fading/discoloration
Optyl
Impact resistant frame materials
Polycarbonate, Polyamide
Datum line/180 line/Fitting line
Horiz line, midway btwn horiz tangents at highest and lowest limits (Along which eye size and bridge size measurements are taken)
Boxing system
Draw horiz and vert lines tangent to lens edge on all four sides, forming box around lens
A dimension
(Eye size) “Width” distance btwn vert lines (in mm)
B dimension
“Height” distance btwn horiz lines (in mm)
C dimension
(Eye size under Datum system) Horiz length of lens along Datum line
DBL
(Bridge size) Distance btwn lenses, from nasal vert line of OD to nasal vert line of OS
DBC
Distance btwn GCs of each lens (= A + DBL)
Info req to order frame for patient
Manu, Frame name, Color, Eye size, DBL, Temple length
Criteria to ensure proper fit
Bridge size, Bridge flair angle, Temple length/style, Eye size
Frame selection for high myope
Small eye size, Round eye shape, Match FPD and IPD (min decentration), Wraparound endpiece
Temple flair
Distance btwn two temples as they course back to the ear
“Truing” the frame
Pre-adjusting the frame
Pre-alignment procedures
1) 4 pt touch (eyewires and crest of temple rest on flat surface, when frame placed upside down), 2) Lenses in same plane (No X-ing, twisting about the bridge), 3) Parallel setback (temple) angles = Positive (more common) > 90 deg @ endpiece, btwn frame front and center line of temple, 4) Slight pantoscopic tilt (lowers OC), 5) Nosepads level, @ same horiz/vertex distance from face, 6) Lenses properly mounted (not loose/tight/pushed out w/ hand P) - Multifocals w/ seg line level on both sides, 7) Eyewire/temple screws properly seated/secured, 8) Proper facial wrap, 9) Proper folding angle
Test for temple fit (not too loose)
Forward Draw/Palpation test
Fitting triangle
(of pts of contact btwn eyewear and skull) - Crest of bridge, Skull at top of R ear/L ear»_space; Bal - Even weight distrib @ each of 3 pts
Frontal angle
(Bridge flair) - How nose angles out from midline (as seen from above)
Splay angle
(Transverse angle, larger for flatter bridge) - Btwn line through center of bridge and face of nosepad (as seen from the front)
Vertical angle
Angle away from vert, indicated by line down pad’s center (as seen from the side)
Eyewire screw vs. Temple screw
Threads all along shaft vs. Threads only at lower part of screw
More heat resistant –> Less heat resistant when doing frame adjustment
Nylon, Optyl = Propionate, Zyl
Lens glazing - Where
Process of inserting finished lens into frame (Gen in front - Easier to insert, Fall out from front, away from patient’s face, if dislodged w/ impact)
Salt pan - Adv and Disadv
(Adv) Less expensive, Easier to pile, Easily dissolved w/ H2O if trapped in eyewire groove, (Disadv) Sticks to frame, Req often replacement, Dirty/lumpy when wet, Heats slower
Glass beads - Adv and Disadv
(Adv) Not req often replacement, No clumping when wet, Heat quicker, (Disadv) More expensive, get stuck in eyewire groove
Where lens clock readings are the same
Entire principal meridian (w/ same surface P), Along any meridian // to meridian of interest
Sig of reticule location
At secondary focal pt of objective, primary focal pt of eyepiece»_space; Position doesn’t change regardless of what lens is against lens stop »_space; // light enters objective, // light emerges from eyepiece
Effect of adjusting eyepiece
// light no longer emerges from eyepiece, changing clarity of the target»_space; Small diff in P reading
Sig of lens stop location
At secondary focal pt of std lens»_space; Peq (btwn std and unknown lens) always = P std (regardless of unknown lens)»_space; Constant image size
Uses of lensometer
Duplication of Rx, Verification of Rx (to det accuracy of fabrication), Neutralization of Rx (to det Rx), Laying out a lens for edging, Conversion of several trial frame lenses to single lens equiv (in back vertex P)
% of frames in dispensary that are typically imported
90%
