Clinical Report: Impact of Light Obstruction on Illuminance in Flexible Ureteroscopes

Overview

This study evaluated the effects of partial light source obstruction on background illuminance in various flexible ureteroscopes submerged in saline. Using a 3D-printed obstructive kidney calyx model, the research quantified illuminance variability across different scopes and obstruction positions, highlighting differences in light intensity and potential clinical implications.

Background

Ureteroscopy is the most common intervention for renal stones in industrialized countries, with image quality heavily dependent on adequate illuminance. Light obstruction can occur due to poor light source design or anatomical factors such as the calyceal neck partially blocking light in difficult-to-reach calyces. Prior studies have not extensively explored the impact of such obstructions or the variability in illuminance intensity and skew on endoscopic visualization. This study aimed to investigate these effects using a controlled experimental setup.

Data Highlights

The study tested seven flexible ureteroscopes from different manufacturers using a 3D-printed pink kidney calyx model submerged in saline. Illuminance measurements were taken at four obstructive positions (12, 3, 6, and 9 o’clock) with repeated measures for each position. Light brightness settings of 50% and 100% were evaluated where adjustable. Statistical analysis included one-way ANOVA with Tukey post hoc comparisons to assess inter-scope differences and variability in background illuminance.

Key Findings

• Partial obstruction by the calyceal neck significantly reduced background illuminance in all tested ureteroscopes.
• Illuminance varied depending on the position of obstruction (12, 3, 6, and 9 o’clock), demonstrating directional variability in light delivery.
• Different ureteroscope models exhibited distinct overall background illuminance levels, indicating variability in light source design and efficiency.
• Adjusting light brightness settings influenced illuminance but did not fully compensate for the reduction caused by obstruction.
• The 3D-printed pink kidney calyx model effectively simulated clinical scenarios of light obstruction encountered during ureteroscopy.

Clinical Implications

Clinicians should be aware that partial obstruction of the ureteroscope light source by anatomical structures can significantly impair illumination and image quality during ureteroscopy. Selection of ureteroscopes with superior light delivery and consideration of light brightness settings may help mitigate visualization challenges. Understanding the directional variability of light obstruction can guide scope positioning to optimize endoscopic views in difficult calyceal anatomies.

Conclusion

Partial light obstruction by the collecting system reduces background illuminance in flexible ureteroscopes, with variability across scope models and obstruction positions. These findings underscore the importance of optimizing light source design and clinical technique to maintain adequate visualization during ureteroscopy.

References

1. 1 -- Ureteroscopy as the most frequent intervention for renal stones
2. 4 -- Factors influencing image quality in ureteroscopy
3. 5 -- Reports of undesirable shadowing from poor light source design
4. 13,14 -- Variability in illuminance intensity and skew in ureteroscopes
5. 15 -- Endocast data for kidney calyx dimensions
6. 16,17 -- Studies on laser lithotripsy using endocast models