Flip-Up vs. Through-the-Lens

(It's a Toss-Up!)

The decision to have adjustable (flip-up) telescopes versus fixed (through-the-lens) telescopes, is a crucial one. The factors affecting the decision, and the advantages and disadvantages of each type of surgical telescope are not as obvious as first meets the eye!

Flip-Up Through-the-Lens

Flip-up Advantages:

can be flipped up for unmagnified appraisals of field of view
can adjust declination angle for multiple users (of same telescope)
faster delivery / replacement than custom system

Flip-up Disadvantages:

increases likelihood of contamination (during adjustment), even with flip-tabs
usually associated with larger scotoma (due to suspension mechanism)
heavier and bulkier than fixed systems
higher likelihood of distortion for astigmatic user with >+2.0 correction and larger declination angle

Through-the-Lens (Fixed System) Advantages:

always in the correct position for viewing the surgical field (if properly customized to working distance and declination angle)
low maintenance (no flip-up mechanism to require attention)
most designs accommodate users with greater declination angle requirements
lightweight to wear

Through-the-Lens (Fixed System) Disadvantages:

not adjustable for extraordinary surgical procedures (thereby demanding postural compromise for those situations)
change of prescription currently requires return shipment to the manufacturer

Many clinicians choose to have both types of telescopes available to them. The adjustable system is ready to accommodate exceptional situations while the lightweight fixed system is used for most general surgical applications.

This also gives them a back-up magnification system for times when one system is being repaired, prescriptions are being changed, or they have been misplaced.

Use of surgical magnification is a dependency built on excellence, but it is nonetheless a dependency. It's always best to be ready for breakdowns in equipment!

Remember: The choice of flip-up vs. fixed (through-the-lens) telescopes depends upon many individual preference factors. Unnecessary adjustability in surgical settings are more often a curse than a boon!

If you have comments or suggestions,

lrucker@interchange.ubc.ca

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