How do you choose the right frame for high prescriptions?

For high prescriptions, select smaller frames with a Frame PD (A + DBL) close to the patient's PD. This minimizes decentration and reduces lens thickness and weight. Full-rim frames are preferred because they conceal thick lens edges. Higher-index lens materials further reduce thickness. Avoid large, oversized frames that create significant decentration.

What B dimension is needed for progressive lenses?

Most progressive lens designs require a minimum B dimension of 28 to 30 mm. Short-corridor designs may work in frames as small as 25-26 mm. The B dimension must be deep enough to accommodate the distance zone, progressive corridor, and near zone. Always check the specific progressive design's minimum fitting requirements before selecting the frame.

How do you match face shape to frame shape?

A general guideline is to choose frames that contrast with the face shape. Round faces benefit from angular or rectangular frames. Square faces are complemented by round or oval frames. Oval faces work well with most shapes. Heart-shaped faces look good with bottom-heavy frames. These are guidelines, and patient preference is the final deciding factor.

What is the most important measurement for frame selection?

Frame PD (A + DBL) compared to the patient's PD is the most important measurement for frame selection, especially for high prescriptions. A large difference between Frame PD and Patient PD creates significant decentration, producing thicker, heavier lenses. Minimizing this difference leads to thinner, lighter, more cosmetically appealing eyewear.

Frame Selection Principles: Matching Frames to Patient Needs and Prescriptions

Frame Selection Is More Than Aesthetics

Selecting the right frame involves balancing optical performance, comfort, durability, and aesthetics. A frame that looks great but does not accommodate the prescription or lifestyle needs will result in an unhappy patient. Effective frame selection requires the optician to consider multiple factors simultaneously.

Prescription Compatibility

The prescription is the primary technical constraint for frame selection:

High Minus Prescriptions

Choose smaller frames to minimize edge thickness
Full-rim frames hide thick edges better than rimless
A Frame PD close to Patient PD reduces decentration and keeps lenses thinner
Higher-index lens materials reduce thickness further

High Plus Prescriptions

Smaller frames reduce center thickness
Full-rim frames help contain the thick center
Avoid rimless frames where thick centers are fully visible

Progressive Lenses

B dimension of at least 28-30 mm to accommodate the progressive corridor
The fitting cross must be positioned at the pupil center, requiring adequate depth above and below this point

For high prescriptions, the relationship between Frame PD and Patient PD has the largest impact on lens thickness and weight. Always calculate the decentration before finalizing the frame choice. A large, wide frame on a patient with a narrow PD creates significant decentration and thick, heavy lenses.

Face Shape Considerations

A general guideline is to select frames that contrast with the face shape:

Face Shape	Complementary Frame Shapes
Round	Angular, rectangular frames add definition
Square	Round or oval frames soften angular features
Oval	Most frame shapes work; avoid extremes in width
Heart-shaped	Bottom-heavy frames balance a wider forehead
Oblong	Deeper frames with decorative temples add width

These are guidelines, not rules. Patient preference is ultimately the deciding factor for aesthetics.

Lifestyle Assessment

Understanding the patient's daily activities guides material and feature selection:

Active/athletic: Flexible materials (nylon, TR-90), spring hinges, wrap designs
Office/computer workers: Lightweight frames, sufficient B dimension for occupational progressives
Children: Impact-resistant materials, spring hinges, cable temples
Safety-required occupations: ANSI Z87.1 rated frames and lenses
Fashion-conscious: Designer frames, acetate with unique colors and patterns

Ask about the patient's daily activities before showing frames. A construction worker needs ANSI-rated safety eyewear, not designer acetate. A graphic designer who stares at a screen all day benefits from lightweight frames with a deep B dimension for comfortable progressive use. Matching the frame to the lifestyle prevents returns and builds trust.

Proper Fit Criteria

A well-selected frame should meet these criteria before ordering lenses:

Width: The frame should be approximately as wide as the patient's face at the temples
Bridge fit: The bridge should rest comfortably on the nose without sliding or pinching
Pupil position: The pupils should be centered horizontally and positioned in the upper half of the lens opening
Cheek clearance: The frame should not rest on the cheeks during normal expression
Temple length: The bend should fall at or just behind the top of the ear
Eyelash clearance: Lashes should not brush against the lens surface

Selecting frames based solely on appearance without checking the prescription compatibility. A patient may love a large, round frame, but if they have a -8.00 prescription with a 60 mm PD and the frame has a 72 mm Frame PD, the resulting lenses will be extremely thick and heavy. Always evaluate the optical implications before finalizing the selection.

Frame PD and Patient PD Relationship

The ideal frame selection minimizes the difference between Frame PD (A + DBL) and Patient PD. This minimizes decentration, which:

Reduces lens thickness and weight
Allows use of smaller (less expensive) blank sizes
Produces more cosmetically appealing lenses
Minimizes the chance of the optical center falling outside the lens area

Clinical Relevance

Frame selection is where the optician's technical knowledge and interpersonal skills converge. Guiding a patient toward a frame that is both flattering and optically appropriate demonstrates professional expertise. The best frame selection balances the patient's aesthetic preferences with the technical requirements of their prescription and lifestyle.

Key Takeaways

Prescription power is the primary technical constraint for frame selection
Frame PD close to Patient PD minimizes decentration, thickness, and weight
B dimension must be at least 28-30 mm for progressive lenses
Face shape guidelines suggest contrasting frame shapes for visual balance
Lifestyle assessment determines appropriate materials and features
Verify fit criteria (width, bridge, pupil position, temple length) before ordering