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newSchoolWorks.com › VoTechWorks › Health & Personal Services › Optician / Optical Technician › Capstone Project: Integrated Optical Dispensing Case › Lesson 2
HLT-OPTI68-08 · Lesson 2 · 54 clock hours · lab

Frame Selection, Measurement, and Pre-Edging Preparation

Objective. Using the approved case plan, the student will select and adjust a demonstration frame appropriate to the patient's prescription and facial measurements, take all required fitting measurements, trace the frame, and produce a fully completed job ticket ready for edging.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Frame Selection, Measurement, and Pre-Edging Preparation

This lab brings together every skill you have practiced so far. You will choose a real frame, adjust it properly, record every measurement on a job ticket, and hand that ticket to an instructor who will verify it is ready for the edger. A mistake on the job ticket—especially a wrong prescription entry—means a lens gets cut to the wrong power. That costs materials, wastes time, and, most importantly, can harm a patient's vision. Accuracy is the professional standard; it is also the ABO exam standard.

Choosing the Right Frame

Begin with your case plan. It tells you the simulated patient's binocular PD, monocular PDs, vertex distance needs, and facial measurements. Use those numbers to narrow your frame choices.

Eye size and DBL check. The frame's eye size (the horizontal width of one lens aperture, measured in millimeters) plus the DBL (distance between lenses, also in millimeters) must be reasonably close to the patient's binocular PD. If that sum is much larger than the PD, you will have to decenter the blank a large amount to place the optical center over the pupil. Excessive decentration wastes blank size and can create unwanted prism. A practical rule: the sum of eye size plus DBL should ideally be within about 2–4 mm of the patient's binocular PD, though some variation is acceptable depending on lens design.

Material and style match. Your case plan specifies frame material (e.g., zyl/acetate, metal, titanium) and style parameters. Pick from the dispensing board only frames that meet those specifications. Record the manufacturer's size stamp—for example, 52□18-140—which gives you eye size (52), DBL (18), and temple length (140).

A, B, and ED dimensions. In addition to the stamp, measure and record:

All four values go on the job ticket because the edger or lab uses them to confirm blank selection.

Pre-Fitting Frame Adjustments

Never trace or ticket a frame that has not been adjusted to the fitting position. Adjusting first ensures the traced shape reflects how the lenses will actually sit in front of the patient's eyes.

Nose pad adjustment (metal frames). Use pad-arm pliers to set the nose pads so they sit level, with even contact on both sides. Uneven nose pads cause the frame to tilt, shifting the optical centers off-pupil.

Saddle bridge (zyl frames). Warm the frame in the frame warmer—follow the manufacturer's recommended temperature range and never overheat, because excessive heat can warp or crack the material. Once pliable, gently adjust the bridge curve to match the simulated fitting measurements.

Pantoscopic tilt. The standard fitting tilt for most eyewear is approximately 8–12 degrees, meaning the bottom rim is closer to the cheek than the top rim. This tilt keeps the optical axis perpendicular to the line of sight during normal reading posture. Set this angle using your protractor gauge or by eye, then confirm with the mannequin head form.

Face-form (wrap). The frame's front should follow the slight curve of the face. Too flat and the temporal edge gaps away; too curved and the nasal edge presses the nose. Adjust wrap in small increments with the frame warmer and gentle hand pressure.

Document with a photograph. Once adjusted, seat the frame on the mannequin head form and take a photograph from the front and from the side. Print and file it in the case folder. This photo is your evidence that the frame was properly adjusted before edging.

Tracing the Frame

With the frame properly adjusted, trace both lens apertures on the manual or digital tracer. On a manual tracer, run the stylus smoothly around the inside of the groove; on a digital tracer, follow the equipment's start procedure exactly. Save or print the trace data immediately. On a digital system, the trace file transfers directly to the edger software; on a manual system, you will cut a pattern or enter measurements by hand.

Verify that the traced shape looks symmetric and complete—a jagged or incomplete trace means the stylus lifted during tracing. Retrace if needed. A bad trace produces a badly edged lens.

Completing the Job Ticket

The job ticket is a legal-quality work order. Every field must be filled in with no blank spaces and no corrections that are not initialed. Required fields include:

Double-check the Rx transfer by reading the prescription source, then reading the job ticket entry, then returning to the source a second time. This two-pass verification is industry standard.

Safety and Scope Notes

Never begin edging without the instructor's signature on the 'approved for edging' line. The approval step exists so a trained professional confirms the job ticket is correct before an irreversible manufacturing process begins. In a licensed dispensing practice, the supervising optician or licensed practitioner signs off similarly. Respecting this chain of approval is a core professional habit, not just a classroom rule.

Key terms10

Eye sizeThe horizontal width of one lens aperture of a frame, in millimeters; one of the numbers in the manufacturer's size stamp.
DBL (distance between lenses)The distance in millimeters between the two lens apertures at their closest point; the bridge width shown in the manufacturer's size stamp.
A dimensionThe horizontal measurement of the lens aperture from nasal to temporal edge; equivalent to eye size.
B dimensionThe vertical measurement of the lens aperture from top to bottom at its widest vertical point.
ED (effective diameter)The diameter of the smallest circle that completely encloses the lens shape when measured from the geometric center; used to determine minimum lens blank size.
Pantoscopic tiltThe forward angle of the frame front so that the bottom rim is closer to the cheek than the top rim; typically set to approximately 8–12 degrees for standard dispensing.
Face-form (wrap)The horizontal curve of the frame front that follows the contour of the wearer's face from temple to temple.
DecentrationThe horizontal distance the optical center of a lens must be shifted from the geometric center of the frame aperture to align with the patient's pupil.
Job ticketThe complete written work order accompanying a lens job from dispensing through edging; contains prescription, frame data, lens specifications, and all processing instructions.
Frame tracerA manual or digital device that measures the exact shape of a frame's lens aperture groove to guide the edger in cutting the lens to the correct outline.

Worked examples4

1. A patient has a binocular PD of 62 mm. A frame on the board is stamped 54□18-140. Is the decentration per eye within a reasonable range, and what is the decentration amount?
  1. Step 1 – Find the frame's PD equivalent: eye size + DBL = 54 + 18 = 72 mm.
  2. Step 2 – Find the difference between the frame PD equivalent and the patient's binocular PD: 72 − 62 = 10 mm total.
  3. Step 3 – Decentration per eye = total difference ÷ 2 = 10 ÷ 2 = 5 mm inward (nasal) decentration per eye.
  4. Step 4 – Evaluate: 5 mm of decentration per eye is on the high end and may require a large blank; confirm the blank's ED can accommodate this decentration plus the lens radius.
Answer: The frame's PD equivalent (72 mm) exceeds the patient's PD (62 mm) by 10 mm, requiring 5 mm of inward decentration per eye. Consider a frame with a smaller eye size or larger DBL closer to 62 mm to reduce decentration.
2. You measure a frame and find: A = 50 mm, B = 38 mm. Calculate the geometric center distance (GCD) for one eye and determine the minimum ED needed if the patient's monocular PD is 31 mm (this is a right-eye calculation).
  1. Step 1 – Geometric center distance (GCD) for the right eye from the frame's center: GCD = (eye size + DBL) ÷ 2. With eye size 50 and DBL 16 (given for this example): GCD = (50 + 16) ÷ 2 = 33 mm.
  2. Step 2 – Decentration = GCD − monocular PD = 33 − 31 = 2 mm inward.
  3. Step 3 – Estimate ED needed: ED ≥ 2 × (decentration + longest radius of the lens shape). The longest radius from the geometric center ≈ ED/2. A common rule: minimum blank diameter = ED + 2 × decentration = effective diameter of frame + (2 × 2) = ED + 4. If the frame's ED is 55 mm, minimum blank = 55 + 4 = 59 mm.
  4. Step 4 – Record minimum blank size of 59 mm on the job ticket under 'special instructions' or lens selection notes.
Answer: Decentration is 2 mm; minimum blank diameter needed is the frame ED plus 4 mm (i.e., 59 mm for a 55 mm ED frame).
3. A student transfers the following Rx to the job ticket. Source prescription reads: OD –2.25 –0.75 × 180, OS –1.50 –1.00 × 005. The student writes: OD –2.25 –0.75 × 180, OS –1.50 –1.00 × 050. Identify the error and state the consequence if edged.
  1. Step 1 – Compare each field of the OS entry: sphere –1.50 ✓, cylinder –1.00 ✓, axis source = 005, ticket = 050.
  2. Step 2 – The axis was transcribed as 050 instead of 005—a 45-degree axis error.
  3. Step 3 – Consequence: the cylindrical correction will be oriented 45 degrees away from the correct meridian, producing a lens that does not correct the patient's astigmatism and may cause blurred or distorted vision, eyestrain, and headaches.
  4. Step 4 – Under the program's policy, any Rx transfer error is an automatic redo: the job ticket must be voided, a new ticket written, and the error documented.
Answer: The OS axis is wrong (050 vs. 005). This is an automatic redo. A 45-degree axis error produces significant uncorrected astigmatism and is a patient safety issue.
4. A frame is stamped 48□20-145. A patient's binocular PD is 64 mm. Calculate the frame's PD equivalent and the decentration per eye.
  1. Step 1 – Frame PD equivalent = eye size + DBL = 48 + 20 = 68 mm.
  2. Step 2 – Difference = 68 − 64 = 4 mm total.
  3. Step 3 – Decentration per eye = 4 ÷ 2 = 2 mm inward per eye.
  4. Step 4 – 2 mm decentration per eye is well within standard limits; this frame is a good size match for this patient.
Answer: Frame PD equivalent is 68 mm; decentration is 2 mm per eye inward, which is acceptable.

The math in this lesson1

Learners compute frame PD 54 + 18 = 72 mm and 5 mm decentration per eye from a 62 mm PD.
7.EE.3
In class: Students select a frame from the program's dispensing frame board that matches the parameters specified in their case plan (material, eye size, bridge size, temple length appropriate to simulated facial measurements); they record all frame measurements—eye size, DBL, temple length, and A, B, and ED dimensions—on the job ticket and verify that the frame eye size plus DBL is consistent with the patient's binocular PD to avoid excessive decentration, referencing the ABO Study Guide fitting chapter. · Students perform a full pre-fitting adjustment sequence on the chosen frame using the program's hand tools and frame warmer: adjust nose pads or saddle bridge for level fit, set pantoscopic tilt to approximately 8–12 degrees, and set face-form wrap, then photograph the adjusted frame against a mannequin head form; the photograph is printed and included in the case file as documentation—maps to ABO exam domain: Frames and Frame Adjustments. · Students trace the adjusted frame on the manual tracer, enter trace data into the edger software (or mark a manual pattern), and complete every field of the job ticket including patient name (simulated), Rx, lens material, lens design, coating order, seg height or fitting cross height, and special instructions; the instructor checks the job ticket against the original case plan for internal consistency before signing the 'approved for edging' line.
Materials: Program dispensing frame board (minimum 40 frames, assorted materials and styles), frame measurement gauge, PD ruler, millimeter rule, manual frame tracer or digital tracer connected to edger, edger job-ticket forms (program standard), hand tools (pliers set, frame warmer, screwdrivers), mannequin head forms, camera or phone for documentation photos
Check: Instructor checks job ticket for completeness and accuracy against the case plan using a 15-point checklist; pass standard is 13 of 15 items correct (87%) and zero errors in Rx transfer from prescription to job ticket; incorrect Rx transfer is an automatic redo.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

ABO – Frames and Frame Adjustments
1. A frame is stamped 52□18-140. What is the frame's PD equivalent (eye size + DBL)?
ABO – Ophthalmic Optics and Lens Application
2. A patient's binocular PD is 60 mm and the chosen frame has an eye size of 54 and a DBL of 16. What is the decentration per eye required?
ABO – Frames and Frame Adjustments
3. Which measurement represents the vertical height of the lens aperture from top to bottom at its widest point?
ABO – Frames and Frame Adjustments
4. The standard range for pantoscopic tilt in everyday eyewear dispensing is approximately:
ABO – Frames and Frame Adjustments
5. Before tracing an adjusted frame, why is it essential that all fitting adjustments be completed first?
ABO – Ophthalmic Optics and Lens Application
6. A student copies the axis from the prescription as 175 but the written Rx clearly states 015. What is the correct program response?
ABO – Ophthalmic Optics and Lens Application
7. Which of the following job ticket fields is MOST directly used by the edger operator to confirm that the lens blank is large enough to fill the frame after decentration?
ABO – Frames and Frame Adjustments
8. A student skips photographing the adjusted frame on the mannequin head form. What is the primary professional reason this step must not be omitted?
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