The Truth About Laser Fiber Diameters

doi:10.1016/j.urology.2014.08.017

Urology

Volume 84, Issue 6, December 2014, Pages 1301-1307

https://doi.org/10.1016/j.urology.2014.08.017 Get rights and content

Objective

To measure the various diameters of laser fibers from various manufacturers and compare them with the advertised diameter.

Methods

Fourteen different unused laser fibers from 6 leading manufacturers with advertised diameters of 200, 270, 272, 273, 365, and 400 μm were measured by light microscopy. The outer diameter (including the fiber coating, cladding, and core), cladding diameter (including the cladding and the fiber core), and core diameter were measured. Industry representatives of the manufacturers were interviewed about the diameter of their fibers.

Results

For all fibers, the outer and cladding diameters differed significantly from the advertised diameter (P <.00001). The outer diameter, which is of most practical relevance for urologists, exhibited a median increase of 87.3% (range, 50.7%-116.7%). The outer, cladding, and core diameters of fibers with equivalent advertised diameters differed by up to 180, 100, and 78 μm, respectively. Some 200-μm fibers had larger outer diameters than the 270- to 273-μm fibers. All packaging material and all laser fibers lacked clear and precise fiber diameter information labels. Of 12 representatives interviewed, 8, 3, and 1 considered the advertised diameter to be the outer, the cladding, and the core diameter, respectively. Representatives within the same company frequently gave different answers.

Conclusion

This study suggests that, at present, there is a lack of uniformity between laser fiber manufacturers, and most of the information conveyed to urologists regarding laser fiber diameter may be incorrect. Because fibers larger than the advertised laser fibers are known to influence key interventional parameters, this misinformation can have surgical repercussions.

Section snippets

Definitions

There are many terms in the literature for the laser fiber components, including “plastic coating,” “polymer jacket,” “buffer,” “cladding,” “primary and secondary cladding,” “fiber core,” “optical core,” “pure silica core,” “outside diameter,” “inner diameter,” “total diameter,” “core diameter,” and “true diameter.”6, 7, 8, 9, 10 Some of these terms refer to the same component or comprise several components, which lead to misinterpretations. To avoid such misunderstandings, the authors called

Results

For all fibers, the measured outer diameter differed significantly from the advertised diameter (all P <.00001). If the advertised diameter is deemed to be the outer diameter, none of the fibers had a measured diameter within the 10% tolerance range. The outer diameters of the fibers exceeded their advertised diameters by a median of 87.3% (range, 50.7%-116.7%). Four of the fibers (fiber numbers 1, 3, 7, and 13) were more than twice as large as advertised (Figure 1, Figure 3; Table 1). Three

Comment

The veracity of the advertised diameter of laser fibers used in medicine has not been investigated systematically. Although differences between the advertised and apparent diameters have been observed and reported 3 times, these observations were only mentioned in an incidental manner and their serious implications were overlooked.6, 7, 9 To our knowledge, only 1 study has focused partially on the discrepancy found between advertised diameter and real diameter.¹¹ The present study showed that

Conclusion

The present study showed that the advertised diameters of the laser fibers currently do not correspond to their outer diameters, which are the most practically relevant diameters for urologists. Moreover, fibers from different manufacturers that are labeled with the same diameter were found to differ significantly in terms of their outer diameters. The packaging and information labels of all of these fibers were observed to be imprecise as they lacked appropriate and clear diameter

Acknowledgments

The authors thank the Surgical Pathology Department of Hospital Professor Doutor Fernando Fonseca in Amadora, in particularly Dr. Rita Theias Manso for providing and helping out with the microscopic equipment.

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Citation Excerpt :
First, the laser energy can be transmitted through fibers as small as 50μ, thereby facilitating irrigant flow and deflection of the ureteroscope. At present the smallest fibers that are available for routine use with sTFL are 200 μm from tip to shaft; this is smaller than the smallest Ho:YAG laser fibers, which although only 272 μm at the tip, the attendant cladding results in upsizing the probe to as large as 445 μm.61,62 Second, sTFL for laser lithotripsy operates at 1940 nm, a wavelength that approximates water’s absorption peak; this results in more efficient energy transmission to the target and may aid fragmentation, given that there are commonly water interfaces within the stone itself.
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This raises questions about the reliability of the information being advertised. This issue was previously the subject of controversy in other series.22,23 Additionally the experiments in our study were done in ideal laboratory conditions.
We evaluated and compared a standard laser lithotripsy fiber to laser fibers claimed to have lithotripsy performance enhancing features.
A special AccuMax™ 200 polished tip fiber and an AccuTrac™ ball-shaped tip fiber, each with an approximately 240 μm core, were compared to a standard 272 μm core fiber (Rocamed™). The polished and ball-shaped tip fibers were used and reused without preparation. The standard fiber was stripped and cleaved according to manufacturer instructions after each experiment. An automated laser fragmentation testing system was used to perform multiple 30-second laser lithotripsy experiments. To mimic most typical lithotripsy conditions soft and hard stone materials were used with high frequency, low pulse energy (20 Hz and 0.5 J) or with low frequency, high pulse energy (5 Hz and 2.0 J) lithotripter settings. Ablation volumes and laser fiber tip photographs before and after lithotripsy were compared.
The standard and ball-shaped tip fibers did not differ in ablation volume (p = 0.72) but they ablated 174% and 188% more stone, respectively, than the polished tip fiber (p <0.0001). The ball-shaped tip showed remarkable fiber tip degradation after short-term use at low frequency, high pulse energy settings. When high pulse energy settings were applied first even for short-term use, the ablation volume achieved by the polished and ball-shaped tip fibers at high frequency, low pulse energy settings decreased more than 20%.
The standard laser fiber was as good as and sometimes better than the specially designed fibers. Rapid degradation of the specially designed laser fiber tips strongly limits their general usefulness but ball-shaped tip fibers may be useful in specific situations.
Comparison of Thulium Fiber Laser versus Holmium laser in ureteroscopic lithotripsy: a Meta-analysis and systematic review
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Thulium-Doped Fiber Laser and Its Application in Urinary Lithotripsy
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Computer Vision Enabled Segmentation of Kidney Stones During Ureteroscopy and Laser Lithotripsy
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: Financial Disclosure: Olivier Traxer is a medical consultant and advisor for American Medical Systems. Peter Kronenberg declares that he has no relevant financial interests.

View full text

Endourology and StonesThe Truth About Laser Fiber Diameters

Objective

Methods

Results

Conclusion

Section snippets

Definitions

Results

Comment

Conclusion

Acknowledgments

J Urol

Eur Urol

J Urol

New technologies for interventional radiology

Invest Radiol

A 10-year experience of managing ureteric calculi: changing trends towards endourological intervention—is there a role for open surgery?

BJU Int

IPG Photonics: Recent News

Learning in a science-driven market: the case of lasers

Ind Corporate Change

Laser light delivery systems for medical applications

Phys Med Biol

Evaluation of a new 240-μm single-use holmium:YAG optical fiber for flexible ureteroscopy

J Endourol

Ureteroscopy: Indications, Instrumentation & Technique

Encyclopedia of Laser Physics and Technology

FlexGuard: a new laser insertion sheath: functional aspects in ureterorenoscopy (URS)

World J Urol

Review of laser fibers: a practical guide for urologists

J Endourol

News from the International Bureau of Weights and Measures

Metrologia

Endourology and Stones
The Truth About Laser Fiber Diameters